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- Creator:
- Katchikian, Hurig
- Description:
- A superior mechanism of detecting cancerous cells and delivering anti-cancer drugs to highly localized targets is currently lacking in the field of oncology. Unfortunately, chemotherapy is not a specialized method of delivering therapeutic reagents to the body, and is therefore toxic to cancerous and noncancerous cells alike. For this reason, it is imperative to seek alternative forms of treatment. Lectins, for example, act as the ideal'bait' because they exhibit a high affinity towards carbohydrate-rich cellular surfaces. Transformed cells have altered surfaces that often express elevated levels of glycoprotein than do healthy cells, and readily bind to lectins. Unlike older lectin assays that are be costly and require fresh, robust cells with no guarantee of actually producing any viable results, our lab has developed a derivatized bead assay that allows for the rapid screening of cell surface markers. This assay involves the use of beads that are derivatized with over a hundred different molecules including various proteins other than only lectins, amino acids, and sugars, that will bind to carbohydrate-rich molecules in seconds to allow for rapid screening of various cell surface markers. Clustering or binding of these lectins to their preferred target cells helps differentiate between cancerous and noncancerous cell lines. Furthermore, characterization of these cells will help determine specific surface markers that are unique for each type of cell. In this study, we test the efficacy of the lectin-bead assay in distinguishing cancerous (HTB-126) and healthy (HTB-125) breast cells from the same patient. Each cell line was cultured and subjected to the bead assay using beads derivatized with the following lectins: Wheat germ agglutinin (WGA), Lens culinaris agglutinin (LCA), Concanavalin A (ConA), and Poly L-lysine (PL) - an adhesive reagent rather than a lectin. Cell binding affinity to each lectin bead was also tested in the presence or absence of haptenic/nonhaptenic sugars. In order to determine cell viability in the presence of these lectins, each cell line was exposed to free lectins of different concentrations over 6, 12, 24, and 48 hour incubation periods. An MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, a tetrazole) assay was performed to measure toxicity levels for each experimental group. Histochemical results using the derivatized bead assay indicated that WGA and LCA preferentially bound to cancerous cell lines only, while ConA did not distinguish between cancerous and noncancerous cell lines. The cell viability assay suggested that WGA is a toxic inhibitor of cell proliferation for both HTB-126 and HTB-125 on a concentration-dependent basis. ConA reduced cell viability to a lesser degree than WGA, while LCA did not prove to be significantly detrimental to either cell line. The major significance of these results is that the lectin bead assay can distinguish cancer from non-cancer breast cells depending on the type of lectin used. In addition, the ability of free lectins to kill cells in culture may offer a new approach in the development of more specific anti-cancer drug
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Bouvier, Lucienne Simone
- Description:
- The rock reef/kelp forest habitat of southern California is among the most productive and well-studied marine habitats. The importance of the cryptic fish fauna, however, has not been studied. This study was undertaken to assess this particular element of the fauna in a rock reef habitat, and to relate the findings to past studies conducted on the conspicuous fishes. Among the aspects of the fauna studied were species compositions, numerical abundance, seasonal and temporal variations, depth distribution, size distribution, biomass density and diversity. The fishes were collected using an ichthyocide (rotenone) and a specially designed net. Bimonthly collections were taken, five samples from each of three depth strata: 2.2 to 3.0m, 4.2 to 5.1m, 6.4 to 7.6m. The collected fishes were weighed and standard length was measured. Conspicuous fishes were censused by visual diver transect at two six-month intervals. Ninety percent of the cryptic fish fauna was made up of five species, Lythrypnus dalli, Paraclinus integripinnis, Gibbonsia elegans, Alloclinus holder and Lythryonus zebra. Water temperature correlated significantly with the numbers of individuals (r = 0.433, p (0.05) and the H (Shannon-Weiner) diversity (r = 0.459, p (0.05). Distribution by depth correlated significantly with greater numbers of L. dalli in deeper water. L. dalli while G. elegans recruited in May and June. Comparisons between this study and previous investigations indicated that the inclusion of the cryptic fishes may have enhanced total density of individuals by an average of 80% and as much as 83%; diversity an average of 44% and as much as 60%; and biomass density by an average of 10% and as much as 15%.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
403. A temperature sensitive TCA cycle mutant of Bacillus subtilis: physiological effects on sporulation
- Creator:
- Goldman, Robert Clinton
- Description:
- A temperature sensitive sporulation mutant of Bacillus subtilis was isolated and and shown to be defective in aconitase activity at the restrictive temperature (37°C). Sporulation specific production of antibiotic and protease a.ppea.r to be unaffected. At 37°C in a minim medium sporulation is almost completely inhibited, while at 30°C, a temperature which allows a very low level of aconitese activity to be expressed, abnormal spores are formed which are non-refractile, lysozyme resistant, and unstable to storage. The addition of glutamate does not affect the behavior of this mutant at 37°C, but at 30°C it permits a production of n0rmal spores at &. frequency near that of the wild type. Temperature shift experiments suggest the possibility of two critical periods during sporulation requiring aconitase activity: one early in the process (T1-T2) prior to the formation of the prespore, and one later in the process (T3-T5) associated with spore maturation.
- 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:
- Altschuler, Sam
- Description:
- S-180 ascites tumor cells were treated with various reagents which induce polymerization of intracellular actin in other cell types. S-180 cells were used because they have short actin microfilaments, no long actin bundles and weakly-structured surface microvilli as compared with normal fibroblasts which have an extensive actin microfilament network, long actin bundles and microfilament-structured microvilli (Pollock, 1978). In vitro and in vivo experiments have shown a relationship between pH and polymerized actin with the lower threshold for actin polymerization being about 6.8 (Monroe and Pollock, 1979). S-180 cells have an intracellular pH of approximately 6.5 compared with a normal cell pH of 7.2, and this difference suggests a possible regulatory role for pH in actin polymerization (Leung and Pollock, unpublished). This study examines the hypothesis that the low intracellular pH of S-180 cells accounts for the disorganized microfilament status of these cells. S-180 cells were treated with various concentrations of NH 4+, Mn++, ca++, K+ and Mg++ ions in culture media at a pH of 7.8. The fixative for the treated cells included tannic acid and saponin to facilitate positional resolution of polymerized actin. Exposure of the cells to 0.020 M NH 4+ resulted in a rapid conversion of the neoplastic, flaccid, microvilli into an erect or extended conformation. These extended microvilli contained 60 Å diameter microfilaments in bundles, the cytosol showed microfilament networks, short filaments connected to ribosomes, and 100 Å diameter intermediate fibers were observed in the perinuclear region. The number of the extended microvilli decreased with time in culture, but the other results persisted. A 0.0875 M Mn++ concentration induced extensive exocytosis of lipid bodies and a retraction of the flaccid microvilli from the cell surface. However, a 0.020 M concentration of Mn++ combined with 0.020 M NH 4+ provided results similar to the NH4+ treatment alone, except that there were fewer extended microvilli and they were less erect. Mn++ enhanced the cell surface contrast by binding to the plasma membrane and the glycocalyx. Longer, but flaccid microvilli containing only short microfilaments were observed when 10 μM Ca++ was introduced to the cells by ionophore A23187. Intermediate fibers were more developed than in the other treatments and fewer microfilaments were observed in the cytosol. Fields of microtubules were seen and the polysomes were three times as dense as compared with the NH4+ and the NH4+ plus Mn++ treatments. In conclusion, Mn++ did not induce actin polymerization. ca++ A23187 ionophore promoted microvilli extensions, intermediate fibers and polysome elongation, but not actin bundles within the microvilli. However, NH 4+ had a profound effect on microfilament formation and did produce actin bundles in extended microvilli, intermediate fibers and microfilament networks. Since NH 4+ and ca++ ionophore exchange for intracellular H+ caused a rise in intracellular pH, the effects are interpreted as evidence that pH, singly or in combination with other factors, regulates actin polymerization in S-180 cells.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Cockerham, William.
- Description:
- When pasture land, is grazed by cattle the composition of the herbaceous vegetation is changed from that of the ungrazed state and the ecology of the pastoral habitat will be variously affected. The object of this investigation was to examine the distribution of small mammal populations on two areas, one moderatly grazed and the other not grazed, to determine the effect of grazing on small mammal distribution. The importance of small mammal habitat preference was also to be determined.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Fresno
- Department:
- Biology
- Creator:
- Canaday, Jim.
- Description:
- Taxonomic and general natural history studies have been complemented by physiological and energetic considerations. This additional emphasis is necessary if the functional role that each species plays in the ecosystem is to be determined. To ascertain each species' energetic relationship, data on food habits, behavior, population dynamics and metabolic physiology must be collected. Once collected, these data can be incorporated into an energetic mosaic evaluating each species capability for capturing and utilizing a limited energy source. Ideally, these energy mosaics can be combined to provide an insight into ecosystem dynamics and to serve as tools in the prudent management of ecosystems.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Fresno
- Department:
- Biology
- Creator:
- Teiman, Mary Jane
- Description:
- The anatomy of six species of ferns belonging to the family Grammitidaceae was examined using standard paraffin and staining techniques. Adenophorus tamariscinus, Adenophorus haalilioanus and Adenophorus hymenophylloides are endemic Hawaiian species, related anatomically by the presence of glandular paraphyses, glandular rhizome epidermal hairs, concolorous scales, differentiated cortex and solenostelic, dorsiventral rhizomes. Xiphopteris serrulata and Xiphopteris trichomanoides from Jamaica, are characterized by the presence of hydathodes, concolorous scales, and erect, dissected solenostelic rhizomes. Grammitis marginella from Jamaica, noted for its sclerified blade margin, which was found to be superficial in origin was also found to have branched sclerified epidermal hairs, and a dictyostelic rhizome. Branches, which have not been described in the family were found in 5 species; branches are extra-axillary in A. tamariscinus, A. hymenophylloides, X. trichomanoides and G. marginella, and rare and random in stelar organization in X. serrulata. Root propagules known in A. haalilioanus are reported for the first time in X. serrulata. This study represents a significant increase in the number of Grammitid ferns examined for the anatomical characteristics that are important for the determination of phylogenetic trends and for solving of taxonomic problems within the family.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Arvesen, Gregory Alan
- Description:
- The initial event in cyclic AMP action is thought to be binding to the regulatory subunit and subsequent activation of protein kinases. As a measure of hormone action distal to cyclic AMP generation, cyclic AMP binding to postmicrosomal supernatant fraction from rat renal cortex was studied. Renal cortical slices were incubated under a variety of conditions in Krebs-Ringer bicarbonate buffer and cyclic AMP binding by 100,000 x g supernatant fraction was determined by trapping [3H]-cAMP - protein complexes on nitrose cellulose filters. Binding characteristics were evaluated by the method of Scatchard. After correcting for nonspecific binding, results were consistent with binding by a single class of sites with an apparent binding constant of 39 nH. There were 1.56 + .20 x 1012 sites per milligram protein and treatment with PTH or PGE1 in doses insufficient to cause significant elevation of cyclic AMP content, decreased these unoccupied binding sites. Affinity for cyclic AMP was the same regardless of the degree of binding site depletion or mode of cyclic AMP elevation. Maximal unoccupied binding site depletion was not increased by additional agonist, despite further increases in cyclic AMP formation. Fluctuations in physiologic concentrations of hormone may therefore regulate cellular activity by inducing only modest changes in intracellular cyclic AMP. Time course studies showed that unoccupied binding site number follows changes in cyclic AMP concentration with a nadir at 10 minutes and restoration to basal levels by 45 minutes. At maximally effective concentrations of PTH and PGe1 cyclic AMP formation was additive, but unoccupied binding site depletion was not greater than that seen with either agonist alone. Persistence of 35% of unoccupied binding sites despite maximal stimulation of cyclic AMP by hormone suggests a physiological role in the binding equilibrium. Depletion of cyclic AMP binding sites appears to fluctuate as a direct consequence of elevations in ambient cyclic AMP concentration and does not appear to be independently regulated.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Gordon, Thomas Randolph
- Description:
- The anatomy and morphology of Chenopodium murale L. was examined by using standard paraffin and clearing techniques. The inflorescence was studied by marking it and making periodic observations of living plants and. also by examining serial paraffin sections and cleared specimens. The anomalous secondary thickening in the stem and root, characteristic of the Chenopodiaceae and related families, is described in detail. Secondary growth in the stem is comparable to that which occurs in C. album L., differing in the process by which secondary phloem is formed. The onset of secondary thickening is correlated with the cessation of stem elongation. Secondary growth in the root of C. murale does not differ significantly from that which has been described for C. album and Beta vulgaris L. The inflorescence, widely regarded as indeterminate and referred to as paniculate, is best described as numerous compound dichasia disposed on a short, determinate axis. The dichasia show an asymmetrical pattern of development, in which one side of each dichotomy elongates more extensively and flowers mature more rapidly than on the opposite side. Two types of flowers are present: perfect and pistillate. Perfect flowers are comparatively rare and tend to occur on the more strongly developed side of the dichasium. Plants are autogamous and abundant seed is produced by plants grown in isolation.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Cruz, Angelica
- Description:
- This project focuses on a novel progenitor cell therapy for type 1 diabetes, a chronic illness that is categorized by pancreatic beta cell death. The current advancements in diabetes research has brought attention to innovative cellular applications that can help increase insulin production. Here, human progenitor cells were used to mimic and replace beta cells in a diabetic rat model induced by a one-time intraperitoneal injection of streptozotocin that selectively damages beta cells. The effects of inducing diabetes were examined by testing blood glucose levels daily using Accu-Chek glucometers. After establishing diabetes in the rats (>400mg/dL glucose), preparation for transplantation began by immunosuppressing the diabetic rat using Alzet pumps that chronically administers cyclosporine over the course of 23 days. During this time, blood glucose and weight were monitored to ensure the rat's viability for successful transplant surgery and post-surgery outcomes. Next, live human progenitor cells, live differentiated pancreatic progenitor cells and dead human progenitor cells (control) were injected into different regions of the diabetic rat: the circulatory system, peritoneal cavity, pancreas, and kidney capsule. The last two treatments require an additional surgery of exposing either the pancreas or kidney capsule in order to transplant the human progenitor cells. Finally, immunohistochemistry of the rat's organs showed the presence of surviving human progenitor cells in the kidney capsule 37 days post-transplantation. One day after cell treatment, pancreatic progenitor cell treatment group via kidney capsule had significant decrease in blood glucose levels (p<0.005) compared to dead progenitor cells injected into the kidney capsule blood glucose levels. This experiment aimed to alleviate pancreatic beta cell death and possibly be one step closer to curing type 1 diabetes.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Amoroso, Danielle
- Description:
- Premise-Dudleya is a genus of succulent perennials containing about 50 species/subspecies. Many are restricted to narrow geographic ranges, and closely related forms live in differing climates. Dorsey and Wilson (2011) found an intriguing set of correlations among nine Dudleya: species with a smaller mature body size had a lower tolerance for an arid inland climate compared to larger bodied species. I asked if such correlations might represent repeated evolutionary trends across the genus more broadly, mainly in terms of seedling ecology. Methods-To elucidate evolutionary trends, I sampled 10 pairs of close relatives. Judgement of relatedness was based on the phylogeny of Yost et al. (2013) and tight morphological similarity. For each pair, one form was judged to be more mesophilic and the other to be more xerophilic, based on climate of origin. I measured seeds, germination rates, and survival success in two gardens, one coastal and one inland. I gathered field data on the size of mature plants, inflorescence height, etc., and then looked for correspondences. I expected to find for many pairs that the xerophilic taxon would have larger mature body sizes and greater rates of survival than its mesophilic relative. I expected seed size would negatively correlate with plant size and would positively affect germination and survival, and that survival would be higher on the coast. Results-There were no trends between climate-of-origin and the direction of significant differences in the recruitment niche. Plant and seed sizes were non- significantly larger for mesophilic relatives, the opposite of what was expected from Dorsey and Wilson (2011). Polyploid species had significantly larger seeds. Seed size did not predict germination rate. At the coastal garden, germination and seed size predicted survival through the first summer. Three pairs show niche divergence by their significant differences in survival at a garden. The habitat dependence of most taxa is clear, as evidenced by plants surviving significantly better through the summer at the coastal garden than at the inland garden. Conclusions-Trends among closely related species were scarce. I did find many cases of divergence in germination rate or seedling establishment, but I failed to find consistent predictors of the direction of divergence. Quite possibly Dorsey and Wilson's correlations were caused by divergence between two or a very few lineages coupled with phylogenetic conservatism. The various Dudleya forms have evidently diverged, but each in its own way.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Tierney, Wesley
- Description:
- The spastic Han Wistar (sHW) rat serves as a model for human ataxia presenting symptoms of motor deterioration, decreased weight and a shortened lifespan. Correspondingly, sHW rats show progressive loss of cerebellar Purkinje cells starting at 30 days. Past experiments in our lab revealed that human neural progenitor cells (NPCs) have been effective in this ataxic rat model, including significant improvements in behavioral assays and human cell survival 20 days post-transplantation. Here, we examined the longer-term effectiveness and fate of human NPCs in this ataxic rat. For this experiment, rats were placed into four treatment groups (equal mix of male and female rats): an untreated normal control group (n=10), an untreated mutant rat control (n=10), a mutant group that received an injection of dead NPCs (n=9), and a mutant group that received live NPCs (n=10). Bilateral cerebellar injections of 500,000 of either live or dead NPCs were performed on mutant sHW rats at 40 days of age, and motor activity (via open field and rotarod assays) was tested twice per week henceforth. All mutant rats started to decline in open field testing around day 35. However, at day 45, the live NPC-treated mutants began to exhibit improved motor activity while dead NPC-treated and untreated mutants continued to display decreased motor abilities. Starting at day 60 (20 days post-transplantation), live NPC-treated mutant's motor behavior was statistically similar to normal rats, and this trend continued until the end of the experiment. Cerebellar decline was tested via the rotarod test. Live NPC mutants were statistically similar to normal rats; yet, dead NPC and untreated mutants showed significant decreases in rotarod performance. All rats were perfused with 4% paraformaldehyde, their brains removed and sliced for histological staining. While immunohistochemistry revealed few surviving human NPCs in the cerebellums of 100 day old NPC-treated mutants, cresyl violet staining revealed that live NPC-treated mutants had significantly more surviving Purkinje neurons compared to mutants that were untreated or received dead NPCs. Long-term implantation of NPCs alleviated the symptoms of ataxia, acting as a neuroprotectant for the remaining Purkinje neurons since paradoxically these human cells did not survive 60 days post-transplantation.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Russell, Cody
- Description:
- Anthropogenic climate change is predicted to increase temperatures and reduce precipitation throughout most Mediterranean-climate regions. Projections indicate that species with narrow, limited distributions are at the greatest risk of climate-induced extinction. One such potentially vulnerable species is Pseudotsuga macrocarpa (Bigcone douglas fir), a large coniferous tree that is endemic to the Transverse Mountain Ranges of southern California. Although the species’ geographic extent is limited, it does occur at a wide range of elevations. Trees growing at lower elevations (300-1400 m) are relegated to cooler, mesic micro-habitats composed of steep, north facing canyons. The most common surrounding vegetation in these semi-arid environments is chaparral and coastal sage scrub. Conversely, trees growing at higher elevations (1400-2500 m) are found in continuous habitat and are more spatially extensive. Stands of P. macrocarpa at these elevations are not relegated to north facing exposure or steep slopes. In semi-arid ecosystems, such as where P. macrocarpa is found, precipitation and to a lesser extent, temperature, are the most common factors that limit growth. The dynamic relationship between limiting climatic factors and a tree’s annual radial growth is commonly referred to as climate-growth sensitivity. Research has shown that tree species growing at their dry distribution limit are more sensitive to changes in climate. I hypothesized that the growth of P. macrocarpa individuals had the highest degree of climate sensitivity at low elevations. To address this hypothesis, I used dendrochronological techniques to extract tree core samples from individuals growing at sites of different elevations. Growth chronologies were created from the annual rings of core samples and the growth patterns were then correlated with local climate data. The analysis showed that lower elevation stands had smaller trunk diameters, greater inter-annual growth variability, increased sensitivity to drought, and a higher percentage of missing annual growth rings. If projected climate scenarios hold true, P. macrocarpa populations are at risk of extirpation at these more stressful lower elevations.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Nguyen, Bao
- Description:
- Cell-based approaches utilizing hematopoietic stem cells (HSC) and T cells with naturally occurring, or experimentally introduced, genetic modifications that confer either HIV resistance or enhanced anti-HIV properties have emerged recently as viable approaches to treating HIV infection. However, a number of technical issues, such as a lack of protocols to maintain and expand HSC in vitro, inefficient gene transfer technologies, and the induction of T cell exhaustion (due to extensive in vitro expansion prior to adoptive transfer) have impeded the progress in this area. Human embryonic stem cells (hESC), which can be used to derive any type of immune cells including natural killer (NK) cells, may be a superior source of genetically modified cells compared with primary NK cells or HSC. hESC can be maintained in culture in an undifferentiated state indefinitely, and as such they can be extensively genetically manipulated, characterized for potential genotoxic events at the nucleotide level, and expanded to clinically relevant quantities. Given that these cells can be clonally expanded from a single cell, virtually all of the progeny of the genetically engineered hESC will carry the same modification at the same genomic position. Furthermore, as these cells can be effectively cryopreserved and differentiated into the desired lineage at different time points, the same cell populations can be used for preclinical studies and patient treatment. Importantly, in the case of lymphoid lineages, due to the extended length of their telomere ends, hESC-derived NK cells are less likely than their normal counterparts to undergo cellular senescence or immunological exhaustion upon expansion. We generated hESC lines that express an anti-HIV chimeric antigen receptor (CAR), which is a fusion molecule consisting of human CD4 with the signaling domain of the CD3 complex zeta-chain. CD4 binding to HIV-1 gp120 envelope on the surface of infected cells will trigger NK-cell recognition of infected cells and activation of their effector functions through zeta-chain signaling. Importantly, this vector also carries two anti-HIV shRNA sequences that confer protection from HIV-1 infection to the transduced cells. Here we present the phenotypic and in vitro functional characterization of the hESC-derived, anti-HIV CAR-expressing, NK cells.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Soliva, Mary Catherine
- Description:
- The inner surface of the uterus is lined by a specialized layer called the endometrium, composed primarily of epithelial glands surrounded by supportive stroma. The human endometrium undergoes approximately 500 cycles of regeneration and breakdown over the course of a woman's reproductive life, suggesting that a pool of endometrial progenitor cells must exist. However to date, little is known about the markers or hierarchy of human endometrial progenitors. In order to identify a potential progenitor in the endometrium, we isolated human endometrial cells based on two cell surface markers, Trop1 and CD10, that are found on endometrial epithelia and stroma respectively. My hypothesis was that cells positive for both markers were the dual progenitor of epithelia and stroma in the human endometrium. First we used IHC staining to demonstrate that these dual positive cells exist and are located at the bases and junctions of epithelial glands. We then isolated these cells and plated them as single cells in vitro. We found that dual positive cells could differentiate into epithelia and stroma, but a different population of cells expressing the epithelial marker alone could only produce epithelia, and a cell population expressing the stromal marker alone could only give rise to stroma. We also developed an in vivo assay for dissociated mouse uterine cells and adapted that for human cells. My in vivo results were inconclusive, and repeated experiments could no regenerate a human epithelial gland in vivo. However the in vitro results are promising and seem to show that these dual positive cells can give rise to both epithelia and stroma in vitro. This suggests that these dual positive cells contain the dual progenitor for epithelia and stroma in the human endometrium, a cell population that has not been previously identified. This dual progenitor population may play a role in the origin and dissemination of endometriosis, a common and painful gynecological disease where endometrial lining implants and cycles on other organs. In order to explore the link between this cell population and endometriosis, we analyzed the endometrial tissue and pelvic washing cells from women with endometriosis. My initial results seem to show an increased percentage of dual positive cells in endometrial tissue of women with endometriosis, and that these cells were present in the abdominal cavity of women with and without endometriosis. More work needs to be done, but it is possible that these dual positive cells are the source the progenitors that play a role in the pathogenesis of the disease. Identification and characterization of this population is part of a long term project in my laboratory to understand the hierarchy of cells in the endometrium and how dysregulation contributes to disease states. More work needs to be done to determine whether these dual positive cells can regenerate epithelia and stroma in vivo, whether there is a difference between dual positive cells in patients with and without endometriosis, and if so, what are the genetic pathways involved in the aberrant differentiation of cells that cause disease.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Iler, Leila L.
- Description:
- In a clinical hematology laboratory, the counting of platelets is increasingly being performed by electronic counting machines. The accuracy and precision of these machines is reported to be excellent for a normal platelet count in the range of 140,000 to 440,000 platelets per microliter. However, when an abnormally low platelet count of 70,000 platelets per microliter or less is obtained, it is good clinical practice to verify the count by another method before this value is reported to the physician. A traditional method to confirm any platelet count is to estimate the number of platelets from a stained peripheral blood smear. Since there is no known published report of a statistical comparison between these two methods in the low platelet count range, it seemed reasonable to determine whether the slide method of estimating low platelet counts is a valid procedure to verify machine counts. Platelet counts of 103 thrombocytopenic patients were evaluated by electronic machine counts, manual counts, and slide estimations of peripheral blood smears. Either platelet rich plasma or whole blood as the specimen source were first counted with the electronic counter. Whenever an electronic count of 70,000 platelets per microliter or less was obtained, a manual count and a slide estimation were also performed. The results obtained from the three different methodologies were compared by linear regression fits and corresponding correlation coefficients were calculated. The data seemed to indicate that the slide estimation of platelets can be a useful tool to verify a low platelet count.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Okazaki, Wayne Masato
- Description:
- The morphogenesis study of Salvia mellifera leaf galls was approached on two levels: histological examinations in the lab and growth studies in the field. Histological results revealed the galls to be neoplasms of the prosoplasmic type exhibiting determinate growth with a constancy in size and shape. Gall tissues were found differentiated into well-defined zones, however they lacked the sclerenchyma and distinctive nutritive tissues previously reported characteristic of insect galls. Histological observations revealed differences in the development of the gall's outer epidermis between galls arising on opposite sides of the leaf. This kind of comparison has been neglected in other studies. Further scrutiny found that ostiole formation involved cell separation by systematic lysis, an occurrence unusual among cecidomyid galls. Results of the field studies revealed growth inhibition in young leaves when galled. Their significantly lower growth rates and reduced biomass compared to young nongalled leaves were indicative of this occurrence. Although older galled leaves displayed a significantly lower growth rate similar to young galled leaves, their large biomass compared to young nongalled leaves indicated that older leaf growth was inhibited little, if any, by galling. No significant difference was found in growth between galls on leaves of different ages. Galls were found on nearly all areas of the leaf and on the sterns. This is the first time that S. rnellifera galls have been reported occurring on surfaces other than the leaf's undersides. No previous studies on the morphogenesis of S. rnellifera leaf galls have been done.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Lewinski, Michael Anthony
- Description:
- The binding of specific polyclonal antitreponemal rabbit immunoglobulin G (IgG) to Treponema pallidum, Nichols strain, was demonstrated by whole mount indirect immunoelectron microscopy. T. pallidum from 7- and 10-day old rabbit orchitides was processed both fresh and after 3-5 h anaerobic incubation at 34 C. Polyclonal IgG with demonstrated treponemicidal activity was isolated from immune rabbit serum, as was IgG from nonimmune serum. IgG bound to treponemes was detected with ferritin-labeled Fe fragment-specific goat anti-rabbit IgG. Treponemes were processed for whole mount immune-electron microscopy and negatively stained. Treponemal integrity depended upon duration of orchitis and length of incubation of the suspension. Specific antitreponemal but not nonimmune IgG was shown to bind to T. pallidum. The amount and distribution of immune IgG bound to treponemes increased with the degree of their disruption; IgG attached to the protoplasmic cylinder, cytoplasmic components, and endoflagella. (See more in text.)
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Chuck, Laurence King
- Description:
- Three pathways of serine biosynthesis are postulated to exist in Neurospora crassa. The three pathways are the phosphorylated, the nonphosphorylated, and the glyoxylate-serine pathway. Evidence now exists that the phosphorylated pathway may be the major pathway of serine biosynthesis in Neurospora crassa. A serine requiring mutant, ser(JBM 5), was found to have a lower specific activity of extractable phosphosering phosphatase, one of the enzymes in the phosphorylated pathway, than its isogenic wildtype. In this investigation, the serine requiring mutant, ser(JBM 5), and its isogenic wild-type strain of Neurospora crassa were tested for phosphoserine phosphatase activity. The Ames’ assay procedure and two modifications thereof were used to assay the extracts for phosphatase activity. The mutant had lower phosphoserine phosphatase activity per gm extract than the wild-type, suggesting that the phosphorylated pathway is the major pathway of serine biosynthesis.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Wymond, John Joseph
- Description:
- Seedlings of six varieties of plants were grown for 8-13 days in blue, red, far-red, white light, or in darkness. Shoots were then measured in length, extracted and phenolics determined. The total phenolic content was measured spectrophotometrically after addition of Folin-Ciocalteu's reagent. In all cases, the dark grown seedlings were longer than those of corresponding plants grown in white light and they had lower endogenous levels of phenolics. Seedlings grown in blue light exhibited the shortest shoot length and had the highest phenolic concentration. If phenolics are causally related to the reduced size, then addition of these extracts should inhibit growth induced by GA3. Extracts from radish seedlings (100gFW/ml) grown under red light and darkness inhibited GA-induced growth in pea seedlings. Extracts (1000gFW/ml) from pea seedlings grown under blue light and darkness inhibited both endogenous and GA-induced shoot growth. The inhibition was greater with the extract from seedlings grown in blue light. These data suggest that phenolics may be involved and play a regulatory role in the light-mediated inhibition of growth. Both the phytochrome and blue light-absorbing pigments appear to be involved in the processes leading to synthesis of phenolic compounds in light-grown plants.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Thompson, Peter Melgäard
- Description:
- Proteins and glycoproteins associated with cell surfaces are thought to be important in mediating selective cellular adhesion (9,21,26,29), while the lipid elements may also be involved (4). In isolating cell surface adhesion proteins for study, biological activity may be lost due to the harsh chemical environments of the extraction procedures. This loss of activity may be due to a distortion of the protein's tertiary and quaternary structures (organization). Electrophoretic extraction of such surface components of live cells (6) when carried out under mild conditions should limit potential structural damage and preserve the in vivo function. By applying this technique to mouse teratocarcinoma some progress has been made in understanding the role of extracted membrane molecules in the adhesiveness of these cells. The protein fraction of an electrophoretic extract of mouse ascites teratocarcinoma has been isolated and appears to be involved in teratocarcinoma cell adhesion. Nonadhering ascites teratocarcinoma cells show substantially increased adhesiveness in the presence of the extract while other cell types do not. In addition, the extract aggregates fixed cells and may bind to surface carbohydrates.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
423. A comparison of membrane lipid in the starfish Patiria miniata oocytes before and after maturation
- Creator:
- Montalbano, Foster Richard
- Description:
- Membranes from immature and mature 1-methyladenine induced P.miniata oocytes were isolated, their lipid extracted, and the fatty acids of the lipid fractions (phosphatidyl ethanolamine, phospatidyl choline, phosphatidyl serine, phosphatidyl inosiltol, triglyceride, cholesterol, free fatty acid, and cholesterol ester) compared. Results of this study show that there is a qualitative and quantitative difference in the lipid composition of these two membrane states. Relative increases in the amount of phosphatidyl choline and cholesterol, with a relative decrease in triglyceride and phosphatydyl serine-phosphatidyl inositol, were observed in the mature oocyte membrane. Additional identifiable trends included a general increase in saturation lengths induced with a corresponding shortening of the fatty acid chain of the membrane lipid in response to 1-methyladenine induced maturation. The possible implications of such results are discussed with regard to the role membrane changes may play in the initiation of development
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Tamaddoni, Sassan
- Description:
- The cyanobacterium, Nostoc punctiforme is capable of differentiating into various cell types that allow adaptation and survival under various environmental threats. It has proven to be a unique model system for investigating genetic regulation leading to cyanobacterial cell differentiation. Heterocysts are a nitrogen fixing cells that form every 15-20 cells within a filament in response to a deficiency in combined nitrogen. Akinetes are another morphologically distinct cell type that differentiate from vegetative cells under low-light intensities and limiting phosphate or potassium. They enable survival of environmental extremes such as cold or desiccation and are thought to allow persistence of the species from season to season. A previous DNA microarray experiment identified a set of eleven genes with homology to known transcriptional regulators that exhibited 1.5 to 2-fold increase in expression during akinete formation. The aim of this project was to verify the microarray results using transcriptional reporter strains. The pSUN119 transcriptional GFP reporter plasmid was fused with promoters of each gene of interest and electroporated into N. punctiforme. Under akinete inducing conditions, 8 out of 11 reporter strains showed GFP fluorescence under epifluorescence microscopy indicating transcriptional up-regulation during akinesis. Of the remaining 3 genes, two showed increased expression in heterocysts while the third had no upregulation in either cell types. Additionally, three mutant strains were created by gene deletion. So far the phenotype of one mutant has been identified; ΔNpF2889 is deficient in heterocyst formation and is unable to fix N2.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Bayliss, Shannon
- Description:
- Genetic variation and diversity provide the fuel for natural selection and evolution, but also play roles in ecological processes. The ability of organisms to respond to global change will depend on their genetic identity-they can migrate, acclimatize, or adapt. While adaptation was traditionally thought to be a slow and gradual process, rapid evolutionary change can occur within populations given adequate genetic variation. As such, it is important to know the responses of genotypes to various environments (genotype-by-environment interactions) to understand potential adaptive ability in the face of shifting selective pressures and potential ecological effects that these changes may initiate. In addition, understanding the role of genetic variation and diversity is especially important for species that play substantial roles in their ecosystems-Symbiodinium is a genus of photosynthetic dinoflagellate best known for its mutualistic association with coral reefs. In two laboratory experiments, I examined 1) how six genotypes of Symbiodinium antillogorgium performed across three nutrient environments (genotype-by-environment interactions) and 2) how genetic diversity (two, four, and six genotype treatments) of S. antillogorgium respond across three nutrient environments (diversity-function relationships). The measured responses were those most likely to influence the resource mutualism between S. antillogorgium and a host (growth rate, quantum yield, minimal chlorophyll fluorescence, in vivo chlorophyll fluorescence, and nitrogen consumption). I found significant genotype-by-environment interactions for a number of traits (quantum yield, minimal chlorophyll fluorescence and nitrogen consumption) and when responses were considered as a multivariate phenotype. Contrary to the expectation of seeing increasingly positive effects of genetic diversity in more stressful nutrient environments, I found that genetic diversity had significantly negative effects on S. antillogorgium growth rate, quantum yield, and minimal chlorophyll fluorescence, while nutrient treatment had a significant independent effect on only minimal chlorophyll fluorescence. These results suggest that genotypes of S. antillogorgium may perform better with fewer intraspecific competitors, but that the variation that exists among genotypes of S. antillogorgium may allow the mutualism to adapt to global change.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Buchanan, Gordon Emery, Jr.
- Description:
- Forty six strains of Simonsiella and two strains of Alysiella, large filamentous, gliding bacteria from the oral cavities of warm-blooded animals, were grown under various environmental conditions in order to study aspects of the taxonomy of these organisms. Differences in growth with changes in temperature, pH, and NaCl and synthetic sea water salts concentrations segregated the strains into several individual groups which correlated with the isolation of the strains from dogs, sheep or humans. These findings add to the information derived from studies on the cellular morphology and on the biochemistry and physiology (Kuhn et al., 1974; Pangborn et al., 1973 and 1974; Nyby, 1974; Gregory, 1975), on the fatty acid profiles (Jenkins, 1976), and on the mole percent G+C content (Kuhn et al., 1974). Microscopic features of gliding motility and growth patterns of Simonsiellaceae are recorded for the first time. Growth on agar viewed microscopically revealed that a small fraction of Simonsiellaceae strains glided, whereas other strains displayed types of colony morphology that ranged from entire-edged to pronounced filamentous growth. Gliding motility rates were found to range from 5 µm/min to 23.8 µm/min. Gliding motility was manifested by individual, frequently well-separated filaments rather than by “armies” of closely-associated cells as described by Stanier (1942a) for the cytophagas. Gliding motility appeared to occur as necessary to reach areas on the agar surface supplying fresh nutrients, and when these areas were reached gliding motility was arrested and secondary colony formation ensued. Gliding motility was frequently most pronounced in regions of heavy growth bordering unoccupied agar surfaces, suggesting that filaments glide in response to gradients of either decreasing waste metabolites or increasing fresh nutrients. The influence of other factors such as light, agar concentration and humid incubation are considered.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Wells, Raymond Alan
- Description:
- Activity patterns in the foraging activity of two species of acmaeid limpet, Collisella limatula (Carpenter, 1864) and Collisella scabra (Gould, 1846) were documented over the entire tidal cycle. Collisella limatula was found to be active only while awash by the tide and during nighttime emergence; periods of inactivity were spent in crevices and on the undersides of boulders. Collisella scabra, which homes to a scar on the upper surfaces of rocks, foraged only while awash in daylight. In laboratory experiments both species of limpet were shown to orient their movement relative to light and gravity stimuli, while turbulence was necessary to elicit a response in C. scabra and produced an increased intensity of response in C. limatula . The activity pattern of C. limatula was demonstrated to be an effective mechanism for avoiding predation by octopus sp., a major visual predators of limpets, in both laboratory and field experiments. The homing habit of C. scabra was also shown to reduce the rate of predation in the laboratory. Fishes and birds, other visual predators, were also found to prey on limpets during the submerged and emerged portions of the tidal cycle respectively. It is suggested that the observed activity patterns have evolved in response to predation pressure from swift-moving predators which locate their prey visually.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Wood, Shannon
- Description:
- How organisms survive starvation is poorly understood at the cellular level. This study uses the model organism Caulobacter crescentus, which evolved to survive long periods of starvation, to address this important question. To determine how the cell cycle circuitry integrates with lipid biosynthesis, we created a FabH-depletion strain to induce fatty acid starvation. In response to starvation various bacterial species produce a molecule known as (p)ppGpp, an intracellular signaling molecule, which is linked to their survial until nutrients become available. (p)ppGpp facilitates the expression of certain genes whose protein products are required to survive starvation. We discovered that this regulon includes CtrA, a cell cycle regulatory protein, which blocks the initiation of DNA replication, and PhaC, an enzyme that polymerizes hydroxybutyrate monomers, forming polyhydroxybutyrate (PHB). CtrA, which normally blocks the initiation of DNA replication, fails to accumulate when FabH is depleted in the absence of (p)ppGpp due to a dramatic decrease in ctrA transcription. FabH depleted cells lacking the ability to produce (p)ppGpp contain multiple chromosomes and, although viable after 24 hours of FabH depletion, are unable to produce colonies. Using fluorescent microscopy we were able to show that PHB, a carbon storage molecule, is produced within the cell in a CtrA-and (p)ppGpp-dependent manner within a localized region of the cell and modulate cell size in response to nutrient availability. Here we present a novel model for the survival of fatty acid starvation in Caulobacter crescentus. (p)ppGpp is responsible for the prevention of the over-initiation of DNA replication via CtrA. Subsequently, CtrA is responsible for the production of PHB that provides not only carbon for the survival of starvation but a mechanism through which cells decrease size and thus nutrient requirements. Thus, my model reveals a three-component genetic pathway that explains the critical changes bacteria make in response to starvation.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Azzam, Elias
- Description:
- A dissociation supernatant (DS), has been previously shown to promote re-aggregation of Strongylocentotus purpuratus blastula cells. The factor(s) was isolated from S. purpuratus blastula cells as they disaggregated from each other in calcium-magnesium-free sea water (CMF-SW). A further purification step was done to isolate a subset of molecule(s) that promote aggregation of fixed s. purpuratus blastula cells by absorbing DS with these fixed cells. This subset was termed (S2). Antibodies raised against S2 (A-S2) were shown, by an indirect immunofluorescence method, to label the extracellular martix of whole embryos and a fibrillar component present in the blastocoel of sectioned blastulae. The purpose of this study was to localize S2 component(s) on sectioned embryos from the unfertilized stage up to and including late gastrula. The localization pattern of fluorescence of S2 was compared to that of different extracellular components (fibronectin, laminin, and collagen types I and IV) that are normally found in the basement membrane of higher organisms. This was accomplished by using antibodies made against these different components and an indirect immunofluorescence method. Also included in this study is a comparison between the localization of S2 with that of hyalin, which is the major component of the hyaline layer. The results using embryo sections suggested that hyalin, fibronectin, and collagen type I were present in the embryos and may be components of DS; and that laminin and collagen type IV were not detected in the embryo sections. A-S2, however, did bind to sectioned agarose gels absorbed with fibronectin, laminin, or collagen types I and IV, suggesting that all of these molecules are present in DS and in blastula stage embryos, while laminin and collagen type IV may not be present in sufficient quantity or in a configuration available for staining on sections of embryos. All positive controls fluoresced. Negative controls did not fluoresce. The pattern of localization of hyalin was somewhat the same as S2 at the different stages of development. The results also suggested that resynthesis of hyalin occurs at the mesenchyme blastula stage. This study helps us to understand the nature of the molecules present during morphogenesis in the sea urchin embryo and lays the groundwork for future elucidation of their function.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Ellis, Satchid Ananda
- Description:
- As a result of anthropogenic increases in atmospheric CO2 concentrations, mean global temperature has increased 0.5 °C since the 1970s, with a further expected increase of 2.6 - 4.8 °C by 2100. If realized, rising temperatures will negatively impact many species including scleractinian coral, which already live near their upper thermal limit. In addition, other abiotic factors (e.g., light and pCO2) have the potential to exacerbate the impacts of high temperature on coral. Much less is known about the effects of these abiotic factors on larvae and recently settled recruits, which are critical life stages that are more sensitive than adults. The goal of this thesis was to study the effects of temperature in conjunction with other biotic and abiotic factors on coral recruitment under current and predicted future environmental regimes. Chapter 2 assesses how the relationship between crustose coralline algae (CCA, a facilitator of coral settlement and post-settlement processes) and the early life stages of Pocillopora damicornis is affected by temperature. P. damicornis larvae settled preferentially onto CCA regardless of temperature; and P. damicornis recruits that had settled onto CCA exhibited higher survivorship at 30 °C than those that had settled onto rock at the same temperature. However, while recruits that had settled on CCA exhibited higher survival, this facilitation was uncoupled when documenting growth with 55% lower growth rates of coral settled to CCA than to rock, regardless of temperature. Chapter 3 documents the effects of temperature and pCO2 on P. damicornis settlement and post-settlement processes. P. damicornis larvae exposed to high temperatures of 30 °C settled 4x faster than those at 26.5 °C. After settlement, recruits in high temperature treatments exhibited high fission rates and a trend toward faster growth (basal tissue area). Elevated pCO2 depressed fission rates, mirroring an antagonistic effect reported previously between high temperature and high pCO2. Survivorship was 30% higher at elevated pCO2 than in ambient pCO2. Collectively, the results of my research demonstrate that temperature, pCO2, and settlement substratum can impact the early life stages of coral by affecting settlement and post-settlement success, two critical early life processes responsible for sustaining coral populations.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Perry, Donald R.
- Description:
- The pollination ecology of Dipteryx panamensis (Pitt) Record and Mell, a leguminous lowland tropical wet forest emergent tree, was studied at Finca La Selva, Costa Rica, on the Caribbean slope. This was done with the aid of a new tree-climbing technique which makes the tropical forest canopy accessible to close investigation. Dipteryx blooms massively from May to mid-July making it visible a long distance away. Floral attractants include odor, a lavender color and nectar. Anthesis and stigma receptivity occur by the time the flower opens at 6 a.m. This tree was determined to be self-incompatible, requiring long-distance pollinators. Its flowers are well adapted to medium and large sized long-tongued bees. Specimens of 19 bee species were collected by handnetting. Microscopic examinaton of their pollen loads revealed Dipteryx pollen was present in sufficient quantities for pollination on specimens of 15 species and seven others were considered to be nectar robbers. A simultaneous population decrease of nearly all the bee species occured between June 17-19, 1975. The cause of this crash was unclear, but extended periods of rain may have restricted foraging by bees, resulting in their starvation. Following the bee population crash was an increase in the average nectar production per flower, which changed from near 6 microliters in the period from June 19 to July 4 to 12 microliters by July 14. This may be an adaptation by the tree to attract an alternate pollinator with greater energetic needs, since a bee population crash appears to be an annual event during the blooming season of Dipteryx.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Van Cott, Marlon Thomas
- Description:
- Five species from two families of Collembola (Insecta: Entomobryidae: Entomobrya (Entomobryoides) guthriei Mills, 1931, Pseudosinella sexoculata Schott, 1902, Sinella (Sinella) curviseta Brook, 1882; Isotomidae: Cryptopygus thermophiles (Axelson), Proisotoma (Ballistura) schoetti (Dalla Torre)) were collected from leaf litter and raised in the laboratory. Single species and pairwise combinations of all species were cultured for up to 24 weeks. Evidence for competitive interactions among the species was found. S. curviseta and P. schoetti were found to be the strongest competitors, while C. thermophilus was the weakest. Data were collected on generation time and percent hatching for each species. The generation times ranged from 14-15 days for C. thermophilus and P. schoetti to 16-19 days for S. curviseta at a temperature of 22-29c. P.schoetti showed the highest rate of population increase. Tests for egg predation by S, curyiseta on P, schoetti eggs were inconclusive, while some evidence was obtained indicating possible chemical inhibition of population growth of several species by S. curviseta. Possible research into competition mechanisms and the possibility of competition among Collembola in the natural environment are also discussed.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Parker, Riley David Jr.
- Description:
- This autoradiographic study was performed to determine the localization of the tritiated amino acids, tyrosine and proline, in the structures of cysticercoids and adults of the rat tapeworm Hymenolepis diminuta. Localization by the cysticercoids was primarily in the invaginated scolex. In contrast, other areas of the cysticercoids incorporated the two amino acids in smaller quantities. The adult tapeworm incorporated the two amino acids in high amounts in the cuticle of the immature proglottids, 15 to 30 J.l posterior of the embryonic neck region. The incorporation of tyrosine by the adult form was greatest in the reproductive organs in the developed regions of the strobila and the amount localized was dependent on maturity. Uptake by the testes was greater than the ovaries in the mature proglottids, while the uptake by the ovaries exceeded the testes in the gravid proglottids. The incorporation of proline by the adult form was primarily in the cuticle of the 3 major divisions of the tapeworm, with comparatively little localization in the internal organs, except the eggs. The highest proline activity was in the anterior third of the strobila. In both the larvae and the adult, the total incorporation of tyrosine was much greater than that of proline. Tyrosine was probably incorporated into polypeptides, keratin-like and conjugated proteins, and to a lesser extent, collagen. Proline was probably incorporated into collagen, quinone-tanned proteins, and a small percentage into polypeptides.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Berger, Joel
- Description:
- The behavioral ecology of feral horses Equus caballus) was studied in Grand Canyon National Park, Arizona, between March, l974, and August, 197 4. Horses became established in the study area about 60 to 200 years ago and currently number about 78 individuals. Individual horses were identified using natural color characteristics. Most bands were composed of three to five horses and consisted of one stallion and his harem. Males which did not obtain a harem remained solitary or formed bachelor herds. Throughout the duration of the study all bands remained stable in composition. Diurnal activity decreased in successive warm months along with rest in the shade of juniper trees. Drinking activity occurred at all hours of the day and night. “Nervous ratios” calculated from data gathered while horses were drinking showed that stallions were less nervous than mares. These rations were correlated with the amount of time spent drinking. Furthermore, a low NR was correlated with individuals leading to drink, whereas a high NH existed in horses initiating flight. No single horse acted consistently as a leader. (See more in text.)
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Halajyan, Armen
- Description:
- Defects in stem cell proliferation and/or differentiation can lead to disease. While many master regulatory genes that promote stem cell self-renewal or differentiation have been identified, we have a relatively poorer understanding of the downstream genetic programs controlled by these master regulators. Even though high-throughput technologies have allowed to identify their putative targets at a genome-wide scale in diverse Drosophila melanogaster stem cell types, these data frequently fall in disuse due to a lack of meta-analysis efforts or further validation. We have developed 2 programs (NetR and AttR) which allow experimental biologists with little to no programming background to integrate diverse datasets into networks that can be easily mapped with Cytoscape to not only visualize interactions among genes and/or proteins, but also display their diverse attributes (expression levels, gene ontology classifications, reagent availability, etc.). In Chapter 1 we introduce NetR and AttR and describe the different ways in which they can be used to generate hypotheses from publicly available datasets with minimal editing of source data. In Chapter 2, we demonstrate how we used NetR and AttR to combine independently generated datasets on putative targets of three key regulators of intestinal stem cells (Capicua, Stat92E and Escargot) and identify putative co-regulated targets of these master regulators. Finally, in Chapter 3, we describe the experimental set up that will be used in future work to validate the co-regulated targets identified in Chapter 2 by genetic manipulation of the master regulators.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Shutt, Nadene Lynda
- Description:
- The hexose monophosphate shunt (HMS) activity increases at ta fertilization. Glucose-6-phosphate dehydrogenase (G6PD) is the enzyme that catalyzes the first reaction of the HMS and is considered to be the site of regulation for the pathway. Previous work has shown that the release of G6PD from the egg cytoplasmic particulate to the soluble fraction and the change in metabolic rate are early events of fertilization. The G6PD pattern in Lubrol extracts of eggs of L. pictus changes at fertilization as observed by activity development in polyacrylamide gels following electrophoresis. One fast-migrating isozyme was unique to unfertilized eggs, one more slowly-migrating isozyine was seen only in fertilized eggs, and an isozyme having an intermediate electrophoretic mobility was present in both fertilized and unfertilized eggs. This shift is accompanied by differences in the activity of the various isozymes and may be correlated with the burst at fertilization. An intermediate pattern including all three isozymes was seen in eggs activated by ammonia. Although eggs treated with ammonia are known from previous work to exhibit the cytoplasmic pH change and the late events of fertilization, they do not show the early events or cleave, even though there is nuclear division. This intermediate G6PD isozyme pattern in ammonia-treated eggs may be related to this partial activation. (See more in text.)
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Flynn, John Michael
- Description:
- Four vegetative characters of leaves (length, width, petiole length and a number of teeth) and two reproductive characters (acorn length and acorn width) were measured in 58 individual plants located in Wildwood Park, a natural area in Thousand Oaks, California, U.S.A. The 58 plants were grouped into seven units, or subpopulations, separated from each other by at least 100 meters. The data was analyzed statistically to determine if these seven subpopulations are distinct interbreeding units. Hypotheses proposed to account for the variation were: genetic drift and founder effect, natural selection, hybridization, nonuniform dispersal of genotypes and environmental factors. The results of univariate and multivariate analysis suggested a pattern of relationships among the individuals and subpopulations related to their distribution. The results suggested that there are not seven units, but three. Each of these units is composed of two adjacent subpopulations. Evidence points to restriction of gene flow as a possible cause of the variation pattern. Other factors, such as environmental fluctuations, could not be excluded. Hybridization with other oak species, however, was rejected. The total variation among these plants was judged to be great, but within limits described by plant taxonomists.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Hillard, Heather
- Description:
- Ocean acidification (OA), the decrease in the seawater pH and carbonate ion concentration due to the uptake of anthropogenic carbon dioxide (CO2) with no change in total alkalinity, threatens coral reefs worldwide as studies predict the decline of calcifiers and increasing growth of non-calcified macroalgae. Future recovery of coral reefs may depend on the ability of corals to survive in association with macroalgae. However, few studies have incorporated multiple species into OA experiments. This research sought to explore the understudied combined impact of macroalgae and elevated pCO2 on corals. Macroalgae can indirectly (e.g., shading, allelochemicals) and directly (e.g., abrasion, overgrowth) harm corals. Alternatively, algae could facilitate coral calcification by reducing pH through photosynthesis. The reef crest surrounding Moorea, French Polynesia, is covered by the fleshy, macroalgal species Sargassum pacificum. Results from photoquadrat surveys showed that scleractinian corals and other biogenic calcifiers covered 15% of the sub-canopy habitat. The same microenvironment experiences on average, increases in pH by 0.031 ± 0.012 pHT and decreases in irradiance by ~98% compared to surrounding, above-canopy conditions. On a larger scale, diel fluctuations in pH (up to 0.197 pHT) were recorded behind the S. pacificum-dominated reef crest. To help predict the future of coral reef dynamics accurately, the present research examined how non-calcifying macroalgae could mitigate, by metabolically reducing CO2 levels, or exacerbate, by shading, the effects of OA on associated scleractinian corals. In Chapter 2, the role of macroalgae as a chemical refuge from OA was addressed through a combined laboratory and field experiment testing the effect of the presence/absence of Sargassum pacificum on juvenile Porites rus exposed to ambient and elevated pCO2. In the field, corals with S. pacificum exhibited less bleaching but did not significantly alter their net calcification rates. P. rus in the laboratory experiment displayed ~23% higher net calcification rates in elevated pCO2 and ~16% reduced calcification in the macroalgal treatments. P. rus was resistant to OA but sensitive to S. pacificum. These results suggest the potential ability of S. pacificum to outcompete corals for a shared carbon resource (bicarbonate) or to induce other harmful chemical changes on the coral. The hypothesis that Sargassum pacificum could positively (chemical refuge) or negatively (shading) alter the effects of OA on the growth and photosynthesis of the coral species Acropora pulchra was tested in Chapter 3 with a combined field and laboratory experiment. A fluctuating pCO2 treatment was used in both experiments to replicate the natural pH fluctuations created by S. pacificum on the reef crest. Similar to Porites rus, A. pulchra did not respond significantly to the manipulated CO2 treatments. In the mesocosm experiment, light played a substantial role in controlling coral growth; shaded corals exhibited significantly reduced net calcification, linear extension and photosynthesis rates, and increased chlorophyll a. In addition, shading slightly exacerbated the impact of fluctuating and elevated pCO2 on coral linear extension and photosynthesis rates. In the field, corals displayed somewhat higher net calcification rates in fluctuating pCO2 over stable pCO2. Thus, the presence of a macroalgal-induced chemical refuge from OA is only apparent qualitatively for A. pulchra while light appeared to be the main driving factor affecting coral growth and metabolism. Across both field experiments, corals with Sargassum pacificum consistently exhibited reduced calcification rates compared to algal mimic treatments. This suggests that S. pacificum may have other harmful chemical effects on corals. The present study provides novel approaches to creating more ecologically relevant OA experiments and motivates OA research to examine the complex relationships between marine organisms and the abiotic environment of a coral reef.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Kruszewska, Barbara
- Description:
- The sites of activity of Na+,K+-ATPase in the sea urchin egg and embryo were determined using a cytochemical localization technique. Fertilized and unfertilized eggs, and embryos at stages of development from 2 to 16-cells were lightly fixed with 2% paraformaldehyde for 3 minutes. Following the method of Mayahara, they were incubated for 20 minutes in an enzymatic reaction medium with p-Nitro-phenylphosphate (NPP) as the substrate and lead as the capture agent. Specimens were then prepared for light and electron microscopic examination using standard techniques. Light micrographs showed that the surfaces of both fertilized and unfertilized eggs were characterized by a circular area of activity at one end of the egg, with only slight activity seen in the rest of the egg. At first cleavage, activity was heavily concentrated in the furrow between the two dividing cells. Electron micrographs of 8 to 16-cell stage embryos showed that activity was most often found on apposed cell membranes, with very little activity on the free surfaces. This asymmetrical distribution of the enzyme may be a reflection of its unique function in embryonic cells.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Foy, James Edward
- Description:
- Fertilized and unfertilized Strongylocentrotus purpuratus and Lytechinus pictus egg membrane preparations including plasmamembranes and egg envelopes, were obtained via gentle homogenization and centrifugation in Tris- MgCl2 solutions. Membrane preparations were then assayed for Mg++ and Na+-K+ and glucose-6-phosphatase (G-6-Pase) activity with pH optima and enzyme-substrate affinity being investigated. The pH optima for G-6-Pase, Mg++ ATPase and Na+-K+ ATPase were found to be 5. 21, 6.3, and 6.91 respectively. The membrane-associated G-6-Pase activity was found to be higher in the unfertilized membrane preparations, while the Na+- K+ ATPase activity was higher in the fertilized preparations. A discontinuous sucrose density gradient (20-67% w/w) separated the membrane preparations into four major protein peaks which were assayed for G-6-Pase activity. A change in distribution of the G-6-Pase activity was noted after fertilization. The effects of pretreatment with mycostatin, NH4OH, phospholipase A, and acetone-4% water upon the activity of membrane-associated G-6-Pase were examined. Mycostatin pretreatment of unfertilized eggs was found to inhibit G-6-Pase and both of the ATPases. The G-6-Pase activities of fertilized and unfertil ized membrane preparations were unaffected by pretreatment with phospholipase A and were inhibited by NH4OH pretreatment. Acetone-4% water pretreatment proved to have no influence upon membrane-associated G-6-Pase activity in fertilized preparations, but inhibited the activity in unfertilized preparations.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Hojjat, Armin
- Description:
- Cardiomyocytes (CM) are the major cardiac cell type. Even so, not much is known regarding the changes that occur during embryonic development as cardiac stem cells differentiate and proliferate to form an adult heart. In order to better understand the changes that occur at different stages of cardiac development, we performed transcriptional profiling of cells during their progression from an immature progenitor state to terminally differentiated cardiomyocytes. Using transgenic mouse models in which cardiac cells can be isolated by a fluorescent reporter protein, we have isolated populations of cardiovascular cells at different stages of development. We generated double transgenic mice by crossing a floxed reporter with cardiac specific-Cre mice. The Cre recombinase was under the transcriptional control of the promoter of Mesp1, Nkx2.5, or α-MHC; markers that are predominantly expressed during the development of the cardiovascular system. The fluorescent-marked cells were then isolated at respective embryonic time points that correlate with the expression of Mesp1, Nkx2.5, or α-MHC. Gene expression analyses were performed using RNA-seq, to identify candidate genes that are potentially important in mediating differentiation and development as well as novel surface markers at each stage. Through the use of MID-REG and deductive reasoning based on gene expression levels we were able to uncover genes that could hold a key role in cardiac cell type development.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
442. Intergenerational lizard lounges do not explain variation in the gut microbiomes of green iguanas
- Creator:
- Wehrle, Beck A.
- Description:
- Herbivory is a rare diet specialization in lizards that requires numerous specializations including hindgut microsymbionts to aid in the digestion of plant meals. Researchers first attempted to identify the sources of the gut microbes hosted by herbivorous reptiles more than 30 years ago. These endosymbionts are needed to digest plant fiber and their fermentation products contribute substantially to their host's energy budget, yet this symbiosis is poorly understood. Green Iguanas (Iguana iguana) are herbivorous throughout life, yet emerge from their eggs with sterile guts. Although rare in lizards, social interactions are a hypothesized route of microbe transfer via direct contact and/or eating feces of older conspecifics or previously inoculated peers. This study is the first to characterize the spatial, temporal, and social variation of these vital microbial communities using modern genomic techniques. I hypothesized that microbial communities will be more similar within than between sites, increase in diversity over viii time, and vary with lounge size and proximity. I observed and individually marked juvenile, subadult, and adult iguanas alone and in social lounges at 11 sites on and around Barro Colorado Island, Panamá over two hatching seasons. Of the 540 focal observations of hatchlings, 38% were of social lounges (mean = 2.9 lizards/lounge). Only 0.7% of observations were of social lounges containing hatchlings and subadults/adults. I also collected microbe samples from the hindguts of adult and subadult iguanas to compare these communities to those from neonates that were sampled during the first 60 days posthatching. The16S rDNA region was amplified from 100 samples and highthroughput sequenced via the Illumina HiSeq platform. Using the QIIME workflow, OTUs were identified by sequences with ≥97% similarity and matched to lowest taxonomic level via the Greengenes database. Proportions of OTUs in each sample were calculated, as were Chao1 alpha diversity and Bray-Curtis beta diversity differences. The hindgut bacterial communities were dominated by Firmicutes (43%), Bacteroidetes (27%), and Proteobacteria (20%). I found differences in the abundances of bacterial taxa by iguana age class, lounge size, and site. Alpha diversity of microbes was higher in adults/subadults than hatchlings. There were significant differences in the beta diversity of samples by individual, age, site, lounge size, and year. I found high variation in microbial community composition overall and by each of these categories, including within recaptured individuals over time. Intergenerational microbial community transmission is unlikely to be as important as previously hypothesized. This finding is based on the near absence of intergenerational associations and the dissimilarity in microbial community assemblages between hatchlings and adults/subadults. However, ix within-hatchling microbial admixing was common, as evidenced by similarities in microbial community composition among hatchlings. Although microbial communities of iguanas differed among sites and lounge sizes, there were few clear patterns, with the exception that these differences likely resulted from ecological factors including microbial community succession within iguana guts. These findings lay the groundwork for understanding the patterns of gut microbial diversity in herbivorous lizards. Future research should focus on testing the role of soil on microbe acquisition, gene annotation of microbial communities to determine the OTUs contributing to digesting plant-fiber or acquiring nutrients, and to determine the effects of microbial community composition on aspects of host lizard biology.
- 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
444. Maternal provisioning and the effect of stress on tetrodotoxin production in terrestrial vertebrates
- Creator:
- Susbilla, Calvin Bron
- Description:
- Chemicals are often sequestered by various organisms to defend against predators by making prey noxious, and in some cases, toxic. Sequestration has been observed in various taxa, however, there are few vertebrate examples available. Further, little is known about maternal provisioning of sequestered toxins. The Asian natricine snake, Rhabdophis tigrinus, sequesters bufadienolides from toxic toad prey and allocates toxins to offspring. Likewise, the common garter snake, Thamnophis sirtalis, sequesters the neurotoxin tetrodotoxin (TTX) in its liver from newt prey. However, maternal provisioning in this natricine snake has yet to be investigated. To investigate maternal investment of TTX in T. sirtalis, gravid snakes from Benton County, Oregon were offered toxic newts for consumption. The liver of female snakes and neonates were later dissected and TTX levels were quantified using a Competitive Inhibition Enzymatic Immunoassay. Dams were found to possess TTX in their livers, whereas, TTX was not detected in any neonate liver samples.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Cardenas, Anjelica MIa
- Description:
- T-cell acute lymphoblastic leukemia (T-ALL) is a hematopoietic malignancy characterized by an overproduction of immature T-cell lymphocytes (blasts) and infiltration into bone marrow and peripheral blood. Deletion and mutation of the tumor suppressor gene, Phosphatase and Tensin Homolog (PTEN), a negative regulator of the PI3K/AKT/mTOR pathway, has been reported in a large percentage of T-ALL patients and is associated with relapse and poor prognosis. In this study, we utilized our previously generated genetic VEC-Cre+Pten loxP/loxP(Pten null) T-ALL murine model and recently derived Pten null T-ALL cell culture to evaluate the effects of potential combination therapies. Pten null T-ALL develops in this model after the activation of β-catenin and a chromosomal translocation of the c-Myc oncogene and the T-cell antigen receptor (TCR) α/δ cluster t(14;15) with subsequent Myc overexpression. Previous studies have shown treatment with the mTOR inhibitor, rapamycin, prolongs survival of Pten null T-ALL mice. However, rapamycin was insufficient to eradicate leukemia stem cells (LSCs), the defined leukemia-propagating subpopulation in this model, and cure T-ALL. Therefore, we hypothesize that a more effective approach to eliminate blasts, LSCs, and ultimately the disease in our Pten null T-ALL murine model and derived Pten null T-ALL cell cultures would be to utilize combination therapy to simultaneously co-target essential alterations and key signaling pathways. Since rapamycin alone has little effect on Pten null LSCs, we intend to eradicate the blasts and LSCs, by selectively targeting critical molecular and genetic abnormalities that have previously been defined as requirements for LSC formation and T-ALL development with dual drug treatment. Recently, small molecule inhibitorsVX-680, JQ1, and Purvalanol A have been shown to either directly regulate Myc expression or indirectly target cells with Myc overexpression. In addition, A70, a synthetic autophagy inhibitor, has been shown to prevent autophagy and may potentially sensitize Pten null T-ALL LSCs cells to rapamycin treatment. In this study, we co-targeted mTOR, the downstream target of the PI3K/AKT/mTOR signaling pathway and Myc overexpression utilizing rapamycin in combination with the selected small molecule inhibitors using both in vivo and in vitro models. We assessed the therapeutic efficacy of selected inhibitors and characterized the molecular mechanisms underlying their effects directed against both the PI3K/AKT/mTOR pathway and deregulated Myc expression. These deregulated pathways, critical for T-ALL development, are common alterations seen in human T-ALL.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
446. Autonomic control of heart rate during heating and cooling in turtles (Pseudemys scipta elegans)
- Creator:
- Berger, Marris Elliot
- Description:
- Autonomic control of heart rate during generalized heating and cooling in water was studied in the red-eared turtle, Pseudemys scripta elegans. Sympathetic blockade with propranolol hydrochloride and parasympathetic blockade with atropine sulfate were used to determine the relative influence of each branch on heart rate changes during heating and cooling. Dose response curves were determined for these drugs. As the body temperature increases in turtles, the parasympathetic branch of the autonomic nervous system contributes more to inhibition of the heart rate than the sympathetic does to its augmentation. The coincidence between totally blocked and unblocked heart rates in turtles suggests that, unlike mammals, normal heart rates are not displaced from the pacemaker rate by overriding parasympathetic activity. Significant, drug-induced changes in heart rate were not correlated consistently with changes in heating or cooling, suggesting that heart rate does not have a direct thermoregulatory significance. Drugs which affect peripheral autonomic control of vasomotor changes were responsible for altering heating rates. Diving behavior was related to a reduction in cooling rates and heart rates. Diving bradycardia was abolished by either atropine or propranolol blockade. The hysteresis of heart rate versus body temperature during heating and cooling was reduced by parasympathetic and augmented by sympathetic blockade.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Aunchman, Paul Andrew
- Description:
- An electron microscopic analysis of cells isolated from 16-cell sea urchin embryos indicates that several morphological differences in the cell types exist. The micromeres, which become migratory and give rise to the primary mesenchyme cells, possess two distinct cytoplasmic regions. The non-migratory macromeres and mesomeres have a uniform cytoplasm. An analysis of five micromeres showed in a 389 square micron area an average of 9 dark yolk granules, 83 light yolk granules and 81 mitochondria. The yolk granule to mitochondria ratio in the micromeres was approximately 1:1. Five macromeres were also studied and in a 389 square micron area there was an average of 104 dark yolk granules, 17 light yolk granules and 41 mitochondria. The macromeres have a yolk granule to mitochondria ratio of 2.6:1. These differences may reflect nutritional and metabolic differences in the two cell types. They may also play a role in the function of the cells and in the developmental fate of their descendants.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Ballou, Leslie R.
- Description:
- The peach-fluffy-cot mutant of Neurospora is unable to produce macroconidia but is able to differentiate great numbers of microconidia after a predictable length of time of vegetative growth. The relationship of lipid metabolism to the differentiation of microconidia was studied by determining changes in the composition of the major lipid classes and the fatty acid composition of these lipid classes during the transition from vegetative growth to reproductive growth. The evidence strongly suggests a relationship between the synthesis of sterols during vegetative growth and the initiation of the microconidial differentiation process. The selective localization of sterols and sterol esters in the microconidia themselves and the rapid degradation of these microconidial lipids after differentiation is complete is further evidence of an inductive role associated with the sterols. It is not clear whether the changes in fatty acid composition affect the morphogenesis of Neurospora, or if the changes are simply part of a NADPH-deficiency common to many mutants of Neurospora.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Ferguson, Evelyn Marie
- Description:
- The morphology and development of the pineal complex are similar in Hyla cadaverina and Hyla regilla . The larvae of both species develop all three structures of the complex , end organ , nerve and body before stage 26. Mature adults of both species lack the pineal end organ and nerve, retaining only the pineal body . Growth of the pineal body was observed from stage 26 through 32, but the structure was only s lightly longer in mature adults than in larval stage 32. I found no evidence that adult Hyla regilla used in this study are capable of using a sun-compass for Y-axis orientation. Similarly there was no evidence that Hyla regilla is able to learn to different iate between parallel and perpendicular orientations of the e-vector of polarized light . Consequently, it is not possible yet to determine for this species if the pineal complex, or any port ion of it, plays a role in these aspects of spatial orientation .
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Weeks, Denita M.
- Description:
- Most aspects of the lives of ectotherms (e.g. distribution, locomotion, digestion, and reproduction) are dependent on body temperature (Tb). For ectotherms living in cool environments, the ability to cope with extreme temperatures and even achieve the warmer Tbs needed for optimal performance can be particularly challenging. Nocturnal ectotherms in such climates face an added challenge because they lack solar radiation as a heat source during periods of activity. Darwin’s marked gecko (Homonota darwinii)—the world’s southernmost gecko species—is broadly distributed from central to southern Argentina and adjacent Chile (35–52 °S latitude) where cold climates and high winds likely pose a thermal challenge for this nocturnal species. I measured the thermal tolerances and temperature-dependent sprint performance of four populations of H. darwinii spanning most of the latitudinal range of this species in southern Argentina. I also estimated rates of temperature-dependent metabolism and evaporative water loss of geckos from the same populations to characterize their physiological response to temperature. Temperature dataloggers were deployed at each field site to record annual operative temperatures (Te). The metabolic data were combined with the Te data in an energetic model to estimate annual energy budgets for the current climate and following predicted site-specific changes in climate. I hypothesized that the lower thermal tolerances (critical thermal minimum, CTmin) of these geckos would differ among populations such that geckos from the southernmost (and therefore presumably the coolest) populations would have lower CTmin relative to northern populations, but that the upper thermal tolerances (panting threshold, Tpant) would not differ among populations. I found that CTmin differed among populations, but not latitudinally as predicted. Remarkably, some populations had subzero CTmin suggesting freeze tolerance or supercooling ability—the first time this phenomenon has been reported for any gecko. Tpant did not differ among populations. Geckos from populations with the most thermal heterogeneity had the widest thermal tolerance ranges. I also hypothesized that the southernmost populations of this species would be the most thermally challenged, as evidenced by lower temperature-dependent sprint performance relative to northern populations. Temperature-dependent sprint performance indicated non-latitudinal shifts in performance over the geographic range of H. darwinii, yet most populations shared a similarly broad range for optimal performance indicating eurythermy. Eurythermy in performance suggests that future climate change may be neutral or even beneficial to H. darwinii. Differences in rates of resting metabolism and evaporative water loss were marginally significant among populations, yet only at higher experimental Tbs. The southernmost population of H. darwinii experiences a relatively mild, thermally homogenous climate and was estimated to have the highest annual energy demands, suggesting both an opportunity and need for longer daily and seasonal activity. Furthermore, my model estimates this population will be the least affected by climate warming. More northern populations that inhabit more thermally variable environments were predicted to experience similarly marginal effects of climate change based solely on abiotic considerations.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Bufalino, Charles
- Description:
- This study included 12 families (157 specimens); 122 specimens represented fourteen species of Emballonuridae (Chiroptera). Four morphologically different sterna have evolved within the family Emballonuridae: 1) a three segment sternum: manubrium, mesosternum, and xiphisternum; 2) same as 1 except the mesosternum extends over the xiphisternum; 3) a two part sternum, manubrium, and a fused meso-xiphisternum; 4) same as 3 except the meso-sternum extends over the xiphisternum. Of the twelve families surveyed; only the emballonurids demonstrated this intergeneric variability. Further, using numerical taxonomic analyses of twenty characters, ten of which were sternal, I was unable to correlate this sternal variation with any other anatomical character. However, the possibility doe.s exist that the selection pressure for sternum type in these bats may be related to some functional aspect of their behavior.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Rajaei, Atefeh
- Description:
- Hereditary Inclusion Body Myopathy (HIBM) is an autosomal recessive disorder characterized by adult onset muscle-wasting, affecting both proximal and distal muscles. HIBM is caused by different mutations in the GNE gene including the common Middle Eastern founder allele, p.M712T. The GNE gene is located on chromosome 9p13.3 of humans. The GNE gene encodes a bifunctional rate limiting enzyme UDP N-acetyl glucosamine 2-epimerase/N-acetyl mannosamine kinase (UDP-GNE/MNK). This enzyme catalyzes the first two steps in the sialic acid biosynthetic pathway. Mutations in the GNE gene may lead to, either decreased sialic acid biosynthesis and reduced sialylation of a variety of proteins like alpha-dystroglycan, Neprilysin and NCAM, (Huizing et al., Broccolini et al., Ricci et al.,) or to increased sialic acid production. Glycosylation defects have recently become recognized as an important cause of muscular dystrophy (Muntoni et al.). The functional capacity of sialic acid production can be restored by introduction and expression of the wild-type GNE gene. In order to demonstrate this, I used lectin resistant Chinese Hamster Ovary (CHO) cells (Lec3), which lack GNE/MNK activity. The CHO cells were transfected with pUMVC3-GNE recombinant constructs expressing either a wild-type GNE, D176V, R263L, M265T, V572L, M712T or R266Q mutant insert. CHO cells transfected with the R263L and R266Q GNE expression plasmid had an increase in sialic acid production. Those transfected with the D176V, M265T, V572L, and M712T GNE expression plasmid showed significantly lower amounts of sialic acid production. We intend to use these data to construct a model for gene therapy in mice and investigate its safety and effectiveness in the alleviation of muscle degeneration manifested in HIBM.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
453. Reproductive biology of the solitary ascidian, Styela plicata, at Marina del Rey, California, U.S.A.
- Creator:
- Frantz, Joseph Charles
- Description:
- Reproductive biology of the solitary hermaphroditic ascidian Styela plicata, was studied at Marina del Rey, California from October, 1971 through January, 1973. Gonadal structure, breeding season, and spawning behavior were examined utilizing histological sections through the gonads, fouling panels, and a laboratory light/dark regime. In the Marina, Styela plicata releases gametes from early May through late November in response to morning light. Temperature appears to be the controlling factor: animals will not release gametes below 15°C nor above 25°C. In the laboratory, the animals behave similarly, although the temperature range (6-8°C) over which spawning occurs depends upon the environmental water temperature at the time of collection. Fertilization, development and settling of larvae are restricted to a narrower temperature range (4-5°C) and are completed within 24-30 hours at 18°C. Both in nature and in the laboratory, gametes which remain in the gonads for six weeks or more are phagocytized.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Nosala, Christopher
- Description:
- Two studies were undertaken that investigate the implications of small biochemical alterations in living systems. First, epigenetic mechanisms have been shown to control gene expression and can permanently silence a gene. We investigate the role of the epigenetic mechanisms DNA methylation and histone deacetylation in the stage specific silencing of the gene VpreB. This gene must be expressed and extinguished at specific stages for the healthy development of the B cell. Reactivation of VpreB gene expression was observed after inhibiting epigenetic mechanisms in Ramos cells in which VpreB is permanently silenced. Furthermore, no DNA methylation was found within the promoter region of VpreB in Nalm6 cells in which VpreB is expressed. Therefore, DNA methylation and histone deacetylation was observed to be correlated with the onset of VpreB silencing in cell lines. Next, we explore the effects on substrate specificity of single point mutations within the active site of the enzyme deoxycytidine kinase (dCK). dCK is the rate limiting step for the salvage of several nucleosides as an alternate to de novo nucleotide synthesis. Furthermore, dCK is responsible for the activation of several chemotherapeutic nucleoside analog prodrugs such as gemcitibine. By making three mutations (A100V, R104M, D133A) within the active site of dCK, we were able to successfully increase dCK's specificity for the thymidine analog 2'-deoxy-2'-5-methyl-1-β-L-arabinofuranosyluracil (L-FMAU) that can be used for positron emission tomography (PET), a medical imaging modality. We also confirmed previous results that the three mutations can broaden dCK's specificity for thymidine. These results indicate that dCK's activity can be easily manipulated to increase specificity and turnover for thymidine analogs including L-FMAU.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Garcia-Flack, Ana Leticia
- Description:
- Indirect immunofluorescence was used to localize specific extracellular components in embryos of the sea urchin Lytechinus pictus. Hyalin and S2 (a group of components found in the disaggregation supernatant from Strongylocentrotus purpuratus blastulae) were uniformly present at all stages (unfertilized up to 32 hour) except hyalin could not be detected at the 12 hour early blastula stage. Laminin was found in 16 cell, 32 cell, 6 hour, 18 hour, 24 hour, and 32 hour stages, with especially bright fluorescence at 18 hours. Collagen I was present at all stages (freshly fertilized up to 32 hour) except little was detected at 12 hours. Fibronectin was uniformly present and blastocoelar fibers stained with anti-collagen I and anti-fibronectin. These results were compared with those for S. purpuratus to produce an overview of the localization of specific extracellular matrix components during development of two species of sea urchins. The results set the stage for future studies that will examine the function of these components at the various developmental stages.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Clark, Brian
- Description:
- Aspects of the reproductive behavior of giant sea bass, Stereolepis gigas, were observed and monitored at Goat Harbor, Santa Catalina Island, CA from June 2014 to August 2015. The site was visited daily during the summer months, which is the assumed spawning season and aggregations were not present during the spring and fall months (October - March). Numbers of giant sea bass ranged from 2 to15 individuals at Goat Harbor. Six individuals were tagged with Vemco V13 tags to determine site fidelity of giant sea bass at Goat Harbor. All 6 were detected at the aggregation site on a daily basis throughout the summer months (July - September) and also detected at the nearby sites of Long Point and Empire Landing. Giant sea bass produced booming sounds, which were often associated with aggressive behavior, but may also to be associated with spawning. Drumroll chorusing also was recorded at the giant sea bass aggregation with two different frequencies 250 Hz and 350 Hz and may be used to attract mates similar to other fish species. These sounds, although not confirmed as giant sea bass vocalizations, coincide with peak giant sea bass activity (1900-2200 hrs) when they are moving about the water column rather than being stationary near the substratum. These vocalizations are not vii known to be associated with any other fishes in the immediate area, supporting the hypothesis that they are produced by giant sea bass. Courtship was observed during the late afternoons and was most prominent around dusk (1900-2100). Courtship involved sexual dimorphic color change, and displays such as circling in pairs and the nudging of the abdominal area of the presumed female by the snout of the presumed male. The courtship behaviors observed were similar to those observed of giant sea bass in captivity. Although spawning was not observed the available evidence suggests that spawning occurs just after dusk. Confirmation of spawning at or near the aggregation site was obtained through DNA barcoding with COI primers of eggs sampled from Goat Harbor. This study has given insight into courtship behavior and how to identify giant sea bass spawning aggregations in the wild, which is crucial for the management of the species.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
457. How does harvesting impact white sage (Salvia apiana) as a cultural resource in southern California?
- Creator:
- Adlof, Cassidy
- Description:
- Demand for non-timber plant products has increased and with the stress of pressures, such as invasive species and habitat fragmentation, the sustainability of some culturally important plant populations may be at risk. Salvia apiana (white sage) is a plant used in cleansing ceremonies by Native Americans and adherents to other nature and Earth-centric spiritualties. Some Native Americans have suggested that the species is in decline and there is concern that over-harvesting may be the cause. This study addresses that concern by examining (1) how different ethnic and spiritual groups harvest or otherwise acquire S. apiana and (2) how plants respond to different harvest practices. People were surveyed to learn about their harvest practices and wild plants were subjected to combinations of harvest treatments to examine their biological effect. Treatments included gathering technique (by hand, cutting, leaf only), removal amount (0%, 5%, 25%, 50%), and harvest season (spring, summer). While various ethnic and spiritual groups acquire and harvest materials from S. apiana differently, these practices did not have significant impacts on plant size, leaf-volume ratio or flower abundance. Therefore, harvest is not a likely reason for decline of this species. A more likely cause of decline is the conversion of coastal sage scrub vegetation to invasive grass-domination due to increases in urban development and fire frequency.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Koch, Karen
- Description:
- Heterologous, or interspecies, transformation is the phenomenon in which bacteria of a given species acquire DNA from another species. This transfer can be exploited to test the functional interchangeability of one or more genes from organisms in one species when inserted into organisms in a different species. Functional interchangeability has been shown for thymidylate synthase (ThyA) genes. Thymine auxotrophs of Bacillus subtilis were cured by transformation with the thymidylate synthase (thyP3) gene of its temperate phage Φ3T in this manner. The ThyA gene of this same phage was also capable of curing a thymine auxotroph of Escherichia coli. The present study was designed to test whether the presumptive thymidylate synthase gene from PG has the ability to cure an Escherichia coli ThyA knockout. Sequence analysis of the presumptive PG thymidylate synthase gene yields homology with the ThyA gene. Successful cure of the E. coli ThyA knockout by this experimental approach would yield evidence that further establishes the conserved nature of the ThyA enzyme. More importantly, success would show that the PG gene and its enzyme are functional across domains (i.e. from Archaea to Eubacteria), and that the phage-encoded gene and its enzyme are functional when substituted for a cellular ThyA gene. An experiment was designed to insert the PG ThyA gene into expression vector pTrc99a, transform the vector into ThyA knockout E. coli DP50, and determine whether the PG ThyA gene functions to reconstitute the knockout E. coli to ThyA prototrophy.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- March, Christine
- Description:
- The benthic invertebrate macrofauna and larger meiofauna in the Mobile-Tensaw Delta was sampled from December 2010 to June of 2011 along a salinity gradient from the brackish waters of Mobile Bay up into the fresh waters of the Tensaw River. Community composition varied, in both composition and abundance, along the salinity gradient. The brackish regions were dominated by polychaetes and crustaceans. These benthic communities transitioned to oligochaete and chironomid larvae dominance as the salinity decreased. There was high abundance in the number of individuals and the number of higher taxa in the spring and summer months, while the winter had very few benthic invertebrates. The high level of variability at the study sites, over short time scales, suggested that the strength and frequency of biotic interactions is reduced and abiotic factors drive ecosystem dynamics. The realized niche overlap among benthic invertebrates varied through time, from periods of moderate of overlap, to very little overlap. As abiotic factors take precedence in shaping these benthic communities, species distributions and abundances may become relatively independent of one another. Abiotic effects have implications for how the food web in this tidal freshwater marsh is structured. If what is shaping benthic invertebrates niches in this area, biotic or abiotic variables, could be distinguished, it could indicate that this delta ecosystem may operate more as a mosaic of independent patches, as opposed to an interconnected ecosystem. Many estuaries are believed to be highly interconnected habitats, not only in terms of food web dynamics and nutrient cycling, but in their ecosystem services to surrounding coastal areas and to humans. It is important to establish the role that abiotic and biotic factors play in shaping the distribution and abundances of the benthic invertebrate communities in this tidal freshwater marsh. Better knowledge about what shapes these freshwater systems can lead to better protection and more informed management choices.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
460. Cell density dependent stimulation of glutamine synthetase activityin cultured mouse teratoma cells
- Creator:
- Connolly, Daniel Thomas
- Description:
- A density dependent stimulation of glutamine synthetase activity (GS) has been observed in cultures of mouse teratoma cells. GS specific activity increases as cultures approach confluency to a level greater than twofold over the basal level found in sparse cultures. After confluency the GS specific activity returns to the basal level found in sparse cultures. The stimulation could not be attributed to age of cultures, medium or glutamine depletion, cell leakage of GS, or change in the amount of cellular protein. Dibutyryl cyclic-AMP plus theophyline repressed GS activity both in cultured teratoma and in teratoma obtained from ascites grown tumors The evidence suggests that the stimulation is contact mediated. The stimulation is prevented by cycloheximide
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Binney, Patricia Ann
- Description:
- A study was made of EMS and X--ray--induced mutations occurring in the immediate vicinity of the vermilion (v, 1-33, 0) locus. This region of the X chromosome was covered by a special Y chromosome containing a duplication extending from salivary chromosome band 9F5 through 10C2, which should permit the recovery of female-sterile or sex determining mutants in this region. Approximately 6000 F1 males were examined and over 2500 chromosomes tested for the presence of male-lethal and female-sterile mutations; no female-sterile mutants were found. Fourteen recessive lethal mutants were induced, of which 3 were in the covered region. Ten viable and fertile visible mutants, including a lozenge (lz, 1-27. 7), a furrowed (fw, -1-36.8), a white (w, 1-1. 5), and a garnet (g, 1-44, 4). The most interesting mutant found was a male -viable v mutant accompanied by a simultaneously induced, independent semi -lethal mutant located approximately 0.6 crossover units to the right of v.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Monroe, John Gordon
- Description:
- Actin was isolated and purified from sarcoma-180 ascites tumor cells by a method employing DEAE-cellulose anion exchange chromatography, polymerization-depolymerization and exclusion chromatography. The actin was demonstrated to polymerize in an in vitro system. SDS-polyacrylamide gel electrophoresis was performed upon crude extracts of the sarcoma-180 cells and the total amount of actin was determined on a per cell basis. Thirteen percent of the total, and 12.6% of the soluble, protein of the sarcoma-180 cell was determined to be actin. This corresponds to an intracellular actin concentration of 6 mg/ml. These results are discussed in terms of current theories of in vivo control of tumor cell actin polymerization and microfilament assembly. The intracellular contents of the sarcoma-180 tumor cells were demonstrated to be very acidic by measuring the change in pH of a cell suspension before and after gentle lysis of the cells. This result, coupled with the experimental results on other tumor cells as reported in the literature, forms the basis for an alternative mechanism for the in vivo control of actin polymerization involving intracellular pH.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Hosseini, Shabnam
- Description:
- Smad4 is the central intracellular mediator of transforming growth factor-β (TGF- β) and BMP signaling pathways. To study the role of Smad4 in skeletal development, we introduced a conditional mutation of the gene in chondrocytes using Cre-loxP system. A high level of Smad4 gene deletion was verified in Cre expressing mice. In vivo, deletion of Smad4 resulted in normal early limb development. That is, the mesenchyme condensed in the correct pattern. However, later in development, depletion of Smad4 resulted in defects in the development of the skeletal elements. The skull was smaller and the limbs were shorter than controls, the deltoid tuberosity was missing, and the joints of the phalanges were fused. The rib cage was smaller and flattened which could lead to respiratory distress and subsequent post-natal death. The abrogation of Smad4 in chondrocytes resulted in dwarfism with a severely disorganized growth plate characterized by expanded resting zone of chondrocytes, reduced chondrocyte proliferation. My data also indicated that loss of Smad4 has a huge impact on the activation of Smad2 and p38 and that phosphorylation of Smad2 and p38 are Smad4 dependent. However, Smad4 is not required for the activation of Smad1/5. Therefore, since loss of Smad4 caused a decreased pSmad2 and p-p38 level, the cells might respond to TGF-β or BMP signaling with a compensatory upregulation of pSmad1/5 level. All vii these data provided evidence demonstrating that Smad4-mediated TGF-β and BMP signals are required for maintaining the normal organization of chondrocytes in the growth plate, and that Smad4 is required for normal development of the skeleton.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Murray, Kelvin Gregory
- Description:
- Investigation of the breeding biology of Xantus’ Murrelet (Endomychura hypoleuca) on Santa Barbara Island revealed that 46% of all eggs laid in one area were eaten by deer mice (Peromyscus maniculatus), while in another only 4% were eaten. Population density of mice in the two areas was comparable, as were murrelet nesting density and total availability of eggs. Vegetational differences between the areas were pronounced, with grasses abundant at the site with low predation rate but nearly absent at the other. Grass seeds were utilized heavily by the mice when available. I concluded that vegetation differences between the two sites, hence the concomitant differences in abundance of alternate food items, were responsible for the differential predation rate on eggs; mice relied heavily on easily obtained, energy-rich grass seeds when available, taking less abundant items such as eggs mainly where grasses were scarce. Survival of dependent young mice was greater in the area where egg predation was severe. Increased survival may have been facilitated through the nutritional input from eggs. These findings were explained on the basis of predictions of current optimal foraging theory.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Holt, Jocelyn R.
- Description:
- Potential Allee effects were investigated in Pentachaeta lyonii, an annual Asteraceae that is listed as federally endangered. Since P. lyonii is self-incompatible and has no evident seed dormancy, pollination service is essential for persistence. Observations of floral visitors showed that insect composition varied by site, year, and over the flowering season. The most common visitors were the bee-flies Lepidanthrax sp. and Paravilla sp. and the bee Ashmeadiella californica subsp. californica. There were also late-season peaks of the bee-fly Exoprosopa doris and bee Exomalopsis sp. These generalist pollinators allowed ample pollination for P. lyonii. The absence of Allee effects was further supported by there being no difference in seed production between open-pollination and hand-augmentation treatments within patches. In 2008 there was a proportional increase in per-capita visitation rates with increasing density. Flower heads in low density quadrats did not suffer a significant reduction in seed production compared to flower heads in more dense quadrats. Flowering P. lyonii in pots were placed in patches of various densities and at distances up to several meters from a patch. The percent of quadrats visited was higher inside a patch (69%) than outside a patch (16%), but seed set was not reduced by being placed outside a patch. Visitation to lone potted plants was equal to or greater than visitation experienced by potted plants inside patches, possibly because an individual flower head is less attractive when surrounded by conspecifics. Isolated plants at one site were visited more by melyrid beetles and Ceratina bees than the visitors to patches of flowers. These results indicate that other factors such as habitat loss and competition with non-native plants are likely responsible for populations not expanding in size and in some cases declining.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Gorchynski, Julie Ann
- Description:
- The calcium-magnesium-free sea water (CMFSW) dissociation supernatant (DS), isolated by disaggregating Strongylocentrotus purpuratus blastulae, specifically promotes reaggregation of S. purpuratus blastula cells. The approach used to investigate cellular adhesion in the sea urchin was to examine the CMFSW supernatant, DS, obtained from disaggregating blastula stage embryos for adhesion promoting molecules that might have been released during the disaggregation process. Attempts to purify the active components within DS by rate density gradient centrifugation gave results indicating that aggregation promoting activity resides in particles and particle aggregates ranging from 4S to greater than 53S. We termed these adhesion mediating components "aqherons", after the term used by Schubert and colleagues. The adherons were found to contain proteins ranging from 12 to greater than 280 kD, as determined by SDS polyacrylamide gel electrophoresis. These adherons appear to be responsible for the promotion of cell reaggregation displayed by DS.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Meschwitz, Paula Johanné
- Description:
- The agonistic behavior patterns of adult males of Peromyscus boylii and Dipodomys agilis were studied in the laboratory to determine if the degree of aggression was influenced by the type of habitat. After being moved from an artificial densely vegetated habitat to an artificial sparsely vegetated habitat, three groups of P. boylii displayed increased agonistic behavior. Two of the three groups formed a dominance hierarchy in the sparsely covered environment, whereas the third group displayed only an increase in activity. Dipodomys agilis displayed unexpected conspecific tolerance and formed a dominance hierarchy in two out of three groups while in the sparsely vegetated habitat. The third group included one extremely aggressive individual. Two of his conspecifics were subsequently found dead. All three groups decreased the frequency and intensity of their agonistic behavior when moved from a sparsely covered environment to a densely covered environment, but individual variation and familiarity with the members of the group may be more important than habitat in influencing agonistic patterns. A habitat preference study of both species indicated Peromyscus boylii selected the densely covered environment and Dipodomys agilis selected both types of habitat about equally.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Younesi, Shahab
- Description:
- Skeletal muscle myofibers contain muscle stem cells called satellite cells that express the transcription factor PAX7, and regenerate muscle after acute injury. These skeletal muscle progenitor cells (SMPCs), or satellite cells in the adult muscle, lie outside the muscle fiber and refurbish the endogenous muscle stem cells upon damage. Human pluripotent stem cells (hPSCs) have enormous potential for use in regenerative medicine, especially for muscle wasting diseases like DMD. In DMD, the satellite cells become exhausted leading to failed regenerative ability. Once these muscle stem cells are depleted, damaged muscles are replaced by excessive fat and extracellular matrix deposition leading to muscle deterioration and fibrosis. One potential target to replenish exhausted muscle stem cells in patients with DMD is to generate an equivalent source from hPSCs. The myogenic activity from SMPCs derived from hPSCs is currently not well understood. We evaluated human fetal muscle in order to better understand the timing and specification of human SMPCs during human development and compare to hPSC-derived SMPCs for in vitro and in vivo myogenic activity. We have also shown that PAX7 is present in week 9 and 17 fetal skeletal muscle tissue, which may be indicative of when SMPC differentiation occurs. hPSC-derived SMPCs will be developed by the use of directed differentiation and synthetic mRNA. We have cloned PAX7 coding region into a VEE vector to enable synthetic RNA mediated overexpression (OE) of PAX7 into pre-differentiated hiPSCs in various plating conditions. PAX7 expression exceeded 700 fold in some conditions. Understanding the developmental and molecular underpinnings of human skeletal myogenesis will provide roads into generating SMPCs from hPSCs for use in regenerative medicine.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Rose, Betty B.
- Description:
- The brain of the toad, Bufo boreas, is used by neurochemists as a model for several abnormal neurochemical conditions in humans. Toad brain tissues can be made hyperosmotic (as is the human brain, for instance, prior to an epileptic seizure) by placing toads in NaCl solutions. Such hyperosmotic stress produces unusual behavior•. In this study I attempted to correlate abnormal behavioral states related to feeding with amino acid levels in the brain. Toads, both NaCl-adapted (hyperosmotic) and freshwater-adapted, were watched every other day while feeding. 1151 observations of 126 toads were made; 19 behavioral parameters were monitored. Discriminant analysis, based on 11 variables, was used to divide the observations into six behavioral groups (normally behaving, poor responders, very poor responders, poor hitters, very poor hitters, and non-responders). Groups are statistically different at the .001 level using a Roy-Bargman Stepdown Manova. Several other behavior patterns, incidental to the act of feeding, were occasionally seen during the tests. Eleven of these were described and their occurrence among the behavioral groups used to reinforce the group structure. Amino acids were extracted from three brain areas (cerebral hemispheres, olfactory bulbs, optic lobes) and the plasma of 64 hyperosmotic and freshwater-adapted animals, and quantified using an automatic amino acid analyzer. Levels of 22 amino acids in the brain and plasma were compared among behavioral groups. Identification of amino acids likely to be related to behavior was based on 2 criteria: 1) levels in normally-behaving hyperosmotic animals did not differ significantly from those of freshwater controls, and 2) levels in at least one abnormally behaving hyperosmotic group differed significantly from those of normally behaving hyperosmotic toads. Ten amino acids were identified as most probably related to behavior. Aspartate, gamma-aminobutyric acid (GABA), and phenylalanine were identified as related to behavior in all brain areas. The significant elevation of GABA among only the most behaviorally depressed groups is in agreement with its neuro-inhibitory role and consequent effect on behavior (Baxter, 1976; McGeer and McGeer, 1980). Aspartate elevation may be serving an osmoregulatory function. (See more in text)
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Nicholson, Phyllis
- Description:
- Niche relationships and coexistence of ten species of rodents occurring in southern California chaparral were studied from October 1975 through September 1976. Habitat selection and utilization were investigated to determine the extent to which the fundamental niche of each species was reduced in size because of effective competitors. A 2.2 hectare study plot with 96 trap stations was used to census rodents regularly. Vegetation at each trap site was quantified using the profile board technique. Neotoma fuscipes selected habits of heavy chaparral cover and socially dominant to N. lepida, which was relegated by fuscipes to the chaparral edges. Peromyscus californicus also preferred dense chaparral and the presence of three congeners did not alter its selection of the preferred habitat. Distributions of P. truei and P. boylii were microparapatric within the chaparral and riparian woodland habitats. This distribution is maintained by direct interaction. Peromyscus maniculatus was found occasionally at the shrub-grassland interface but more often in the grassland habitat. It was excluded from the richer habitats by socially dominant congeners. It coexists in the grassland habitat with Microtus californicus and Reithrodontomys megalotis by being socially subordinate to M. californicus and dominant to R. megalotis. Dipodomys agilis was trapped at chaparral edges, open areas between chaparral shrubs and in grassland areas. Its negative pair-wise association with N. fuscipes represents fundamental differences in habitat requirements for these two species. Perognathus californicus coexists with the cricetids in the chaparral by being the most socially subordinate and by filling the interstices among species already present.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Gregory, David Alexander
- Description:
- A population of college students with presumably healthy mouths was surveyed for the gliding, mulcicellular filamentous, aerobic oral bacterium Simonsiella. The microscopic examinations of swabbings from the palate showed 32.1% of 212 individuals to harbor this organism on the hard palate. The 7.8% sexual difference between the frequency in males (35.2%) and in females (27.4%) was not significant (P = 0.05). Seventeen pure strains of Simonsiella were isolated from humans as well as two from cats and one from a dog by means of a direct isolation technique. The strains of human origin were included in a taxonomic study comprising additional strains from 19 dogs, 8 cats, 4 sheep, and the neotype strain of Simonsiella crassa. The taxonomic study established the existence of three distinct physiological groups of Simonsiella, that corresponded to their source of isolation. The sheep strains were similar to the neotype strain of S. crassa and were different from the other strains by their proteolytic activity on casein agar, gelatin, inspissated serum, and litmus milk, and by their ability to produce acid from glucose, maltose, trehalose, mannitol, sucrose, fructose, and ribose. The human strains produced acid only from glucose, maltose, and trehalose, and did not display proteolytic activities. The dog strains did not produce acid from carbohydrates nor did they demonstrate proteolytic activity on gelatin, inspissated serum, or litmus milk. The cat strains were similar to the dog strains. Morphologically, the California sheep isolates formed a uniform group and could be classified as S. crassa. The human strains possessed filament widths that fall into the range of S. crassa and S. muelleri. Most dog strains generally possessed filaments that were wider than those isolated from other sources. The cat strains displayed great morphological variation; some resembling the sheep and human strains, and others resembling the wider dog isolates. The distinction of the physiological groups of Simonsiella strains on a morphological basis was not possible.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Dodson, Snowdy Denise
- Description:
- The phosphorylated pathway has been proposed as the major source of serine in Neurospora Crassa (Sojka & Garner, 1967). Chuck (1980) demonstrated that a serine deficient mutant of Neurospora crassa, ser (JBM5), which is isogenic with its progenitor prototrophic strain, shows a marked decrease in its phosphoserine phosphatase specific activity when compared to the activity of its prototrophic strain. This lowered activity in the enzyme catalyzing the terminal step of the phosphorylated pathway of serine biosynthesis in a serine requiring mutant which has a single gene difference compared to its prototrophic strain supported the phosphorylated pathway as the major source of serine in Neurospora crassa. The present study assayed the phosphoserine phosphatase activities of two allelic serine requiring mutants of Neurospora crassa, ser-3 and ser (JBM5). In all assays, both mutants had significantly lower phosphoserine phosphatase specific activities than did their respective prototrophic strains. This finding lends further support to the phosphorylated pathway as the principal route of serine biosynthesis in Neurospora crassa.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Koller, Ronald Lewis
- Description:
- A study was made of the helminth parasites infecting the Pacific treefrog, Hyla regilla, and the California toad, Bufo boreas, at Malibu Creek and Big Tujunga, California. Malibu Creek represented a cool, humid coastal habitat and Big Tujunga represented an arid inland wash habitat. Examinations of the frogs were performed on a regular basis to determine seasonal infection rates. Frogs were collected and necropsied, and helminths were isolated and identified from prepared slides. Statistical tests were used to analyze associations between size of host and sex of host with infection rates. Different infection rates between localities and hosts were analyzed statistically. Nematodes were the most frequent helminths found, and of these, Oswaldocruzia was most abundant. Rhabdias, Cosmocercoides, Distoichometra, and Glypthelmins were also recovered. Oswaldocruzia infections in Hyla regilla and Distoichometra infections in Bufo boreas are recorded here for the first time. Seasonal occurrence of the helminths showed no definite pattern. Regression analyses indicated that helminth intensity varied significantly with host size. Erratic seasonal fluctuations of infection were related to the distribution of host age groups. Significant differences between localities existed regarding the incidence of infection. Factors responsible for these differences included host age, host-parasite density, and environmental conditions affecting infective helminth larvae. Significant differences between host species did not exist regarding incidence and intensity of infection. Both hosts were sympatric, inhabited similar environments, and were subject to similar infections.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Paterson, Corinne Nichole
- Description:
- Fishery management relies on aspects of the life history of a fished species to implement effective management strategies. One aspect that has been underutilized is molecular markers. The addition of these methods can lead to a better understanding of a fishery stock and thus better management strategies. This study looks at barred sand bass (commonly, sand bass), Paralabrax nebulifer, a commonly fished species in southern California and Baja California, Mexico. Sand bass form large spawning aggregations in the summer months of June-August, which makes them highly susceptible to overfishing. In the last decade, populations of sand bass in southern California have experienced a severe decline in numbers and subsequently the recreational fishery has been seriously impacted. Large population declines, such as a fishery decline, can lead to a decrease in genetic diversity and potentially a genetic bottleneck. This is a concern for barred sand bass populations; however, the population structure and genetic diversity of barred sand bass populations was previously unknown. This study looks at both aspects using the d-loop region of the mitochondrial DNA and microsatellite markers for populations throughout California and Mexico. Samples of barred sand bass were collected between 1997 and 1999 and from 2010 to 2013. DNA was extracted and amplified using PCR for the mitochondrial DNA control region and for microsatellite primers developed for barred sand bass. Microsatellite primers were designed and tested for this study. Both markers show a high degree of genetic diversity indicating one large, panmictic population. However, there is some genetic structuring around the San Quintin upwelling zone in Baja California, Mexico. This upwelling zone is likely an oceanographic barrier to larval transport; however it is an incomplete barrier as evidenced by the high degree of gene flow between the two populations. There is no evidence of a genetic bottleneck; however, it may be that not enough time has passed to reflect a bottleneck due to the fishery decline. This study provides a base line for the genetic diversity of barred sand bass and can be used to monitor barred sand bass in the future.
- 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:
- Dufault, Aaron Matthew
- Description:
- Ocean acidification (OA), caused by the dissolution of anthropogenic CO2 into the surface waters of the ocean, threatens the fate of calcifying marine organisms. The effects of OA on adult coral calcification have been well-studied over the past decade and generally results in decreased calcification rates with increasing pCO2, although the effects of OA on early life history stages are less well-studied. This thesis addresses the effects of OA on coral recruit physiology with an emphasis on filling key gaps in the ecological relevance of previous manipulative OA coral studies. Chapter I: In March and June 2010, two experiments were conducted exposing newly settled Seriatopora caliendrum recruits to low (440, 456 μatm), high (663, 837 μatm; March,June respectively) and diurnally oscillating pCO2 which mimicked the conditions at Hobihu reef, Taiwan where adult corals were collected. Calcification and survival of coral recruits was elevated in diurnally oscillating pCO2 relative to static ambient and high pCO2, hypothesized to be the result of increased DIC stored in coral tissues at night. Chapter II: In March 2011, newly settled Pocillopora damicornis recruits were exposed to low (493 μatm) and high pCO2 (878μatm) in varying light intensities (226, 122, 70, 41, 31 μmol photons m-2 s-1) to test the effects of light and OA on coral recruit physiology. Coral recruit calcification and survival in both pCO2 treatments was light-dependent, with large differences in calcification at intermediate light intensities (41, 70 μmol photons m-2 s-1) though calcification at high and low light intensities did not differ (226, 31 μmol photons m-2 s-1). Survivorship was not correlated with size and was highest in both ambient and high pCO2 at 122 μmol photons m-2 s-1. Chapter III: Finally, the activity of carbonic anhydrase in S. caliendrum juveniles (< 3 cm ) exposed to ambient, high and diurnally oscillating pCO2 was measured to elucidate the mechanistic basis for increased calcification in diurnally oscillating pCO2. CA activity was decreased in both high and diurnally oscillating pCO2 during the day, which is consistent with the DIC buildup hypothesis proposed in Chapter I. Together these findings provide novel insight into the physiology of corals exposed to OA under ecologically relevant seawater chemistry and light conditions. Coral recruits are biologically quite different than their adult counterparts therefore further work is needed to determine the extent to which these results apply to adult corals.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Alvey, Gerald Lee
- Description:
- Both stream-dwelling and pond-dwelling Hyla regilla home rapidly and accurately after displacement. The majority of returns occurred within 24 hours and the homing rates ranged from a minimum of 37 m/day (overland) for pond-dwelling frogs to a maximum of 125m/hour (aquatic) for stream-dwelling frogs. A very high degree of fidelity to a limited home range was noted as most animals returned to within a few meters of their original capture site. Juvenile and adult Bufo boreas exhibited accurate Y-axis orientation, both in a terrestrial arena and in an aquatic arena, via sun-compass. No evidence was found indicating that these toads can successfully orient utilizing stellar cues, although some evidence indicates that they may mistake a full moon for the sun under certain conditions. The Y-axis orientation of B. boreas was shown to degenerate over a six-day period when the toads were kept in light-tight boxes and thus deprived of their usual celestial, solar and other cues. Attempts to alter the natural Y-axis direction of B. boreas by exposing them to artificial shorelines and an advanced diel cycle resulted in inconclusive data. Both pond-dwelling and stream-dwelling H. regilla oriented successfully in the terrestrial arena using stellar cues, as well as a sun-compass. Their orientation during night was not as accurate as that exhibited when the sun was visible. Hyla regilla oriented towards a recorded chorus in preference to celestial cues. The frogs were also able to distinguish between a recording of their home chorus and that of a foreign chorus; they preferentially moved to their home chorus. Bufo boreas did not respond to tape recorded calls. Larval frogs and toads tested in an aquatic arena did not exhibit Y-axis orientation in response to solar cues. Adult H. regilla and B. boreas tested in a Y-shaped wooden maze did not move toward airborn scents of water from their home area, mud from their home area or a female frog or toad. Thus, no evidence was obtained to show that these animals are capable of utilizing olfactory cues to orient or home.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Scordato, John Charles
- Description:
- Previous studies of teratoma cells in batch culture demonstrated that glutamine synthetase (GS) specific activity was cell density dependent, increasing as the culture approached confluency. Other studies also showed that intercellular adhesion and GS specific activity increased in the presence of hydrocortisone. Confluency frequently reflects a non-cyclic cell population. Hence, in batch culture the increase in GS activity at confluency may be a consequence of the cells either leaving the cell cycle or coming into register at a given point in it, e.g. G1. Therefore it is desirable to determine if GS activity and adhesion are properties of non-cyclicing as well as actively growing populations. These studies were undertaken to determine if there is a relationship between intercellular adhesion and GS specific activity during the cell cycle and if hydrocortisone effects these parameters. To determine if increased cell adhesiveness and GS specific activity occur at specific times during the cell cycle, cell populations were synchronized with thymidine (3m.M) plus colcemid (5ug/ml). (See more in text.)
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Samuelian, Dale.
- Description:
- A population of three-spined sticklebacks Gasterosteus aculeatus L. from the San Joaquin River below Friant Dam near Fresno, California, was found to be infected with the plerocercoid larval stage of a pseudophyllidean cestode, Schistocephalus solldus (Muller, 1776). Schistocephalus solidus belongs to the class Cestoidea, subclass Cestoda, order Pseudophyilidea, family Dibothrio- cephalidae. During the plerocercoid larval stage it is a coelomic tapeworm of the three-spined stickleback Gasterosteus aculeatus. Members of this genus are widely distributed in many parts of the world, with the majority of infections being reported in Great Britain and Ireland (Smyth, 19-4-6; Hopkins and McCaig, 1963; Arme and Owen, 1967; Chappell, 1969a,b; and Pennycuick, 1971a, b, c, d. In California, S. solidus has been studied by Markley (19^-0) and Haderlie (1953). The present study will: (1) demonstrate the seasonal incidence and variation of the parasite infection, (2) indicate the differences in the sizes of the infection in stickle- backs of different sexes and sizes, and (3) show the frequency distributions of the parasite within the host population.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Fresno
- Department:
- Biology
- Creator:
- Thorpe, Gary Stephen
- Description:
- Rates of evaporative water loss were obtained for two geographically and climatically isolated populations of Uta stansburiana hesperis Richardson under specified conditions of temperature, relative humidity and air flow. From these data, equations for the two populations predicting evaporative water loss were derived in an attempt to show: (1) habitat correlation of evaporative water loss and (2) differential, genetically-determined response patterns of evaporative water loss in respect to reproductive isolation. In this study it was found that the rate of water loss in the two lizard populations did not differ significantly in relation to the effects of air temperature, relative humidity and convection.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Rossitto, Joseph James.
- Description:
- Chromosomes were analyzed from the mitotic bone marrow of nine mountain pocket gophers (Thomomys monticola J. A. Allen, 1893). All the specimens, collected from three different localities in the'Sierra Nevadas, had a diploid number (2N) of 40. Animals from two localities exhibited slight variations in chromosome morphology. Pocket gophers from Lake Tahoe possessed a fundamental number (FN) of 76 while those from Huntington Lake and Kaiser Pass Meadow had a FN of 74. The difference in the karyotypes is attrib- uted to non-Robertsonian variation: pericentric inversions and reciprocal translocations.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Fresno
- Department:
- Biology
- Creator:
- Restani, Mark.
- Description:
- The structure of intermittent streams has been described by Abell (1956) . Her work was based on the analysis of Dry Creek, Fresno County, California, which she considered a typical intermittent stream. An earlier work (Stehr and Bransen, 1938) had given the faunal makeup of a similar stream in Southeastern Ohio. The effect of drought on the fauna of two small mountain streams turning them into intermittent streams is described by Hynes (1958) and Kamler and Riedel (1959). The apparent patterns of recolonization of temporary streams with the return of water is discussed by Abell (1956), Clifford (1966) and Harrison (1966), and a generalized overview of the subject of intermittent streams is presented by Hynes (1972). A tributary of Cottonwood Creek, which unlike Dry Creek has no permanent pools, was followed from November 20, 1972, just after the first rains, until the stream dried up on June 15, 1973, to establish the diversity of insect forms, their temporal sequences and to permit speculation on reinvasion patterns and habitat preferences or limitations. Samples were taken once every other week with a surber sampler and an aquatic net. Stream current was measured with a Gurley Pygmy Current Meter. The stream proved to have a diverse insect fauna as well as a variety of other forms including molluskans, annelids, acarines, crustaceans, amphibians and reptilians. One fish, Gambusia sp., was taken, a likely contaminant from year-round water sources near the stream.
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Fresno
- Department:
- Biology
- Creator:
- Uppal, Sabrina K.
- Description:
- Seizures, trauma and many neurologic diseases induce damage to the hippocampus, which can result in deficits in spatial navigation, memory consolidation and depressive-type behaviors. Current drug treatments have limited effectiveness in improving symptoms. Celavie Biosciences LLC has developed a human fetal brain-derived, pluripotent, nontumorigenic, hypoimmunogenic stem cell line with a normal karyotype (hfSC) that has previously shown an ability to migrate, differentiate and reduce structural and functional deficits in other neurodegenerative animal models. In this study, I examined if injected hfSCs into male Wistar rat CA3 hippocampal lesions will survive and possibly differentiate into mature pyramidal neurons, thereby diminishing neuronal damage. It has been established that the CA3 region of the hippocampus is involved in consolidating short-term memory to long-term memory and in spatial navigation. I stereotactically lesioned the CA3 regions at 50 days bilaterally with the neurotoxin NMDA (1μl containing 7.5 mg/ml; -3.5 mm AP; ±2.0 L and -2.5 V). At 54 days of age, live hfSC (500,000 cells in 5μl cell suspension media) for our treatment group, frozen-killed hfSC (500,000 cells/ 5μl), HEK293T cells (500,000 cells/5μl), or cell suspension media (5μl) were bilaterally implanted directly into the NMDA damaged area. The rats were tested two weeks later (68 days) with various memory tests, including the water-maze task, and novel and place-object tests. My results showed that rats receiving live hfSC implantation performed significantly better in the water maze task than control groups. Novel and place object tests showed no significant differences among the treatment groups. Histology confirmed the survival of implanted hfSCs up to 28 days post-implantation. My study has shown that Celavie's human derived pluripotent stem cells were able to survive in vivo and improve hippocampal functionality, highlighting the potential promise for stem cell treatment of brain damage in neurodegenerative diseases.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Aguirre, Socorro Maria
- Description:
- Legionella pneumophila is a gram-negative bacterium that causes a severe pneumonia known as Legionnaires' disease. L. pneumophila is engulfed by macrophages via phagocytosis, where it avoids being dismantled by the lysosomes through the establishment of, and proliferation inside a Legionella-containing phagosome (LCP). L. pneumophila secretes effector proteins into the cytosol of the host cell via the Dot/ICM type IV secretion system to allow its survival. SdhB is one of those effector proteins, and it has two paralogues, SidH and SdhA, which are also introduced into the cytoplasm of an infected cell. SdhA plays a role in inhibiting apoptosis. A previous yeast two-hybrid screen suggested that there was an interaction between SdhB and Sec22b, a Soluble NSF Attachment Protein REceptor (SNARE) on endoplasmic reticulum vesicles. Sec22b is involved in vesicular trafficking that takes place between the endoplasmic reticulum-Golgi intermediate compartment (ER-GIC) and the Golgi apparatus. Sec22b normally binds to three SNARES on the ER-Golgi intermediate compartment or on the Golgi apparatus. It was hypothesized that the N-terminus of SdhB interacts with the SNARE Sec22b; the regions of the N-terminus that are important for this interaction remain to be identified. To investigate potential protein-protein interactions between SdhB and Sec22b in vitro, the C-terminus portion of sdhB was cloned into a glutathione-S-transferase expression vector pGEX-5x-1 to create a protein fusion between glutatione S-transferase (GST) and SdhB. Expression of the GST-SdhB fusion protein in E. coli was optimized, and conditions for binding specific amounts of GST-SdhB from lysates cleared of cell debris onto glutathione-coated beads was determined. Beads previously coated with GST-SdhB were unable to bind His-tagged Sec22b. This was shown in both stained protein gels and by Western blotting. Sec22b was also unable to bind to GST-only controls. Similar results were obtained if Sec22b and the fusion protein underwent simultaneous incubation with the glutathione beads to control for the requirement of pre-association of proteins prior to glutathione binding. These results indicate the L. pneumophila effector protein SdhB C-terminus is not involved in a protein-protein interaction with Sec22b.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Estrada, Jessica Mayra
- Description:
- Hereditary inclusion body myopathy (HIBM) is a genetic neuromuscular disorder characterized by progressive muscle wasting and weakness. HIBM is caused by mutations in the GNE gene which encodes the bifunctional enzyme uridine diphosphospho-N-acetylglucosamine (UDP-GlcNAc) 2-epimerase/N-acetyl-mannosamine (ManNAc) kinase (GNE/MNK). The GNE gene product catalyzes the first two committed, rate-limiting steps in the biosynthesis of 5-N-acetylneuraminic acid (Neu5Ac, also known as sialic acid). One of the most frequent mutations is an exchange of methionine to threonine at position 712 (M712T). There are no effective treatments for HIBM yet. Investigators are working toward finding an effective treatment. In order to make progress toward a cure, it is paramount that an effective animal model be developed. Thus, the purpose of this study was to help determine whether the FVB;B6-GNE M712T/M712T knock-in mice developed a similar phenotype as humans in order to allow future testing of therapeutic approaches. I assessed this through the use of a grip-strength meter to determine the presence of muscle weakness. Grip strength of the mice was measured using the Chatillon DFIS-10 digital force gauge apparatus to determine progressive muscle weakness in the homozygous mutant group. The results of the homozygous mutant group were then compared to results from the mice heterozygous for the mutation and to the wild-type (control) mice. In order to assess the effects of the mutation on muscle strength, it was necessary to determine the genotypes of each mouse in the study. Genotypes were determined by PCR and restriction enzyme digest. Attempts were made to increase the colony size by breeding based on the genotyping results. The average force exerted by the mice revealed that there were no significant differences found between the GNE M712T/M712T and the control mice in grip force of either the forelimb or the combined forelimb and hindlimb. The average force exerted by the mice when using the forelimb was 0.09kg for the wild-type, 0.12 kg for the mutant, and 0.09kg for the heterozygous group. The average force exerted using combined forelimb and hindlimb was 0.24kg for the wild-type, 0.23kg for the mutant, and 0.22kg for the heterozygous group. Unexpectedly, some of the dissected homozygous GneM712T/M712T mice appeared to exhibit signs of abnormal kidneys. Either the grip-strength protocol was not sensitive enough to detect differences in forelimb and combined forelimb and hindlimb strength, or the knock-in mice with the M712T mutation do not show the same muscle-wasting phenotype found in humans at the age in which the mice were tested. The experiment should be repeated with different parameters in the grip-strength protocol and larger sample size. Mouse muscle tissues and necropsies should be arranged for all the mice in poor health to see if their internal organs, especially the kidneys, are healthy. These data could be used to construct a more suitable mouse model to further investigate treatments in alleviating muscle deterioration found in HIBM.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Lopez, Ulises
- Description:
- Photosynthetic microbial mats are complex, stratified microbial ecosystems found in a variety of environments including intertidal regions of salt marshes. Generally, phototrophic organisms dominate the top layers, while diverse heterotrophic organisms can be found throughout a well-developed mat. This study focuses on how seasonally fluctuating environmental factors (salinity, temperature, and pH) influence the diversity and composition of an intertidal microbial mat located in Southern California, USA. Using high-throughput sequencing of the 16S rRNA gene and the ITS1 region of fungi, I characterized the microbial communities of the top (0 – 0.5cm) and bottom layers (0.5 – 1.0cm), and the underlying sediments of a mat system seasonally for two years beginning in the summer of 2014. Over the observation period, salinity (3.7% – 10%), temperature (11.0°C – 30.4°C) and pH (5.6 – 8.4) were variable, revealing a dynamic environment influenced by seasonal changes in tide height, solar radiation, and precipitation. Microbial communities were compared for changes in diversity and community composition. The top layer of the mat was composed primarily of Cyanobacteria, algae, purple sulfur bacteria, and aerobic heterotrophs, but the relative abundance of each varied seasonally. In the bottom layers of the mat and underlying sediment, the depletion of oxygen and filtering of light selected for anaerobic heterotrophs, primarily sulfate reducing bacteria. In contrast, fungal communities throughout the layers of the mat were less variable, but some fungal lineages did change seasonally. Ongoing seasonal characterization of this mat system will provide foundational data that will allow for the identification of factors structuring this mat system and will ultimately lead to a better understanding of how photosynthetic microbial mats contribute to carbon cycling within salt marsh environments.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Johnson, Joseph Thomas
- Description:
- Macrocystis pyrifera (12) were subjected to a controlled shore wash-up treatment to determine which animals leave from and which remain within holdfasts detached from a rocky substrate. The procedure encompassed five phases: 1) separation from bottom and drift to surface 2) Drift at surface; 3) Wave wash in surf zone; 4) Out of water on shore; 5) Recovery of the holdfast. Among the varieties of animals inhabiting M. pyrifera holdfasts, amphipods and polychaetes make up the great majority (75%). Most of the animals capable of leaving the holdfasts did so during the ascension to the surface and during the early part of the drift phase. Responses varied for groups and species. Indirect evidence suggests that pressure change may be primarily responsible for the exodus.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Shepard, Wayne Kent
- Description:
- Ascites fluid from mice 'bearing the Sarcoma 180 ascites tumor enhances the rotation mediated aggregation of S-180 ascites tumor cells, Evidence presented suggests that the aggregation promoting component of the ascites fluid is not produced by the host, and is therefore probably an extracellular product of the ascites tumor cells. This aggregation promoting substance increases the rate of aggregation of two other ascites tumor lines and the reaggregation of chick neural retina. The effect of S-180 ascites fluid on these heterologous cell types, however, is usually less than that on S-180 cells. (See more in text.)
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Hackitt, Justin Dale
- Description:
- Settlement patterns and pre-settlement larval traits of fish species can directly influence the local population and community structure. Lunar cycles may play a role in determining these settlement patterns and traits. Depending on the lunar phase, onshore transport may vary in strength, directly influencing larval supply from the pelagic environment to suitable reefs. Also, without suitable onshore transport, larvae may delay their settlement, increasing their size and age at which they settle to a reef. The purpose of this study was to examine the effects of lunar variation on settlement rate and settler quality of two temperate reef fishes. This was accomplished by examining settlement rates and pre-settlement traits in the señorita, Oxyjulis californica, and the blacksmith, Chromis punctipinnus. SCUBA surveys of settlement rates and collections of each species took place within 1-2 days of the New, 1st Quarter, Full, and 2nd Quarter lunar phases, from June-August 2012, at two sites at Santa Catalina Island, California. Using the lapillar otoliths, size at settlement, pelagic larval duration (PLD), and average daily larval growth rates were examined in both species. The effects of lunar phase on settlement were inconsistent, with no apparent lunar pattern in señorita and peaks in settlement occurring during the New and 1st Quarter moon phases in blacksmith. The physical factors that vary with lunar phase such as temperature, tidal amplitude, and internal waves, most likely did not impact settlement for either species. Adult spawning behavior may drive the settlement patterns observed in this study. Larval traits did not differ significantly among lunar phases in either species. Both species had relatively narrow ranges of size at settlement, with highly variable PLDs. This variability could be, in part, due to variation in growth rates, caused by either pre-hatching or pre-settlement variables, rather than environmental cues near the time of settlement, such as lunar phase. This study adds to the limited number of studies on settlement patterns of temperate fish species. Understanding the processes that affect settlement rates and larval traits helps us understand population dynamics and community structure.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Ellis, Hugh Irl
- Description:
- A study was made of Protothaca staminea in the Mugu Lagoon, California. Two areas were studied: a sandy channel and a muddy sand backwater. Random sampling of the two areas was done to determine the relative densities and dispersions of P.staminea. The organisms were measured for length, height, width, and age. "Size" was determined as a composite of length, height, and width. Age was determined by the presence of annual rings. The amount of growth in each ring was measured in order to compare yearly growths of bivalves in each area. Sediments were analyzed for particle size, e.g.,silt and clay, fine sand, etc. Bivalves were also taken from the Venice Canal and from Tomales Bay, California for the purpose of comparison. The density of Protothaca s taminea in the muddy sand was three times that in the sandy channel. In both areas the' showed contagious distributions. Student's t-tests showed significant differences in first year growth among all four of the areas. Differences in other years were reflected by their mean values although not all these differences were statistically significant. Within any one year class, significant seasonal differences were seen in growth. The sediment in the two Mugu Lagoon areas was shown to be dependent upon current velocity. Great current velocity inhibits growth in young Protothaca staminea, but moderate current increases growth rate. Current flow is the factor responsible for the weak associations between growth as a function of "size" and certain sediment components in a multivariate correlation analysis. Age, an index of survival, was correlated to certain sediment sizes also. Food availability, defined as plankton or, in one instance, possibly organic detritus,caused this correlation.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Walker, Eldon Mac
- Description:
- The binding to the surface of Treponema pallidum, Nichols strain, of six mouse-derived monoclonal immunoglobulin G (IgG) preparations was demonstrated by whole mount indirect immunoelectron microscopy. T. pallidum from 10-day old rabbit orchitides was processed fresh and after 4 hours aerobic incubation at 34°C. Monoclonal IgG bound to treponemes was detected with colloidal gold-labeled Fe fragment-specific goat anti-mouse IgG. Treponemes were processed for whole mount immunoelectron microscopy and were negatively stained. Treponemal integrity depended on the length of incubation of the suspension. Each of the six monoclonal antibodies, but not a monoclonal antibody with specificity for Neisserig gonorrhea, was shown to bind to the intact surface of T. pallidum. The gold label was distributed randomly and was not seen on endoflagella or in areas of obvious membrane disruption. Colloidal gold alone did not bind to any combination of treponemes with monoclonal IgG. Binding occur red at low levels both in terms of the number of gold spheres per organisms and the number of labeled organisms per grid. These results indicate that the cognate epitopes of the monoclonal antibodies are domains of surface-exposed outer membrane immunogens.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Giovannone, Dion
- Description:
- Neural crest cells emerge by delamination from the dorsal neural tube and give rise to various components of the peripheral nervous system in vertebrate embryos. The cells change from non-motile into highly motile cells migrating to distant areas before further differentiation. Mechanisms controlling delamination and migration of neural crest cells are not fully understood. Neural crest cells originating in the trunk region do not migrate into the developing gut while those at the vagal region will populate the gut. Slit2, a chemorepellent for axonal guidance, repels and stimulates motility of trunk neural crest cells during migration away from the gut. The goal of this study was to investigate the role of Slit2 in trunk neural crest cell migration. Via electroporation, pre-migratory neural crest cells were manipulated to either inhibit or express constitutively Slit2. In situ hybridization was performed on Slit2 knockout mice for neural crest using SoxlO. We looked for a phenotypic effect on migration and delamination. Data images suggest Slit2 over expression impairs cell motility and alters morphology after neural tube delamination in vertebrate embryos. Inhibition of Slit2 via Morpholinos suggests early delamination of trunk neural crest cells. Our data indicates that Slit2 plays a role in neural crest delamination and migration.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Nunheimer, Lillian.
- Description:
- An estuary is a coastal area where river water meets oceanic water. A characteristic of a tidal estuary is brackish water which shows fluctuations in salinity. These fluctuations are due to the diurnal periodicity of the tide and the influx of fresh water from precipitation. The differences in water density due to salinity and temperature prevent immediate mixing of the two water types and stratification frequently occurs. The river water usually contains a high concentration of nutrients which promote larger phytoplankton populations in most estuaries than those in adjacent oceanic areas (Sverdrup et al. 19*4-2).
- Resource Type:
- Masters Thesis
- Campus Tesim:
- Fresno
- Department:
- Biology
- Creator:
- Brewer, William Allan
- Description:
- The sequential development of a marine fouling community was studied by the use of submerged glass surfaces which served as the substratum for the attachment and growth of sedentary marine organisms. Four separate stages in community development were distinguished: The primary film community , consisting of a bacterialdiatom film community; the establishment of a microenvironment, represented by species that form a three - dimensional habitat; an attachment and development period, characterized by the rapid colonization by numerous invertebrate species; and the annelid–ascidian-ectoproct community, distinguished as a stable period dominated by encrusting annelids, ascidians, and ectoprocts. The developing fouling community underwent distinct stages in succession and evolved into a stable climax community after 18 months immersion.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Sorrells, Lisa
- Description:
- The ectoderm differentiates into three derivatives, the neural tube, non-neural ectoderm and neural crest cells. Our lab studies the processes controlling the specification and differentiation of these three tissues. Neural cadherin (CDH2) is a calcium dependent cell-cell adhesion molecule required for the development of the neural ectoderm, however its role in the neuroectodermal cell cycle remains understudied. Recent data obtained using gastrula stage chick embryos shows that in vivo loss of CDH2, produced embryos with abnormal ectodermal derivative specification and increased expression of phosphorylated histone H3 (PH3), a mitotic marker. To determine whether the increase in PH3 is due to cell cycle defects or hyperproliferation of neural tube cells, we conducted novel cell imaging analysis using a macro designed to work within Fiji to obtain in-depth quantification of changes to both cells and chromatin after CDH2 perturbation. We hypothesize that alterations to cell morphology indicate CDH2 is necessary for proper cell polarity, mitotic spindle formation and cell cycle progression during ectodermal derivative specification in gastrula stage chick embryos. Recognition of the expanded role of CDH2 may have implications for other aspects of development involving CDH2 such as gastrulation, neural crest migration and the formation of the heart and gut.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Kovacheva, Ekaterina
- Description:
- One of the most spectacular examples of insular adaptive radiation can be found among the Hawaiian silverswords (Asteraceae-Madiinae). This monophyletic group was transported to the Hawaiian archipelago about five million years ago, and today comprises 32 species in three genera. Having to adapt to very varied and dynamic environments, the plants display stunning morphological and physiological diversity. However, their genotypic diversity is low, as evidenced by the ease with which species of different genera form hybrids in nature and in the lab. This discrepancy can be explained by differences in just a few key loci, which could modify entire pathways. The closest relatives of the silverswords are thought to be the tarweeds (Asteraceae-Madiinae) on the west coast ofNorth America. Two tarweed ancestors hybridized to form the allotetraploid ancestor of all known silverswords, which was then transported to the Hawaiian islands, most likely by a bird. The pathway I am concemed with is the anthocyanin-producing pathway, in particular anthocyanidin synthase (ANS), a late gene in the pathway. Anthocyanins are pigments responsible for blue, red and purple color in flowers. However, due to their many other functions, such as light attenuation in chloroplasts, I expect the genes of this pathway, including ANS, to be intact in most silverswords, even though only one species has red flowers. I also expect to find two copies in silverswords due to tetraploidy. Degenerate primers were designed in conserved regions of ANS and PCR was done to obtain the gene from two tarweeds (Madia elegans, Madia gracilis) and two silverswords (Dubautia linearis, Wilkesia gymnoxiphium). Gene sequences were spliced and edited with BioEdit, and were aligned with ClustalW 1.8. A maximum likelihood tree was made with MEGA 5, and a bayesian tree was made with MrBayes 3 .1.2. A Z-test of selection and a Ka/Ks test were done using MEGA 5. A RACE reaction wasperfonned on mRNA from the flowers of M elegans. The entire gene (except 20bp of primers in the flanking regions) of two exons and one intron was sequenced from all species studied. The RACE in M elegans produced the entire gene, and showed there was some expression in the floral tissues of this plant. As expected, two copies were found in the silverswords and only one in each of the tarweeds. No premature stop codons were found within coding sequences. Phylogenetic analysis groups the Madiinae separately from other Asteraceae, and the tarweeds separately from the silverswords. Within the siverswords, copy 1 from both species is separate from copy 2 from both species. Interestingly, intron size seems to be conserved within the tarweeds and copy 2 (547bp), and also within copy 1 (485bp). Purifying selection was detected in the silversword copies, while no positive selection was found in any copy. The positions of all copies studied and their relative position to other Asteraceae support the allopolyploid origin of the silverswords. Each copy in the silverswords most likely came from each of the two mainland ancestors. Given the overall similarity of the sequences within all Madiinae, it is reasonable to conclude that the gene starts and ends in the same position in all Madiinae. The lack of premature stop codons indicates that the gene may be at the very least functional, although we have no knowledge of its level of expression within the floral or other tissues. The flower color of all plants in this study is yellow, indicating no accumulation of anthocyanins, although they may be found in other tissues. The lab is cunently investigating the sequences of other genes in the pathway, and future studies will focus on sequencing the promoter region and known regulators of ANS expression. This will give us a more complete picture of the evolution of the pathway, helping us understand the genetic mechanisms behind adaptive radiations.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Jarvis, George
- Description:
- How an organism responds to predation risk can greatly affect its reproductive success. When threatened by predators, prey often change their foraging and mating behavior, presumably to maximize current and future fitness. These responses have been studied in numerous terrestrial and aquatic taxa, yet how risk affects reproductive output in marine fishes is poorly understood. To determine whether risk directly affects fitness in nature, I tested the effects of predation risk on reproductive output and behavior of the bluebanded goby, Lythrypnus dalli. During three experiments, similar populations of gobies were established on artificial reefs and predator exclusion cages were used to manipulate perceived and actual risk of predation. Reefs were assigned one of three caging treatments to alter the level of risk that gobies likely perceived from predators: large exclusion (low risk); small exclusion (no actual risk, but perceived risk); and no exclusion (actual and perceived risk). Reproductive output and behaviors of gobies were compared among risk treatments, and all gobies that remained on the reefs at the end of each experiment were recollected to assess any effects of risk and predation on survival of L. dalli. Remote video revealed that the treatments manipulated the presence and proximity of predators as intended. Gobies altered their behavior in the presence of predators, but despite this, reproductive output was similar among all risk treatments. Similar numbers of gobies were present in all treatments, but they were observed less frequently in high-risk treatments because they spent more of their time hidden within the reef. These results indicate that sublethal effects of predators did not reduce fitness of L. dalli over periods of 1-4 weeks. Based on their relatively short lifespan and duration of lifetime spawning, L. dalli may be less affected by the sublethal effects of predators than other fishes, at least in terms of reproductive output.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Valentino, Lauren Michele
- Description:
- Coral reefs are among the most diverse ecosystems on the planet and have been compared to rainforests because of their complexity and high species diversity. Tropical reefs have relatively nutrient-poor waters, but they are one of the most productive ecosystems providing benefits and ecosystem services to society in the form of coastal protection, food, and economic resources such as tourism. Rising carbon dioxide emissions by humans will have serious environmental implications for the ocean environment. Coral reef ecosystems are particularly vulnerable to this unprecedented increase of CO2 due to their carbon chemistry and thermal sensitivity. Anthropogenic CO2 is predicted to decrease ocean surface pH by 0.14-0.35 units by 2100 causing ocean acidification (OA). Most studies have focused on how OA will affect rates of calcification of coral reef organisms. However, bioerosion also could be sensitive to rapid changes in ocean carbonate chemistry. I tested the effects of decreased pH on the distribution of bioeroders in the field and on the boring capacity of the mollusk Lithophaga laevigata living within corals, massive Porites spp. (a complex of three species: P. lobata, P. australiensis, and P. lutea) in the lab. Field studies showed higher external bioeroder abundance on coral bommies, and higher internal bioerosion in coral rubble, however, there was no differences in bioerosion between variable pH environments found at upstream and downstream transects. L. laevigata, a boring bivalve, is abundant within massive Porites sp. on the back reef of Moorea, French Polynesia. L. laevigata abundance in massive Porites across the back reef ranged from 3 to 95 ind/m2. Size analysis of L. laevigata showed a significant correlation of the borehole opening and the size of the bivalve, which allowed for a non-destructive method for collection of uniformly sized bivalves as a way to standardize bioerosion rates for analyses. I conducted a month-long mesocosm experiment where massive Porites cores with and without L. laevigata, were incubated in ambient (400 μatm) and elevated (850 μatm) pCO2 treatments held at a constant temperature. Net calcification rates of Porites cores significantly decreased in the elevated treatment. Presence of L. laevigata decreased net calcification rates of Porites regardless of CO2 treatment. I also compared the bioerosion rate of L. laevigata in coral cores (based on changes in buoyant weight) and tested the hypothesis that OA increases the ability of bivalves to bioerode in elevated pCO2 conditions. For this experiment, there was no significant effect of OA on bioerosion rates of L. laevigata. However, respiration rates of L. laevigata increased under elevated pCO2 conditions. These results provide a better understanding of this abundant and active bioeroder under simulated future environmental conditions and give insight to the poorly understood effects of OA on bioerosion.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Liang, Stanley Den-kuang
- Description:
- One approach to the study of cell adhesion is isolation of factors that promote cellular re-aggregation. This laboratory has isolated factors that promote re-aggregation of Stronglocentrotus purpuratus blastula cells. The factors are released from the cells as they disaggregate from each other in calcium-magnesium-free sea water. The supernatant obtained from the disaggregation process is termed DS (dissociation supernatant). A subset of molecules that promotes aggregation of fixed S. purpuratus blastula cells has been isolated from DS by adsorption with fixed S. purpuratus blastula cells. This subset of molecules is termed s-2 In this study polyclonal antibodies were produced against S-2, (A-S-2). Using a ring test, the affinity of A-S-2 was confirmed. An indirect immunofluorescence technique was developed to localize S-2 in blastula-stage embryo with the A-S-2. The staining pattern obtained was a patchy one and almost all cells took up stain. Sodium dodecyl sulphate (SDS) polyacrylamide gel electrophoresis revealed at least 17 molecular species in DS. In a native gel, only 4-8 bands were detected. western blotting of DS with A-S-2 revealed only 8 bands. One band, 144,000 in molecular weight, appears to correspond to the monomer described by Noll et al. (21). Possible dimer and trimer forms were discovered accidentally by not boiling the sample (DS) for sufficient amount of time in the presence of SDS before running the sample in SDS gel electrophoresis. A theoretical framework based on two chemical equilibrium formulas is presented to demonstrate that the 22S adheron of the Noll group (21) may also be present in DS. This study represents a first attempt to investigate the molecular species contained in DS and its subset (S-2). It also provides an initial examination of the localization of some of these molecules in the embryo. Further work will help elucidate the nature of the molecules in DS.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Partridge, Thurlow Melvin, Jr.
- Description:
- Foraminiferal concentration above the Santa Catalina Basin was low at the surface and increased with depth to a maximum concentration at 25 to 75 m. The concentration decreased below 75 m to a minimum at 120 m and remained low at greater depth. The concentrations and species present changed with the seasons. Highest Concentrations were present in January, 1963, and February, 1964, with the lowest numbers present in August, 1963, and October 1963. The peak in numbers of cold water species occurred in, January, l963, while that for warm-water species occurred in August, 1963. (See more in text.)
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology