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- 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
7. 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:
- 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
13. 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:
- 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:
- 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:
- 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
21. 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
45. 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
61. 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
64. 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
- Creator:
- Warner, Jason R.
- Description:
- The ability to survive freezing temperatures is of paramount importance to organisms living at high elevations. Many ectothermic vertebrates have traits that allow them to cope with extreme cold, such as the ability to supercool and/or tolerate freezing of extracellular fluids. I studied several aspects of cold-hardiness of six lizard species in the genus Liolaemus (Iguania: Liolaemidae) living along a 2525-m elevation gradient (1550-4075 m) in northwestern Argentina. Specifically, I tested for supercooling, freeze tolerance, and the temperature of ice inoculation. I hypothesized that high-elevation (>3000 m) species would have greater capacities to supercool and tolerate freezing, while being more susceptible to ice inoculation, relative to their low-elevation congeners. Both conventional statistical analyses and those using independent contrasts with phylogenetic regressions revealed no correlation between supercooling capacity and elevation. Because of this, and the fact that all six species were able to supercool, this ability may be the ancestral condition for the lineage. This may have enabled independent invasions of cooler climates by members of this diverse genus. However, independent adaptation appears to explain freeze tolerance, as larger individuals were more susceptible to ice formation and high-elevation lizards survived longer during freezing events than their low-elevation congeners. Body size may partially explain freeze-tolerance capacity, as larger lizards have greater thermal inertia, which allows them to retain heat longer. Also, large-bodied Liolaemus generally occur at higher elevations. The cold-hardiness capacities characterized in this study also were correlated with seasonal low temperatures experienced in each environment. These results may explain the success of Liolaemus, which has numerous independent origins of species living in cold climates. Future studies should consider cold hardiness in a more holistic context of the biology of these lizards (alongside behavior, morphology, and biochemistry) and include comparisons among more species, including those from high latitudes, to further test cold hardiness as an adaptation to cold environments.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Dang, Thomas
- Description:
- Recent studies have shown bacteriophages infect living organisms from all three domains of life, however, not much is known about phages that infect the Archaea. Of the approximate 50 reported archaeal phages, PG is one of only three known viruses that infects methanogens and falls within the order of tailed-bacteriophages, Caudovirales. Tailed bacteriophages have differing DNA replication strategies that is reflected by the various terminal chromosomal ends created by the terminase large subunit. Although PG's replication and packaging process is unknown, bioinformatic studies of PG's terminase large subunit could help identify potential DNA packaging strategies. Comparative analysis between other phages demonstrate that they cluster together according to the type of terminal ends they create. PG was shown to cluster with termini short direct terminal repeats and cohesive ends. Studying the terminase large subunit of PG could lead to a better understanding of its replication strategy, genetic history, and increase our understanding of viruses in general.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Haley, Thomas Eugene
- Description:
- Male guinea pig vocalizations emitted in response to conspecific aggression were tape recorded. This was done by using an experimental method through which vocalizations of a starved individual could be recorded as it protected a single piece of food from the remainder of a four member hierarchy. In order to quantify results “silent,” vocal units (A-type, B-type, squeal, shriek, and E-type) and behavioural categories (undisturbed, approached, and harassed) were defined using non-overlapping characteristics. The vocal responses were graded in unit type and in physical properties (maximum frequency and duration) as conspecific aggression increased. These graded responses were utilized differently by individuals of different hierarchical status. Positionally related vocal differences were explained in terms of positionally related ambivalences during the food defense period.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Milgrom, Etan
- Description:
- Certain physical properties (e.g. density, viscosity and refractive index) of saline-based solutions of the density gradient solutes sucrose, Ficoll, metrizamide, Ludox, Percoll and CsCl were determined at 4°C and 22°C. The values obtained were compared with the same solutes prepared in water. Data were used in a series of experimental studies in which the sedimentation rates of nylon beads and human red blood cells at unit gravity and in centrifugal fields were followed visually. Experimental results were compared with theoretical predictions of behavior.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Nelson, Hannah
- Description:
- While it is known that octocorals and trees share many similarities in form and function due to their sessile, modular nature, and octocoral communities create dense canopies termed "animal forests," there has been little quantification of whether these two groups are shaped by the same ecological and evolutionary processes. This thesis is comprised of two different studies that take classic concepts developed in the terrestrial plant literature (e.g. phenotypic integration, self-thinning, shading) and examines how well they can be applied in octocorals. In Chapter 2, I examined the extent to which variation in octocoral morphology is constrained by covariation among traits (i.e. integration), including how traits scale with overall colony size (i.e. allometry) by comparing five morphological traits among and within eight species of the common Caribbean octocoral Eunicea. I found that polyp, branch, and colony level traits covary with one another, but the pattern of trait covariation depends on whether covariation is investigated at an intra- or interspecific scale. Species with more branches tended to have shorter, thinner branches. This pattern of integration has been well established for many higher plants, suggesting modularity may have given rise to similar constraints in both groups. This study highlights the role of covariation among traits in constraining the morphology of modular organisms. In Chapter 3, I investigated whether self-thinning models can be applied to mixed-species octocoral assemblages by exploiting natural variation in the density of octocorals at two shallow reefs in St. John, U.S. Virgin Islands. I found a negative power relationship between mean colony width and the density of colonies, which suggests that mixed-species octocoral communities experience density-dependent mortality due to competition (e.g. self-thinning) for space, waterborne resources, and/or light. Light was reduced next to octocorals, but shading could not account for differences in spacing among species. A substantial fraction (50-73%) of the variation in average colony size was not explained by variation in octocoral density. These results suggest that self-thinning models can be applied to mixed-species assemblages, but the predictive power of these size-density relationships may be weakened by asymmetries in competitive abilities or resource use among species.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Holdridge, Erica
- Description:
