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- Creator:
- Hernandez, Trang Manny
- Description:
- There is a possibility to eradicate infectious diseases with antibiotics. However, new infectious diseases are continually being identified and some known pathogens are again becoming a threat because of antibiotic resistance. Amphibians mostly live in a moist environment which is the best condition for the growth of bacteria and fungi as well. Antimicrobial peptides produced by serous glands in the amphibian skin play a key role in limiting microbial growth and preventing infections with pathogenic microorganisms. In addition to the antimicrobial peptides produced by serous glands, microbial symbionts on the bullfrog skin are also a source of antimicrobial peptides that can protect the amphibian against diseases. In this research, we investigated whether cutaneous bacterial species isolated from Rana catesbeiana (North American Bullfrog), an amphibian species that is resistant to chytridiomycosis, produce secondary metabolites that could be used to inhibit the growth of three species of dermatophytes (Microsporum gypseum, Epidermotphyton floccosum, Trichophyton mentagrophytes) which are known to cause skin infections in humans. The isolated bacterial species from R. catesbeiana may be useful as producers of antifungal metabolites that kill, or inhibit the growth of, dermatophytes known to cause topical or subdermal skin infections in humans.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Lewis, Ryan D.
- Description:
- Purpose of the Study: The endangered Sonoma County population of the California tiger salamander, Ambystoma californiense, undergoes migrations between breeding pools and upland dry-season refugia. Orientation in this species during breeding migrations has been addressed minimally in previous studies, and literature is particularly sparse concerning newly metamorphosed juveniles. Previous works have not addressed the ability of metamorphs to orient or the way in which they search for upland refugia. The purpose of this study is to evaluate if California tiger salamander metamorphs can re-orient during initial migration and if search movements constitute a Correlated Random Walk. Procedure: We evaluated fine scale movements of newly metamorphosed California tiger salamanders as they moved away from breeding pools, by capturing salamanders with a drift fence. Metamorphs received different orientation treatments, and subsequent movement was tracked with fluorescent powder. We measured turning angles and step lengths at each segment of the tracks, and compared the effect of different treatments. Findings: Here we show that newly metamorphosed juveniles can re-orient to their upland migration path after being interrupted and disoriented. Further, we demonstrate that while searching for burrow refugia, metamorph movement is a correlated random walk. Conclusions: The initial migration from natal pools to uplands following metamorphosis has been identified as a crucial life history juncture for the persistence of this species. Our findings show that these migrations are directed by some orientation, and that these movements are not random. The presence of a Correlated Random Walk is consistent with search patterns in many vertebrates.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Sonoma
- Department:
- Biology
- Creator:
- Grimes, Adam John
- Description:
- The blunt-nosed leopard lizard (Gambelia sila) is a federally and state-listed endangered species, endemic to the San Joaquin Valley, Carrizo and Elkhorn Plains, and Cuyama Valley of central California. Habitat degradation has had a profound impact on the historic distribution and population size of G. sila. Although recognition of G. sila as a distinct species has been questioned by some authors (e.g., Cope 1900, Smith 1946), it is currently recognized as a full species separate from the wide-ranging long-nosed leopard lizard (G. wislizenii); however, genetic support for the specific status of G. sila is lacking. Furthermore, the genetic identity of leopard lizards in the purported hybrid zone between these two species in the Cuyama Valley in Santa Barbara and Ventura counties has not been evaluated using modern molecular techniques. Understanding the genetic identity of leopard lizards in the Cuyama Valley has practical as well as systematic implications. I investigated the sister taxon relationship of G. sila and G. wislizenii using 603 base pairs of sequence from the mitochondrial cytochrome oxidase III (CO3) gene from 37 individuals representing the two species sampled from various populations in western North America. Phylogenetic analysis revealed 17 haplotypes that are partitioned into two major clades that correspond to the range of G. sila and that of G. wislizenii haplotype groups, thus supporting the recognition of both lizards as distinct species. Additionally, I sequenced 682 base pairs of the mitochondrial cytochrome oxidase b (cyt b) gene from 34 individuals representing six populations of G. sila, including lizards from a remnant hybrid population. Phylogenetic analysis indicated that the cyt b sequences consisted of 18 haplotypes that are partitioned into three geographic clades: northern, central, and southern. All lizards from the Cuyama Valley exhibited the G. sila mitochondrial DNA signature and formed the "southern" clade that was joined as a sister group to the "central" clade. My morphological analysis placed some leopard lizards from the hybrid zone with true G. sila, whereas some aggregated with G. wislizenii, indicative of hybrid status. However, genetic signatures suggest that all lizards in the hybrid zone are true G. sila, and not hybrids.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Tennant, Erin Nicole
- Description:
- The Tipton kangaroo rat (Dipodomys nitratoides nitratoides), is an endangered subspecies of the San Joaquin Valley kangaroo rat, found in the Tulare basin of the San Joaquin Valley. Dipodomys n. nitratoides and the larger Heermann’s kangaroo rat (Dipodomys heermanni) are often found sympatrically throughout the San Joaquin Valley. However, potential competitive interactions and the nature of population fluctuations between these two species are largely unknown. Because I thought that D. heermanni could be negatively affecting a translocated population D. n. nitratoides on Allensworth Ecological Reserve, Tulare County, California, I initiated a study on potential competitive interactions between these two species. In this study my objectives were to (1) determine whether the presence of D. heermanni affects space use and foraging behavior of D. n. nitratoides and (2) compare D. n. nitratoides abundance and population trends between areas with and without D. heermanni. I found that in an exclusion area where D. heermanni were removed, D. n. nitratoides increased exponentially since the start the study, whereas on a control site with both species, D. n. nitratoides decreased significantly. My results suggest that D. heermanni are competitively depressing a population of translocated D. n. nitratoides on the study site. Furthermore, eliminating competitive effects of larger, coexisting species during reintroduction or translocation efforts for D. n. nitratoides may be an important factor in success. To further test optimal translocation and reintroduction methods for protected kangaroo rats in the San Joaquin Valley, possibly an important conservation strategy, I translocated the group of non-protected D. heermanni that was removed from the exclusion area during the competitive interactions part of my study. During this part of my research, my objective was to determine whether soft-release methods, which involve a 30-day acclimation period in a wire mesh cage, help to improve survivorship of translocated kangaroo rats. My results indicated that hard-released individuals had higher survivorship than soft and semi soft- released individuals. I believe that one of the factors that may have contributed to the success of hard-released individuals was the high number of available burrows on the translocation site, often not found at sites, which provided refugia for translocated individuals. ii
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Keldgord, Heather Elayne
- Description:
- Rhus ovata is an evergreen shrub species that is common to low elevations in southern California. This species is subdioecious, i.e. some individuals are functionally females and produce fruit while others are functionally male and produce flowers with pollen. I hypothesized that because female plants allocate greater resources to reproduction through the formation of both flowers and fruit, female plants have fewer resources available for vegetative growth, survival, and defense. Therefore, I predicted that female plants would be smaller and less competitive. I sampled Rhus ovata populations at six sites across a rainfall gradient (221mm/yr to 701 mm/yr) and predicted that populations would be male dominated at drier sites because of their greater stress tolerance. At each site I measured the ratio of male to female plants within the sampled population. For a subset of individuals at each site, I measured crown size, stem tissue density, specific leaf area, reproductive investment, and distance to the nearest neighbor. As expected, female plants had greater total reproductive investment although the amount of investment was highly variable and females exhibited more variability than males. However, this differential reproductive investment did not lead to sexual size dimorphism. Ratios of functional male plants to functionally female plants differed among sites, but these differences were not correlated with rainfall and across sites the ratio of males to females did not significantly differ from a one to one. Plasticity in allocation to reproduction among females in this long-lived woody species may mitigate reproductive costs and reduce sexual dimorphism.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Atwood, Robert Christopher
- Description:
- Opuntia basilaris Engelm. & Bigelow var. treleasei (J.M. Coult.) Toumey (OBT), commonly known as Bakersfield cactus, is endemic to parts of Kern County, California. O. b. var. treleasei is one of four varieties of Opuntia basilaris and is state and federally listed as endangered (USFWS 1990). The purpose of this study was to assess the genetic differentiation between OBT and Opuntia basilaris var. basilaris (OBB), and within and among populations of OBT throughout its range. Samples were collected from 200 individual plants representing 32 populations of OBT and one population of OBB and were analyzed using amplified fragment length polymorphisms (AFLP). The AFLP protocol was successfully used to differentiate between an outgroup population of OBB and the great majority of the sampled populations of OBT using 195 polymorphic fragments. Two dendrograms were created using unweighted pair group method with arithmetic mean (UPGMA); one for all individuals and the other where each population was treated as a discreet unit. In the dendrogram based on all individuals, most samples did not cluster as distinct geographic populations, suggesting little genetic differentiation, due to a partial or complete restriction of gene flow, among the majority of OBT populations. Extensive genetic variation was found within and among OBT populations based on an analysis of molecular variance (AMOVA). Twenty three percent of the genetic differentiation was found among fragmented populations and 77%from within individuals of OBT populations suggesting that genetic variation exists between individuals within the OBT populations analyzed. In the UPGMA diagram by population, all five of the Wheeler Ridge populations clustered together. Moreover, three of the Wheeler Ridge populations formed a distinct cluster in a principal coordinates analysis (PCoA) suggesting some level of genetic structure among OBT populations. The only population with a large sample size where virtually all representative samples grouped together was for ‘OEO2’, which is located in the eastern portion of the Southern San Joaquin Valley. The results of this population genetics study will likely be useful in the conservation management of this endangered taxon.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Castaneda, Alejandro Realivazquez
- Description:
- The purpose of this study is to investigate the level of genetic divergence among populations of Vaejovis confusus in the southern San Joaquin Valley and across the state of California. Although there has been considerable research to measure genetic variation among and within scorpion species, little work has been done to investigate the impact of anthropogenic factors on genetic variation within populations. Anthropogenic factors such as man-made barriers can fragment populations and may serve as mechanisms of reproductive isolation. Particularly in the southern San Joaquin Valley, vast arrays of canals and artificial channels have been constructed to divert water from the Kern River for agricultural purposes. In the southern San Joaquin study, the level of genetic divergence is examined in a fragmented population as a result of an anthropogenic barrier, the California Aqueduct, at Coles Levee Ecosystem Preserve. Sequencing of the mitochondrial 16S ribosomal RNA gene in 20 Vaejovis confusus individuals of each fragmented population was performed. Neighbor-joining and maximum parsimony analysis of DNA sequences elucidated the level of genetic divergence. For comparison, an identical analysis was performed across a natural barrier, the Kern River at the Panorama Vista Preserve, which has separated Vaejovis confusus populations for a much longer period of time. The results of this study showed the presence of five haplotypes at the Coles Levee Ecosystem Preserve, with three haplotypes common to both sides of the California Aqueduct. Similarly at Panorama Vista Preserve, five haplotypes were found, with two haplotypes shared at both field sites across the Kern River. These results indicate that scorpion populations across the California Aqueduct and Kern River are not genetically partitioned, despite the isolating effect of these barriers. The existence of the California Aqueduct for over 50 years is not enough time to cause genetic divergence among fragmented populations. The occasional drying of the Kern River may promote gene flow between the populations or amount of time after reproductive isolation may be insufficient to cause evolutionary divergence between the two populations. In the California analysis the mitochondrial 16S rRNA gene is examined in 22 individuals from 9 counties to determine the effects of isolation by distance on the geographic-genetic structure of Vaejovis confusus populations. Scorpions were obtained from a collection of samples from the California Academy of Sciences, San Francisco. Neighbor-joining and maximum parsimony analyses were used to resolve the level of evolutionary relatedness among the populations of Vaejovis confusus throughout California. Fourteen haplotypes were found in this analysis. Eleven haplotypes were unique to their field site, whereas three were common across the state across large geographic distances (approximately 350 miles). Mitochondrial markers found high genetic variation (9.6%) in this species. Nearly half (154/325) of pairwise distance comparisons showed a 2.0% or higher sequence divergence and supported an overall isolation by distance effect. The occurrence of three haplotypes across the state results in a weak association between geography and genetic structure of V. confusus. Notably however, there is some geographic partitioning between haplotype D common in western California and haplotypes A and C common in eastern California. However, the overall lack of genetic partitioning with respect to geography among the California populations is likely due to an insufficient amount of elapsed time to promote genetic differentiation.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Hayes, Christine C.
- Description:
- The phorid fly genus Apocephalus is the largest assemblage of ant-parasitizing Phoridae. Apocephalus is currently organized into two subgenera: A. (Apocephalus) and A. (Mesophora). The species of A. (Mesophora) attack a wide variety of non-ant hosts including stingless bees, spiders, wasps, bumble bees, and cantharoid beetles. The species of A. (Apocephalus) are the true “ant-decapitating flies” and are divided into six species groups: the A. attophilus group (parasitoids of attine leaf-cutting ants), “A. miricauda group” (parasitoids of ponerine ants), A. pergandei group (parasitoids of Camponotus carpenter ants), A. mucronatus group, A. feeneri group, and A. grandipalpus group. Here I report on a preliminary molecular phylogenetic study of Apocephalus, including representatives of both subgenera and exemplars of five currently recognized species groups. Maximum parsimony, maximum likelihood, and Bayesian phylogenies were inferred using four nuclear (AK, TPI, CAD, 28S) and four mitochondrial (12S, 16S, COI, ND1) gene fragments (4284 bp total). For all analyses Apocephalus was recovered as a monophyletic group relative to the outgroup taxa included in the study. In addition, subgenus A. (Mesophora) was recovered as a monophyletic group, but was not a sister group to the subgenus A. (Apocephalus).A phylogenetic hypothesis for exemplars of five Apocephalus species groups is presented and compared to hypotheses based on morphology.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Duquette, Marc Roland
- Description:
- With over 1,300 known species, the genus Megaselia Rondani is the largest phorid genus, largely the result of high cryptic diversity and a past tendency for researchers to lump species into the genus that defied convenient classification. For many of these species, little information is available beyond one or two morphological characters. The first molecular study of such a species, Megaselia sulphurizona Borgmeier, is presented here. New sequence data from two mitochondrial loci (cytochrome oxidase, COI; NADH 1 dehydrogenase, ND1) for a total of 792 bp were obtained from 22 M. sulphurizona specimens collected from four populations in California, plus 12 other phorid taxa using standard DNA extraction and PCR techniques. Neighbor-joining, maximum likelihood, and maximum parsimony analyses revealed M. sulphurizona to be a cryptic species complex, constituting three distinct species in the Riverside, Monrovia, and Bakersfield/Tehachapi areas. These findings suggest greater cryptic diversity within M. sulphurizona, and have broader implications for phorid biodiversity.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Blackhawk, Nicole Cherri
- Description:
- The Giant Kangaroo Rat (Dipodomys ingens) is a federally and state-listed endangered species, endemic to the San Joaquin Valley, Carrizo and Elkhorn Plains, and the Cuyama Valley. Populations of the endangered Giant Kangaroo Rat (Dipodomys ingens) have decreased over the past 100 years because of habitat fragmentation and isolation. Changes in the population structure that can occur due to habitat fragmentation can significantly affect the population size and the dispersal of these animals. Dr. David Germano and I collected small ear clippings from male and female Giant Kangaroo Rats from six sites along the southern San Joaquin Valley to determine the genetic population structure of this species in this part of their range. We predicted that geographic distance and isolation of populations would decrease genetic relatedness compared to populations closer together. Having a better understanding of the genetic structure in this species will help with conservation actions, such as translocating individuals within the range of the species. These data were compared to published estimates of genetic diversity of Giant Kangaroo Rats in the Carrizo Plain to the west and the Panoche area to the north, the other large population centers of this species.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- MacKinnon, Evan D.
- Description:
- Non-native grass invasion is a major concern for land management and native plant conservation. In the southern San Joaquin Valley of California, human-disturbed environments that are heavily invaded by non-native grasses often contain some native annual species. These “weedy” native species apparently have the functional traits and life history characteristics to compete and persist in disturbed and invaded landscapes. We categorized several native plants into either a weedy or non-weedy habit based on several criteria, and confirmed this habit designation using a field trial where we controlled for other factors likely to influence species abundance under field conditions. We then measured functional traits for a group of five non-weedy species that occur locally but are not abundant in invaded areas, to a group of four weedy plant species that included the invasive grass red brome. We hypothesized that a suite of functional traits would define the weedy plant habit. We examined this hypothesis in a specific community, where we compared functional traits between weedy and non-weedy plant habits, and between native species and red brome. A principal components analysis (PCA) identified three distinct ecological clusters among the analyzed species (weedy native forbs, non-weedy native forbs, and grasses), and suggested the presence of a weedy functional type. Weedy species were different from non-weedy species in several traits (larger leaf area investment, larger root biomass allocation, heavier diaspores, and dormant seeds requiring cold-stratification for germination). The PCA suggested complementarity as an explanation for the co-occurrence of weedy native species and red brome, but individual trait similarities and a competition experiment suggested that competition can occur for some resources. Further understanding of the traits shared among weedy native plant species may lead to cost-effective approaches to restoring invaded landscapes.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Turnbull II, John
- Description:
- Examination of fish skeletal remains from archaeological sites serves both archaeological and biological interests. For archaeologists, it can establish the role of fish consumption in a people’s diet, provide clues to their fishing technology and overall maritime capability, and even suggest movement patterns and settlement (Rick et al. 2001, Erlandson et al. 2008, Des Lauriers 2010). Analysis of fish bones from excavations on San Miguel Island, of the southern California coast, suggested use of boats and early evidence of hook-and-line fishing techniques, concurrent with an estimate that fish comprised over 50% of the edible meat for the early islanders (Rick et al. 2001). Fishbone identifications have contributed to determining where early Paleocoastal peoples settled, to indicating occupation in some areas earlier than previously thought, and to suggesting that at least some southward Pacific coastal migration in North American may have been by sea (Erlandson et al. 2008). For ichthyologists, identifications of fish remains provide a historical or prehistorical survey of fishes in an area, and with comparison to modern surveys of those same areas, provide bases for examining fish distribution, fish diversity, and marine habitats over time (Gobalet 2000, Salls 2000, Erlandson et al. 2008). In supporting Point Conception, California, as a landmark for a marine faunal break, Gobalet (2000) compared the distribution of fishes identified from the archaeological record to their current distributions. Salls (2000) used bone identifications from archaeological sites on Southern California’s San Clemente Island to describe probable offshore habitats for as early as 9,000 calendar years before the present (cal BP). For over a decade, archaeological excavations on Cedros Island, which lies off the Pacific coast of the Baja California peninsula, have unearthed evidence of early colonization in the Cedros area, with implications for Paleo-human migrations (Des Lauriers 2010). Unfortunately, no on-site scientific survey of the fishes or marine habitats at Cedros Island has been published against which to compare fishbone analysis, but modern surveys of the waters close to Cedros Island exist and can be useful. Regarding habitats, Quast (1968), Engle (1993), and Bond et al. (1999) represent influential earlier studies that established the use of fish species associated with specific habitats. More recent marine faunal surveys that included the Cedros marine environment (but not specifically Cedros Island) also describe fish assemblages associated with habitats. Stephens et al. (2006) examined such associations for the rocky reef/kelp bed habitats of the southern San Diego Province, as did Pondella II et al. (2005) for the San Benito islands that lie close to Cedros. Allen and Pondella II (2006) provided a comprehensive ecological review of the California coast south to central Baja and identified fish species associations with a wide range of habitats. In this thesis, I report the identifications of fish bones from archaeological excavation sites on Cedros Island. The archaeological investigation indicates the settlement of the area about 12,000 cal BP and the establishment of a society that existed into the 18th century of our current era (CE; Des Lauriers 2005, 2008, 2010). These identifications then are provided to assist this investigation on Cedros in its efforts to better understand the Cedros islanders and to lend some insight as to the types of fishes they harvested and the predominant habitats those fishes represented.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Madsen, Angela
- Description:
- Ecological interactions can vary in strength depending on environmental conditions. The outcomes of these interactions are often dependent on the abiotic environment, but can also depend on the presence of other biotic species, including mutualists, which can further alter these effects due to trade-offs in nutrient allocation for multiple interactions. For example, some plants produce extrafloral nectar, a specialized nectar used to attract ants that will defend the plant against herbivory. If plants with extrafloral nectaries also have a second mutualistic relationship with the soil bacteria rhizobia, this second mutualism has been shown to alter the attraction of ants to the extrafloral nectar of the plant. This change in ant attraction could be caused by changes in nectar production or nectar composition, although the exact reason is unknown. Plants do alter extrafloral nectar production and composition for other reasons, for example if a plant is experiencing herbivory the plant will increase the quantity of the extrafloral nectar which will attract more ants. What is not well understood is what specific changes to the nectar, if any, cause it to become more attractive or if the attraction is simply due to a higher quantity of the extrafloral nectar. In my thesis research I explored how the chemical composition of extrafloral nectar, specifically nectar quantity and sugar, is affected by rhizobia mutualists, soil nutrients, and herbivory. Moreover, I explored how these changes influence the ant community and herbivorous arthropod community, as well as plant traits and overall fitness of the Vicia faba plant and its associated mutualistic rhizobia. I tested the effects of these factors through a series of greenhouse and field experiments, running the extrafloral nectar through a total carbohydrate assay to quantify carbohydrate (i.e. sugar) content. I found that under most conditions, the composition of the extrafloral nectar remained constant. However, when plants associated with the soil bacteria rhizobia, the rhizobia mutualism caused a decrease in sugar content in extrafloral nectar but increased the overall quantity of extrafloral nectar produced when outside of herbivory pressure. The reason for this could be due to limited resources, as the plant has a finite amount of carbon and has to allocate this carbon to both the extrafloral nectar and to rhizobia. This need for resource allocation and the altered quantity and composition of extrafloral nectar had no effect on plant fitness traits nor on ant or arthropod visitation in my study, although so few ants were present that conclusions on ant visitation effects cannot be made. These results allow for other new and exciting questions in plant and insect ecology, such as what effect these resource allocations have on plant competition, growth, fitness, and how it impacts the broader ecological community.
- Resource Type:
- Masters Thesis
- Identifier:
- 10091
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Castro, Viridiana
- Description:
- Transporting water efficiently is one of the chief functions of plant vascular systems. Highly efficient transport is generally beneficial; however, tradeoffs arise because vascular systems have multiple functional roles that interact with one another. One example of a tradeoff may be related to how plants respond to water deficits. Some plants growing in arid and semi-arid environments form xylem networks that are able to tolerate water deficiencies and cope with embolism spread. Distinguishing patterns in embolism spread is important to understand how plants are vulnerable to water stress and what tradeoffs are involved in water stress resistance. Flowering plants found in mediterranean-type ecosystems differ in conduit (vessels and tracheids) presence and abundance. Little is known about how embolism spreads in plant vascular systems and the role tracheids play in the spread of emboli in vessel-bearing plants. I hypothesized that patterns in vessel embolism spread are linked to the type of conduit connections. I assumed that the propagation of embolism most commonly occurs through vessel-to-vessel connections. Therefore, I predicted that the presence of tracheids minimizes embolism spread compared to species with only vessels that have greater numbers of vessel-to-vessel connections. By contrast, greater vessel-to-vessel connections promote greater hydraulic transport efficiency. To test this hypothesis, I quantified embolism spread using computer assisted tomography (microCT) and hydraulic efficiency (hydraulic conductivity per unit xylem area; Ks) in six different species of woody plants that differ in tracheid presence, vessel structure, and hydraulic function. In Chapter 1, I briefly review how plants respond to water stress and what effects have been noticed to occur within their xylem conduits as a result. In Chapter 2, I present microCT, hydraulic efficiency, and percentage loss in conductivity (PLC) results from dehydration treatments for six species native to mediterranean-type climate regions in California, Cercoparpus betuloides, Malosma laurina, and Heteromeles arbutifolia; and the Mediterranean Basin, Laurus nobilis, Olea europaea, and Cistus ladanifer. In Chapter 3, I summarize my findings in the broader context of plant vascular function. My chief conclusion is that the connections between vessels are a key determinant of the tradeoff between hydraulic safety from cavitation and transport efficiency.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Stevens, Samantha K.
- Description:
- Purpose of the Study: The Russian River watershed stretches across a significant portion of Sonoma and Mendocino counties, covering 1,485 square miles, and is home to not only humans, but countless fish and wildlife species as well. The Russian River valley is famous for being an ideal place to grow wine grapes and other agriculture, in part for its fertile soil, as well as the region’s Mediterranean climate. In addition to this, the Russian River is a year-round recreational hotspot for both tourists and locals alike. Maintaining a high quality of water in any area is important, and this is especially true when the local economy relies so heavily upon surface water. According to the North Coast Regional Water Quality Control Board, the entire Russian River watershed is impaired for sediment and temperature, and recent data also show pathogen impairment throughout the watershed. The Laguna de Santa Rosa sub-watershed is also impaired for phosphorus and dissolved oxygen, in addition to the impairments throughout the watershed (Russian River Watershed Overview, 2019). Land uses and water quality are interconnected in the Russian River watershed, but causal patterns between the two are not well understood. Procedure: Water quality data was obtained via the United States Geological Survey (USGS) and input into Microsoft Excel to generate time series graphs of different water quality constituents. The three sites selected are Jimtown, Digger Bend, and Hacienda Bridge. A model from the USGS ScienceBase inventory was utilized for this project, which consists of future land use, land cover, and population projections for the state of California for the period of 2001-2101. This model was projected as a layer in ArcGIS Pro in order to estimate the land cover changes based on low, medium, and high population projections for the years 2050 and 2100. In order to estimate the nutrient input for these different scenarios, models were constructed using WikiWatershed’s Model My Watershed tool. Within Model My Watershed, the land cover was altered to emulate the six models by adding polygons of the desired land cover, running the model, and observing the resulting nutrient and total suspended sediment load output. An additional aspect of this project is to conduct an analysis of policies. Findings: As land is developed into managed cropland, nutrients are typically added in order to increase production and profit. As a result, the runoff from cropland is typically nutrient rich when infiltration rates are low. Records from the Sonoma County Crop Reports indicate that the acreage of vineyards nearly doubled between 1990 and 2000. The exploration of potential land use and land cover changes through the projection of the USGS ScienceBase layers in ArcGIS and the modeling of nutrient load in Model My Watershed showed both an increase in agricultural land use as well as an increase in nutrient load, which is expected. The data obtained from the USGS Water Quality monitoring site did not show many points of interest or concern and generally followed a seasonal pattern. The policies in place in Sonoma County regulate both point source and non point source pollution, which is an extremely effective way to minimize polluted runoff from entering the streams and river in the Russian River watershed. The federal, state, and county regulations seem to be adequately minimizing point source agricultural pollution, and could benefit from increased riparian vegetative buffer zones to help slow the flow of polluted runoff, increase infiltration, and minimize the amount of nutrients that reach the waterways throughout the watershed. Conclusion: While this project did not result in a definitive answer as to what is causing the most nutrient pollution in the Russian River watershed, based on the findings of project, it is safe to speculate that total loads of suspended sediment, nitrogen, and phosphorus were lower throughout Sonoma County when there was less agricultural land use since the modeling data predicts higher total loads as agricultural land use increases. In addition to an increase in vineyard, the Sonoma County Crop Reports recorded a two - fold increase in the number of cattle in the county between 1990 and 2018.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Sonoma
- Department:
- Biology
- Creator:
- Phalen, Carol Marie
- Description:
- Paralabrax clathratus, commonly known as the kelp bass, is an important sportfish to the Southern California angler, ranking among the top sportfish on commercial passenger fishing vessels since the 1950's. They commonly occur in a patchy distribution from Monterey Bay, CA to central Baja California, Mexico, preferring a habitat associated with structure. They are broadcast spawners and have the potential for high levels of gene flow during the 28-30 day pelagic larval stage. The purpose of this investigation was to determine the extent of genetic variation of the kelp bass at various locations throughout their range. Seven populations were examined for genetic variation and population subdivision using two variable molecular markers. Restriction fragment length polymorphism (RFLP) of the internal transcribed spacer regions (ITS) of the nuclear ribosomal DNA repeat unit revealed no genetic variation or geographic subdivision. Although direct sequence analysis of the 5' portion of the mitochondrial DNA revealed a high level of genetic variation , no geographic subdivision was detected based on neighbor joining, maximum parsimony, and analysis of molecular variance (AMOVA). These results suggest that a high level of gene flow exist among locations, most likely due to the dispersal of pelagic larvae via prevailing currents, episodic events, and adult movements.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Mohtashemi, Iman
- Description:
- Clusterin is a multi-functional protein that was initially isolated from ram testis. It was first identified for its ability to promote aggregation of cells, hence the name clusterin (Fritz et al., 1983). Subsequent research has identified clusterin in many mammalian fluids and organ systems. A number of functions have been hypothesized for clusterin from independent labs which produced a variety of acronyms. For example, clusterin has been shown to protect cells from the innate immune response such as complement mediated lysis , complement lysis inhibitor, CLI (Oda et al., 1995) and is also involved in cholesterol transport, ApolipoproteinJ, Apoj , (Gelisseb et al., 1998). It is the major secretory product from sperm cells (sulfated glycoprotein 2,SGP-2). It is also known as Testosterone repressed prostate message (TRPM) due to the fact that it is up- regulated after castration and is involved in apoptosis. The role of clusterin as a neuroprotectant has been investigated, however, data supporting a neuroprotective role remain under debate. In this report we combined immunoaffinity chromatography with HPLC to purify clusterin from human serum. We also utilized a clusterin knock-out model to determine the role of clusterin under toxic insults. A recombinant protein purification protocol was also developed.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Kuwadekar, Pradnya Sanjeev
- Description:
- Cell surface properties play an important role in embryonic morphogenesis and in malignant invasion. Cell surface sugar chains extend away from the cell membrane and are believed to be involved in cellular migration and adhesiveness. Some of these sugar complexes also act as receptor sites for lectins. Plant lectins are often used to detect these receptor sites on embryonic cells. At the 16 cell stage, sea urchin (Strongylocentrotus purpuratus) embryos exhibit cell size differentiation into larger cells (macromeres), medium sized cells (mesomeres) and smaller cells (micromeres). A difficulty in separating these embryos into single cells is the presence of a fertilization membrane. In this study, prior to fertilization the eggs were treated to prevent fertilization membrane formation. Following fertilization and development to the 16 cell stage, the embryos were disaggregated and the cell surface properties of the individual cells (macromeres, mesomeres and micromeres) were analyzed by their differential adhesiveness to agarose beads coated with various lectins. The results show that each of the three cell types of the 16 cell stage embryo have specific surface properties as indicated by their differential ability to bind to specific lectin beads. Moreover, the adhesive specificities demonstrated in this study for the 16 cell stage embryo differ somewhat from those of blastula stage embryos as reported in an earlier study from this laboratory. The results indicate that there is both a stage-specific and cell type-specific differentiation of cell surface sugar containing receptors that may be important in controlling morphogenetic events.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Abboud, Randa I.
- Description:
- Ammonia, glutamate, or glutamine can be utilized as sole source of nitrogen by Sporosarcina ureae. The growth rate is proportional to the concentration of ammonia up to a set value of 0.6 div./h at 84 mM, but concentration independent for glutamate at 0.5 div./h and glutamine at 0.33 div/h. When glutamate or glutamine is supplied as the sole source of carbon, energy, and nitrogen a diphasic type of growth is observed. Glutamate synthase (GOGAT; EC 1.4.1.13) is not detected in extracts of cells grown in tryptic soy yeast (TSY) medium nor in defined media containing acetate and ammonia, glutamate or glutamine; however, glutamine synthetase (GS; EC 6.3.1.2.) exhibits both biosynthetic and transferase activities at basal levels in extracts of cells grown under all growth conditions. A two-fold increase in the GS basal activity is observed in extracts of cells grown in ammonia-limited media. Two distinct glutamate dehydrogenases were detected and separated electrophoretically. One is specific for NAO (NAO-GOH; EC 1.4.1.2) and the other for NAOP (NAOP-GOH; EC 1.4.1.4). The NAO-GOH has an unusually high degree of thermal stability maintaining 95-100% of its activity after incubation for 15 minutes at 75�C; however, it irreversibly loses its activity upon freezing. The NAOP-GOH maintains 100% of its activity upon freezing but cannot survive the treatment at 75�C. The NAO-GOH exhibits increased activity in extracts of cells grown with glutamate as carbon and energy source, whereas the NAOP-GOH activity increases in extracts of cells grown in limiting ammonia concentrations. The Km values for glutamate in extracts of cells grown on TSY at pH 7.7 are 5mM and 30 mM for NADGDH and NADP-GDH, respectively. Two heat-labile glutaminases were separated electrophoretically; glutaminase ? is constitutive and glutaminase ? is repressed in complex media. Possible mechanisms of nitrogen assimilation in this organism are discussed.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Keshishian, Arbi
- Description:
- Many studies have examined the effects of free lectins such as Concanavalin-A (Con-A) on sea urchin development and suggested that lectin binding ligands play a role in embryonic cellular interactions. In this study, the effects of immobilized Con-A on sea urchin cellular interactions were examined by incubating embryos 2 hours after fertilization, 24 hours after fertilization right before invagination, and 27 hours after fertilization when invagination has occurred, with no Con-A beads, low, medium, and high counts of Con-A derivatized agarose beads and the embryos were observed at various times after beads addition. The results showed that archenteron development and attachment were interrupted when high and medium counts of Con-A beads were added before invagination. Once invagination occuffed, the Con-A beads had no significant effect on further development. The results were statistically significant (P < 0.0001) when archenteron attachment was compared between controls and experimentals when beads were added before invagination. There were no significant differences in the controls and experimentals when the beads were added after invagination (P>0.061). Analysis of protein concentration in the supematants from Con-A beads alone, beads with embryos, and embryos alone, suggested that small quantities on order of ug/ml of Con-A might have been released from the beads by the embryos, although it is very possible that no Con-A was released and what was released was sea urchin proteins resulting from cell lysis in the presence of Con-A beads. Further study of this issue is required to determine if immobilized Con-A (and not free Con-A) can effect specific embryonic cellular interactions in this system, an issue that is of importance in identifying mechanisms of morphogenesis.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Spiegler, Marci A.
- Description:
- The sea urchin is the material of choice for studying many early developmental events. Methods to extend the viability of sea urchin gametes have not received much attention, but it is well known that the eggs are easily damaged by freezing (4). This study was designed to extend the viability of Lytechinus pictus eggs and sperm without freezing. Gamete viability measurements were based on relative numbers of fertilized vs. unfertilized eggs, % fertilization and on observations of embryonic development. Results indicate that gametes can be stored longer and at lower temperatures than previously described (7) . Sperm were consistently kept viable for at least 11 days with little decrease in viability when stored in glass test tubes or plastic petri dishes and submerged in ice inside a refrigerator at 0�C � 1�C. In one experiment, sperm stored in glass test tubes on ice remained viable up to 20 days after extraction. Eggs were maintained from 1 to 7 days, rather than the one day or so previously reported (7) when stored in glass test tubes submerged in ice in a refrigerator at 0�C � 1�C. Results of egg and sperm experiments varied at different times in the season. Such variations may be caused by seasonal cytoplasmic changes (9), population differences, or the time mature individuals were maintained unfed in aquaria prior to use. Results from this study should be useful for a variety of research, mariculture, and teachin9 applications where sea urchin supplies are limited or when the same gamete population is required for subsequent experiments.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
22. Molecular cell adhesion modeling using nucleotide and carbohydrate derivatized beaded agarose resin
- Creator:
- Traxler, Vern S.
- Description:
- Cell adhesion has been studied for almost a century beginning with H.V. Wilson's classic studies on sponge cell aggregation. Cell adhesion plays an important role in morphogenesis and malignancy, but its molecular basis is poorly understood. As the cell surface often consists of hundreds of different molecules, it has been difficult to identify those molecular groups that function in the specific adhesion that occurs between cells. Students in this laboratory have approached this problem in a novel way. By examining the adhesion of agarose beads derivatized with only one type of molecule, one can learn more about which molecules, when isolated from all others, can adhere and which cannot, under conditions of the assay. Approximately 20,000 molecular combinations are being tested for adhesion in this laboratory. This thesis describes the work on 570 combinations of nucleotides and carbohydrates, each repeated at least three times. Although there is no evidence that interactions of these molecules are involved in cell adhesion, or even that nucleotides commonly occur on cell surfaces, it was important to examine all available molecular combinations because they may offer clues about the types of bonds that can form stable adhesions. For example, if nucleotides and carbohydrates adhered to each other via hydrogen bonding, this would provide evidence that hydrogen bonding can mediate adhesion. Fifteen different nucleotide derivatized beads were crossed with thirty-eight different carbohydrate derivatized beads and examined for adhesion to each other in distilled water and artificial sea water. All combinations that displayed any positive adhesion were repeated by at least two individuals. All 570 bead combinations did not adhere under the conditions of the assay, indicating that this set of nucleotides and carbohydrates did not form bonds stable enough to hold cell sized particles together. Previous experiments in the lab have shown that certain bead combinations could adhere under these conditions, leading to hypotheses concerning adhesion mechanisms that are being tested in living systems (Acta histochemica 98:441-451, 1996). The negative results presented in this study are meaningful in improving our understanding of what types of molecules can or cannot form stable bonds in a cell-like model system that allows the study of isolated molecular combinations.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Nosrati, Dorit
- Description:
- Iranian Jews constitute a growing minority in metropolitan cities around the United States. They are part of a close-knit community, with strong family and cultural values. Prevailing negative attitudes in the Iranian Jewish society towards disease and disability often cause the isolation and rejection of individuals with impairments. Having a child with a genetic disorder or a birth defect is to be avoided at any cost, since it may bring shame upon the entire family. There is limited information available in the field of genetic counseling about the Iranian Jewish community. Since prenatal choices reflect a person's cultural and social understanding of birth defects and genetic disorders, increased awareness of the community's values and characteristics is valuable in providing culturally sensitive genetic counseling services. The purpose of the study was to explore factors that play a major role in prenatal choices and that influence perceived causes of disabilities among Iranian Jews living in the United States. I hypothesized that a direct correlation exists between (a) acculturation, (b) education, (c) religious affiliation, and personal reproductive choices and perceived causes of disabilities in this population. A four-part questionnaire was designed based on self-written questions, and a pretested and validated instrument. The questionnaire assessed demographics, beliefs about causes of birth defects and genetic disorders, personal reproductive choices, and acculturation. The overall participation rate was 55%. Participants were 74 male and female Iranian Jews living in the greater Los Angeles area. Data were analyzed separately for male and female participants. The majority of participants were Conservative Jews, single, educated, and childless. The survey data showed low degree of acculturation, with the vast majority identifying themselves as either bicultural or Iranian. Among female and male participants, the study showed a strong correlation between (a) acculturation, (b) education, (c) religious affiliation, and personal reproductive choices. Among females only, the study also showed a strong correlation between these factors (acculturation, education, and religious affiliation) and perceived causes of disabilities. The correlation analysis showed that acculturation, education, and religious affiliation play roles in influencing prenatal decision-making. Therefore, it is important to explore these issues in the genetic counseling session, and consider their influence on the client's prenatal choices.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- DeCilla, Patricia Lucy
- Description:
- The purpose of this study is to determine whether the level of folic acid (FA) in human blood serum affects the number of fragile sites observed in cultured T-lymphocytes. Private practice patients (Internal Medicine) who evidenced no symptoms of significant disease, but did exhibit low levels (less than 5 ng/ml) of serum FA, were asked to participate in this study; 10 consented to do so. Each provided a blood sample that was prepared for a quantitative cytological study of fragile-site expression in their dividing lymphocyte chromosomes. Then, each patient was given supplementary FA (10 mg/day) for 2 months, when a second blood sample was drawn so that an "after" fragile-site determination could be made and compared with the "before" figures. The data, as a group, show that there is a significant decrease in the number of fragile sites after FA supplementation. Evidence in the literature suggests that fragile sites on chromosomes may have a connection to cancer by predisposing to chromosome breaks and thence to rearrangements characteristic of cancer cells. Therefore, FA supplementation may not only serve to decrease fragile site expression but possibly reduce cancer incidence.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- LaGrave, Danielle
- Description:
- The homocystinurias are a group of autosomal recessive disorders which are caused by various inborn errors of metabolism. Tnese disorders are characterized by high plasma and urinary ieveis of homocysteine and methionine, and low levels of cysteine. The most common cause of homocystinuria is a defect in the enzyme cystathionine f3-synthase (CBS) which converts homocysteine to cystathionine. Patients who are homozygous for CBS deficiency can be responsive or non-responsive to pyridoxine (vitamin B6), a cofactor of CBS. BB-responsive patients usually have a milder clinical phenotype and later onset of symptoms as compared to B6 non-responsive patients. The common clinical manifestations of homocystinuria are ectopia lentis, skeletal abnormalities and osteoporosis, and mental retardation. The skeletal features and eye findings of patients with homocystinuria are very similar to those of patients with the more common genetic disease, Marfan syndrome, an autosomal dominant disorder affecting the connective-tissue fibrillin. Pneumothorax, relatively common in Marfan syndrome, is rarely seen in homocystinuria. In this paper I describe a patient with pyridoxineresponsive homocystinuria and repeated spontaneous pneumothoraces.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Sperou, Emily S.
- Description:
- Purpose of the Study: Long-lived iteroparous females may suppress reproduction during unfavorable conditions to maximize lifetime reproductive success. Capital breeders must accrue sufficient body reserves to support reproductive effort or they may exhibit reproductive failure. The basis of these reproductive decisions is not well understood. Northern elephant seals are seasonal, colonial breeders with a period of embryonic diapause and biannual foraging trips divided by a breeding and molting haul out. Being capital breeders, they use the post-breeding foraging trip to recover body mass lost during lactation and the gestational foraging trip to accumulate resources for lactation. Females exhibit high natality, roughly 15% of females skip breeding each year. A previous study suggested alteration in baseline cortisol concentrations may be the proximate mechanism linking foraging success and reproductive suppression, but evidence of an interaction between cortisol and reproductive hormones is currently lacking. Procedure: We investigated a suite of reproductive hormones (progesterone, 17β- estradiol, inhibin A, prolactin) and cortisol, to determine patterns across life-history stages. We analyzed 1,029 serum samples from 441 adult female NES during their biannual haul outs. Included in this dataset were 30 females known to have skipped breeding. Findings: The data confirmed a highly seasonal pattern to changes in sex hormones. Estradiol and inhibin were high during the late breeding haul out, suggesting the timing of ovulation. Progesterone was highest at the end of the molt, indicating implantation had occurred. Path analysis revealed strong influences of estradiol and prolactin on progesterone, indicating these three hormones are key for implantation. Individual variation suggests important regulatory roles for prolactin, inhibin, and cortisol in modulating implantation. The data suggest that some females suppress implantation under the modulation of cortisol and inhibin. Most females that skip breeding appear to implant but fail to maintain gestation. Conclusions: Failure to recover body reserves from the preceding reproductive event may inhibit implantation, but most non-breeding females fail to maintain pregnancy during the gestational foraging trip. This bet-hedging strategy is likely one component of a capital breeding life-history that buffers females against short-term changes in foraging success, but limits fitness costs to reproduction through multiple check-points for body reserves.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Sonoma
- Department:
- Biology
- Creator:
- Hudson, Daniel
- Description:
- Purpose of the Study: To understand male and female mate choice patterns affecting species and gender recognition via long distance chemical cues, this study examined the rough skin newt, Taricha granulosa, in both pond and creek habitats. Response to chemical cues of males vs. females was examined for T. granulosa, whereas the California newt (Taricha torosa), and the red-bellied newt (Taricha rivularis) were used to examine how T. granulosa would respond to heterospecific chemical cues as compared to conspecific cues in a region of the species’ ranges where all three species occur in sympatry. Methods: To simulate mate choice decisions in nature as closely as possible, we conducted behavioral experiments in the field using a Y-maze apparatus (olfactometer). All trials were run in the field using unique individuals. Data were combined across multiple years. Mate choice was analyzed using a nominal logistic regression model accounting for variation among year, researcher, Y-maze apparatus, sex, and species. Findings: T. granulosa females chose chemical cues of conspecific males significantly more than heterospecific males, whereas males showed no preference between chemical cues of conspecific and heterospecific females. In addition, T. granulosa males chose chemical cues of conspecific males over conspcific females, whereas females showed no preference between chemical cues of conspecific males and females. Conclusions: The results of this study support long-standing theoretical paradigms that males, who have less parental investment in offspring will adopt a strategy of seeking matings with females regardless of quality, whereas females, with greater levels of parental investment, will engage in a more discriminating mate choice strategy. In this case, females use chemical cues to avoid heterospecific males during breeding season encounters and reduce wasting her singular mating event on an act of hybridization. A result of this mating strategy is that reinforcement of reproductive isolation is maintained in this region of sympatric range overlap. In contrast, will mate with any female across multiple mating events, and use chemical cues to either locate females or to avoid other males (or both).
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Sonoma
- Department:
- Biology
- Creator:
- Tercero, Anthony D.
- Description:
- The perciform suborder Notothenioidae is comprised of Antarctic and sub-Antarctic fishes, several of which have lost their ability to rapidly upregulate major heat shock proteins (HSP’s) in response to thermal stress. In fact, some notothenioid species have instead adopted a pattern of expression resembling ancestrally constitutive genes. It is possible that evolution in the Southern Ocean has selected for increased expression of molecular chaperones given the denaturing effect extreme cold temperature has on proteins. The selective pressures of the sub-zero water may have also favored duplication events that bolster quantitative output of chaperones via gene dosage effects. Given that newly duplicated genes are under more relaxed selective pressures, it is plausible that gene duplication preceded alterations in the regulatory regions of the inducible HSP genes, enabling altered regulation of such highly conserved gene products. To test for evidence of these mechanisms, gene copy number of ancestrally inducible and constitutive isoforms within the major heat shock gene families were characterized via qPCR and compared for the Antarctic notothen Trematomus bernacchii, which has lost the inducible HSR, and the non-Antarctic notothen, Notothenia angustata, which has maintained an inducible HSR. Results indicate duplication of inducible isoforms within the Hsp70 and Hsp40 superfamily have occurred in the genome of T. bernacchii. The findings from this study suggest adaptive gene duplications may have played a role in maintaining increased protein folding efficiency in the sub-zero waters of the Southern Ocean and provided a mechanism for the evolution of alternative regulation of these conserved gene families.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Sonoma
- Department:
- Biology
- Creator:
- Rzucidlo, Caroline L.
- Description:
- Purpose of the study: Adipose tissue is essential to endotherms for thermal regulation and energy storage as well as functioning as an endocrine organ. Adipose derived hormones, or adipokines, regulate metabolism, energy expenditure, reproduction, and immune function in model systems but are less well studied in wildlife. Female northern elephant seals (NES) achieve high adiposity during foraging and then undergo natural prolonged fasts while breeding, lactating, and molting, resulting in large changes in adipose reserves. Procedure: We measured circulating levels of four adipokines, leptin, resistin, adiponectin, and kisspeptin-54, in 196 serum samples from female NES at the beginning and end of their breeding and molting fasts. We examined the relationships between these adipokines and life history stage, adiposity, mass, cortisol, and the immune cytokine interleukin 6 (IL-6). Findings: All four adipokines varied with life history stage. Leptin concentrations were highest during the beginning of the breeding haul-out and resistin concentrations were higher throughout the breeding haul-out compared to the molt haul-out. Adiponectin was highest during the beginning of both haul-outs and kisspeptin-54 concentrations were highest during the end of the breeding haul-out. Leptin, resistin, and adiponectin were associated with measures of body condition, either adiposity, mass, or both. Resistin, adiponectin, and kisspeptin-54 were associated with circulating cortisol concentrations. Resistin was strongly associated with circulating IL-6, a multifunctional cytokine associated with the innate immune response. Adiponectin was associated with glucose concentrations and may be a driver of tissue-specific insulin sensitivity during life history stages categorized by high adiposity. Increased cortisol concentrations late in lactation were associated with increased kisspeptin-54 which may play a role in initiation ovulation in NES. Conclusions: This study suggests dramatic changes in circulating adipokines with life history and body condition that may exert important regulatory roles in NES. Differences from biomedical model systems suggest the potential for modifications of expression and function of adipose-derived hormones in species that undergo natural changes in adiposity as part of their life-history.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Sonoma
- Department:
- Biology
- Creator:
- O’Gorman, Cory James
- Description:
- Purpose of the Study: California black oak, Quercus kelloggii, plays an important role in the lifeways of many indigenous tribes throughout California. Native peoples tend black oaks using Traditional Ecological Knowledge (TEK) to encourage the development and proliferation of specimen oaks. These mature, large, full crowned trees provide a disproportionate amount of ecosystem services, including acorns and habitat, when compared to smaller black oaks. Altered approaches to land management and the cessation of frequent low intensity cultural burns places these specimen oaks at risk from encroachment, forest densification, and catastrophic fire. Procedure: This project is a collaboration between Sonoma State University and the Native Advisory Council of Pepperwood Preserve. Data were collected from 55 specimen black oaks at Pepperwood Preserve in north east Sonoma County. Ecological variables were measured to identify abiotic and biotic drivers of growth habit, scorch height and fire fuels. A certain crown shape is desired by many of today’s traditional gatherers including those represented on the Pepperwood Native Advisory Council. Findings: Encroachment was found to have a significant negative effect on both canopy area (p=0.0027) and live crown ratio (p=0.0378). Encroachment did not affect surface and ladder fuel load accumulation since the Tubbs Fire in October 2017 (p>0.05). Neither surface and ladder fuels nor encroachment variables significantly affected scorch height on the specimen oaks (p>0.05) following the Kincade Fire. Conclusions: This work will allow for the reimplementation of TEK to nurture specific specimen black oaks at Pepperwood Preserve at the discretion of the Native Advisory Council and increase access to land and culturally significant plants by local tribal communities. This has far reaching implications on tribal peoples’ well-being, their ability to engage in cultural practices, and ecosystem health.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Sonoma
- Department:
- Biology
- Creator:
- Molinaro, Holly
- Description:
- Hamadryas baboons (Papio hamadryas) live in a complex multilevel social system with the one-male-unit (OMU) at the core. OMUs consist of an adult alpha male with one or several adult females, their dependent offspring and sometimes a few follower males. Previous research has documented that OMUs form in four distinct ways in wild populations. In December 2015, Oakland Zoo introduced two juvenile males into the hamadryas baboon exhibit. At the time of this study, these males were approaching sexual maturity. The complex social structure of this species and the changing social dynamics that might result as they reach sexual maturity provide a unique opportunity to utilize social network analysis (SNA) methods to examine OMU formation in a captive setting with an eye towards potential management strategies. SNA is a visualization method of looking at social data that allows researchers to understand sociality in terms of the importance of each individual, any subgroups, as well as the larger overall group dynamic. Behavioral and proximity data were collected over a six-month period (July- Dec 2019). These data were then transformed into networks to analyze the two now subadult males’ behavior over time and the presence of any subgroups. I found that one of the subadult males formed his first OMU following one of the four pathways found in wild studies. Despite changing group dynamics, overall group cohesion remained unchanged. This study reveals hamadryas OMU formation patterns in captivity as well as suggests potential welfare management issues that might arise.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Sonoma
- Department:
- Biology
32. Interactions among Sudden Oak Death, Fire Fuel Loads, and Climate in Sonoma County Oak Woodlands
- Creator:
- Hernandez, Manuel
- Description:
- Purpose of the Study: Understanding impacts of invasive pathogens and wildfire on forests is a major challenge facing scientists, land managers, and policymakers. In this study, I used a long-term plot network in eastern Sonoma County to disentangle the interactions among an exotic pathogen (Phytophthora ramorum), fire fuels loads and climate in oak woodlands. I investigated the interactions among: 1) sudden oak death (SOD) inoculum loads, disease prevalence and pre-fire surface and ladder fuel loads, 2) surface and ladder fuel loads and canopy condition, and 3) canopy condition and post-fire surface and ladder fuel loads. Procedure: From 2004-2016, measurements of disease prevalence, tree growth, tree mortality and tree survival were collected for the three most abundant SOD host tree species: coast live oak (Quercus agrifolia), California black oak (Quercus kelloggii), and California bay laurel (Umbellularia californica). In 2014, surface fire fuel loads were quantified, and airborne Lidar data were collected. Elevation, slope, average potential solar insolation, and topographic moisture index, and climate water deficit were also calculated for these plots to determine the interactions of microclimate and topography on pre-fire fuel loads. In 2019, I recorded tree mortality and survival of these same species and quantified surface and ladder fuel loads across 33 plots (15 x 15 m) with a range of burn severity following the 2017 LNU Complex Fires. To analyze the interactions among abiotic and biotic factors over time I created a hypothesized pathway to describe potential direct and indirect effects of oak mortality, disease load, microclimate, topography, climatic water deficit, pre-fire fuel loads, and canopy condition on post-fire fuel loads. I tested this pathway using a path analysis. Findings: I found that P. ramorum disease load had no effects on pre-fire fuel loading. However, oak mortality in 2014, indirectly affected by P. ramorum disease load, significantly increased the amount of large surface fuels, and decreased ladder fuels. Plot elevation and maximum temperature also had a positive correlation with pre-fire ladder fuel amounts. Pre-fire ladder fuels, in concert with drought intensity and slope interacted to effect canopy condition post-fire (in particular, percent canopy damage). Percent canopy damage was greater in less sloped plots with greater amounts of ladder fuels and increased drought severity. Pre-fire ladder fuels also had a significant direct effect on post-fire ladder fuels, whereas increased amounts of post-fire ladder fuels were observed in less-sloped plots with greater amounts of pre-fire ladder fuels and more percent canopy damage. Surprisingly, plots with increased fire severity due to increased fuels had increased re-sprouts and re-growth of U. californica trees immediately following fire. Conclusions: Current management practices in oak-woodlands include the removal of U. californica in the presence of oaks to reduce the potential P. ramorum inoculum load. My results support this practice, as SOD indirectly increases fire fuel loads, which may in turn increase both the future susceptibility of the ecosystem to fire and the severity of these future wildfires.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Sonoma
- Department:
- Biology
- Creator:
- Ghavamian, Yasmeen
- Description:
- All zoos grapple with challenges of keeping captive animals engaged in natural behaviors, especially for bears which prove to be among the more challenging species to keep stimulated. In captivity, a common indicator of poor welfare is the presence of stereotypic behaviors. In this study, we test whether providing increasingly complex feeding enrichment decreases the duration of stereotypic behavior and increases enrichment interaction for three adult female sun bears (Helarctos malayanus) at Oakland Zoo in California. We compared the effects of two different feeding enrichment devices- presented to the bears at three complexity levels- on sun bear stereotypic behavior. After three weeks of baseline data collection when no complex enrichment was present, we introduced the complex enrichment three times a week per level over six weeks. In addition, we measured each bear’s interaction with the enrichment devices to examine the effect of complexity on enrichment use. Providing increasingly complex enrichment decreased the duration of stereotypic behavior when compared to the baseline phase. Across the six weeks, the duration of stereotypic behavior was significantly less on the complex enrichment days compared to the days when complex enrichment was absent. Increasing enrichment complexity had variable effects on enrichment use. Our results indicate that providing complex enrichment decreased the duration of stereotypic behaviors, however, the effects of complex enrichment did not carry over on the days when the enrichment was no longer present. These results suggest that providing increasingly complex enrichment may have a positive influence on the behavior of captive bears.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Sonoma
- Department:
- Biology
- Creator:
- Chen, Sylvia
- Description:
- Worldwide, there are 65 million people that have epilepsy and approximately 200,000 additional individuals are diagnosed with epilepsy annually. There is no cure and currently available anticonvulsants, which are medications to treat seizures, are not universally effective. Additional studies are needed to generate better treatment options. Drosophila melanogaster provides a valuable and efficient model to study seizure disorders due to the low cost of maintenance, genetic tractability, and short lifespan, which allows for observation at various life stages. D. melanogaster also possesses similarities to humans on cellular and subcellular levels. These advantages allow the development of a model for the high throughput study of epilepsy. This study aims to induce single and multiple seizures and monitor locomotion, learning, and memory. The results from the negative geotaxis assay, which takes advantage of D. melanogaster’s innate climbing behavior, suggest that single seizure events have minimal impact, whereas multiple seizures result in deficits in visuo-motor/motor behavior. Additionally, a visual place learning assay was used to study the cognitive abilities and results suggest a single seizure event impacts learning and memory. Lastly, whole brain slides were made and determined lesions in brain tissue result from repeated seizure events. The significant findings from this research may contribute to improve therapeutics for epilepsy by providing a method of high throughput screening.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Fresno
- Department:
- Biology
- Creator:
- Gonzalez, Dalia Banesa
- Description:
- This study involved Drosophila melanogaster, the common fruit fly, as the model organism to study the behavioral differences seen in flies overexpressing the human tau protein throughout their adult life span. The tau protein (MAPT – microtubule associated protein tau) is linked to Alzheimer’s Disease (AD). It is seen in both humans and Drosophila and has been noted to decrease learning and cognitive abilities in both. This study aimed to look at the cognitive and behavioral difference seen as adult flies age. The adult flies were tested at three different ages (young, middle, elderly) in order to look for any progression declines in behavior as the flies aged and expressed the human tau for longer periods of time. The human tau was driven into two different areas of the brain (ellipsoid body, mushroom body) that have been shown to be important regions for learning and memory in insects. The flies were tested in two different behavioral assays, a visual place learning assay and a negative geotaxis assay, in order to quantify spatial learning and memory. Additionally, fluorescence microscopy was used to analyze the amount of tau present in the brain at different times of the adult’s life, which confirmed the increased expression of tau as flies aged. As tau-expressing flies aged, both visual place learning and memory were impacted. These flies also showed a decline in planning ability. The behavioral declines seen in this study can be correlated to patients with AD who also overexpress this abnormal tau protein. This study aims to create a better Drosophila melanogaster model for AD. Moreover, the findings of this study can contribute to a better model organism for AD, which allow us to test interventions prior to the onset of dementia.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Fresno
- Department:
- Biology
- Creator:
- Montiel, Christian M.
- Description:
- The Escherichia coli cAMP receptor protein (CRP) requires both DNA binding and RNA polymerase recruitment for its transcriptional activation function. The DNA recognition of CRP is performed by the F-helix (residues 180-185) and several F-helix residues (Arg180, Glu181, Gly184, Arg185) are well-characterized as to their importance in DNA binding. However, no apparent function has been known for the other two residues (Thr182 and Val183). In this work, I show that the position-183 amino acid (Val 183) is important for the transcriptional activity of CRP. First, Ala substitution at position 183 led to an increase in transcriptional activation activity. Second, CRP mutants altered at position 183 were created to show an inverse correlation between amino acid size and transcriptional activation activity (V183A > V183G > wild type CRP > V183I > V183M > V183F = no activity). Third, the loss of the activity in V183F could be restored by a smaller amino acid substitution (IleGly) at position 172, implying that it is the combined size of positions 172 and 183 which is important. A structural analysis of CRP reveals that the position-183 amino acid faces the opposite of target DNA and is in close proximity to the position-172 amino acid. The requirement of a small residue at position 183 is hypothesized to avoid steric hindrance to the position-172 residue as steric hindrance would misalign the nearby AR1 residues, leading to poor RNA polymerase recruitment and transcriptional activation.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Fresno
- Department:
- Biology
- Creator:
- Thomas, Jason Michael
- Description:
- Bacteria must be able to withstand a myriad of stresses from both their environment, and in the case of pathogens, from their host. Low molecular weight thiols serve as redox buffers to maintain a reducing environment in the cell and participate in various protective mechanisms, including detoxification of reactive oxygen and nitrogen species, resistance against electrophiles and antibiotics, and protection against environmental stressors. In this study, I analyze the transcriptome of two heterotrophic clinically relevant bacteria, Pseudomonas aeruginosa PAO1 and Staphylococcus aureus SAUSA300 and transposon mutants disrupted in thiol biosynthesis. The transposon mutants are disrupted in P. aeruginosa glutathione biosynthesis gene, gshA, and S. aureus bacillithiol biosynthesis gene, bshC. I also analyze the transcriptome of the autotrophic cyanobacterium, Synechocystis PCC 6803 as well as a knock-out mutant disrupted in egtB, which is involved in ergothioneine biosynthesis. P. aeruginosa gshA mutant is downregulated in type II and type VI secretion systems and upregulated in type III secretion systems while the S. aureus bshA mutant is downregulated in type VII secretion suggesting that thiols play a role in secretion of effectors. Strikingly, both P. aeruginosa and S. aureus switch to anerobic respiration with nitrate as the electron acceptor in the thiol mutants. A number of other virulence factors are also differentially expressed in these mutants agreeing with the attenuation of the mutants in disease models. In contrast, genes related to high light resistance, acid stress tolerance, and osmotic stress tolerance are downregulated in Synechocystis PCC 6803. This suggests that ergothioneine is involved in abiotic stress tolerance in the autotrophic bacteria. Overall, we demonstrate that LMW thiols are involved in a myriad of functions have not been previously identified.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Fresno
- Department:
- Biology
- Creator:
- Ajanel Gomez, Jehiel Abigail
- Description:
- Discovered in 2004, tunneling nanotubes (TNTs) are actin-based, bridge-like structures that allow the intercellular transport of cellular components, electrical signals, and pathogens. Thus, TNTs have been implicated in viral propagation, neurodegenerative diseases, and cancer. Most research has focused on examining the molecules within cells that aid in TNT formation and function, but little has been documented on the role that exogenous molecules have in TNT formation. Past research has determined that hydrogen peroxide (H2O2) induces TNTs in various cell lines; however, the amount of H2O2 used was above was high (100μM). The aim of this study was to establish if TNT formation can be induced by pathophysiological H2O2 concentrations. In addition, we also investigated glutamate, an inducer of actin-based filopodia in astrocytes, as a possible TNT inducer. The data obtained using fluorescence microcopy suggest that low concentrations of H2O2 and glutamate are able to increase TNTs in both HeLa and CAD cell lines. Furthermore, cells treated with low concentrations of H2O2 or glutamate showed an increase in the expression of Myo10, a protein that has been linked to TNT formation and function. Lastly, the data obtained with a microscope capillary single cell sorting system suggest that H2O2 and glutamate can induce the formation as well as the elongation of cellular protrusions in distances ranging from 14-96 μm. Altogether, these results provide useful insights regarding TNT formation pathways in cells as well as the exogenous molecules involved in the formation of TNTs.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Fresno
- Department:
- Biology
- Creator:
- Surber, Lisa L.
- Description:
- Research on animal movement patterns and factors that influence these patterns is vital to conservation of endangered species. The California Red-legged frog (Rana draytonii) is a threatened species native to California. Their rapid decline has been largely attributed to habitat loss and introduction of invasive species, including the American Bullfrog (Lithobates catesbeianus). The aim of this research was to compare the nocturnal habitat use and seasonal movement patterns of R. draytonii and L. catesbeianus. I conducted a radio telemetry study in Sonoma County, California and mapped the locations of 13 L. catesbeianus and 51 R. draytonii from May 2017 to June 2018. Using a mixed model, I evaluated the effects of species, sex, size and rainfall on frog movement rate and compared habitat use relative to a water source. Within this model species, size and sex were found to have significant effects on movement rate. Rainfall was not found to have a significant effect on movement rate for either species. When comparing nocturnal habitat movement, I found that in the summer months species occupy different places relative to water sources in a creek environment; R. draytonii position themselves higher and further away from the nearest open water than L. catesbeianus. My work suggests that there are significant differences between the seasonal movement patterns and nocturnal habitat use of native R. draytonii and invasive L. catesbeianus. These differences may be helpful to conservation practices facilitating the survival of threatened R. draytonii.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Sonoma
- Department:
- Biology
- Creator:
- Karabidian, Eddie
- Description:
- A variety of models of cell adhesion have been proposed by previous investigators; each depended heavily on details of the biochemistry of cell surface sugars. In this study, Lytechinus pictus sea urchin embryos were used to study the molecular mechanisms involved in cellular interaction. The interaction between the tip of the archenteron and the blastocoel roof during gastrulation in sea urchin embryos has been of interest to developmental biologists for over a century. This interaction is fundamental to morphogenesis. An understanding of the molecular mechanisms of the interaction between the archenteron and the blastocoel roof will be of major importance to the field of cell adhesion. These findings will provide a better understanding of what goes wrong in abnormal adhesive interactions, which may lead to diseases such as cancer. This is why the National Institute of Health (NIH) has designated the sea urchin embryo as a model system for studying basic mechanisms in human heath and disease. Here, we examined the effects of two glycosidases (sugar cleaving enzymes) on the surface of the sea urchin embryo cells. The enzymatic activities of two commercially prepared glycosidases were verified by direct chemical assays on known substrates as well as live and fixed sea urchin material to determine the interaction of the tip of the archenteron and the blastocoel roof. SDS-PAGE was carried out to measure possible protease contamination and the purity of the glycosidases. Azocoll test was also performed in order to check for cryptic protease activity. The results suggested there was no detectable smearing or degradation of the substrate and only minor levels of contaminating protease activity. In order to find out if sea urchin embryos have exposed glycans that can be degraded by α-amylase or α-glucosidase live and fixed embryos were disrupted and were used as substrates for these enzymes. A colorimetric assay with 3,5-dinitrosalicylic acid was used to measure the amount of maltose released. α-amylase enzyme did not release detectable amounts of maltose from embryos exposed to formaldehyde for long periods of fixation, but did release small amounts of maltose from live embryos or embryos fixed for shorter terms (1 day). These results suggest that the enzyme we use has specific sites of cleavage that may become inaccessible during long-term formaldehyde fixation. α-glucosidase released a small amount of maltose from the substrate sea urchin. To confirm that the sea urchin embryos do not release inhibitors of α-amylase and other glycosidases, mixed reactions were also conducted in which the defined substrates were tested in the presence of long-term fixed sea urchin embryos. The results suggested that there was no evidence of inhibition of these enzymes. I incubated glycosidases (active and denatured) on microdissected archenteron and blastocoel roofs in adhesion assays to learn if they directly inhibited the adhesive interaction. α-amylase had no effect, while α-glucosidase only substantially inhibited adhesion after 12 hours incubation. While glycans have been implicated in mediating this cellular interaction, this is the first study that directly implicates polyglucans with exposed 1,4 terminal ends in the adhesion of the archenteron tip and blastocoel roof.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Saxton, William Manning
- Description:
- Applications of a low-speed centrifuge rotor designed to separate whole cells at very low g-forces in partially reoriented, shallow density gradients are presented. The particle separation chamber was fabricated using Lucite so that gradient behavior and particle sedimentation could be monitored visually during rotor operation by using stroboscopic illumination. Runs were recorded on videotape for later study and frame-by-frame analysis. Rotor performance was tested using a model system consisting of polystyrene microspheres of known sizes and densities. The resolution obtained exceeded that of previously reported centrifugal separations. Cells from an ascites-grown tumor were separated into three discrete subpopulations. Cells comprising each subpopulation were characterized in terms of size distributions and sedimentation rates. Experimental results are discussed in relation to theoretical considerations about the behavior of particles in partially reoriented density gradients.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Trujillo, Andreina
- Description:
- Tunneling nanotubes (TNTs) have been recently discovered as an essential form of cell-cell communication in multicellular organisms. Although TNTs appear to be an important cell-cell signaling pathway, its mechanism of formation and functions are still not fully understood. A central issue is determining whether mitochondria play a vital role in the formation of TNTs. Previous studies have shown that exposure to a low concentration of ethidium bromide (EtBr) in mammalian cells caused a complete loss of mitochondrial DNA (mtDNA) leading to non-functional mitochondria (Rho0 cells); therefore, this technique will be applied to produce a HeLa Rho0 cell line to study the effects of non-functional mitochondria on TNT. Here we will determine if Rho0 cells were successfully engineered by labeling the mtDNA with Quant-it PicoGreen Reagent and labeling of the plasma membrane with WGA Rhodamine to determine the effects on TNT formation. We will also determine the expression levels of Myosin-X (Myo10), a known TNT inducer, in Rho0 cells versus control cells. Overall results revealed that mitochondria do play a role in TNT formation. As cells were in the process of becoming Rho0 cells, TNT formation increased peaking at week 4. As Rho0 cells stabilized, TNT formation significantly decreased. In addition, cells were seen to expel their mitochondria into the extracellular medium in week 6, a process known as mitochondrial extrusion. Lastly, Myo10 protein levels significantly increased during the production of a stable Rho0 cell line at week 4. The increase in Myo10 protein levels correlated with an increase in TNT formation.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Fresno
- Department:
- Biology
43. Partitioning the effects of habitat fragmentation on rodent species richness in Southern California
- Creator:
- Johnson, Alex M.
- Description:
- Habitat fragmentation plays a major role in species extinction and the loss of biodiversity around the globe. When fragmentation occurs, the initial loss of overall habitat alone causes species extirpation. However, species that survive this initial loss and persist in the remaining small fragments of habitat continue to experience changes that may lead to their eventual extirpation. Previous research has determined that species richness in habitat fragments is affected by a number of characteristics. These include fragment age, size, and isolation, edge effects, vegetation coverage, habitat heterogeneity, and matrix content. Although most studies focused on one or a few of these characteristics, multiple characteristics work together to affect species richness, showing that the effects of habitat fragmentation are complex. The goal of my study was to partition the complex effects of habitat fragmentation by determining the direct, indirect, and cumulative effects of multiple habitat fragment characteristics on rodent species richness. In 2013, I determined rodent species richness in 25 habitat fragments within a suburban landscape of Thousand Oaks, California. In addition, I measured the following characteristics for each fragment: fragment age, area, isolation, shrub coverage, habitat heterogeneity, perimeter/area ratio, and percent non-urban buffer. Path Analysis was used to test the hypothesized model which described the direct, indirect, and cumulative effect of each habitat fragment characteristic on rodent species richness. Habitat heterogeneity had the greatest direct and total effect on rodent species richness. In addition, fragment area had the greatest indirect effect on rodent species richness through its influence on habitat heterogeneity, suggesting that large fragments containing the greatest diversity of habitats will support the most species. Overall, the path model explained 67% of the variation in rodent species richness among habitat fragments. From a conservation and management standpoint my findings suggest that the most important fragments to protect are the largest and most habitat diverse.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Ginther, Samuel
- Description:
- The susceptibility of ecosystems to the introduction of non-native species has increased drastically with the development of advanced transportation technologies. It is now quite common for organisms to be easily transported by humans across physiological, ecological, or behavioral barriers that once served as natural population constraints. Despite this increased rate of introductions to locations that were previously unreachable, most organisms that are introduced perish because they are not able to withstand the new environmental pressures of the introduced location, or there are simply not enough conspecifics to perpetuate the population. However, when introduced organisms are able to thrive and reproduce, they may have devastating economic or ecological consequences. A new opportunity to document and understand the effects of an invasive alga on native community members has presented itself in southern Californian waters. Native to northeastern Asia, Sargassum horneri is a macroalga that was presumably transported in ballast water and discovered in Long Beach Harbor in 2003. By 2006 it had spread to the western side of Santa Catalina Island, California, and within a year spread along the entire leeward coast, forming dense stands in numerous areas. Although not all exotic species are ecologically harmful, S. horneri has attributes (fast growing and occurs in high densities) that may allow it to readily establish and outcompete marine flora critical to the community structure of fishes. The purpose of this study aimed to document the effects of S. horneri on kelp forest fishes at Santa Catalina Island, California. I first employed observational, correlative methods to explore the role of S. horneri in shaping biotic and abiotic habitat characteristics of reefs and fish assemblages. I also explored habitat characteristics that predict fish assemblage structure, as well as species-specific responses of fish to habitat predictor variables during 4 distinct time periods. Fish assemblages changed over the course of my 4 sampling periods, and a number of habitat variables (including S. horneri) explained variation in fish assemblage during those times. However, there is more evidence that favors M. pyrifera as a driver of fish assemblage change, as indicated by species-level responses. Additionally, a field experiment testing whether the removal of S. horneri from reef areas affected the fish assemblage was used to evaluate whether patterns documented in the observational portion of my study that could be attributed to S. horneri do in fact appear to be caused by the invasive alga. Removing S. horneri from established areas of reef did not affect multivariate or univariate metrics of fish assemblage over the course of 7 sampling periods. Removal and control (unaltered) areas of reef contained strikingly similar fish assemblages, fish richness, and fish densities over time. Despite a drastic change in reef landscape, it appears that M. pyrifera, rather than S. horneri, was a more significant driver of differences in kelp forest fish assemblages observed in my study. Second, I compared the role of relatively low-lying S. horneri and vertically extensive M. pyrifera in shaping recruitment patterns of a popular sport fish (Paralabrax clathratus) by using an observational and experimental study. I first examined kelp bass recruit abundance on naturally standing S. horneri and M. pyrfera to better understand how fish recruitment rates differ between the introduced and native species. Additionally, I experimentally isolated 3 treatments (M. pyrifera only, S. horneri only, and M. pyrifera and S. horneri together) over a sandy bottom to understand whether the presence of S. horneri, and increased benthic complexity for young fish, enhances kelp bass recruitment. An overwhelming majority of kelp bass recruited to M. pyrifera, and larger recruits were located in the bottom two-thirds of the thalli. Kelp bass recruitment was were observed with S. horneri, regardless of whether the alga was alone or paired with M. pyrifera. Similar to my observational results, larger kelp bass recruits were observed in the bottom third of M. pyrifera treatments. Additionally, I found that that the presence of larger, predatory conspecifics explained a spatial pattern of declining recruitment rates across treatment plots. My study presents the first evidence that S. horneri negatively impacts the recruitment of an important southern California reef fish. Results from both of my studies offer contrasting outlooks on S. horneri's role in southern California kelp forests. When focusing on the entire fish assemblage, little evidence is in favor of S. horneri as a driver of kelp forest fish structure. However when focusing on a particular early life history characteristic of a common kelp forest fish, the effects of S. horneri are dramatically negative. The contrasting results of my studies are important reminders for the need of additional studies to generate a more comprehensive understanding of this invasive alga's impact on kelp forest organisms.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Parker, Jeffrey Thomas
- Description:
- The purpose of this study is to compare the genetic distances of Mimetus hesperus and Theridion neomexicanum within and between the San Joaquin Valley and Mojave Valley regions. To my best knowledge this is the first genetic study of M. hesperus. Mountains and distance are well known barriers to gene flow in species with lower vagility. For short lived spiders, the only non-synanthropic transport method over mountains is ballooning. Ballooning spiders rely on surface area for lift, and larger spiders have a difficult time sustaining flight as they have less surface area per unit weight. M. hesperus hunts other spiders and probably has large spiderlings which make it difficult to balloon from hatching. With insufficient ballooning the Sierra Nevada Mountains should act as a barrier to gene flow for M. hesperus. I predict that comparisons between populations of M. hesperus on the same side of the Sierra Nevada Mountains will show smaller genetic distances than comparisons between populations on opposite sides of the mountains. M. hesperus and T. neomexicanum were collected from sites around the Sierra Nevada Noubtains and either died of natural causes or were humanely euthanized in <0°C ethanol. DNA was extracted and PCR was run to amplify the cytochrome oxidase 1 sununit c gene. Amplified sequences were run in two percent agaorse gel to look for banding of appropriate length and gels showing target band were purified and sent to the University of Florida for sequencing. All other bands were heavily troubleshooted and re amplified Sequence chromatograms were analyzed to ensure only pure sequences were used in analysis. Insufficient numbers of T. neomexicanum were resolved so they were used as outgroups in analyzing M. hesperus. Sequences were aligned using clustalW and cut in MEGA to ensure accurate comparisons. Pairwise distances were calculated between all specimens. A neighbor joining tree was calculated, and overall percent divergence based on collection sites, and tree groupings was computed. Character based maximum parsimony and maximum likelihood trees were calculated to confirm results seen in neighbor joining analysis. Haplotype diversity was shown by grouping all single nucleotide polymorphisms for comparison of haplotypes and by collection site and tree groupings. Genetic distance and trees reveal three distinct groupings of M. hesperus, but a permutation test found distance within populatioins from both sides insignificant, so all specimens were grouped as either east or west of the mountains. Although anecdotal at best, haplotype diversity hints that M. hesperus may have brached from the west to the east. The Sierra Nevada Mountains appear to separate populations of M. hesperus in the Central Valley and in the Mojave more than distance alone. M. hesperus populations collected over 100 miles apart on the west side of the mountains showed no significant divergence, indicating some unknown mechanism of gene flow linking these populations, but a larger sample size is needed to confirm this.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Kolan, David Martin
- Description:
- In sea urchin eggs the hexose monophosphate shunt is the main glycolytic pathway before and after fertilization, and glucose-6-phosphate dehydrogenase (G6PD) is the main regulatory enzyme of the pathway. Activity of the enzyme increases with fertilization, thought to occur as a result of activation of NAD kinase and glycogen phosphorylase and simultaneously increased titers of NADP and glucose-6-phosphate (G6P). Part of the enzyme activity is associated with the egg surface membrane complex. Experiments have been done to determine the effects of extraction pH upon isozymes in unfertilized eggs, and what effects dithiothreitol (DTT, a sulfhydrl reducer), papain (a well known thiol protease), NADP, NAD, G6P, and other substrates have when added exogenously, upon the formation of isozymes and the mechanics of isozyme change as a part of the program of fertilization. Control extracts of pellet and gel fractions of unfertilized egg homogenates of the species Strongylocentrotus purpuratus show three isozyme bands when extracted using 0.01M MgCl2; these bands are designated B1, B2, and B3, the slowest to fastest migrating respectively with electrophoresis. Extraction with Lubrol WX yields an even slower moving band, BL. Fertilized eggs are shown to lack a B3 band. Extraction pH has been found to have no effect upon formation of isozymes between pH 6.4 and 7.9, whether pellet or gel extract. Unfertilized and fertilized egg pH 7.9 extracts with DTT added show the apparent extinction of activity of all but the B2 isozyme band, thought to be due to sulfhydryl inhibition of the binding of NADP to cysteine residues of the G6PD isozymes inactivated by DTT. Papain added to unfertilized egg extracts has no visible effect upon the isozymes, while fertilized egg extracts take on somewhat the appearance of unfertilized eggs, gaining the B3 band and partially losing B1, indicating a relationship between B1 and B3. Addition of NADP and G6P together causes the apparent disappearance of the B3 isozyme in unfertilized egg extracts and slightly increased mobility in both fertilized and unfertilized cases. With the experimental results in mind, it is proposed that increased NADP titers cause a release of lower molecular weight isozymes from membranes to soluble phases of the cell, and increased concentrations of substrate and specific cofactor complete formation of a larger G6PD isozyme, with the greater enzyme activity available to supply the energy for the metabolism of the newly formed sea urchin zygote.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Hult, Susan Marie
- Description:
- The Blainville's Horned Lizard (Phrynosoma blainvillii) is endemic to California and ranges from northern California (Butte County), to the northwestern tip of Baja California in the southern part of its range, west of the Sierra Nevada Mountains and the southern California deserts in the eastern part of its range, and along the Pacific coast from northern Baja California to Monterey, California in the western part of its range. Phrynosoma blainvillii is listed as a California Species of Special Concern and a Bureau of Land Management (BLM) Sensitive Species. Human activities have been primarily responsible for declines in populations. There has been few field research studies published on the general ecology of P. blainvillii, particularly in the San Joaquin Valley. I initiated a radio-telemetry study to collect data on home range size and habitat use at two sites (Atwell Island and Semitropic Ridge Preserve) in the southern San Joaquin Valley, California. I calculated home range size from 10 lizards, five at each site. Using the 100% Minimum Convex Polygon (MCP) estimator I found home range sizes were between 0.58 ha to 13.93 ha, with an average size of 4.98 ha (± 1.54). When above ground and active, P. blainvillii at either site used areas of bare ground more often than expected based on equal use. At the Semitropic site, the lizards used areas under shrubs almost as often as bare ground, while at the Atwell site the lizards used areas of sparse vegetation more often than expected, but not as much as bare ground. Lizards at both sites used medium-dense and dense areas of vegetation much less than expected based on equal use. In adult P. blainvillii, we recorded a moderately skewed sex ratio of more males than females, but in young P. blainvillii, there were more females than males. Average snout-vent length (SVL) of females was 72.31 mm and for males 68.81 mm. The adult horned lizards were most active in April and May while young horned lizards were most active in August and September. In the spring, the morning activity hours peaked at 0900–1100, in summer, it was 0900–1000, and in fall, it was 0900–1300. All age classes of P. blainvillii were most often above ground and active at surface temperatures of 28–34°C. The presence of alkali flats and sandy soil correlated with a high abundance of horned lizards, and within our two study locations, they revealed a distinct preference for Sandridge loamy fine sand over other available soil types. The lizards used kangaroo rat burrows rather than shrubs for heat refugia but used shrubs frequently as an escape from predators. Food items found in scats were predominantly ants, but beetles and other arthropods were also found in large numbers.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Jones, Maureen Gertrude
- Description:
- In most temperate coniferous forests, the vast majority of vascular plant species richness can be found in the understory layer. While the large-scale conversion of forests to plantations has made it increasingly important to understand how understory flora responds to timber harvesting, there is a surprising paucity of data concerning this topic. Ideally, long-term studies using permanent plots would be used to directly assess post-logging patterns of recovery, both for whole floras and for individual species of conservation interest. Unfortunately, these studies are lacking, and alternative approaches are critical. I used a 420 year forest chronosequence to assess the relationship between stand age, overstory cover and vascular plant understory richness and composition in one watershed in the Siskiyou Mountains of Oregon. The chronosequence consisted of six young managed (age 7-44) and nine older unmanaged (age 90-427) stands. All stands were similar in underlying geology, slope, elevation, and aspect. I found a non-linear relationship between stand age and richness, in which richness showed a steady decline as young stands entered canopy closure, then increased as stands gained older forest attributes such as light gaps and structural diversity. I also found that percent open canopy was correlated with total percent understory cover, richness, diversity and changes in species composition. In general, young stands were characterized by high shrub and graminoid cover and old stands were characterized by an abundant herb layer. In my study area, a large proportion of young managed stands are currently entering canopy closure, a stage characterized by low vascular plant species richness and abundance. I use my results to discuss the potential effects of past and future forest management on vascular plant understory species.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Humboldt
- Department:
- Biology
- Creator:
- Pucci, Jolene R.
- Description:
- Invasive plants threaten native biodiversity and ecosystem function. Non-native plants can out-compete native plants for resources, reducing population sizes. For rare species, this can increase the chances of extinction. Pentachaeta lyonii is an endangered, endemic sunflower, currently ranging entirely within the urbanized Santa Monica Mountains and Simi Hills. Its former range and number of populations have been reduced in recent decades due to pressures from urbanization, and the remaining populations are in decline. This study examined the effects of competition from invasive plants as a possible cause of declines by evaluating both effects from competition and effects from community alteration. Three invasive plant groups (annual grasses, Erodium spp., and Centaurea melitensis) were studied in (1) direct competition experiments in the field and in pots, (2) observational studies comparing sites where P. lyonii is extant and extirpated, and (3) manipulative community-level experiments. In the field and pot competition experiments, all three invasive groups competitively reduced the reproductive capacity of P. lyonii, and had differing effects on P. lyonii height. Observational studies showed that the presence of annual grasses and its associated litter were correlated with extirpation, and retention of bare ground was correlated with P. lyonii persistence. Restoring P. lyonii habitat to pre-invasion conditions by removing non-native plants, scraping the soil surface, and adding cryptobiotic crust increased native species richness and reduced the cover of annual grasses. Seeding P. lyonii increased its density in existing sites, and was successful in establishing plants in new sites. Removal of invasive plants and their associated litter in P. lyonii habitat, and seeding existing and new populations are recommended for restoration and recovery of the species.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Schmidt, Susan Yolande
- Description:
- The growth in length and weight of immature fruit and seed of carob (Caratonia siliqua L.) was studied over a period of seven months. During the early periods of development, seed and fruit growth follow a parallel course; however, the seed continue to grow even after the fruit growth has ended. The embryo and endosperm grow at a faster rate than the seed coat during this later phase of growth. Extracts for growth inhibitors were also made from the developing fruit. All the extracts were significantly inhibitory in the pea bioassay at concentrations of extract from 0.5 mg FW/plant. During the last two months of growth prior to desiccation quantitative extractions of inhibitor from the seed coat, endosperm and embryo were made. At least 92% of the inhibitor in the seed is concentrated in the seed coat. The whole extract and one partially purified fraction, C, were studied for the effect of germination of ripe carob seed. They were found to delay germination, inhibit the growth of the germinating seed, and to decrease the amount of reducing sugar in the medium of the germinating seed. It is inferred that the inhibitor imposes a block to either the synthesis or the release of enzyme(s) involved in the breakdown of the reserve galactomannnan.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Brisson, Chelsea
- Description:
- Quantifying the effects of bacterial communities and temperature on coral-associated endosymbionts adds to our understanding of coral health. Genetic variation in endosymbionts may increase the fitness of the holobiont - coral and associated microbes - during periods of temperature stress by increasing the breadth under which symbiosis can be maintained. Increased temperatures and variation in the bacterial communities that endosymbiotic cells interact with were replicated in lab experiments with isolated strains of Breviolum antillogorgium, a photosynthetic coral endosymbiont. The novel bacterial communities were isolated from each endosymbiont strain, or "genotype", or sampled from the original marine environment. Every genotype was inoculated with each bacterial community in a full reciprocal transplant at two temperatures in order to assess the effects of bacterial community and temperature on the physiology of the endosymbionts. Each endosymbiont genotype was associated with a distinct bacterial assemblage, which had significant effects on some of the physiological traits generally assigned as endosymbiont/algal traits. The endosymbiont genotype had a significant effect on growth rate, but the bacterial community explained more of the variation in photosynthetic rate and efficiency, respiration rate, chlorophyll a, and nitrate. Temperature played a significant role in endosymbiont growth rate, photosynthetic rate, and respiration, independent of the bacteria present. The bacterial community associated with genotype 16-0630 was the most stable; the initial diversity did not change regardless of which endosymbiont genotype was present. The environmentally-collected bacterial community decreased in diversity throughout the experiment and did not alter the fitness of the endosymbionts. At elevated temperatures, neither the bacterial communities examined nor the genotype had a significant effect on physiological traits. Physiological traits that are important to the mutualism with coral are susceptible to change in the presence of different bacterial communities at ambient temperatures. Future work analyzing the physiology of these important dinoflagellates should control for the bacterial community; providing a beneficial bacterial community post-thermal stress periods could be a method of aiding coral survival.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Chand, Shristi
- Description:
- Bacterial second messenger, c-di-GMP, regulates important functions such as biofilm formation, motility, and virulence. C-di-GMP also has an immunostimulatory property, so can be used as a vaccine adjuvant. In this project, DgcZ (a diguanylate cyclase) was engineered to create hyperactive mutants in c-di-GMP production. For this, two protein sites were targeted: substrate (GTP) binding site and product (c-di-GMP) inhibition site. At the GTP binding site, three residues (L134, D182 and R204) were tested through codon randomization and in vivo c-di-GMP production assay, but none of the positions provided high activity DgcZ mutants superior to wild type DgcZ. In contrast, the engineering at the product inhibition site was fruitful as superior mutants could be made at both R197 and E200 positions. So far, R197T, E200A and E200G were identified to be better than wild type DgcZ in in vivo c-di-GMP production based on both Clp toxicity-masking assay and c-di-GMP toxicity assay. These mutants were toxic to the host cell when highly produced. The toxicity problem was circumvented by tagging one of the mutants (E200A) with PelB, a signal sequence to the periplasmic space, at the N- terminus and the fused PelB-E200A was not toxic to the cells. In the future, the resultant PelB-E200A needs to be tested thoroughly through protein expression, purification and in vitro c-di-GMP production assay for mass production of c-di-GMP.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Fresno
- Department:
- Biology
- Creator:
- Thomas, Daniel Franklin
- Description:
- Hereditary Inclusion Body Myopathy (HIBM) is a homozygous recessive disorder characterized by the M712T mutation. Humans who inherit this disorder develop skeletal muscle wasting, which is largely attributed to a sialic acid deficiency. In order to develop a treatment for HIBM, a suitable animal model must be developed. Thus, my aim was to use the rotarod mechanism to determine if mice homozygous for the HIBM disorder developed a similar phenotype as humans. I also aimed to determine the differences in litter sizes between affected and normal mice. I used the rotarod treadmill to assess the muscular strength of three groups: mice homozygous, heterozygous, and wild-type for the mutant M712T allele. I also compared the litter sizes of both heterozygous and normal mice breeding pairs. To perform genotyping on the mice, I used polyacrilamide gel electrophoresis. I found that there were insignificant differences between the three groups regarding rotarod performance time. As a group, heterozygotes performed the worst (1.30 seconds), followed by homozygotes (1.37 seconds), and then wild-type mice (1.60 seconds). Also, the strain of the mice dictated the severity of the M712T mutation. Regarding litter sizes, normal mice had greater litter sizes than mice heterozygous for the M712T mutant allele. Either our rotarod machine is not an ideal indicator of animal strength, or mice with the M712T mutation do not exhibit the muscle-wasting phenotype. The experiment should be repeated with a larger sample size, and histology studies should be performed to confirm the presence of muscle wasting.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Mor, Carolina
- Description:
- The oceans have absorbed excess carbon dioxide (CO2) resulting from anthropogenic activities such as the burning of fossil fuels and deforestation. As a result, seawater chemistry has shifted causing an increase in bicarbonate ions (HCO32-) and hydrogen ions (H+) and leading to a reduction in carbonate (CO32-) concentration. This shift in seawater chemistry leads to a decrease in aragonite saturation state and pH. Eventually, the ocean will accumulate most of the extra CO2 produced over many years resulting in extreme acidified conditions where aragonite saturation levels will not support the chemical process of calcification that is vital to marine calcifiers. This thesis investigates the combined effects of elevated pCO2 with temperature and light on the calcification and photosynthesis of the green calcareous algae Halimeda. Halimeda, is a major contributor to sediment production for coral reef accretion and island reef formation. Based on carbonate data from biologists and geologists it is estimated that vertical accretion of CaCO3 by Halimeda ranges between 0.18 to 5.9 m in 1000 years. The role that light plays in the coupling between photosynthesis and calcification in Halimeda macroloba was investigated experimentally through a combination of two pCO2 levels (360 and 1200 uatm) and three irradiances (80, 150, and 595 μmol quanta m-2 s-1). A decrease in calcification at low light intensity and elevated pCO2 suggests that light is a limiting factor for the physiology of H. macroloba. The effects of elevated pCO2 and temperature on the photosynthesis and calcification of Halimeda incrassata were tested through two experiments using two pCO2 levels (390 and 900 uatm) and four temperatures (26, 29, 30 and 34 °C). Elevated temperature can mitigate the effects Ocean Acidification (OA) in H. incrassata. An estimate of current carbonate production by H. incrassata in Key Biscayne Florida Lagoon was obtained from biomass, CaCO3 content and turnover rate. Calcification rates from laboratory experiments were used to estimate future (200 years from now) seasonal carbonate production rates, which were then compared against current summer carbonate production. Future summer carbonate production rates were not affected by elevated pCO2 in relationship to current summer carbonate production. Elevated temperatures ~2 °C above summer maximum average could promote calcification of H. incrassata under ocean acidification conditions and, therefore, overall carbonate production of the reef. Results throughout the thesis revealed that the tolerance of the green calcareous algae Halimeda to OA could change depending on light and temperature conditions. In a more acidic future ocean, growth rates and sediment production of Halimeda will be affected under low light and temperature and will be enhanced under high light and and moderate elevated temperatures.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
55. Localization of a 3.7 KB plasmid of Polytomella Parva using photobiotin as a non-radioactive probe
- Creator:
- Williams, Jeffery Morris
- Description:
- The electrophoresis of whole cellular DNA from the non-photosynthetic alga Polytomella parva revealed a distinct 3.7 kb band. This band of DNA was isolated from the agarose gel and used to construct a non-radioactive probe utilizing Photobiotin. Cellular fractions were then isolated by sucrose gradient centrifugation and the mitochondrial fraction identified by succinic dehydrogenase activity. DNA was then isolated from the fraction that showed maximum enzymatic activity and used as a target for the 3. 7 kb Photobiotin probe in a Southern Transfer procedure. A successful annealing of the Photobiotin probe with a similar 3.7 kb segment of DNA is mitochondrial in origin. Lack of annealing with the nuclear and mitochondrial chromosomal DNA indicates that its sequence is not present in those DNA fractions. The Photobiotin probe was used to visualize the plasmid by attaching colloidal gold labeled avidin to the probe. The electron-micrographs indicate that the plasmid may be linear in structure.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Bowman, Carla Jeanne
- Description:
- Investigation into the acclimation patterns of Embryonic Limax flavus clearly suggests that heart rate, when measured over a period of time or throughout a temperature range) shows compensatory response patterns similar to those described for oxygen consumption and other rate functions in the adults of this species. The sequence of larval development described by prior workers has been more precisely defined by detailed analysis of phases in the development of two larval organs, the anterior cephalic vesicle and the posterior podocyst. Several unreported relationships were suggested by this analysis. It appears that, at least at lower temperatures, the cephalic vesicle and, to a lesser degree, the podocyst may change pulsation rate or even developmental phase in response to temperature change. These larval organs may play an important adaptive role in the response of the embryo to a varying natural environment. It was determined that the heart begins to beat between day 25 and 30 in most embryos developing at 10°C.. Acclimation studies are reported on over 700 embryos. Compensatory response to higher temperatures was demonstrated within 48 hours. Acclimation patterns at lower temperatures were not so clear and required an additional analysis due to the activity of the larval vesicles and prolonged periods of no observable heartbeat. When the rate -temperature curves of the heart beat are plotted for animals maintained at 6°, 10° 15°, 20° and 25°C and measured acutely at a series of temperatures from 6° to 25°C, translation is demonstrated in which the curve is shifted to the left or up after cold acclimation and to the right or down after warm acclimation. No change in slope or rotation of the rate-temperature curve appears within the normal temperature range. Homeostatic mechanisms do exist in the developing embryos which allow it to make adjustments to a constantly changing natural environment.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Ireland, Joseph
- Description:
- Nostoc punctiforme is a filamentous cyanobacterium capable of multiple cellular differentiation from vegetative cells into akinetes, heterocysts and hormogonia. In order to control this differentiation, tight regulation of gene expression is required. Previously, a model system was developed for Nostoc punctiforme involving a glucose-6-dehydrogenase mutant strain of N. punctiforme (zwf mutant) that forms akinetes at high frequencies following a switch from photoautotrophic to dark heterotrophic growth condition in the presence of fructose. From this model system, a hormogonia/akinete peptidase (aapN) gene was identified as an up-regulated gene during akinete formation by differential display and microarray analysis. A reporter strain of aapN was created by transcriptional fusion of the promoter region to a promoterless gfp-gene in the pSUN119 plasmid, which further showed transcriptional expression specific to akinetes and hormogonia (Argueta et al., 2006). Random amplification of cDNA ends (RACE) analysis was used to identify the transcriptional start sites for the aapN gene as well as two transcriptional start sites for the upstream putative dnaK heatshock gene (NpR5998). ix Bioinformatic analysis of orthologous genes in closely related cyanobacteria identified conserved sequences in the intergenic region upstream of the +1 transcriptional start site suggesting putative relevancies to transcriptional control. To elucidate the important areas of the promoter region for these for transcriptional or translational control, a series of labeled promoter fragments of increasing length were fused to GFP in the pSUN119 plasmid and electroporated into N. punctiforme wild-type to create a series of reporter strains. Epifluorescence microscopy following akinete induction indicated the cis-acting regulatory element required for silencing gene transcription was located downstream in the aapN open reading frame. Experimental results from the reporter plasmids (GFP fused with aapN promoter fragments) showed that the smaller fragments (59 bp - 381 bp) had zero capacity at silencing gene transcription regardless of cell type (akinete, heterocyst, hormogonia, and vegetative). It was a 516 basepair promoter fragment that reached 240 basepairs past the putative aapN translational start site and into the open reading frame length that achieved tight negative regulation of gene transcription. Subsequent longer promoter fragments repeated the same result of tight negative regulation.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Bar-Lew, Schmuel Sanford
- Description:
- Conidiation in N. crassa can be either induced or suppressed by altering the growth media. When grown in standing cultures, strain Lind+ forms about 105 conidia per ml of medium. This conidial production occurs during the second to fifth day. The level of the enzyme NADase, which destroys NAD and NADP, rises more than twenty-eight fold during conidiation. At the time of peak activity of NADase, the NAD level falls to less than one-tenth the level of nonconidiating cultures, and the NADP content falls to undetectable levels. NADH and NADPH levels of conidiating cultures are slightly higher than those of nonconidiating cultures. As a consequence, the total pyridine nucleotide content of conidiating cultures is about one micromole per gram dry weight at the time the rate of conidial formation is highest, whereas it is sixty to ninety percent higher in cultures that do not form conidia. The ratio of oxidized to reduced pyridine nucleotides is greater than 1:1 when conidiation does not take place. However, during conidial formation, this ratio drops to 1:20. The effects that the altered levels of these key coenzymes could have on many areas of metabolism are considered.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Garner, Daniel J.
- Description:
- The purpose of this investigation was to study the metabolism of three species of young and adult Peromyscus by means of oxygen consumption. Young Peromyscus were used to determine the timing of the onset of homeotherapy and to ascertain whether age or weight triggered the onset. The zone of thermal neutrality for P. maniculatus was 22.5C - 25 [degrees]C and for P. californicus was 20 [degrees] C - 25 [degrees] C. In P. boylii only one point was determined, 25 [degrees] C for the temperature intervals used in this study. The mean basel metabolism of adult P. maniculatus is 3.8 cc of oxygen per gm hr at 25 [degrees] C, and of P. californicus 1.9 cc of oxygen per gm hr at 25 [degrees] C. In developing young there is a linear relationship between weight and metabolism. The onset of homeothermy in three species of Percmyscus is a function of weight, and homeothermy is fully developed in the three species of Peromyscus prior to weaning.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Karabidian, Eddie
- Description:
- A variety of models of cell adhesion have been proposed by previous investigators; each depended heavily on details of the biochemistry of cell surface sugars. In this study, Lytechinus pictus sea urchin embryos were used to study the molecular mechanisms involved in cellular interaction. The interaction between the tip of the archenteron and the blastocoel roof during gastrulation in sea urchin embryos has been of interest to developmental biologists for over a century. This interaction is fundamental to morphogenesis. An understanding of the molecular mechanisms of the interaction between the archenteron and the blastocoel roof will be of major importance to the field of cell adhesion. These findings will provide a better understanding of what goes wrong in abnormal adhesive interactions, which may lead to diseases such as cancer. This is why the National Institute of Health (NIH) has designated the sea urchin embryo as a model system for studying basic mechanisms in human heath and disease. Here, we examined the effects of two glycosidases (sugar cleaving enzymes) on the surface of the sea urchin embryo cells. The enzymatic activities of two commercially prepared glycosidases were verified by direct chemical assays on known substrates as well as live and fixed sea urchin material to determine the interaction of the tip of the archenteron and the blastocoel roof. SDS-PAGE was carried out to measure possible protease contamination and the purity of the glycosidases. Azocoll test was also performed in order to check for cryptic protease activity. The results suggested there was no detectable smearing or degradation of the substrate and only minor levels of contaminating protease activity. In order to find out if sea urchin embryos have exposed glycans that can be degraded by α-amylase or α-glucosidase live and fixed embryos were disrupted and were used as substrates for these enzymes. A colorimetric assay with 3,5-dinitrosalicylic acid was used to measure the amount of maltose released. α-amylase enzyme did not release detectable amounts of maltose from embryos exposed to formaldehyde for long periods of fixation, but did release small amounts of maltose from live embryos or embryos fixed for shorter terms (1 day). These results suggest that the enzyme we use has specific sites of cleavage that may become inaccessible during long-term formaldehyde fixation. α-glucosidase released a small amount of maltose from the substrate sea urchin. To confirm that the sea urchin embryos do not release inhibitors of α-amylase and other glycosidases, mixed reactions were also conducted in which the defined substrates were tested in the presence of long-term fixed sea urchin embryos. The results suggested that there was no evidence of inhibition of these enzymes. I incubated glycosidases (active and denatured) on microdissected archenteron and blastocoel roofs in adhesion assays to learn if they directly inhibited the adhesive interaction. α-amylase had no effect, while α-glucosidase only substantially inhibited adhesion after 12 hours incubation. While glycans have been implicated in mediating this cellular interaction, this is the first study that directly implicates polyglucans with exposed 1,4 terminal ends in the adhesion of the archenteron tip and blastocoel roof.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Koprowski, Edward Vincent
- Description:
- Cultures of a serine auxotroph of Neurospora crassa, ser (JBM 4-13), demonstrate a high frequency of spontaneous reversion to prototrophy. This study examines two questions: First, whether the phenomenon of spontaneous reversion occurs in all vegetative cultures and, second, whether reversion occurs in stored ascospores. Eight vegetative cultures, which had not shown reversion from ser (JBM 4-13) to wild-type in a previous study, were repeatedly tested for the presence of revertant nuclei. Each of the eight stocks ultimately displayed a high frequency of revertant nuclei during a study of serial subcultures of the mutants. Reversion of ascospores stored in water at different temperatures was examined in the second part of this study. Results obtained over a twenty-week period indicated that reversion of ser (JBM 4-13) does not occur at any temperature in stored ascospores. During the course of this study freeze-drying was to be used to exclude the possibility of DNA synthesis during storage. This treatment was found to result in total inviability of ascospores. Separate factors involved in the freeze-drying technique were examined to determine the cause of lethality. Results reported in this thesis indicate that reversion of ser (JBM 4-13) is a property of all vegetative cultures of the mutant and does not occur in stored ascospores.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Brown, Darren James
- Description:
- Motivated by the growing number of studies reporting inter-specific differences for the effects of OA on calcifying taxa, this study tested the hypothesis that taxonomically diverse calcifying cnidarians show differential responses to OA. Phylogenetic analyses show that the Scleractinia consist of two clades (Robusta and Complexa), with the split between the two occurring prior to the evolution of calcification. Further, milleporine hydrocorals arose after the Scleractinia in seas of different chemical composition. The potential for the Robusta, Complexa, and milleporines to represent different responses to OA due to independent evolution of calcification contextualized the present analysis. Scleractinians representing Robusta (Pocillopora meandrina) and Complexa (Porites spp. and Acropora pulchra) as well as the milleporine hydrocoral (Millepora platyphylla) were grown in 3 PCO2 regimes (400, 750 & 900 μatm) crossed with 2 temperatures (28.0 & 30.1 °C), with calcification measured after 3 weeks. Porites spp. and A. pulchra (= Complexa) and M. platyphylla were unaffected by PCO2, while calcification in P. meandrina (= Robusta) declined 33% and 55% at high PCO2 (750 & 900 μatm respectively) and 30.1 °C. These patterns clearly demonstrate differential responses to OA among phylogenetically diverse taxa, and raise the intriguing possibility that differential evolution of calcification could modulate the impacts of OA on these taxa. Due to differences in the response between Pocillopora meandrina and Millepora platyphylla to OA, I tested the hypothesis that the scleractinian, Pocillopora meandrina, and the hydrocoral, Millepora platyphylla, respond differently to increased PCO2 due to differential utilization of particulate food. To test this hypothesis, PCO2 treatments of 380 μatm and 710 μatm, were crossed with feeding treatments created through the supply of seawater filtered to ~100 μm (control zooplankton), seawater filtered to ~2 μm (low zooplankton), or seawater enriched with natural zooplankton (high zooplankton). M. platyphylla was unaffected by increased PCO2 at control and low zooplankton treatments, but high PCO2 increased calcification 19% in the high zooplankton treatment. P. meandrina was unaffected by increased PCO2 at the control zooplankton treatment, but increased PCO2 decreased calcification 32% and 29% for high and low zooplankton treatments, respectively. In control and low feeding treatments, calcification of M. platyphylla, may be nutrient limited, with the effect removed with additional zooplankton. P. meandrina interacts with food in different ways, as calcification was depressed by PCO2 both when additional zooplankton were supplied and when the smallest particulates were removed, but not with access to control seawater. We speculate that the differences between scleractinian and hydrocorals in their response to PCO2 as a function of food supply may reflect the evolutionary origins of these taxa in ancient seas differing in chemical composition.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Adamian, Yvess
- Description:
- Metastatic breast cancers carry a 5-year survival prognosis of less than 20%. Thus, it is highly desirable to identify therapeutic strategies that specifically target both primary and metastatic tumors. It is generally accepted that epithelial-mesenchymal transition (EMT) is an important component of the metastatic cascade in solid tumor types such as breast cancer. In this regard, we have previously established that PEAK1 promotes breast cancer metastasis by switching Transforming Growth Factor β (TGFβ) signaling toward its EMT-promoting functions. Eukaryotic Initiation Factor 5A 1/2 (eIF5A1/2) are unique translation factors in that they are the only known protein substrates for the post-translational hypusine modification - a key modification required for eIF5A translation activity. Since eIF5A is required for Pseudopodium-Enriched Atypical Kinases 1 (PEAK1) translation, we hypothesized that TGFβ may induce PEAK1 upregulation during EMT by directly activating the eIF5A hypusination pathway. We show evidence of an active eIF5A/PEAK1 pathway in undifferentiated, mesenchymal breast cancer tissue. Notably, inhibition of eIF5A hypusination blocks PEAK1 translation, cell viability and TGFβ-induced EMT in breast cancer cells. In this regard, we demonstrate that TGFβ induces post-translational hypusination/activation of eIF5A in metastatic breast cancer cells. While it remains to be determined whether canonical TGFβ signaling factors directly activate hypusination pathway enzymes, TGFβ is known to activate other eIF5A regulatory enzymes that have previously been reported to mediate EMT in breast cancer. For example, TGFβ-induced EMT requires Activin Receptor Type-1B (ACVR1B/ALK4)-dependent Histone Deacetylase 6 (HDAC6) activation and HDAC6 promotes eIF5A deacetylation leading to its rapid nuclear export and hypusination; therefore, we hypothesize that cytoplasmic localization of eIF5A and eIF5A hypusination are required for cell proliferation/survival and TGFβ-induced EMT in breast cancer. Since HDAC inhibitors are promising new anti-cancer agents being evaluated in clinical trials, we designed experiments to test whether blockade of eIF5A hypusination could increase the potency or efficacy of HDAC6 inhibitors. Most notably, we demonstrate that dual treatment with non-cytotoxic doses of HDAC6 and eIF5A hypusination inhibitors synergize to potently and selectively kill metastatic breast cancer cells and block TGFβ-induced EMT. This also resulted in a further accumulation of eIF5A in the nucleus regardless of TGFβ treatment. In this regard, we have formulated a pathway in which we believe TGFβ stimulates HDAC6 and DHPS function to export eIF5A into the cytoplasm and promotes PEAK1 translation to result in EMT, invasion and metastasis in breast cancer cells. Taken together, these results pave the way for pre-clinical trials designed to selectively target breast cancer metastasis.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Rhoades, Nicholas
- Description:
- The human gut is home to trillions of microbial cells whose functions are essential for normal human physiology. However, quantitative linkages between diet and gut microbiome composition are lacking, particularly in post-weaned, pre-pubescent children. To address this knowledge gap, we conducted a community-based research project at a children's center located in Los Angeles, CA. Study participants (n=70, 2-8 years old) provided one fecal sample and three dietary recalls of the foods consumed over a 24-hour period. Dietary data was averaged across the three recalls to approximate the average daily intake of each child. Functional capacity of the gut microbiome was assessed using shotgun metagenomic sequencing on an Illumina HiSeq, yielding 334.3 Gbp of clean sequence data. Average dietary intake was disaggregated and converted into macro- and micronutrients using ASA24, a program developed by the USDA. Taxonomically, an individual's gut microbiome could be clustered into two groups based on the abundances of the Bacteroidetes and Firmicutes phyla. These taxonomic differences strongly correlate to functional differences such as the gut microbiomes ability to metabolize starch and synthesize vitamins. When we scale nutrient intake by the recommended daily allowance for each subject, many species level and functional attributes were correlated with consumption of specific dietary features such as processed grains, vegetables, B-vitamins, and zinc. The strongest relationships we observed were between microbiome features and a select set of micronutrients (zinc, folate, iron, Bvitamins). These nutrients co-varied suggesting a common food source, most likely enriched and fortified grains. Only by understanding relationships between diet and gut microbiome function in diverse populations of healthy individuals during different lifestages will we be able to link subtle changes in the gut microbiome with human health outcomes later in life.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Grenfell, John Kemp
- Description:
- The feeding behavior of five species of tellinaceans was studied in four locations in California, USA. The organisms were studied in areas where they occurred sympatrically with other tellinaceans and in other areas where no other tellinaceans were present., Random samples were taken to determine population densities. Shell sizes were measured to determine if there was any difference due to competition. Each population was examined to ascertain the type of feeding behavior. Feeding behavior was determined from the stomach contents and from the behavior of the inhalent siphon. It was observed that when closely related species occur in the same location they exploit different microhabitats. Some organisms use suspended material as their primary food source, while others ingest deposits. Macoma nasuta is a deposit feeder when not in competition with other tellinaceans, but fed on both deposits and suspended material when coexisting with other deposit feeding Tellinacea. There is not any significant change in the population denslty or shell size which can be attributed to differences in feeding behavior. Growth of tellinacean species was the same in different geographical locations.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Swanson, Stella A.
- Description:
- Recent studies suggest that species identity is of great importance in determining how herbivores structure coral reef communities. This study provides evidence that echinoid species differentially shape the community through unique feeding strategies and abilities. In Moorea, French Polynesia, the echinoids Diadema savignyi, Echinothrix diadema, Echinothrix calamaris, Echinometra mathaei, and Echinostrephus aciculatus differ both morphologically and behaviorally. They range from grazers, traveling distances of meters at night, to others utilizing a suspension feeding strategy and these differences impart differential abilities to influence the benthic community. By examining benthic community patterns on the coral reefs of Moorea on a small (<1 m2) spatial scale and at a larger (individual coral bommies several m2 in size) scale, this study reveals species-specific effects of echinoids on benthic community structure. Analysis of photoquadrats (25 x 25 cm) surrounding Echinometra mathaei and Echinostrephus aciculatus revealed that they are associated with benthic cover of crustose coralline algae and algal turf, respectively. Multivariate analyses revealed that on the scale of individual coral bommies only D. savignyi is correlated negatively with macroalgal cover and positively with coral cover. Despite having a less robust Aristotle's lantern, D. savignyi has greater mobility than E. mathaei and therefore likely removes more macroalgal biomass per unit area per time. The differential ability of the echinoids D. savignyi and E. mathaei to reverse a phase shift from macroalgal dominance was tested by manipulating echinoid densities on artificial reefs established with the macroalga Sargassum pacificum. Macroalgal cover decreased significantly only on reefs with D. savignyi, indicating a greater ability of D. savignyi than E. mathaei to alter community structure and potentially reverse a phase shift from macroalgal dominance back to coral dominance. These results are consistent with benthic patterns found on Moorea coral reefs and demonstrate the ecological importance of species-specific interactions shaping reef communities. A second portion of this study examined the distribution, abundance, and unique feeding behavior of the echinoid Echinostrephus aciculatus in order to understand the different role these echinoids play on contemporary coral reefs. Most echinoids function as grazers on the benthos and occasionally capture drift macroalgae from the water column. E. aciculatus, however, appears to be a suspension feeder, and unlike many reef echinoids, does not influence benthic community structure adjacent to their burrows. Feeding experiments in a laboratory flume demonstrated E. aciculatus captured pieces of the macroalga Sargassum pacificum and were more successful at capturing algae in flow speeds similar to what they experience in the natural environment (12 cm/s) compared to high (26 cm/s) flow. However, periods of high water motion likely are important for dislodging and delivering macroalgal fragments to the backreef environment and under these conditions large quantities of drift algae may provide a critical food source to these suspension-feeding echinoids. In the field, E. aciculatus were 2.25-times more abundant, exhibited larger test sizes, and had greater gonad indices in habitats close to the macroalgal-dominated reefcrest compared to 200 meters downstream and in this location, there was a greater quantity of drift algae available. These findings suggest that the distribution and success of E. aciculatus is driven by food availability, which is greatest behind the reefcrest in comparison with downstream habitats. If coral reefs continue to transition toward macroalgal dominance, species such as E. aciculatus may benefit from increased particulate drift algae and become a more prominent member of these coral reef communities.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Saxton, William Manning
- Description:
- Applications of a low-speed centrifuge rotor designed to separate whole cells at very low g-forces in partially reoriented, shallow density gradients are presented. The particle separation chamber was fabricated using Lucite so that gradient behavior and particle sedimentation could be monitored visually during rotor operation by using stroboscopic illumination. Runs were recorded on videotape for later study and frame-by-frame analysis. Rotor performance was tested using a model system consisting of polystyrene microspheres of known sizes and densities. The resolution obtained exceeded that of previously reported centrifugal separations. Cells from an ascites-grown tumor were separated into three discrete subpopulations. Cells comprising each subpopulation were characterized in terms of size distributions and sedimentation rates. Experimental results are discussed in relation to theoretical considerations about the behavior of particles in partially reoriented density gradients.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Zimmermann, Sigfrido
- Description:
- Scleractinian abundance has declined over the last few decades on most coral reefs. This reduction in scleractinian cover is associated with multiple types of disturbances including outbreaks of predators and diseases, mass coral bleaching, storms and overfishing of key grazers. Disturbances lead to dramatic changes in community structure that can lead to a phase shift of one group of dominant organisms by another. On coral reefs, such transformation can affect the abundance and community structure extending from a decline in abundance of scleractinians to an increase in abundance of sponges, octocorals, and most commonly, macroalgae. Coral post-settlement growth and survival, and competition are major forces driving community structure of coral reefs, both of which are essential in understanding the decline or recovery of scleractinian populations on coral reefs. This study examined the effects that microhabitats have on coral post-settlement growth and survival in the reefs of Moorea, French Polynesia, and the effects of competition between an aggressive peyssonnelid algal crust (PAC) on scleractinians and octocorals on the reefs of St. John, US Virgin Islands. Coral reefs of Moorea, French Polynesia have suffered several major disturbances over the last decade, from a crown-of-thorns seastar outbreak, Cyclone Oli, and bleaching events. However, coral populations on Moorea, specifically Pocillopora spp., have been able to recover within 5 years and theoretically are capable of producing sufficient larvae to support local recruitment following disturbances. In this study, I describe the results of an experiment designed to examine the distribution of juvenile Pocillopora spp. colonies in microhabitats across the back reef and to evaluate the roles played by microhabitats affecting juvenile coral growth. In 2017, juvenile corals growing at 3-m depth in the backreef were less abundant on crevice microhabitats (narrow-deep and shallow-wide) compared to no crevice microhabitats. Furthermore, juvenile corals calcified less in deep-narrow crevices compared to shallow-wide crevices. In the Caribbean, PAC has emerged as a possible threat to shallow coral reefs in the region. In 2010, PAC was documented in Lac Bay, Bonaire, where it rapidly spread and overgrew many sessile benthic organisms including scleractinians. PAC has also appeared in Puerto Rico, Jamaica, and the Virgin Islands. In this study, I describe the extent of PAC on shallow reefs of St. John, US Virgin Islands and its effects on other sessile benthic organisms. In 2015 along the south of St. John, PAC cover ranged from 0.2 - 20.6% of the benthos. By 2017 at the same sites, PAC covered 3.2 - 61.0% of the benthos. In August 2017 at 5-m depth at 10 sites, PAC cover was 1.4 - 61.6% and at 9-m depth, PAC cover was 0.8 - 41.0%. Scleractinians and octocorals were in frequent contact with PAC (42 - 47% of colonies), however scleractinians (74% of colonies) were more frequently being overgrown by PAC compared to octocorals (39% of colonies). St. John was struck by two category 5 hurricanes in September 2017, and total cover of PAC decreased from 26% in August 2017 to 23% in November 2017. The present study shows that PAC may have a large impact on the community structure of shallow Caribbean reefs, accentuating the trend of community shift from scleractinians to macroalgae.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Vigil, Luigi
- Description:
- Phorid fly parasitoids of ants are capable of decapitating their host during development and have been used as attempted biological control agents for imported fire ants. Little is known about the interactions between the native Velvety Tree Ant host, Liometopum occidentale, and its phorid fly parasitoids. This system is native to Southern California, occupying endangered habitats that have been in decline due to human development, changing weather patterns, and fierce competition from invasive species. To further understand the ecological significance and behavior of this system, I examined interactions of these parasitoids and the Velvety Tree Ants by observing and quantifying the behavioral displays exhibited in the presence of phorid fly parasitoids. To understand parameters of activity of the parasitoids, I measured temperature and time of day through five temporal periods encompassing the parasitoids' season. Two different phorid species were found attacking Liometopum occidentale: Pseudacteon californiensis Disney and an undescribed species of Pseudacteon herein designated Pseudacteon sp A. Because P. sp A keys to the genus Microselia Schmitz, I carried out molecular analyses to determine the phorids' evolutionary relationships. Based on analysis of three gene regions, Pseudacteon sp A and Pseudacteon californiensis are sister-species relative to other Pseudacteon parasitizing Solenopsis fire ants. The status of some North American phorid species, currently assigned to Microselia, needs to be further investigated.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Kass, Danny Martin
- Description:
- The effects of the telomere, centromere, and centric heterochromatin on recombination were assessed using two paracentric inversions, scute-4 (sc4) and scute-8 (sc8) in both homozygous and heterozygous combination. The centromere effect was verified by the results, with regions brought by inversion into close proximity to the centromere exhibiting reduced recombination. In addition, this study suggests that heterochromatin acts as a buffer zone with respect to the inhibitory effects of the centromere and telomere. An intrachromosomal effect of inversions on recombination was noted in the sc4 /sc8 studies, indicating that synapsis and recombination were entranced by structural heterozygosity in the heterochromatic regions of these chromosomes. Heterochromatic recombination was tested in inversion sc8 homozygotes and in sc4/sc8 heterozygotes with results indicating that heterochromatin does not recombine more readily when removed from centric inhibitions.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Cassell, Ronald Zachery
- Description:
- Mitochondrial differentiation and development within Fucus sperm is characterized by a series of internal rearrangements and mass acquisitions relating to overall form and organelle disposition within the mature sperm cell. Moreover, it seems clear that these changes are essential to the functional mode of these free swimming cells in a hazardous environment. Among the more notable structural changes are: increase in the number of cristae, density changes of the matrix and cristae spaces, enhanced membrane staining, appearance and disappearance of inclusions, cristae alignment and reorientation and, of special interest, the formation of intracristal components within all cristae of mature sperm. The intracristal comuonent appears to signal functional capacity for these cells, and its ubiquitous nature marks it f0r taxonomic importance for this group of algae as well. Collectively, these changes represent multiple transformations of the mitochondria in Fucus sperm cell development.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Kaiser, Joshua Daniel
- Description:
- Bone marrow transplantations for leukemia patients are currently limited because Hematopoietic stem cell (HSC) ex vivo expansion is constrained. We investigated a cell surface marker, GPI80, which isolates for a purified population of human HSC in the fetal liver. After identification of GPI80 in the placenta and BM, we were able to track HSC with GPI80 throughout fetal development. Next, detection of GPI80 on limited hematopoietic lineages allowed us to characterize unique HSC pathways. Finally, the colocalization of GPI80 with integrin alphaM suggests a regulatory role for GPI80 during HSC migration. In conclusion, GPI80 allows tracking of human HSC throughout fetal development and will aide in understanding the difficulties of HSC ex vivo expansion.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Zalusky, Steven Leigh
- Description:
- The cranial osteology of the genus Uma is described in detail, interspecific variation is analyzed, and the natural selective forces which produced this variation are discussed. The variation is interpreted with respect to the phylogeny and biogeography of the genus. Statistically significant interspecific variation was found in seventeen of the twenty-one skull characters examined in this study. Based on these characters, the genus Uma has been divided into subgroups: a southern one consisting of U. exsul and U. paraphygus and a northern one consisting of U. notate, U. inornata and U. geoparia. The major source of variation distinguishing these subgroups is in their dentition. This divergence appears to be the result of natural selection operating through diet. Uma inornata is more phenotypically similar to U. scorparia than to U. notate. This relationship is consistent with previous comparative physiological studies of the genus but not with comparative studies of external morphology or behavior. The latter indicate that U. inornata is more similar to U. notate than to U. scoparia. This pattern of variation can be explained in terms consistent with the phylogeny of the genus Uma as proposed by Norris (1958).
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Baresi, Lee Alan
- Description:
- A cell line of Polytomella parva resistant to the metabolic inhibitor antimycin A was isolated. These cells are resistant at a concentration of 2 X 10-5M. Studies on the growth of this resistant cell line (designated P. parva 17-9AA) showed significant changes over that of control cells. Resistant cells in the presence of antimycin have a longer lag phase and generation time than control cells. Resistant cells in antimycin also show an extended stationary phase compared to control cells, and lack the ability to produce cysts. Resistant cells grown in a medium without inhibitor show a decrease in lag time and generation time. Respiration rates were significantly diminished in resistant cells. Resistant cells in the presence of antimycin A respire at a rate approximately 80% that of control cells. Resistant cells show a 1.5 fold increase in specific activity of both succinate and NADH dehydrogenase over control cells. Cytochrome c oxidase activity in resistant cells was 78% that of control values consistent with the notion of a block in the electron transport chain between respiratory complexes I or II and complex III. The specific activity of ATPase in both crude homogenate and mitochondrial fractions was approximately 1.6 times greater in resistant cells compared to control cells. This increase in ATPase activity may provide a mechanism whereby the resistant cell compensates for the inhibition of respiratory complex III by antimycin.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Moshava, Adorina
- Description:
- In the dimorphic aquatic bacterium Caulobacter crescentus, genes are transcribed immediately before their protein products are required. Groups of genes, or genetic modules, are temporally controlled by oscillating master regulators. Oscillation is driven by cell-cycle-dependent transcription and proteolysis. One of the master regulators is the transcription factor CtrA. ctrA has two temporally regulated promoters, P1 (weak) and P2 (strong), with P1 transcription occurring prior to P2 transcription. To investigate the role of the P1 promoter in cell cycle progression, we inactivated the ctrA P1 promoter. β-galactosidase transcriptional assays in rich PYE broth indicate a ~40% reduction in ctrA transcription that results in a ~40% reduction in CtrA protein accumulation in the ctrA P1 mutant compared to wild type C. crescentus. ctrA P1 mutants with a nonfunctional P1 promoter have severe growth defects and accumulate multiple chromosomes per cell. The cells elongate and some have ectopic poles, suggesting a polarity defect. Therefore, the ctrA P1 promoter is critical for the normal growth and development of C. crescentus.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Lonquich, Paul David
- Description:
- Santa Catalina Island, twenty-two miles off the southern California coast, Has the site of a study on the ecology of feral house. cats (Felis domestica). Observation of behavior physical characteristics and capture sites were used to determine whether a cat was existing in a feral state. All cats observed or captured on the island were in good physical condition, appeared to prefer dense chaparral with rocky outcroppings and were more abundant near dumps and water supplies. Examination of the digestive tracts of twenty-three cats revealed certain food preferences; 95% of the digestive tracts contained insects, 81%had vegetation, and 64% had garbage, rodent remains were found in 41%, bird remains in 22%, and reptilian forms in 23%. Digestive tracts of 68% of the cats had internal parasites. A computer analysis of factors which would discriminate between the island sample and a sample collected from the West Valley Animal Shelter in Chatsworth, California was performed. The analysis showed that the length of the maxillary tooth row, the tympanic bulla length, the greatest width of the zygomatic arch and the mandibular length were the most powerful discriminating measurements. It is suggested that stronger controls be placed on cat owners to eliminate the constant drift of cats from populated areas in conjuction with the gradual elimination of feral cats already on the island.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Nuryyev, Ruslan
- Description:
- Background: In this study, we assessed the ability of human neural progenitor cells (hNPC) to repair and restore the function of dying neurons within the spastic Han-Wistar rat (sHW), the mutant variant of a normal Han-Wistar. The sHW rat suffers from neurodegeneration of specific neurons, including cerebellar Purkinje cells and hippocampal CA3 pyramidal cells. The sHW rat experiences symptoms of fore limb tremor, hind leg rigidity, gait abnormality, motor incoordination, muscle wasting, and a shortened lifespan, which are akin to those seen in human ataxia patients. To alleviate the symptoms of neurodegeneration and to replace dying neurons, neuronal human progenitor cells were implanted into the sHW rats. Methods: At 30 days of age, male sHW rats underwent subcutaneous implantation of an Alzet osmotic pump that infused cyclosporine (15 mg/kg/day) used to suppress the rat's immune system. At 40 days, sHW rats received bilateral injections of live human NPCs (hNPC), dead human NPCs (dNPC), live human embryonic kidney cells (HEK), or growth media (MED) either into the cerebellar cortex or hippocampus. To monitor results, motor activity scores (open field testing) and weights of the animals were recorded. Results: The sHW rats that received hNPC transplantation into the cerebellum, at 60 days of age, displayed significantly higher motor activity scores and sustained a greater weight (both p<0.05) than dNPC, HEK, MED treated sHW rats or any hippocampal group. Along with activity scores and weight, the hNPC cerebellum treatment groups elicited greater longevity (p<0.05). Conclusion: This study reveals that implanted human progenitor cells reduce the ataxic symptoms in the sHW rat, identifying a future clinical use of these progenitor cells against neurodegenerative diseases.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Spies, Brenton Tyler
- Description:
- In benthic associated fish species, the time an individual spends in the larval phase until settlement to a benthic substratum is a vulnerable and critical period determining survival. In many species, the length of this period can strongly influence dispersal potential, further affecting a species geographic range, population connectivity, and community structure. The type of habitat in which a fish resides can significantly influence its larval development due to variations in the abiotic environment, such as temperature. In addition, the degree of habitat isolation can strongly influence dispersal potential, as seen in seasonally closed, or isolated, estuaries in California when compared to fully tidal marine estuarine systems. This study examines the variations in larval traits of two California endemic gobiid species found in differing estuarine habitat types. The arrow goby, Clevelandia ios, is commonly found in fully tidal bays, estuaries, and mudflats with consistent marine influence. The tidewater goby, Eucyclogobius newberryi, is the sister species to the arrow goby, and prefers estuaries and lagoons with some degree of seasonal isolation from the sea. This habitat preference exposes the tidewater goby to much greater temperatures and limits its dispersal potential. In the first part of this study, I used otoliths to examine the larval duration, size at settlement, and pre-settlement growth rates of newly settled gobies collected in eighteen estuaries along the California coast in the summer of 2011. I found that the arrow goby, on average, had a longer larval duration than the tidewater goby, but smaller size at settlement based on back-calculated size measurement. Additionally, larval growth rate of the arrow goby was slower than that of the tidewater goby. Although variations in larval traits between these two species were significantly different, they were much more similar than initially expected. In the second part of this study, I examined the effects of temperature and latitudinal distribution on the larval traits of the arrow and tidewater goby in eighteen study systems. Hourly temperature measurements were recorded in 18 study sites in order to determine the mean temperature experienced by each fish during its larval phase. Temperatures found in seasonally closed estuaries inhabited by the tidewater goby had greater variability among sites (10o C range) than the fully tidal marine sites inhabited by the arrow goby in (5o C range). Among site variation in larval traits was greater for the tidewater goby, likely linked to the greater temperature range of seasonally closed estuaries. On average, for both species, fish that experienced warmer temperatures had a shorter larval duration, faster growth rates, and were smaller in body size (SL) at settlement. Projected increases in global temperatures will likely accelerate larval development for many species. For the arrow goby, tidewater goby, and related estuarine species, this can either be beneficial or damaging depending on local habitat conditions and community structure. A decrease in larval duration could potentially reduce dispersal distance and gene flow between populations. However, decreases in larval duration could potential increase the rate of survival to settlement by reducing predator exposure. This would, in turn, decrease the size at settlement, which could prove to be detrimental in populations where a larger body size at settlement gives a greater competitive advantage in the juvenile stage. Therefore, further knowledge on the effects of temperature on endemic species can be useful for planning conservation and management strategies in the face of climate change
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
79. The influence of cover on the breeding biology of western gulls on Santa Barbara Island, California
- Creator:
- Winnett, Kathy Ann
- Description:
- The breeding biology of Western Gulls (Larus occidentalis) on Santa Barbara Island is strongly influenced by the distribution and abundance of certain forms of cover, especially the shrub, Suaeda californica (seablite). Early in the breeding season, nesting gulls concentrated in areas where cover was relatively abundant; higher breeding success was associated with these same areas. Analysis of offspring mortality in relation to several characteristics of the nesting environment -- general cover in the nesting area, concealment, shade, cover provided by the incubating parent and artificial cover -- indicated that cover enhanced survival by providing protection from two major sources of mortality, conspecific predation and heat exposure, and by influencing chick movements. While other gulls constituted the major threat to egg and chick survival on this colony, observations made during this study demonstrated that heat stress, also, is a potential danger to gull offspring. Eggs containing very young embryos heated within a few hours to dangerously high, if not lethal, internal temperatures when left exposed in the sun, while 50% of all chick mortality in 1976 occurred during a heat wave in June of that year. Interpretation of results showing a higher proportion of undeveloped eggs in areas containing little cover is complicated by the fact that the eggs may have been either infertile or dead at very early stages in development. Other results presented here provide indirect evidence that younger, inexperienced breeding gulls may contribute to greater hatching failure in the poorer habitats. The importance of cover to gulls nesting on this island has serious implications in light of a severe, long-term decline of Suaeda and other native island vegetation.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Tracy, Clarence Richard
- Description:
- In the spring, adult toads move several hundred meters from the surrounding hills to the breeding site in Seminole Lake to spawn, commonly swimming more than 80 m across the lake to the breeding congress. When artificially displaced from the breeding area and followed with a trailing device, toads quickly returned; on clear nights the return movement was direct, but under overcast skies they first moved to the nearest water and then along the shore to the breeding site. Tested in an orientation arena, toads oriented using celestial and auditory cues. However, blinded toads homed directly after displacement even when there was no calling. Anosmic animals appeared unable to orient accurately, thus, olfaction seems to be a key sense in guiding the toads' movements. Auditory cues, visual landmarks, celestial cues, learned travel routes, kinesthetic sense, geotaxis, and hygrotaxis were apparently necessary as cues for orientation in this toad.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Oliver, Andrew
- Description:
- Sporosarcina ureae is an aerobic, motile, spore-forming Gram-positive cocci that was originally isolated in the early 20th century from soil enrichments with elevated levels of urea. The species is unique in that it is the only known spore-forming cocci, and is currently placed in a genus exclusively composed of bacilli. Current research has been focused on the biotech potential of the unique outer cell surface layer (S-layer), and the ability to efficiently convert urea into ammonia. Specifically, researchers are using organisms that hydrolyze urea in applications such as self-healing concrete, biofuel production, and more efficient means to make fertilizer. The goal of this study is to utilize Pacific Biosciences (PacBio) DNA sequencing technology to generate complete genome sequences and to investigate genetic and epigenetic variations between strains of S. ureae that differ in their spatial and temporal isolation. We have sequenced the first six complete genomes and methylomes of S. ureae. Genomes were assembled using PacBio SMRT Analysis (v2.3.0) and Geneious (Biomatters; v9.0.4) software programs, and annotated using the Prokaryote Genome Automatic Annotation Pipeline . The average S. ureae genome is 3.3 Mb in size, and contains an average 3160 CDS, 66 tRNAs and 8 rRNAs, while only one of the strains contains a plasmid (64 kb). Epigenetic analysis, using SMRT Analysis and REBASE (New England Biolabs), of the strains demonstrated evidence of several novel adenine and cytosine methylases present in S. ureae. Examination of the species requirement of 97% sequence identity across the 16S rRNA gene was met by all six strains. However, further analysis using in silico DNA-DNA hybridization (DDH), average nucleotide identity (ANI), and additional core- and pan-genome analysis demonstrated a highly divergent species or possibly some of the strains were a subspecies or new species. Further genetic analysis of the entire genus is needed to determine exactly how S. ureae, a spore-forming cocci, relates to the other spore-forming bacillus species in the genus Sporosarcina. Utilizing genomics, our analysis has begun to clarify the make up of the genus, and also found that there may be additional species of spore-forming cocci other than just S. ureae.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Sanger, Margaret Patrice
- Description:
- Fourteen phenolic compounds and three related nonphenolic compounds were tested for their ability to inhibit GA 3 -induced growth of dwarf pea seedlings. Test concentrations of 10:1, 100:1, and 1000:1 (phenolic or related nonphenolic to GA3 ) by weight were used. The related, nonphenolics, benzene, benzoic acid, and flavone, did not significantly reduce GA3-induced growth at any of the concentrations tested. Phenolic compounds alone did not reduce growth of dwarf peas. At a ratio of 10:1, only four of the compounds mixed with GAn reduced growth significantly from GA~ controls: quercetin (29%), phloridzin (19%), vanillic acid (18%), and tannic acid (18%). At the highest concentration (1000:1) all phenolic compounds except p-hydroxybenzoic acid reduced growth significantly from GA3 controls. Eleven of the 14 phenolics reduced growth by less than 42% while three compounds, quercetin, catechin, and tannic acid reduced growth from 70% to 82%. Catechin, a precursor to condensed tannins, was tested for reversibility of inhibition. Increasing the amount of GA3 completely reversed the inhibition so that plants treated with catechin and saturating doses of GA3 were indistinguishable from plants receiving saturating amounts of GA3 without catechin. Aspects of the chemical structure of phenolics were discussed with respect to the observed inhibition of GA3-induced growth.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Mendez, Nickte
- Description:
- Orthotrichum (Orthotrichaceae) is a species-rich genus of mosses in California. The last key to Californian Orthotrichaceae was produced in 2004 and included 35 species. Since that time, new discoveries have been made, and new identification tools are being posted on the site called the California Moss eFlora. As a model for the eFlora, I created an updated key to Orthotrichaceae in California with photographs at each couplet. I included 47 species known from California and adjacent states. My key will be useful in verifying the thousands of Orthotrichum specimens currently housed in herbaria. Species distribution maps produced after verification of those specimens could allow for tests of hypotheses regarding the biogeography of Orthotrichum in California.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Ramadoss, Niveditha
- Description:
- Flooding is a common natural disaster that causes severe crop and soil damage throughout the world. Studies on ethylene have proven that it is effective in improving the flood tolerance in plants. One of the vital enzymes that is involved in ethylene biosynthesis in plants, is ACC oxidase (aminocyclopropane-1-carboxylic acid oxidase) that converts aminocyclopropane -1-carboxylic acid to ethylene. Therefore, we hypothesize that overexpression of ACC oxidase gene in plants can make them flood tolerant by synthesizing more ethylene. ACC oxidase gene was PCR (Polymerase Chain Reaction) amplified from Arabidopsis thaliana and cloned into pBINmgfp5-er vector, under the control of a constitutive Cauliflower Mosaic Virus promoter. GV101 strain of Agrobacterium tumefaciens containing recombinant pBINmgfp5-er vector was used for plant transformation by the 'floral dip' procedure. The transformants were identified through kanamycin selection and grown till T3 generation (third transgenic generation). The ACC oxidase gene expression was analyzed and confirmed through quantitative PCR (qPCR). The flood tolerance was assessed by placing both control and transgenic plants on plastic trays filled with tap water that covered the soil surface. Our result shows that wild-type Arabidopsis could not survive more than 20 days under flooding while the transgenic lines remained unaffected suggesting development of flood resistance with overexpression of ACC oxidase. Moreover, the transgenic plants developed flood adaptive traits that were not common in wild type plants. This study on Arabidopsis thaliana was carried out as a 'proof of concept'. Further studies must be done to replicate the same in agriculturally-important food crops.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Haberkern, Andrea
- Description:
- With more than 42,000 species currently described, spiders are one of the most diverse and abundant predators in terrestrial environments (Platnick 2011; Cardoso et al. 2011; Foelix 2011) and an integral part of well-functioning ecosystems (Uetz et al. 1999). Despite this, their evolution and ecology are not well understood (Garrison et al. 2016). Here I use an ecomorphological approach to answer broad questions regarding spider functional ecology across diverse foraging guilds of temperate and tropical Araneomorph species. I examined the morphology of 30 families within several clades of Araneomorphs to test whether morphological measurements of the size and shape of the cephalothorax, abdomen, and leg segments can be used to distinguish among spider foraging guilds based on multivariate morphology even after correcting for body size. I found that spiders within the same foraging guild have similar morphologies, despite diverse phylogenetic relatedness. I found that guilds were significantly different from each other based on overall morphology. Discriminant function analyses correctly classified the majority of taxa to guild, especially so for the species-rich Wanderer and Web Builder guilds. Body shape, and the relative lengths of the abdomen and of the femur and patella of the fourth leg were the most important morphological traits in distinguishing groups. These results show that distantly related taxa of spiders within the same functional group are morphologically convergent, suggesting that morphology reflects the fitness landscape of diverse spider groups. This study represents the first taxonomically and ecologically broad application of ecomorphology to the exceptionally diverse Araneomorphs, and suggests that detailed examination of functional morphology within select groups would be productive.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Dunagan, Sean
- Description:
- Urbanization subdivides natural landscapes creating isolated fragments separated by novel urban habitats. Species vary in their sensitivity to the process of urban fragmentation where some species can tolerate living in urban areas by exploiting resource subsidies. Mammalian carnivores have been shown to vary in their sensitivity to urban fragmentation where more tolerant species can exploit anthropogenic resources. Bobcats (Lynx rufus) represent an intermediate response to urban fragmentation as they are present in fragmented natural areas but do not thrive in urban development. Bobcats are known to enter urban areas and may tolerate urban fragmented landscapes by harvesting prey from urban environments. Using resource selection functions (RSFs), I modeled the habitat occupancy of 7 female bobcats in the urban fragmented landscape of Thousand Oaks, California. Occupancy models were compared to the distribution and abundance of cottontail rabbits (Sylvilagus spp.) to test if bobcats use urban areas due to an inflated urban rabbit population. Bobcats did go into urban areas, primarily at night; however, rabbit densities in urban areas varied more than rabbit densities in natural habitats. Bobcats occurred more frequently in coastal sage scrub habitats and used habitat edges during nocturnal hours. Rabbit densities in natural habitat patches were the most stable with highest densities in natural edge habitats. Bobcats appear to tolerate urban fragmented landscapes by behaviorally adjusting to resource distribution in natural habitat patches, and not by exploiting urban resource subsidizes. As landscapes become more urbanized, the presence of bobcats can be used to evaluate the ecological integrity of natural fragments as bobcat presence in these areas is likely not mitigated by urban resources.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Nystrom, Robert Ray
- Description:
- In cultured mouse teratoma cells, actinomycin D has been shown to stimulate glutamine synthetase (GS) specific activity with a concomitant increase in intercellular adhesion. Cultured mouse teratoma cells were preincubated for 24 hours with 5 ug/ml actinomycin D. They were then dissociated and incubated for 1 hour on a gyratory shaker. The decrease in single cell number, as determined with an electronic particle counter, was used to calculate the percent adhesion. The GS specific activity of these cells was then determined by an assay involving the glutamyltransferase reaction. It was found that the actinomycin D treated cells showed a 31.4 ± 9. 9% [mean ± standard error (S.E.)] increased intercellular adhesion and a 53+ 17% increase in GS specific activity. The increased adhesiveness of these cells may be due to the stimulated GS specific activity and subsequent synthesis of L-glutamine, which has been shown by Oppenheimer et al. (1969) and Oppenheimer (1973) to be required for teratoma intercellular adhesion. They suggest that the L-glutamine is required for the synthesis of complex cell surface carbohydrates involved in intercellular adhesion of teratoma cells.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Avina, Erin
- Description:
- Euphorbia terracina is an aggressive and invasive non-native plant that has recently become abundant in some parts of southern California. Its distribution has dramatically increased over the last eight years, with large populations scattered throughout Ventura and Los Angeles Counties, including the Santa Monica Mountains National Recreation Area. Management efforts have focused on controlling expanding populations and restoring invaded parkland. Nevertheless, the species continues to establish in intact native plant communities, including coastal sage scrub. Successful invasion and spread of a non-native species relies on the physical attributes of microhabitats within the recipient plant community that are conducive to seedling recruitment and establishment of the pest species. In Mediterranean plant communities, including coastal sage scrub, the factors that have been shown to impact the establishment of other non-native species include the amounts of seed predation, overhead canopy, and understory litter. How these factors affect seedling germination, growth, and survivorship of a non-native species can determine whether or not it will successfully pass through the recruitment and establishment phases of invasion. In this study I sought to identify features of the native plant community (coastal sage scrub) that could be manipulated in order to reduce the establishment and reproductive success of E. terracina, and possibly even favor establishment of native plant species. I experimentally manipulated seed predation, leaf litter, and shrub canopy and evaluated the impacts on E. terracina as well as Salvia leucophylla, the most common co-occuring native shrub in invaded coastal sage scrub. I found that although predation significantly reduced emergence in both species to less than 1%, E. terrracina and S. leucophylla responded somewhat differently to the experimental treatments. Predation combined with the presence of leaf litter significantly increased seedling emergence and survivorship in E. terracina whereas S. leucophylla was most affected by the combined effects of predation and lack of canopy. These findings indicate that additions of leaf litter mulch would not be an effective means of suppressing E. terracina. In addition, they suggest that canopy gaps should be prioritized for weed treatment because these microhabitats are favorable for S. leucophylla regeneration and probably other native species.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Deakers, Timothy William
- Description:
- The combination of histochemical methods and electron microscopy provides useful technique for the ultrastructural localization of enzyme activities. Cells from log and stationary phase cultures of the flagellate polytomella agilis were fixed in glutaraldehyde and then incubated in Gomori type lead stains for the enzymes acid phosphatase and g1ucose-6-phosphatase. Following incubation the cells were fixed in osmium and processed for electron microscopy. The cells were viewed for the presence of lead deposits which are the indicators of the enzyme activities. Lead deposits were observed in the proplastid network of a relatively small number of mature trophs incubated for acid phosphatase activity. This was interpreted as a possible indication of acid phosphatase activity in this organelle. The proplastid undergoes considerable differentiation during life cycle changes. It is proposed that the proplastid network may be a site of hydrolytic digestion. No evidence of lysosomes was observed. A significant number of mature trophs and a few pre-cysts incubated for glucose- 6-phosphatase activity contained heavy lead deposits along the membrane limits of storage vesicles and the proplastid network. Some cells also contained deposits along the nuclear membrane. No deposits were observed in the endoplasmic reticulum. These deposits were interpreted as a strong possibility of glucose-6-phosphatase activity in these areas. These storage vesicles and the proplastid are believed to be involved in the manufacture and storage of starch. Glucose-6-phosphate is an integral enzyme in carbohydrate metabolism. It is proposed that the enzyme may also be involved in the intracellular transport of glucose. Various factors concerning the validity of the use of lead stains for enz;yme localizations were reviewed.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Zamudio, Sylvia
- Description:
- Due to elevations in atmospheric CO2 caused by anthropogenic activity, global temperatures are projected to increase 1.8 °C by 2100. The rate and magnitude of this thermal change will have negative impacts on tropical corals and significantly alter reef community structure. It remains unclear how early life stages will be affected by increases in temperature. The goal of this thesis was to evaluate the role that maternal coral colonies play in modulating larval response to thermal stress. Chapter 2 describes exploratory research, the results of which demonstrate that the upper thermal threshold of Pocillopora damicornis is ~32 °C and Symbiodinium densities are not closely associated with larval mortality. Second, utilizing these results, I show that maternal colonies had differential offspring provisioning, but this did not alter larval energy content in sub-lethal temperatures of 31 °C over 6 d. Finally, I describe a significant maternal effect with colonies incubated in a high temperature of 30 °C during larval development exhibiting advanced release of ~1 day, a 52% increase in larval output, and larvae containing 34% less energy than those spawned from corals kept at ambient temperatures of 27 °C. Chapter 3 documents this temperature-induced maternal effect on offspring from larval development to post-settlement. In Taiwan, Seriatopora caliendrum colonies exposed to elevated temperatures of 28 °C during larval development produced larvae that were 19% smaller and had 15% less protein content than those from 26 °C. Larval cohorts were settled into recruits and growth was monitored over 18 d at 25 °C and 28 °C. Recruits from colonies exposed to 28 °C had significantly reduced protein content and planar area, but an 18% increase in polyp division. In general, recruits incubated at 28 °C had 11% higher polyp division rates than recruits grown at 25 °C. There was no effect of temperature or maternal temperature on calcification rates. In Japan, larvae from P. damicornis colonies maintained at 31 °C had significantly reduced protein content and underwent higher rates of mortality during settlement than colonies incubated at 29 °C. Recruits incubated at 29 °C for 21 d had 43% higher polyp division than those at 31 °C, while recruits grown at 31 °C that originated from colonies of the same temperature did not divide. Collectively, these results demonstrate that the temperature of the maternal environment during reproduction in brooding corals significantly impacts offspring by shaping larval phenotypes, altering spawning characteristics, and influencing the post-settlement growth of larvae primarily through polyp division.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Ghazarian, Anasheh
- Description:
- Lectins, which are carbohydrate binding proteins, are used in the purification of glycan-containing molecules and in histochemical studies that have identified important cellular properties. Differences in cells with various carbohydrates on their surfaces influence malignancy and pathogenicity. Pathogenic organisms often bind to human cell surfaces via lectin-glycan interaction. Pharmaceutical companies are developing medications based upon their ability to inhibit carbohydrate mediated binding reactions. In this study, I used microbeads derivatized with concanavalin A (Con A), a mannose-binding lectin, as a model in order to examine the binding properties of mannose-rich yeast, a model for pathogenic organisms. Ten sugars- including monosaccharides and oligosaccharides, at four concentrations each, were examined for their ability to inhibit cell-lectin binding in this model system. If a reagent causes disaggregation of yeast from lectin derivatized beads, that reagent might for example, block pathogen binding to cells. T- tests were performed to determine if any disaggregation of yeast from the Con A beads in the experimental samples was significantly different from the controls. About 500 total trials were performed at each of the four concentrations of the ten sugars studied and controls, by counting the number of yeast that remain bound to the beads over a 60 minute time course. It is generally accepted that reagents that are most active are those that are effective at the lowest concentrations, suggesting that they bind most strongly to surface receptors. Here we found that Methyl-a-D-mannopyranoside, D(+)mannose and D(+)melezitose were most effective in disaggregating yeast from Concanavalin A at the lowest concentration tested (0.005M) at 60 minutes. A similar but slightly different ranking was observed at the 20 minute time. Most important is that the method used in this study is highly quantitative and can easily identify reagents that may be useful in anti-infection, anti-biofilm and anti-cancer venues
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Kelley, Walter Almond
- Description:
- Analysis of a number of morphological characteristics in the herbaceous genus Calandrinia H. B. K. (Portulacaceae) suggest that two natural groups of species exist, one in western North and South America and the Galapagos Islands, another in Australia. The morphology of pollen grains, seeds, and hairs proved most useful in establishing the limits of the subgeneric taxa. The twelve sections created by Reiche for the American species are accepted. One new section is created to accommodate two American species described since the work of Reiche. The sections recognized by von Poellnitz for the Australian representatives of the genus appear, with one exception, to be invalid. The genus probably originated in the early Tertiary. Continental drift may prove to be the best explanation for the present pattern of distribution of the genus.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Cassel, Nicole
- Description:
- Akinetes are spore-like cells resistant to desiccation and cold that differentiate from vegetative cells of the filamentous cyanobacterium N. punctiforme in response to phosphate or potassium limitation and low light. Previous microarray data has identified a putative extracytoplasmic function (ECF) sigma factor, NpF4153 (SigG), and an adjacent downstream anti-sigma factor, NpF4154, as potential genes involved in akinete induction in N. punctiforme. GFP transcriptional reporter strains confirmed the array results, showing increased expression from the sigG promoter in akinetes, heterocysts, and following stresses imposed by heat or EDTA. The zwf model system of akinete induction was used to unveil a potential regulon for SigG by two separate microarray analyses comparing the zwf/sigG double mutant relative to a zwf strain under both vegetative growth conditions and during akinete formation. Genes showing decreased expression in the double mutant included outer membrane proteins, lipid biosynthesis proteins, proteases, as well as many hypothetical proteins. Transcriptional start sites of genes shown to be down-regulated due to deletion of sigG in both microarrays were determined by random amplification of cDNA ends, and a putative SigG consensus sequence was determined. To determine interaction between SigG and the N-terminal end of the NpF4154 anti-sigma factor, a GST pull down assay was performed. The N-terminal predicted cytoplasmic domain of the anti-sigma fused to GST was able to pull-down SigG-His6 from an E. coli crude lysate, indicating a specific interaction between SigG and F4154N-GST. A strain expressing a SigG-GFP protein fusion was shown by confocal laser microscopy to have GFP-fluorescence localized to the periphery of the cell under normal growth conditions. Such protein localization was lost following exposure to short periods of heat, indicating release of sigma factor from the cell membrane following stress. Survival studies comparing wild-type and ΔsigG mutant strains following exposure to heat or outer membrane disruption using EDTA showed reduced survival for the mutant strain. The mutant also exhibited a significant delay in heterocyst formation following nitrogen starvation relative to the wild-type strain. Together these data support the hypothesis that NpF4153-4154 encode proteins that act in a manner that is typical of an ECF sigma / anti-sigma factor pair that is important for normal expression of genes involved in cell differentiation and envelope biosynthesis/repair.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Kay, David William
- Description:
- Adult Hyla cadaverina are found in the open in abundance along lower Trail Creek during spring and fall when temperatures are moderate. During winter, the animals seek shelter in crevices above the high water mark, thereby escaping flash floods. In summer, they inhabit cool, moist crevices near the stream which provide protection from the summer heat. As in many other anurans, individual H. cadaverina tend to occupy limited overlapping home ranges, usually less than 5 m long, aggregated near large pools created by stream boulders. A small percentage emigrate relatively long distances up to 250 m to new pools, usually also inhabited by several other H. cadaverina. Such movements may serve to maintain genetic variation in the population. When tested in the field for y-axis orientation, individual H. cadaverina clearly showed a preference for a familiar shoreline. (See more in text.)
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
95. Social behavior and response to predators in California ground squirrels (Spermophilus Beecheyi)
- Creator:
- Parker, Joan Marie
- Description:
- Seven California ground squirrels (Spermophilus beecheyi) were captured, introduced into a large, outdoor enclosure and observed over one year's time. In addition to observing social behavior, I conducted an experiment to determine the squirrels' responses to two-dimensional models, of varying shapes and sizes, moving above them. Comparing responses of squirrels to all aerial models together and to a control sound, I found that males responded more frequently to models than to noise alone. Females, on the other hand, responded to models and the control sound at about the same frequency. Within the social group males were typically dominant to females. There was an inverse relationship between dominance and frequency of occurrence of alert behaviors. Thus females were more often the sentinels. Nose-to-nose contact and approahces, considered to.be greeting behaviors, occurred primarily between juveniles. Adults did greet other adults, but rarely greeted a juvenile squirrel. During many agonistic encounters tail flicking was commonly seen. Subordinate squirrels usually did the flicking. I conclude from this that tail flicking is an indication of tension, and perhaps a sign of subordination. (See more in text.)
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Hill, Brian Jerome
- Description:
- Home range, homing and orientation in a population of Uta Stansburiana were studied over a period of thirteen months. I found the home range sizes (males 36.8 m2, females 30.7 m2 and juveniles 16.4 m2} to be smaller than those reported in previous studies, with no significant difference between adult male and female home range size. There was considerable overlap among the home ranges of both adult males and females. About 25 % of the adults of both sexes which were displaced 50 to 60 m homed. Juveniles were not observed to home. Anosmic adult lizards, those with the parietal eye covered, and normal animals oriented and homed equally well. Blind adults did not orient or home. Uta released in an open arena in the field showed significant orientation to toward their original capture site if displaced less than 40 m from their home range area were visible. Lizards farther than 40 m from their home area, or which could not see landmarks within their home area from the arena center, failed to show significant orientational ability. Lizards tested in enclosed arenas exhibited behavior related to thermoregulation rather than orientation toward home.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Salerno, Dominick Clayton
- Description:
- Seedlings of five species of plants were grown in darkness or light for two weeks. Shoots were measured in length and exhaustively extracted. The total phenolic content was determined colorimetrically after addition of Folin-Denis reagent. In all species, the lengths of the dark grown seedlings were longer than the corresponding light grown plants. It was found that the endogenous levels of phenolics were substantially higher in the light grown seedlings. The gallotannin content was also found to be higher in light grown seedlings. Dwarf pea seedlings were grown in continuous darkness and watered with water alone or solutions of tannic acid (0.5g/l and 5.0g/l ). At the lower concentration, there was a stimulatory-effect on growth relative to the water control. At higher concentration, although there was an increase in total length, there was substantial reduction in the length of the first two internodes and development of a fourth internode not present in either the water control or the lower concentration of tannic acid. Lettuce hypocotyl sections were incubated in light or darkness in water or solutions of GA3, tannic acid, dialyzed extracts from light or dark grown peas, or mixtures of GA3 and tannic acid or pea extracts. Tannic acid and pea extracts inhibited growth of hypocotyl sections regardless of lighting conditions. The degree of inhibition was greater in dark incubated sections and extracts from light grown peas were more inhibitory than extracts from dark grown peas. These data suggest that phenolics may be involved and play a regulatory role in the light-mediated inhibition of growth.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
98. The effects of lectins in sea urchin Lytechinus pictus during gastrulation in low calcium sea water
- Creator:
- Nikkhou, Siavash
- Description:
- In order to help learn about the possible role of carbohydrate – containing molecules in gastrulation in the model sea urchin embryo (Lytechinus pictus), 24 hr sea urchin embryos were incubated with 3 lectins (carbohydrate binding proteins) Triticum vulgaris (wheat germ agglutinin), Artocarpus integrifolia agglutinin and Phaseolus vulgaris PHA-L agglutinin at 0.1-0.00001 mg/ml. Triticum is a specific binder of N-acetyl-D-glucosamine- like residues, as is Phaseolus, while Artocarpus is a specific binder of D-galactose-like residues. The embryos were treated with and without these lectins at all 5 concentrations for an additional 24 hrs at 15 ⁰C in lower calcium artificial seawater (that speeds entry of molecules into the interior of the embryos) in 96 wells well flat bottom microplates. The wells were treated with 10% formaldehyde to fix the embryos at the 48 hr stage (late gastrula). All embryos in each well were scored as to their morphologies: complete archenteron, incomplete archenteron, non-invaginated, exogastrulated or dead. Thousands of embryos were scored. Means of percentages of each morphology for each concentration of each lectin was plotted with standard error bars and a t-test was used to determine if any differences in the experimentals vs. controls were statistically significant (P<0.05). The results indicated statistically significant concentration dependent effects of all 3 lectins on altering the morphologies of the embryos. These preliminary results suggest that N-acetyl –D- glucosamine and D-galactose groups maybe involved in archenteron elongation and organization. The microplate assay is an effective means of quantitatively determining the precise effects of reagents on sea urchin morphologies, an NIH designated model for higher organisms including humans.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Karl, Alice Elizabeth
- Description:
- To determine the distribution, relative densities and habitat associations of Gopherus agassizi in Nevada, a 5500 square mile study area was surveyed using 312 strip transects. Evidence of tortoises was found to the eastern, western, and southern boundaries of the state and nearly as far north as Leith (T8S) in Lincoln County and Beatty (Tl2S) in Nye County. Although other studies have suggested that tortoises range as far north as Tl2S in Nye County and T7S in Lincoln County, the vegetation associated with these northern sites is unlikely to represent tortoise habitat. Over 90 percent of the surveyed area (approximately 5000 mi2) was estimated to have densities less than 50 tortoises/mi2; this density has been previously suggested to represent the lower critical level for survival. Ten areas are estimated to have densities exceeding fifty tortoises/mi2 : Coyote Springs Valley, Hidden Valley, Dry Lake Valley, Moapa Valley, the Virgin Mountains, Eldorado Valley, Piute Valley, Goodsprings Valley, Arden, and Pahrump. The viability of the tortoise in Nevada is discussed with respect to population densities, natality rate, mortality rate, amount of available habitable land, and degrees of disturbance. It is suggested that only the Virgin Mountains, Piute Valley, Eldorado Valley, Moapa Valley, Coyote Springs Valley, and Hidden Valley populations may be viable as a result of environmental constraints and current size. Evidence of tortoises was found primarily in the Larrea tridentata community (94.7 percent of 171 transects where tortoise presence was positively identified). Tortoise evidence was also found in the L. tridentata-Coleogyne ramosissima ecotone and the C. ramosissima community. However, there was a significant negative correlation between estimated tortoise density and the dominance of c. ramosissima in the shrub layer, probably as a result of either climatic constraints associated with c. ramosissima or associated Bromus rubens. A significant negative correlation also existed between estimated tortoise densities and the domiriance of B. rubens in the understory. No evidence of tortoises was found in the Pinus monophylla-Juniperus community. Tortoise sign was found on slopes with steepnesses up to 60 percent; however, estimated tortoise densities were lower than expected on mountain slopes, using a x2analysis. Elevations between 1320 and 4560 feet showed evidence of tortoise habitation; the data were inconclusive in establishing an elevational limit, although 4000 feet is suggested. Difficulties encountered in employing the transect method for determining tortoise densities are discussed. It is determined that the method is appropriate for estimating regional densities and thereby identifying critical areas to be more closely investigated during land usage decisions.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Weiss, Grant Lee
- Description:
- Legionella pnuemophila is an intracellular pathogen that is phagocytized by macrophage of our immune system. The bacterium uses a Type IV secretion system to secrete proteins across the phagosome membrane into the cytosol. Secreted effector proteins bind to host cell proteins to change the fate of the Legionella-containing phagosome (LCP) in two important ways. Legionella inhibits the endocytic pathway from fusing the LCP to endosomes/lysosomes, allowing the Legionella to escape proteolytic degradation. Furthermore, Rab1 and Arf1, exocytic host GTPases, are modulated by Legionella secreted proteins resulting in ER-derived vesicle fusion with the LCP creating a replicative niche for the Legionella. ARF1, a small GTPase that governs Golgi to ER retrograde transport, is switched "on" by a translocated Legionella effector protein, RalF, which acts as a guanine nucleotide exchange factor (GEF). A yeast two-hybrid screen in our laboratory identified several potential Arf1 GTPase activating proteins (GAP), potentially capable of switching ARF1 "off." Here, a putative Arf1 GAP, SamA (Sensory-box and ARFGAP Motifs), was shown to bind to ARF1 in a GST pull-down. An endpoint phosphate assay was developed and may be useful in determining GAP activity of SamA for ARF1. These data reveal a novel secreted effector protein that may aid in intracellular survival by modulating host cell trafficking.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology