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- Creator:
- Arteaga, Erik Santigo
- Description:
- Klebsiella pneumoniae is a problematic gram-negative bacterium which commonly causes nosocomial infections such as pneumonia, urinary tract infections, burn wound infections, and bacteremia. K. pneumoniae is particularly virulent due to its ability to form biofilms within its host. Recent studies have revealed an upward trend of nosocomial infections caused by multidrug resistant (MDR) strains of K. pneumoniae. Most worrisome are extensively drug resistant strains (XDR), as they can withstand treatment with carbapenems, which are considered the most effective antibiotics in treating microbial infections caused by gram-negative organisms. RNA-sequencing of a biofilm of an MDR strain of K. pneumoniae (BAMC) treated with carbapenems for two hours demonstrated significant differential gene expression in treated biofilms compared to untreated controls. One gene of interest was the alternative sigma factor rpoS which controls the cells’ entry into stationary phase. In this study we attempted to identify the role of RpoS in antibiotic tolerance, virulence, and heat tolerance in K. pneumoniae. A rpoS knockout mutant was generated in the BAMC background. We found that the mutant was not defective in antibiotic or heat tolerance. We believe these responses may be modulated through another mechanism. Our rpoS knockout strain was found to be deficient in virulence in our infection model, Galleria mellonella. This research may provide potential drug targets for MDR or XDRorganisms.
- Resource Type:
- Thesis
- Campus Tesim:
- Fresno
- Department:
- Biology
- Creator:
- Khorshidchehr, Darius Mehrnoosh
- Description:
- Fish execute a C start when they escape from a predator. Previous studies suggest that fish randomize their horizontal escape trajectories, but bias the response away from the stimulus. The fewstudies that looked at the vertical trajectory found that fish larvae respond to a horizontal stimulus with a downward escape trajectory. This study quantifies the escape trajectories of fish larvae in three dimensions. We use a vertical and a horizontal suction stimulus to explore the effect of stimulus direction on the escape trajectory. We found that zebrafish larvae (age 3 to 12 days post-fertilization) consistently responded to a horizontal stimulus with a downward trajectory. For the horizontal stimulus, out of 70 video recordings, 54 showed escape responses (77.1%). Fifty twoof those responses showed a downwards trajectory (96.3%). Thesedata suggestthat the same trend holds true when we use a vertical stimulus, simulating a benthic predator. The vertical stimulus, out of 131 video recordings, 131 showed escape responses (100%). From those responses, 129 showeda downwards trajectory (98.8%). Given the age range of the larvae, the downward trajectory cannot be explained by asymmetry of the body due to the presence of a yolk sac; the yolksac is absorbed usually at age 5 to 6 days. So the downward trajectory might be a hardwired response (zebrafish larvae are demersal) or indicate that fish have less control over their pitch than their yaw angle �the body movements during an escape response might be able to generate a wide range of yawing moments, but not pitching moments, leading to the observed bias in the trajectories.
- Resource Type:
- Thesis
- Campus Tesim:
- Fresno
- Department:
- Biology
- Creator:
- Whalen, William, Alexander
- Description:
- Traditional cell culture techniques grow cells in a two-dimensional (2D) format on compatible surfaces, but cells do not grow like this in vivo. A fast-emerging alternative is three-dimensional (3D) cell culture, which encourages cells to work together while suspended in a matrix rather than relying on adhesion to a treated surface. Most studies utilize a commercially available, industry standard recombinant basement membrane substitute--Matrigel ; however, this is proprietary and expensive. For these studies, my goal was to refine an alternative to Matrigel for use as a suspension media and surrogate extra-cellular matrix (ECM). My efforts focused on economical methylcellulose (a synthetic derivative of cellulose dissolved into basal growth media and called Methocel) in combination with rat-tail collagen (Type I). Optimized concentrations were evaluated towards the formation of spheroids among several cell lines including all three isogenic variants of a metastatic breast cancer cell line, MDA-MB-231, notoriously difficult to adapt to spheroid culture. I chose to use the metastatic breast cancer cell line MDA-MB-231 and two isogenic variants, MDA-MB-231Bo and MDA-MB-231Br, shown to regularly metastasize to either bone or brain respectively. This cell line series was used to evaluate the potential of this low-cost matrix to facilitate spheroid cultures; to determine expression changes in the canonical cell adhesion components Integrins (2, β1, and β4), as well as, E-Cadherins (ECAD) and N-Cadherins (NCAD); and to evaluate the functional significance of the spheroids to a relevant drug treatment. Here, by image analysis of spheroid metastatic progression and semi-quantitative RT-PCR analysis of metastatic cancer cells, we show the potential of this system in observing cancer cell migration and cellular behavior under more in vivo-like conditions, bridging the gap between basic two-dimensional cell culture and the animal model. Furthermore, through the use of this powerful model, we showed the efficacy of zoledronic acid to inhibit osteotropic breast cancer cell migration by up to ~14% post-72h treatment time. Lastly, zoledronic acid treated spheroids showed a continued improvement towards regaining more epithelial-like gene transcription profiles in genes associated with cells having undergone epithelial-mesenchyme transition. Together, these data add validity to our claim that metastatic studies using a surrogate extracellular matrix, such the one suggested in this study, continue to bridge the gap between typical two-dimensional cell culture and the animal model.
- Resource Type:
- Thesis
- Campus Tesim:
- Fresno
- Department:
- Biology
- Creator:
- Castro, Jamie
- Description:
- Early sexual maturation (precocity) of male salmonids is a serious issue in the modern conservation hatchery. Previous studies have demonstrated a ‘decision window’ of time for sexual maturation for Spring-run Chinook salmon beginning in the fall, during which the fish use biological and environmental cues to “decide” whether to mature for the following season. The months signifying the beginning and end of this fall decision window for California strains remains unclear. Therefore, an experiment was designed to elucidate the beginning and end of the decision window for California strains of male Spring-run Chinook salmon. A total of 628 juvenile males were randomly distributed among six tanks and fed a reduced ration diet during the predicted maturation decision window by adjusting duration and timing of diet reduction for each group. An additional 53 males were fed a high ration diet throughout the decision window. Individual weights and lengths were measured monthly. Precocity ranged from 32% to 10%, with the highest rate observed in the group fed a reduced ration between July- January and the lowest rate observed in the group fed a reduced ration between August-February. Additionally, condition factor (an estimation of adiposity), was observed to increase for males who would mature during the spawning season subsequent to the study period. Thus, it may be possible for hatcheries to implement feed reduction strategies to manage adiposity and precocity in broodstock.
- Resource Type:
- Thesis
- Campus Tesim:
- Fresno
- Department:
- Biology
- Creator:
- Fok, Katherine Sik-Ling
- Description:
- An earlier study on the effect of excess DL-methronine on Saccharomyces cerevisiae strain 3701B when cultured on a rich medium showed that there was an inhibition of cultural development during the first 6 to 12 hours. However, a sudden and sharp increase in cultural development occurred after the inhibition period. The purpose of the present study is to observe the effect on S_. cerevisiae when grown on defined and minimal media in the presence of varying concentrations of DL-methionine. The ∝-hydroxylmethyl group of serine is the dominant donor of methyl group in methionine synthesis, and the enzyme catalyzing the transfer of the ∝-hydroxylmethyl group in the formation of methionine is serine hydroxy-methylase. It is our present interest to note the effect of varying concentrations of DL-methionine on the production and activity of serine hydroxymethylase. It is also of Interest to note if varying concentrations of methionine would have any effect on the production of glutamic-oxalacetic aminotransferase, an enzyme which is not directly involved in methionine biosynthetic pathway.
- Resource Type:
- Thesis
- Identifier:
- ocm58533112
- Campus Tesim:
- Fresno
- Department:
- Biology
- Creator:
- Janzen, Whitney Jean
- Description:
- In response to a stressor, an animal�s physiology is altered in an attempt to maintain homeostasis. Cortisol, a corticosteroid hormone that binds to the glucocorticoid receptor (GR), has widespread actions which mediate the stress response. In an aquaculture setting, fish are exposed to many stressors, which may negatively impact their growth and metabolism. The objectives of my thesis were to investigate the effect of cortisol on food intake, the hormonal regulators of appetite, glucose metabolism, and the growth axis. The tilapia (Oreochromis mossambicus) was used as the model because of its rapid growth and worldwide popularity as an aquaculture species. It was found that cortisol reduced food intake, which appears to be mediated by a reduction in the mRNA levels of the orexigenic hormones (NPY and ghrelin) in the telencephalon and diencephalon regions of the brain, as well as suppressed plasma and stomach ghrelin levels. mRNA levels for genes related to growth (IGF-I, GHR1, and GHR2) were elevated in the liver and muscle in response to cortisol. Total glucose levels were also elevated, as well as INSR mRNA in the liver. Treatment with the GR antagonist (RU-486) generally reversed the effects of cortisol, except in certain tissues, which may indicate the presence of multiple GR isoforms in tilapia. These results provide a mechanism for cortisol�s anorexigenic effects in tilapia.
- Resource Type:
- Thesis
- Campus Tesim:
- Fresno
- Department:
- Biology
- Creator:
- Anderson, Kathleen Mary Kennedy
- Description:
- In this study, substrate and water agitation of the echinoid habitat are related to the entocommensal incidence. Host species examined at Eniwetok had higher densities of entocommensal ciliates in lagoon waters than in surf waters on the fringing reef (Berger, 1964b). Lower infaunation rates for irregular hosts have been related to the ingestion of substrate unsuitable as food for ciliates (Berger, 1963b). Echinoid distribution and habitat data for areas having taxonomically similar echinoids to those of American Samoa have been reported for the Indo—Pacific islands of Hawaii (Ebert, 1971) and the West Indies-Florida area of Key Largo, Florida (Kier and Grant, 1965).
- Resource Type:
- Thesis
- Identifier:
- ocm56986158
- Campus Tesim:
- Fresno
- Department:
- Biology
- Creator:
- Upton, Kelli Renee
- Description:
- The general stress response principally results in the release of cortisol, with the overall effect of mobilizing metabolic energy and redirecting it towards homeostatic maintenance. Consequently, an important factor altered by stress is food intake. In several teleost species, a decrease in food intake following stress has been observed, though the neuroendocrine mechanism controlling the reduction in food intake during stress has yet to be determined. These studies were designed to investigate the effect of an acute stress on food intake and brain expression of corticotropin-releasing hormone (CRH), neuropeptide Y (NPY), ghrelin and ghrelin�s receptor and whether these effects are mediated by cortisol. Therefore, metyrapone, a cortisol synthesis inhibitor, was administered via feed in three doses of 10, 25, and 50 mg/kg body weight for 1 wk prior to a 30 min crowding and handling stress. Following the stressor, fish were allowed to feed for 1 h. Stress reduced food intake, while elevating mRNA levels of CRH, an appetite suppressor. Additionally, metyrapone treatment dose-dependently blocked the stress-induced reduction in food intake. While NPY and ghrelin levels were unchanged, an increase in ghrelin receptor activity suggests a function for ghrelin in regulating overall metabolism in response to stress. The elevation of CRH mRNA levels was also reversed with metyrapone treatment, suggesting cortisol and CRH play a role in mediating reduction of food intake during stress in tilapia.
- Resource Type:
- Thesis
- Campus Tesim:
- Fresno
- Department:
- Biology
- Creator:
- Sarvabhowman, Preethi
- Description:
- In the present study, we studied the growth characteristics of two species of green algae; Dunliella primolecta and Botryococcus braunii, in fruit industry wastewater and also studied the COD removal from wastewater by these species. We found that both the species of algae could grow better in 25% (v/v) wastewater reaching the stationary phase when compared to other concentrations of wastewater. However, Dunaliella primolecta was found to be growing faster than Botryococcus braunii, reaching a concentration of 8x106 cells/mL in 15 days. Also, it was found to remove 63% of COD from fruit industry wastewater obtained from Wawona Frozen Foods, CA. We also reported the first successful Agrobacterium tumefaciens method of transformation for the green algae Dunaliella primolecta using the binary vector pCAMBIA 1301 containing the genes coding for GUS (B-Glucuronidase) and hpt (hygromycin phospho- transferase). The developed transformation protocol would pave a way for easy manipulation of Dunaliella primolecta for the production of biofuels and other secondary metabolites.
- Resource Type:
- Thesis
- Campus Tesim:
- Fresno
- Department:
- Biology
- Creator:
- Holland, V. L
- Description:
- The purpose of the present study is to gain some insight into the complex of factors that create the canopy effect with emphasis on the microenvironment that is associated with the vegetative differences. Data recorded weekly included the measurement of plant growth, precipitation, air temperature, soil moisture, and soil temperature. Other studies involved pH, bulk density, permanent wilting percentage, moisture equivalent, field capacity, organic content of the soil and. plant distribution. The determination of all factors involved was not possible in the two growing seasons studied, but accrued data suggests certain ecological relationships. The investigation was undertaken at the San Joaquin Experimental Range (SJER) near O'Neals, California, 25 miles north of Fresno. The SJER is situated on the east side of the San Joaquin Valley in the Sierra Nevada foothills. The natural vegetation is typical of the foothill woodland community (as recognized by Munz, 19&3) consisting of trees 15-70 feet tall in an open woodland with scattered brush and grassland between the trees.
- Resource Type:
- Thesis
- Identifier:
- ocm58723865
- Campus Tesim:
- Fresno
- Department:
- Biology
- Creator:
- Slonka, Stephanie Marie
- Description:
- As California continues to persist in a state of severe drought, residents of the Fresno Clovis Metropolitan Area (FCMA) are slowly making changes to reduce their water usage and to be conscious of how this resource is utilized in their landscape. Since the advent of water metering in 2013 and the Governor’s declaration of California’s state of emergency, it is unknown how the response of our wildlife populations will fare, in particular, avian populations. Several studies have indicated that a long-term drought and the reduction of water availability can have adverse effects on the avian communities within a city. A pre-metering (2008) to post-metering (2015) comparison was conducted using multivariate analyses to determine how the landscape changed over time and if avian communities have responded to the “effective drought” that the FCMA is experiencing. Since pre-metering, bird abundance and the species richness of the FCMA has decreased and new habitat variables are now shown to predict bird species richness and abundance. Other essential aspects of the urban landscape that have been shown to make an impact on the bird communities had a negative response to certain socio-economic variables and there being no effect on foraging guilds in relation to certain irrigation intensities as reported in pre-metering years.
- Resource Type:
- Thesis
- Campus Tesim:
- Fresno
- Department:
- Biology
- Creator:
- Healer, Rain
- Description:
- The Endangered Species Recovery Program (ESRP) is supervising land restoration in southwest Fresno County through the federally funded Land Retirement Project. The reclaimed land is adjacent to currently farmed land, and there is grower concern that native vegetation on the reclaimed land will function as a reservoir for insect pest infestation. The purpose of my research was to conduct an initial inventory of Diptera present on some of the California native plants that are utilized in habitat restoration by the ESRP in southwest Fresno County. Dipteran populations were sampled on three of the species of native plants grown within the ESRP�s native plant seed nursery and on the same three plant species that also occur within non-nursery sites in the general area surrounding Tranquillity. This research provided preliminary information on dipteran trophic guilds and the potential amount of ecological redundancy present within this ecosystem. It also provided baseline biodiversity data for future research. Future work will estimate species richness, abundance, and pest/beneficial significance from this baseline data. No significant difference was found between collection sites in taxa collected, trophic guild, number of Diptera collected, and pest status.
- Resource Type:
- Thesis
- Campus Tesim:
- Fresno
- Department:
- Biology
- Creator:
- Houk, James L
- Description:
- Gregarines are parasitic protozoa belonging to the sporozoan subclass Telosporidia. They occur most often in invertebrate groups with a metameric level of development. Some, however, have been described from mollusks which do not have a metameric level of development (Cheng, 1967; Leger and Duboscq, 1908). The eugregarines of arthropods, including barnacles, are typically members of the suborder Cephalina. Cephaline gregarines are described as polycystid organisms to contrast them with the unsegmented monocystid gregarines. The bodies of cephaline gregarines are divided into two segments, an anterior protomerite separated from the posterior deutomerite by a membrane which does not restrict movement of the endo-plasm but does set off the nucleus in the deutomerite. A holdfast, the epimerite, is located on the anterior end of the young sporont. The gregarine remains temporarily attached externally to the cell in which it developed. It subsequently loses the epimerite and becomes a trophozoite which moves about freely, usually in the gut lumen.
- Resource Type:
- Thesis
- Identifier:
- ocm60129979
- Campus Tesim:
- Fresno
- Department:
- Biology
- Creator:
- Benjamin, Christina Joyce
- Description:
- Zebrafish is an important model species to study vertebrate development. One particularly interesting aspect of fish ontogeny, which zebrafish larvae exhibit, is the high tail beat frequency up to 10 times higher than that of adult fish. Larvae therefore require a different muscle fiber type than adult fish. This study identifies the changes in muscle protein composition that might underlie this change in muscle contraction frequency. This question is interesting because contraction frequencies above 80 Hz require the so-called superfast muscles, a muscle type so far only been identified in non-locomotory muscles not required to generate significant forces. Superfast muscles are known to differ from normal fast muscles in several proteins, including myosin heavy chain. In this study we will focus on myosin, the largest protein fraction of a muscle that constitutes 40- 50% of total muscle. This study identifies and validates a protocol for myosin protein extraction and identification of myosin isoforms. Fast myosin heavy chains (210 kD) were identified in hatchlings (not yet swimming actively) and in adult Zebrafish (tail beat frequency 10 Hz). In 6-d old larvae (swimming actively, tail beat frequency 100 Hz), we found an isoform (160kD) that was identified in cat masseter muscle, which is a muscle with superfast contraction characteristics. We identified isoforms by probing Western blots with primary antibody (MYH1/2/3) against myosin heavy chains. BCA and ImageJ analysis were performed to quantify the amount of total protein and the myosin content.
- Resource Type:
- Thesis
- Campus Tesim:
- Fresno
- Department:
- Biology
- Creator:
- Wilder, William H
- Description:
- The Goraori acetylthiocholine technique was used to investigate the distribution of cholinesterase in fourth instar larvae of Culiseta inornate (Nilliston). Fixed and especially prepared larvae were incubated in the substrate solution for the required time, the larvae were imbedded in paraffin, and serial sections were prepared. Microscopic examination of the material revealed a strong histochemical reaction throughout the central nervous system. Faint reactions, not apparent in many of the preparations, were sometimes found associated with muscle, gastric caecae, or Malpighian tubules. The use of selective enzyme inhibitors indicated that the cholinesterase in C. inomata larvae cannot be catagorized as either acetylcholinesterase or pseudo-cholinesterase.
- Resource Type:
- Thesis
- Identifier:
- ocm64178425
- Campus Tesim:
- Fresno
- Department:
- Biology
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