- Natural communities are expected to undergo shifts in composition and species interactions as a result of environmental change, such as changes to regional temperature regimes and increased nutrient input into ecosystems. Predicting how communities will respond is complicated by three factors: non-additive effects of multiple stressors, differences in response among trophic levels, and trait evolution leading to adaptation. This study addressed all three of these factors using a natural microcosm community. The purple pitcher plant, Sarracenia purpurea, is a carnivorous plant that retains rainwater inside of its cup-shaped leaves. Within this water, an inquiline community of microbes and invertebrate larvae forms. I used a subset of this community consisting of a single protist species, Colpidium sp., and a community of bacteria to explore how the interaction between temperature and increased nutrient input affects different trophic levels ecologically and evolutionarily. I factorially manipulated temperature and nutrient input and maintained these conditions for 28 days (~150 protozoan generations). I then performed reciprocal transplants to each treatment, resulting in four common garden environments to test how evolutionary effects may depend upon ecological context. I found that historic nutrient input levels affected two protist traits - cell size and peak density - but the magnitude of these effects depended on the contemporary environment. The combined effects of historical temperature and nutrients did not differ significantly from the expected additive effect. Protist and bacterial abundances differed in their response to treatments, with protist abundance affected by both historical and contemporary environments while bacterial abundance was only affected by contemporary environment. Finally, bacterial community composition was affected by treatments both directly and indirectly, through their effects on protist traits and abundance. The results of this study show that the ways in which communities respond to environmental change can differ in light of evolutionary responses, the trophic levels being considered, and additivity of multiple stressors. The future success of management and conservation of natural systems rests upon the best possible understanding of not only the ecological implications but also, and perhaps even more importantly, the evolutionary consequences of a changing abiotic environment.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Solomon, Aryeh
- Description:
- Direct reprogramming offers a promising alternative method in producing cells for regenerative medical applications. However, a major obstacle in this process is the selection of transcription factors best suited to initiate reprogramming. By comparing differential gene transcription levels across numerous tissue samples, the Core Expression Module Analysis (CEMA) developed by the Lowry lab identified and compiled compact sets of genes unique to a given cell lineage. With additional gene ontology analysis, a list of 3-10 transcription factor (TF) were generated for each cell type. We hypothesized that ectopic expression of these selected TF can induce direct reprogramming in terminally differentiated somatic cells and direct differentiation and maturation in pluripotent stem cells. To test this, we incorporated these lineage conversion factors into a YFP marker gene containing lentiviral polycistronic cassette that uses an rtTA Inducible Tet-On promoter system. For the direct reprogramming project, two plasmids were generated to produce two distinct cell lineages; tissue endothelial cells and mature neural progenitor cells. Fibroblast were infected with rtTA and TF cassette lentivirus and using puromycin and neomycin selection, with YFP expression, we were able to positively identify infected cells. Treatment with doxycycline over an extended period resulted in morphological changes appearing in a small subset of infected cells, with ectopic and endogenous up regulation of key genes measured via IF staining and qRT-PCR. Using a similar protocol with ESCs/iPSC, infected YFP positive colonies ectopically expressing early neural progenitor cell transcription factors were selected and differentiated towards the neural fate using lab established methods. After sorting and analyzing cells with FACS and qRT-PCR, cells that had received continuous doxycycline treatment while remaining YFP positive demonstrated a decrease in Lin28B expression, a microRNA preventing cell maturation, with cell and colony morphology comparative to fetal NPC samples. With additional refinement to CEMA and the reprogramming protocols, mature cells from all lineages may be generated, with applications ranging from disease modeling to cell replacement therapy.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Shargo, Eric S.
- Description:
- The use of off-road vehicles (ORVs) in the California desert has become increasingly popular during the past 15 years. This study was designed to assess the impact of this activity on habitat quality and the small vertebrate fauna in the creosote bush community of the Mojave Desert. Two ORV-frequented sites in each of two localities and four control areas (one for each experimental site) were compared. Vegetation, small mammals and reptiles were sampled during late spring. Density and diversity of mammalian and reptilian vertebrates were significantly lower in all ORV-used areas, as was habitat quality. Moderately used areas contained 49% as much perennial plant cover, supporting 81% as many individuals and 76% as many species of vertebrates as the control areas. Where vehicular activity is concentrated, areas become denuded, supporting little or no animal life or vegetation. These "pit areas" averaged 5.3% as much plant cover as controls, while the number of individuals and species was 12.4% and 34.5% of the controls, respectively. These results indicate that ORVs have a detrimental effect on the desert habitat proportional to the degree of usage.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Idoni, Brian Anthony
- Description:
- Using the NIH designated sea urchin embryo model, we are studying the molecular basis of a set of cellular interactions that have interested investigators for over a century, archenteron organization/elongation/attachment to the blastocoel roof. Here we evaluate the effects of four commercially available glycosidases: alpha and beta amylase and alpha and beta glucosidase, that we independently characterized, on embryo development. In quantitative dose-response experiments we show an I-50 of 10-30 units/ml, in artificial sea water or low calcium artificial sea water, of beta amylase and alpha glucosidase in inhibiting archenteron organization/elongation/attachment to the blastocoel roof in living 48 hr Lytechinus pictus gastrula embryos using a microplate assay that allows quantitative assessment of embryo morphological characteristics. All concentrations tested (up to 5000 units/ml) of alpha amylase and beta glucosidase had no significant effects on archenteron morphology. All experiments involved assessing 3600-5600 embryos in at least 144 replicate wells for each enzyme. The differences in archenteron XVll morphology compared with controls were significant with p values of less than 0.05, while any differences observed with the ineffective enzymes had p values of greater than 0.05, using two-tailed t-tests. All enzymes used were tested for their activity on known substrates, and found to be active, and specific unit activities were established. Product inhibition studies suggested that the effective enzymes acted by their specific glycosidase activities and polyacrylamide gel electrophoresis suggested that there was no detectible protease activity in the enzyme samples. The results suggest that glycans are involved in these cellular interactions and we discuss possible conformations of these glycans.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
76. Immunofluorescence localization of extracellular matrix component (s) in two species of sea urchin
- Creator:
- Alikani, Mina
- Description:
- An indirect immunofluorescence method was used to localize and trace the expression of an aggregation-promoting factor(s) (S-2) in the early stage embryos (1, 2, 4, 8, and 16-cell) of two species of sea urchin, Strongylocentrotus purpuratus and Lytechinus pictus. The S-2 antigen(s) was isolated from the supernatant of calcium-magnesium-free sea water dissociated S. purpuratus blastulae. Whole embryos from which fertilization membranes had been removed were incubated with purified anti-S-2 antibody (AS-2). Bound AS-2 was labeled with a second antibody (goat anti-rabbit IgG) that had been conjugated with fluorescein isothiocyanate. Immunofluorescence was assessed and photographed using a fluorescence microscope. The fertilized eggs and early stage embryos of both species of urchin displayed peripheral fluorescence. The antibody did not bind to the surfaces of unfertilized eggs nor did it penetrate the hardened fertilization membrane of embryos. Embryos incubated with preimmune rabbit serum showed no staining. (See more in text.)
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Amir Ali, Arsalan
- Description:
- Nostoc punctiforme is a filamentous cyanobacterium that has an immense potential to be used as a platform to produce biofuels and other high-value compounds. Their ability to synthesize lipid droplets and other valuable metabolites while eliminating the requirement for land also considerably increases their commercial prospective. N. punctiforme grows using plant-like oxygenic photosynthesis and can also differentiate into spore-like akinetes, nitrogen-fixing heterocysts, or motile hormogonia in response to stress. This unique ability to adapt to environmental stresses by differentiation also makes them a valuable model for studying cellular differentiation. A subset of the genes involved in stress responses are hypothesized to be regulated by the twelve alternative sigma factor subunits of RNA polymerase, which were previously identified in the genome (along with the housekeeping sigma, SigA). The sigma factors are known to be post translationally regulated by the anti-sigma factors, that are hypothesized to sequester the sigma factors until stress induces their release. However, unlike the sigma factors, the anti-sigma factors are well conserved at the primary sequence level. Thus, not much is known about anti-sigma factors in general or about the specific sigma/anti-sigma interactions in N. punctiforme. Seven putative anti-sigma factors were identified in N. punctiforme by sequence homology. We screened for the interaction of all thirteen sigma factors with these putative anti-sigma factors using a bacterial 2-hybrid assay (BacTH). Each of the anti-sigma factors interacted with two or more sigma factors in the BacTH analysis, but no interactions were found with group 3 sigma factors or the highly divergent sigma factor SigI. Twenty-three positive interactions were identified using the BacTH system, which were then quantified by using beta-galactosidase assays. We then tried to confirm twelve of the interactions showing the highest beta-galactosidase activity by using GST-pulldown assays and Western blotting. Two novel sigma/anti-sigma interacting pairs were identified by this study. The sigma factor SigB2 was shown to interact with the anti-sigma factor SapB2 and the sigma factor SigD was shown to interact with the anti-sigma factor SapD. These findings will help increase our understanding of complex regulatory processes that occur at the transcriptional level during cellular differentiation, and following stresses associated with production of high-value compounds in N. punctiforme.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Aleksanyan, Heghush
- Description:
- The sea urchin embryo is a NIH designated model system to study mechanisms that may be involved in human health and disease. In order to determine if mannose residues are involved in sea urchin embryo cellular interactions at gastrulation, 6324 Lytechinus pictus embryos were incubated with varying concentrations of independently characterized (assayed for purity and activity) α-mannosidase for 24 hours using a quantitative microplate assay. The results showed a variety of morphological deformations even for α-mannosidase activity of as low as 0.06 U/ml. These effects did not occur using heat treated (that we call denatured) α-mannosidase. Thousands of replicates were statistically evaluated and the results suggest that α1-2-, α1-3-, and/or α1-6-linked mannose residues may play an important role during sea urchin gastrulation. Additionally, formaldehyde fixed, 48 hour old Lytechinus pictus embryos were microdissected to attempt to identify a specific site of α-mannosidase action within the embryo. The procedure involved separation of archenterons from the blastocoel roofs. Microdissected control groups maintained the adhering properties of the cells located on the tip of the archenteron to the roof of the blastocoel when the dissected pieces were placed back together. But, in these small sample preliminary experiments embryo pieces that were incubated with α-mannosidase lost their adhesive properties suggesting the tip of the archenteron and roof of the blastocoel are possible sites for the effect of alpha-mannosidase. Both the microplate and microdissection approaches used here independently suggest a role for D-(+)-mannose residues in sea urchin gastrula adhesive interactions.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Patterson, Nancy Diana
- Description:
- A population of Polytomella agilis was synchronized with hydroxyurea, which inhibits cells at the onset of DNA synthesis (the G1/S border). To gain information on the sites of mitochondrial enzyme synthesis (succinic dehydrogenase, NADH dehydrogenase and cytochrome c oxidase} or proteins involved in their assembly or incorporation into membranes, the effects of chloramphenicol (an inhibitor of mitochondrial protein synthesis) and cycloheximide, an inhibitor of extramitochondrial protein synthesis) on the specific activities of these enzymes were studied, through the cell cycle. In untreated cells, peak patterns of enzyme synthesis were observed. A mitochondrial site of succinic dehydrogenase is suggested since its activity declined in chloramphenicol-treated cells during the first cycle. Cycloheximide had no effect on its activity. NADH dehydrogenase is apparently synthesized under mitochondrial control since chloramphenicol results in decreased activity in the first cycle. In the subsequent cell cycle little, if any, activity was detected. Cycloheximide affected the pattern of activity during the cell cycle, suggesting the inhibition of some cytoplasmic components involved in the regulation of the assembly, membrane-integration or activity of the enzyme. In the presence of chloramphenicol, cytochrome c oxidase activity did not decline until the second cell cycle. Enzyme activity was not inhibited in either cycle by cycloheximide. This suggests a mitochondrial site of synthesis. The diminished activities of both cytochrome c oxidase and NADH dehydrogenase in the second cycle following the addition of chloramphenicol suggests that the mitochondrion of P. agilis arises by growth and division. Cell division was not inhibited by chloramphenicol after the first cell cycle, suggesting that a completely functional mitochondrion is not an absolute requirement for cell division. Cell division does depend on cytoribosomal protein synthesis, since it is blocked by cycloheximide.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Van Kummer, Brooke
- Description:
- Moderate aerobic exercise has been shown to enhance motor skills and protect the nervous system from injury and neurodegenerative diseases, like ataxia. Our lab uses the spastic Han-Wistar rat as a model of ataxia. Mutant rats develop fore limb tremor, hind limb rigidity and have a significantly decreased life span. Our lab has previously shown that moderate treadmill exercise reduced Purkinje cell degeneration in the cerebellum, delayed the onset of visible motor dysfunction, and significantly increased life span. This suggested that aerobic exercise ameliorates the observed cerebellar dysfunction in the sHW rat. The focus of this thesis is to understand the mechanism of how exercise may mediate neuroprotection by studying Brain-Derived Neurotrophic Factor (BDNF). BDNF is known to increase after exercise and has been reported to be crucial in Purkinje cell survival through activation of various signaling cascades. The actions of BDNF are mediated by the TrkB receptor. To link BDNF to exercise-induced neuroprotection, 28-day-old mutant and normal rats received surgically implanted Alzet osmotic pumps that chronically infused the TrkB antagonist K252a or the control vehicle (1% DMSO) into the third ventricle. During the 28 day infusion rats were subjected to five-day-per-week exercise regimens on a motorized treadmill. Mutant rats receiving K252a exhibited a 21.4% loss in Purkinje cell survival compared to control mutants. Cerebellar TrkB expression was evaluated using non-drug treated 30-day-old rats that were subjected to various regimens: 7 days of running, 30 days of running, or non-running controls for each age. Running animals expressed up to 3× more TrkB than sedentary animals. BDNF was quantified via Sandwich ELISA, and cerebellar expression was found to be 26.6% greater in mutant rats on 7-day treadmill exercise regimen compared with those subjected to 30 days of treadmill exercise. In normal animals, BDNF expression in acute runners was 10% greater than in chronic runners. Rats did not express significantly more BDNF than sedentary controls in either exercise duration group. In summary, these results suggest the neuroprotective benefits of aerobic exercise can be blocked using the K252a TrkB antagonist, and that BDNF activation of the TrkB receptor signaling pathway is involved in mediating exercise-induced neuroprotection.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
81. Evolution of temperature-dependent sprint performance in nocturnal and secondarily diurnal geckos
- Creator:
- Luken, Alissa
- Description:
- Temperature has a profound influence on most aspects of an ectotherm's life. Most of the world's 1500+ gecko species are nocturnal and therefore presumably active at body temperatures (Tbs) that are suboptimal for performance. However, several clades and numerous gecko species have independently reverted to diurnality and are therefore active at warmer Tbs allowing for comparisons of temperature-dependent sprint performance between nocturnal and secondarily diurnal species. Following the hotter-is-better hypothesis, which states that warm-adapted species will have better performance than cold-adapted species, we hypothesized that diurnal geckos would have faster maximum speeds than nocturnal species at their thermal optimum. Likewise, the optimality hypothesis predicts co-adaptation between environmental temperatures and optimal Tbs for performance. Thus, we hypothesized that diurnal geckos would sprint faster at warmer Tbs and slower at cooler Tbs relative to nocturnal geckos. We tested these hypotheses by comparing the temperature-dependent sprint performance of 27 gecko species over a range of ecologically relevant Tbs to determine how activity time (nocturnal/diurnal) affected sprint performance. Conventional statistics and those that accounted for the genetic distances among the species were used to compare the sprint performance of nocturnal and diurnal geckos. Additionally, two clades with closely related nocturnal and secondarily diurnal species were compared using conventional statistics. Nocturnal geckos had slower sprint speeds than diurnal geckos overall, which is consistent with the hotter-is-better hypothesis. In accord with the optimality hypothesis, diurnal species sprinted relatively faster at higher Tbs and slower at cooler Tbs relative to nocturnal species suggesting that there has been an evolutionary shift in the temperature-dependent sprint performance of diurnal species with the higher activity temperatures associated with diurnality. Phylogenetic history did not influence temperature-dependent sprint performance because diurnality has evolved independently several times among the species included in this study and clades with diurnal species are spread throughout the gekkotan tree. Our study provides insight into the ways in which an evolutionary change in activity time can affect the evolution of temperature-dependent sprint performance in geckos and illustrates the likely constraints on performance for other cold-adapted nocturnal species.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Yan, Jun
- Description:
- Melanoma is the most dangerous form of skin cancer because it is resistant to most common cancer treatments, such as chemotherapy and radiation. In 2014, a novel immunotherapy based on the blockage of the PD-1/PDL-1 signaling pathway was approved for malignant melanoma. However, this treatment is only effective with patients with high-level expression of PD-1/PDL-1. Therefore, developing an alternative melanoma treatment is an urgent mission. The goal of this proof of principle study was to augment the ability of natural killer (NK) cells to effectively target and kill melanoma cells by engineering them to express a T cell receptor (TCR) specific for melanoma antigen Mart-1. TCRs are not normally expressed on NK cells, although the protein components necessary for TCR signaling exist in these cells. By using this approach, the NK and T cell anti-melanoma properties would be consolidated within one cell type. Furthermore, as melanoma cells generally use different strategies to suppress T and NK cells, the TCR expressing NK cells could compensate for the lack of T cell activity when these cells are absent or viii immunosuppressed. In this study, human embryonic stem cells (hESC) were used as the source of genetically modified NKs, as they are relatively easy to genetically manipulate, expand to clinically relevant quantities, and to differentiate into NK cells that are phenotypically and functionally indistinguishable from their blood derived counterparts. TCRs require the CD3 complex of proteins for transport to the cell surface and proper signaling. To provide all the elements needed to support normal TCR function, the coding sequences for the CD3 γ, ζ, δ and ε chains, along with the Mart-1-specific TCR genes, were introduced into H1 hESC. Individual transgenic hESC lines were selected, the expressions of both Mart-1 TCR and CD3 on their surfaces were confirmed, and then they were differentiated into TCR/CD3 NK cells. In the future, Mart-1-specific TCR and CD3 expressing cells will be used in in vitro and in vivo experiments to establish that the presence of the Mart-1 TCR should endow these transgenic NKs with a higher anti- melanoma cytotoxic potential. Importantly, this technology could be adapted and expanded for treatment of other tumors and malignancies.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Taghavifar, Forough
- Description:
- The genetic causes of β-thalassemia are largely well described. However, the disease is very heterogeneous at both the molecular and clinical levels. Studying the transcriptome profiles of β-thalassemia patients, especially individuals who carry novel mutations in the β-globin gene (HBB), may improve our understanding of the heterogeneity and molecular mechanisms of the disease and its possible treatment. Here, I characterized members of a family with β-thalassemia using whole genome expression analysis. I report a novel mutation in the exon 1 region of HBB (HBB:c.51C>T) that was associated with an unexpected phenotype of β-thalassemia in a heterozygote who also carries a typical β-thalassemia allele. I analyzed effects of the novel mutation at the transcriptome level by RT-qPCR and high-throughput RNA sequencing using an Illumina Hiseq2500 system. The results revealed that the novel mutation creates a cryptic donor splice site in the HBB, which causes alternative splicing from the site and down-regulates (~0.7) expression of the β-globin. Gene expression profiling analysis showed that there were more than 300 differentially expressed genes (DEGs) in β-thalassemic blood. The DEGs were enriched in pathways that are directly or indirectly related to β-thalassemia such as hemopoiesis, heme biosynthesis, response to oxidative stress, inflammatory responses, immune responses, controlling of Circadian rhythms, apoptosis, and other cellular activities. It was possible to compare these findings with published results of RNA-seq analysis of sickle cell disease and KLF1-null anemia, and recognize similarities and differences in their transcriptional expression patterns. While many DEGs involved in response to hemolysis, iron homeostasis, and anemia were in common between these three types of anemias, over 200 DEGs were unique to β-thalassemia. Although this study was limited by the small sample size of the patients, it provides a wealth of data on β-thalassemia because it is the first broad investigation of blood cell gene expression in this disease, and gives us novel insight that can be used in drug discovery to identify novel therapeutic approaches for the disease.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Meyer, James T.
- Description:
- The complex nature of the teratoma cell adhesion system has been demonstrated. Fractionation of crude ascites fluid on a DEAE cellulose ion exchange column made it possible to show that two or more components are involved in teratoma adhesion factor (TAF) activity. Glycoproteins in fractionated ascites fluid were localized on polyacrylamide gels. The possible role of these glycoproteins in teratoma cell adhesion and current hypotheses on the mechanism of carbohydrate involvement in intercellular adhesion are discussed.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Carnes, Michael Andrew
- Description:
- TIhe effects of mechanical habitat conversion on eight species of rodents were studied in the San Gabriel Mountains north of Pacoima, Los Angeles County, California, from November 1973 to December 1974. Two kinds of 'type-conversion', fuel break grassland and rejuvenated chaparral were live-trapped and comparisons were made between them and with immature and mature chaparral. Openland-preferring species were favored on type-conversions and species composition in rejuvenated chaparral were similar to that in immature chaparral. Rodent densities were approximately the same on both type-conversions and in both cases were greater than that in immature chaparral and less than that in mature chaparral. Rodent species diversity was high in rejuvenated chaparral and immature chaparral relative to grassland and mature chaparral. Rodent diversity was not correlated with density. (See more in text.)
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Thorne, Richard Charles
- Description:
- The serine auxotroph, ser (JBM 4-13), appeared to be highly unstable and displayed a highly variable revertant frequency of 1 x 10-6 to 2.8 x 10-1. The mutant's characteristics were examined with respect to the properties of unstable genes predicted by current models explaining genetic instability. After a sustained effort, no auxotrophic strain could be isolated with a non-variable revertant frequency. Time and temperature were tested for their ability to alter revertant frequency. A revertant was isolated for comparison with the auxotroph and with a nutritionally wild-type strain for the effects of time and serine concentration on growth. Both the auxotroph and the wild-type strain were exposed to UV irradiation to determine dose response curves as well as the effect of UV irradiation on the revertant frequency in the auxotroph. Mixed cultures of known ratios of revertants to auxotrophs were grown at various serine concentrations to determine the effect on the revertrant frequency. The results of these studies indicate that it is unlikely that the high revertant frequency is due to extrinsic mechanisms such as controlling elements, episome-like factors, mutator genes, virus particles or defective repair mechanisms. Genetic instability due to an intrinsic factor has not been excluded by the present study; however, considerable evidence was obtained indicating that the high revertant frequency is due to a selective advantage of the revertant over the auxotroph in mixed cultures grown on low concentrations of serine supplement. The selective advantage of the revertant over the auxotroph was not apparent at higher concentrations of serine. The variability in the revertant frequency between cultures could be a result of differences in the time at which the reversion event occurred in the individual cultures.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Vishlaghi, Neda
- Description:
- The cerebral cortex is a specialized region of the brain responsible for higher neurological functions such as sensory processing, learning and memory, cognition, and abstract thinking. This region is disproportionally enlarged in humans and other primates, and thought to be one of the factors that allows for our enhanced intellectual capacities compared to lower species such as rodents. Hence, rodent models are not ideal tools for studying the primate-specific features that drive brain growth and complexity. Several studies have shown that human embryonic (hESCs) and induced pluripotent stem cells (iPSCs) have the ability to form three-dimensional cortex-like structures called organoids that recapitulate distinct aspects of human brain development. However, our and others' results indicate that cortical organoid formation is variable and often not reproducible, differing between hESC and hIPSC lines and maintenance methods. One of the biggest influences that we have found is growth under mouse embryo fibroblast (MEF)-dependent vs. independent conditions. Maintenance with MEFs permitted robust and reproducible organoid differentiation from either hESC or hIPSC. Importantly, cells initially grown under feeder-free conditions can be entrained to produce organoids when passaged with MEFs. Moreover, the positive effects of MEFs on organoid differentiation require sustained MEF-dependent culture. Organoids differentiations have been checked by immunostaining for cortex main markers. The transcriptome of cells cultured under different conditions, analyzed by RNA-seq to identify hallmarks of successful cortical organoid differentiation. A better understanding of how these different maintenance conditions influence organoid development will help predict experimental outcomes and improve the application of these methods for modeling normal and diseased human brain development.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Gutierrez, Nicholas
- Description:
- Mating signals play an important role in both mate selection and species recognition. Acoustic mating signals have been shaped under various evolutionary constraints with remarkable malleability in response to variable conditions. These same traits have been shown to serve as indicators of species identity and mate quality. But how will sexually selected signal traits be expressed as environmental conditions change and as species diverge? Using three closely related Gryllus crickets (Gryllus lineaticeps, G. personatus, and G. sp15/"G. staccato"), I assessed how components of male song (chirp rate, pulse rate, frequency, and pulses per chirp) and morphology responded to varying environmental dietary conditions within and among genetically structured family groups (sibships). Experimental diets had some effects on morphology with differences in mass and pronotum width in some species, but the diets had no effects on body condition or components of calling song, save one trait in one species. In contrast, sibship consistently affected chirp rate and frequency but did not affect pulse rate and pulses per chirp either within or among species. Interestingly, the dynamic song traits, chirp rate and pulses per chirp, exhibited broad variation in all species, as expected, but responded differently from each other to sibship. Likewise, the static song traits, frequency and pulse rate, exhibited limited within-species variation, as expected, but had different contrasting effects of sibship. Overall genetic variation in song traits was most strongly associated with species divergence, and then with dam but not sire effects within species. Overall, these results suggest conservation across species of the major sources of within-species song variation; that is, divergence among species appears to be associated with changes in the average values of song traits, especially static ones, but not consistent divergence in the sources of within-species variation.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Holmes, Jacob
- Description:
- The vulture guild is comprised of two distinct groups, Old and New World, that provide a unique insight into how morphology varies among convergent species. All vultures are considered to be large birds of prey that utilize a style of flight called thermal soaring to search and feed primarily on already dead animal flesh. Even though this flight style is exhibited among all 23 species, slight variations in their skeletal morphology may relate to their differences in ecology. I hypothesized that vulture humeral morphology varies in relation to these organisms' habitat, average body mass, courtship displays, and migration capabilities. To address this hypothesis, I used three-dimensional geometric morphometrics to measure the overall shape differences of vulture humeri. Computer models of each bone were created to observe the crucial skeletal features that relate to muscular functions and were analyzed using discriminant function analyses. Humeral morphology was found to vary most by habitat preference and body mass. Vultures that inhabit forested areas have humeri that exhibit features that suggest increased flapping flight compared to those in open and mountainous regions. The results for the heaviest species allude to these birds enhancing their wingbeats in ways other than humeral morphology
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Cornejo, Martha
- Description:
- Schwann cells are vital to sustaining the neurons and making myelin in the Peripheral Nervous System, and play a key role in some neurodegenerative illnesses such as the Charcot-Marie-Tooth disease. The Schwann cell is derived from a transient population of cells, the neural crest, in the early stages of embryogenesis of vertebrate organisms. Understanding the factors influencing NC and SC migration in reaching their final destinations during development would have fundamental applications to help neuropathies and degenerative diseases from the Peripheral Nervous System. Here we have investigated the effect on chemotaxis and chemokinesis that the protein ligands NRG1 and NGF have on chick Neural Crest cells and mouse Schwann cells. The findings from this research shows that NRG1 and NGF play a chemoattractant role in the migratory guidance for the NC and the SC.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
91. Comparative ecomorphology of cormorants (Phalacrocoracidae) from three mediterranean climate regions
- Creator:
- Harell, Allan
- Description:
- Cormorants (Phalacrocoracidae) are seabirds that depend on their hind limbs and beak to pursue and capture their prey underwater, rendering these apparatuses critical for their survival. Although the group is cosmopolitan, cormorant communities of three or more sympatric species are only found in mediterranean climate regions characterized by nutrient rich currents. I used morphological parameters (from museum specimens) related to feeding and locomotion in cormorants from three such regions- California, central Chile, and western S. Africa-to assess convergent functional patterns. Morphological designs were explained by feeding category in 8 of 9 focal species, and a higher resemblance in design pattern was seen between California and S. Africa. Discriminant Function Analysis (DFA) was used to create three feeding categories-generalist (G), pelagic (P), and benthic (B)-based on ecological and dietary information from three Californian feeding types (Phalacrocorax auritus, P. penicillatus, and, P. pelagicus) and three S. African types (P. carbo lucidus, P. capensis, and P. coronatus). All six species were classified to their consensus groups with probabilities ≥85%. Chilean species, P. olivaceous and P. bougainvillii, were assigned by the DFA to their predicted groups G and P, respectively with probabilities ≥82% and 100%, but P. gaimardi was not assigned to its predicted group B, but instead was assigned to P, suggesting a more pelagic feeding ecology. Proportional knee and tarsus lengths, and beak depth were found to be the strongest determinants of feeding category and may be useful tools in predicting feeding ecologies of other hind limb pursuit diving waterbirds.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Wenner, Sarah
- Description:
- Landscape genetics combines principles of landscape ecology and population genetics to determine the effect of landscape characteristics on the functional connectivity of populations. Functional connectivity, the degree to which organisms move across the landscape, provides a proxy for gene flow and is limited by characteristics of the species and the environment. Identifying the landscape variables that promote or impede functional connectivity can provide a comprehensive look at the fine-scale genetic effects of natural and anthropogenic fragmentation and landscape change. Here, I examine population genetic structure and functional connectivity among populations of an ecological specialist, the Blainville's horned lizard (Phrynosoma blainvillii), in a fragmented landscape in southern California. I studied horned lizards from Los Angeles and Ventura counties at the boundary between evolutionary lineages. Using RADseq SNP data, I assessed population genetic structure, as inferred from Bayesian assignment tests. I interpreted the results in the context of broad-scale phylogeography, as well as at a fine-scale among habitat fragments in the highly urbanized region. Based on the ecological requirements of P. blainvillii, I developed a suite of hypotheses to test the at-site landscape variables that promote production of horned lizards and the between-site landscape variables that impede gene flow. I used gravity models to test which of the hypotheses best explained the estimates of functional connectivity. My results show strong population genetic structure across small habitat fragments in the study area, indicating an effect of habitat fragmentation. Further, the gravity models show that elements of topography, microclimate, soil and vegetation types, fire history, and anthropogenic development are important components of functional connectivity in this part of the species' range. Together, my results highlight the importance of natural and anthropogenic landscape factors at- and between-sites, species-specific characteristics, and habitat fragmentation on the patterns of genetic structure and connectivity of P. blainvillii in Southern California.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Capelle, Christopher B.
- Description:
- An aggregation inhibitory factor (AIF) has been extracted from mouse ascites teratoma cells that retards adhesion of cultured teratoma cells of the same cell line. Preliminary characterization of AIF on polyacrylamide gels suggests that AIF is a carbohydrate-free protein composed of four subunits. Extraction of AIF from ascites teratoma cells was accomplished without significant loss of viability by a novel technique involving the application of an electric field to large numbers of whole cells suspended in a hypertonic electrode buffer. Assumptions were made regarding the force developed by this field on charged transmembrane proteins in order to measure the potential of this technique for extracting proteins of possible significance in adhesion. In tests of adhesion, AIF consistently inhibited auto-aggregation of cultured teratoma cells after 5, 10, 15, and 30 minutes of incubation with cells. Furthermore, a reduced concentration of AIF resulted in a corresponding decrease in inhibition, suggesting a concentration dependent action. Further work with AIF may reveal if this factor plays a role in the adhesion mechanism of cultured teratoma cells.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Modarresi, Yasamine
- Description:
- Muscular dystrophies are a group of inherited disorders characterized by progressive muscle weakness, and degeneration. One approach to treatment would be the replacement of the deficient protein via gene therapy. For effective gene therapy, both efficiency of gene delivery and stable expression of the transferred gene are important factors. Our goal was to determine which of the following mammalian expression vectors would be more useful (more stable) for muscle gene therapy; pAcGFP1-C1 and pEPito. We were also interested in switching/substituting both vectors' CMV promoter/enhancer region with the muscle specific promoter, Desmin (DES), to increase their stability for muscle gene therapy. This was accomplished by transfecting C2C12 myotubes with the aforementioned vectors. Both vectors showed relatively continuous GFP expression. Myotubes transfected with pEPito continued to express GFP till day 8. Cells transfected with pACGFP1-C1 also showed continuous GFP expression till day 6. Our results show that both vectors are promising candidates for gene therapy in muscle cells as they maintained stable gene expression of the GFP reporter gene for at least 6 days. Further studies should be done in order to determine the maximum duration that the myotubes would be able to maintain the plasmids and show continuous expression. Future studies could be done to assess stability of these vectors in mice which may lead to future gene therapy trials for muscle disorders and improving gene therapy strategies for other disorders.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Becker, Danielle
- Description:
- Coral reefs, some of the most diverse ecosystems in the world, face increasing pressures from global and local-scale anthropogenic stressors. Nutrient enrichment and sediment loading could make corals more vulnerable to global climate change by suppressing calcification and reducing their photosynthetic performance. Yet, some nutrient-enriched reef environments have exhibited higher coral growth rates, coral productivity, and coral thermal performance. To properly inform management in coastal coral reef ecosystems, a better understanding of warming and land-based inputs (i.e. sedimentation rates and nutrient loading) on coral reef ecosystems is necessary. This thesis is comprised of two studies that address the ecological and physiological influence of land-based inputs on two branching coral species to thermal stress. The first study tested how a natural nutrient and sedimentation gradient affected multiple facets of coral functionality, including algal endosymbiont and coral host response variables, holobiont metabolic responses, and percent cover of Pocillopora acuta colonies on the north shore fringing reefs in Mo'orea, French Polynesia. Algal endosymbiont % nitrogen content, algal endosymbiont densities, and total chlorophyll a content increased with nutrient input, while algal endosymbiont nitrogen content cell-1 decreased, likely representing competition among algal endosymbionts. Nutrient and sediment loading decreased coral metabolic responses to thermal stress in terms of their thermal performance and metabolic rate processes, and the percent cover of P. acuta colonies decreased by nearly two orders of magnitude along the nutrient gradient. The second study focused on the direct effects of nutrient enrichment on the thermal performance of corals on a fore reef in Mo'orea, French Polynesia. In this study, I measured how chronic nutrient enrichment affected coral physiology, including endosymbiont and coral host response variables, and holobiont metabolic responses of Pocillopora spp. colonies in Mo'orea, French Polynesia. I experimentally enriched corals with nitrogen and phosphorus combined for 15 months on the oligotrophic fore reef of Mo'orea. I first characterized symbiont and coral physiological traits due to enrichment and second used thermal performance curves to quantify the relationship between metabolic rates and temperature for experimentally enriched and control coral colonies. I found that the nutrient-enriched coral's endosymbiont densities, total chlorophyll a content, and tissue biomass were 54 %, 38 %, and 22 % higher, respectively, while algal endosymbiont nitrogen content cell-1 was 74 % lower relative to the control colonies. In addition, thermal performance metrics indicated that the maximal performance rate for gross photosynthesis was 29 % higher in enriched colonies, while the rate of metabolism at a reference temperature (26.8 °C) for gross photosynthesis was 33% higher compared to the control colonies. These findings illustrate that the relationship between land-based inputs, such as nutrient and sediment loading, and coral physiology is dependent on the local environmental context. Together these results help us better understand how local-scale stressors influence coral functionality and thermal performance in varying reef habitats. By understanding the complexities of coral-nutrient dynamics, research-based reef management approaches can be taken, particularly on where to mediate the influx of land-based inputs into coastal coral reef ecosystems.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Pregerson, Bernardine S.
- Description:
- Fifty-one strains of Sporosarcina ureae were isolated from 198 soils by plating diluted soil samples onto a complex agar medium containing 1. 5% filter sterilized urea. S. ureae was found to be widely distributed the United States and in various parts of the world. The primary habitat of this organism appears to be concentrated in certain urban soils closely associated with the activities of man and especially of dogs. However, a variety of soils cannot support growth of S. ureae. This organism was not found in soils obtained from zoos, corrals, stables, grazing lands, deserts, or from cultivated fields. Nor was it found in salt water samples. Sixty-one strains of this organism were tested for their ability to utilize 45 different organic compounds as sources of nitrogen, carbon and energv, or as growth factor requirements. The vast majority of strains required only ammonium salts for a nitrogen source but all of the organisms showed limited ability to metabolize carbon sources. Sugars are not utilized or are utilized very poorly, and glucose could not be attacked by any strain. Acetate (or butyrate) and glutamate are apparently universal substrates. The overall metabolic pattern was one of random variation but there was a clustering of strains according to growth factor requirements. The pattern that emerged was that of gradation in growth factor requirements ranging from organisms which required no growth supplements to those organisms whose nutritional requirements are complex. In general, the ecology, morphology, cultural characteristics, or biochemical reactions revealed no consistent differences that could be correlated with nutritional differences . Nor did this study reveal a constellation of differential characters that would permit recognition of additional species of Sporosarcina. The results did suggest that the leading criterion for species identification and classification may be the nutritional differences shown by this organism.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Anderson, Bruce Nicholas
- Description:
- A deterministic model for growth of species of giant kelp, Macrocystis, of the southern California coast was developed and analyzed using FORTRAN. Factors modifying only light and temperature are required to simulate empirically derived growth curves. The model was used to determine optimum time of the year for new growth which was found to be early June, and optimum time of the year for regeneration of harvested canopy, found to be early July. Critical values for turbidity which will prevent new growth for any given kelp bed depth were determined. At twenty meters depth, reduction of transmitted light to 82% per meter caused by introduction of particles, e.g. sewage effluent, into coastal waters reduces growth time by only 20%, but when transmitted light is below 76% per meter growth time is zero. Possibilities for further development of the model by the quantification of additional variables are discussed.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Qubrosi, Mirey
- Description:
- Hereditary Inclusion Body Myopathy (HIBM) is a disorder caused by a mutation in the GNE gene. Although there are 60 known mutations, this research study focused on the M712T mutation. The mutation causes complications in the production of sialic acid, and produces skeletal muscle wasting. The next step in the development of a cure is to produce an animal model. The purpose of this research study was to use the wire hang test to see if mice heterozygous and homozygous for the disorder developed strength deficits. I also tested a new method of genotyping that is faster and cheaper to perform than testing by restriction analysis. I used an animal model with the M712T mutation that was between 12-16 months of age. I tested their grip strength through the wire hang test. Also, I used an advanced rapid method of genotyping the mouse, which included designing two sets of primers specific for the mice GNE gene to determine which mutation the mice contained. The wire-hang test showed that the wild-type mice (WT) performed much better than both the heterozygote (HT) and mutants (MT). On average as a group, mutants performed the worst (32.62 s), followed by heterozygotes (47.35 s), and then wild-type mice (89.33 s). Moreover, the results show that there is a definite difference between the wild-type and mutant mice; both the mutant and heterozygous mice showed similar levels of strength, which indicates that even heterozygotes for the disorder suffer losses in skeletal muscle. Furthermore, my novel genotyping method also showed that it can reliably determine the genotype of the mice. This method is cheaper and quicker to perform.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Vanesian, Michael Ara
- Description:
- Cyanide exerts its toxic effects by inhibiting cellular respiration, specifically by inhibiting cytochrome oxidase. In many bacteria, algae, protozoa and plants cyanide resistance has been demonstrated and is usually associated with an alternate electron transport pathway. A strain of Bacillus cereus was isolated using an elective culture containing cyanide. In 1 mM cyanide, the population growth rate was one-third that of control cells grown in the same medium lacking cyanide. The rate of oxygen consumption was approximately 50% of controls. The addition of 2 mM cyanide to respiring control cells resulted in virtually complete inhibition of oxygen uptake, but only 40% inhibition in cyanide-grown cells. No qualitative or quantitative differences in the cytochromes of the electron transport systems were noted between control and cyanide-grown cells in reduced-minus oxidixed difference spectra. In CO-difference spectra, control cells had one absorption peak at 430 nm. CO difference spectra of cyanide-grown cells lacked this peak, but showed peaks at 500 and 550 nm. The absence of the peak at 430 nm in cyanide-grown cells suggests either that alternate oxidases are produced or that cyanide alters the cytochrome a. (See more in text.)
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Knapp, Loren Walter
- Description:
- Agglutination of S-180 ascites tumor cells mediated by Concanavalin A (ConA) and biologically active succinyl and acetyl ConA derivatives was quantitatively measured and compared, using an electronic particle counter assay. ConA causes agglutination of tumor cells in vitro. Compared to ConA, succinyl ConA (SConA) and acetyl ConA (AConA) cause a substantial reduction in agglutination. Agglutination mediated by ConA, SConA and AConA was affected by pretreatment of the tumor cells with cytochalasin B (cyto B) and colchicine. Cyto B causes inhibition of cellular microfilaments while colchicine causes inhibition of microtubules. ConA mediated agglutination of cyto B pretreated tumor cells was greater than ConA mediated agglutination of untreated cells. Agglutination mediated by SConA and AConA contrasted sharply from the ConA profile. SConA and AConA mediated agglutination of cyto B pretreated tumor cells was less than SConA and AConA mediated agglutination of untreated cells. ConA mediated agglutination of tumor cells was not substantially changed by colchicine pretreatment; however, reduced agglutination of colchicine pretreated tumor cells with SConA and AConA was observed. Inhibition of protein synthesis with cycloheximide does not appear to affect agglutination, while reduction in temperature decreases agglutination. This decrease in agglutination may be related to reduced ConA receptor site clustering which is necessary for effective intercellular connections. These results indicate that derivatized ConA may have a reduced binding affinity for ConA receptor sites on the cell surface. This may reduce the clustering of ConA receptor sites and therefore reduce agglutination of these cells. Although microfilaments and microtubules have not been shown as fine structural elements in these cells, the results suggest that ConA receptor sites on the cell surface may be associated with microfilaments and microtubules.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology