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- Creator:
- Percolla, Marta I.
- Resource Type:
- Thesis
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- Yanez, Ivette
- Resource Type:
- Thesis
- Identifier:
- 10047
- Campus Tesim:
- Bakersfield
- Department:
- Biology
- Creator:
- DeBevoise, Devon
- Description:
- Fouquieria splendens (ocotillo) is a large, basally branching, shallow-rooted, drought deciduous shrub native to the Chihuahuan and Sonoran Deserts. Ocotillos, like all Fouquieriaceae, have gelatinous fibers (g-fibers), which typically occur in tension wood (TW) of eudicotyledons and can reorient stems and roots. The goal of the research was to determine whether the presence of g-fibers in TW in branches was a response to mechanical stress and whether g-fibers in roots functioned in pulling ocotillos towards the soil. It was hypothesized that TW in the branches aided in resisting gravitational stresses and bending from high winds and that TW in the roots would pull the shoots downward to prevent them from falling over, or provide tension to prevent uprooting. To address the hypotheses, the anatomy of shoots that were displaced or fixed in place was compared to those in their native state in the field. To study the g-fiber function in roots, young ocotillos were planted at different depths and with their caudices (stem/root axis) at different angles from vertical. Shoots had far greater TW coverage in cross-section in sides of the branches experiencing tension than in sides experiencing compression for all treatments. There was also greater TW coverage in the basal regions of branches than in more distal regions, suggesting that they were resisting bending due to static loads as well as possibly dynamic loads (wind). Coverage of TW in taproots differed between sides experiencing tension and compression for plants with half-exposed caudices planted 45 from normal. Further, there was no evidence of contraction in ocotillo roots. However, because g-fibers occurred in lateral roots, all roots may function in resisting tensile stresses. In addition to g-fibers, several other fiber types occurred in ocotillos, indicating an unusual amount of fiber diversity.
- Resource Type:
- Thesis
- Campus Tesim:
- Pomona
- Department:
- Biology
- Creator:
- Marentes, Adam
- Description:
- ∆9-tetrahydrocannabinol (THC), marijuana’s principal psychoactive component, is known to suppress resistance to bacterial, viral and protozoan infections. However, the effect of THC on resistance to fungal infections is unclear. Recently, we found that chronic THC treatment decreased resistance to the yeast Candida albicans (C. albicans) in immune competent mice. However, nothing is known about how THC affects resistance to a fungal infection in an immunocompromised mouse. Our objective was to assess how chronic THC affects an immunocompromised mouse’s ability to ward off systemic candidiasis in an acute and secondary model of infection. 5-fluorouracil (5-F) is a commonly prescribed anti-cancer drug and is also a potent immunosuppressor, increasing susceptibility to C. albicans infection. We found that 5-F treatment severely decreased survival, white blood cell count, splenic IL-12p40 production and increased kidney fungal load. To investigate the effect of THC on resistance to C. albicans in immunosuppressed mice, c57BL/6 female mice were treated via an intraperitoneal (IP) injection with vehicle (ethanol, cremophor, saline (1:1:18)) or THC in vehicle (16mg/kg) 4 days a week, for three weeks (experimental days 1-18). For the secondary infection model, on day 2, the mice received a priming dose (0.75x105 cells) of C. albicans. On day 16, mice received an intravenous (IV) injection of 5-F (0.1ml of 50mg/ml). On day 19, mice were infected with an IV injection of 5x105 C. albicans cells. For the acute infection model, the mice only received an IV injection of C. albicans on day 19 without a priming dose. On day 22, tissues were harvested from some mice to assess tissue fungal load. In addition, splenocytes were cultured and treated with either Concanavalin A (Con A, 5µg/ml) or heat killed (HK) C. albicans (6.25x106 yeast cells/ml) to assess cytokine production responses. Remaining mice were observed for up to 2 weeks for survival and morbidity. We found that in both infection models, mice treated with 5-F and THC succumbed a day earlier to the yeast infection compared to 5-F and vehicle treated mice. In both infection models, 5-F decreased Con A stimulated splenocyte INF-γ secretion from vehicle and THC groups, with no significant difference between the groups. However, the decrease by 5-F was much more pronounced in the acute infection model compared to the secondary infection model. In both infection models, C. albicans-stimulated IFN-γ levels were significantly lower in the THC group compared to the vehicle group. These results strongly suggest that THC has an effect on splenic immune response, and they also suggest that although THC does make the 5-F treated mice slightly more susceptible to the infection, it is not significant enough to conclude that chronic THC treatment is detrimental to immunocompromised mice.
- Resource Type:
- Thesis
- Campus Tesim:
- Pomona
- Department:
- Biology
- Creator:
- Jacobson, Lianne M.
- Description:
- The fitness of an organism depends on its energetics, which includes both the amount of energy entering the individual and the distribution of energy within the individual. The present thesis examined the energetics of a scleractinian coral during and immediately following resource limitation. The first study (Study 1) questioned how long energy reserves could support normal metabolic activity, and whether corals are capable of a downwardly shifting respiration rates (i.e. metabolic depression) to preserve energy reserves during resource limitation. Study 1 provided the first empirical evidence from a single study necessary to parameterize a Dynamic Energy Budget model of a symbiotic coral. A second study (Study 2) investigated if coral recovery from resource limitation is dependent on the source of energy (autotrophic or heterotrophic) or the temperature of the seawater. Study 1 indicates that corals are able to adjust respiration rates, biomass catabolism, and calcification during resource limitation. Study 2 provided no evidence that recovery of biomass is dependent on the source of energy or temperature, however the availability of autotrophic resources enhanced the recovery of calcification and respiration. Both studies investigate how and when a coral adjusts its energetic expenditure and investment, providing insight into how and when a coral is able to perceive a change in its environment.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Liang, Jing
- Description:
- Gastrulation is a fundamental process that mediates formation of ectoderm, mesoderm and endoderm in most animals. Revealing the mechanism of gastrulation will provide a better understanding of embryonic development. Due to its transparency, simplicity of the structure and similarities to complex organisms, the NIH-designated sea urchin embryo model was used in this study. By treating sea urchin embryos with characterized α-L-rhamnosidase and observation of archenteron development, I investigated the role of L-rhamnose terminal in the mechanism of sea urchin gastrulation. I showed that the α-L-rhamnosidase treatments used did not contain any detectable contamination and using quantitative protein assay I demonstrated that this enzyme inhibited archenteron development during gastrulation. Denatured and sugar-inhibited α-L-rhamnosidase lost most of its inhibitory activity. The results combined with a previous study using L-rhamnose, provide convincing evidence, I believe for the first time, for a role of L-rhamnose in the gastrulation process.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Dimashkie, Anupama Reddy Sadhu
- Description:
- The differentiated state of somatic cells can be reprogrammed to induced pluripotent stem cells (iPSCs), leading to the reactivation of the inactive X chromosome (Xi) of female differentiated cells in the mouse. In somatic cells, the Xi is very stable however, when reprogramming mouse embryonic fibroblasts, the Xi reactivates upon completion to a pluripotent state. How somatic character is reversed as well as the sequence of epigenetic events leading to X chromosome reactivation during reprogramming to iPSCs, is not well understood. We found that, the non-coding RNA Xist and DNA methylation are present on the Xi in clonal late reprogramming intermediates, pre-iPSCs, suggesting that these are reversed late during reprogramming. To test whether these function in maintaining Xi repression at this stage of reprogramming we functionally interfered with Xist and DNA methylation using pre-iPSCs genetically deleted for Xist and/or treated with siDNMT1 (DNA methyltransferase 1) and DNA methyltransferase inhibitor 5AzadC (5-aza-2'-deoxycytidine). Reactivation of the X chromosome occurs upon deletion of Xist and both treatments. We used bisulfite sequencing to confirm the loss of DNA methylation of X-linked genes in pre-iPSC and found the loss of DNA methylation on the Xi occurs in the presence or absence of Xist with both 5AzadC and siDNMT1. This suggests DNA demethylation is a late event in Xi reactivation and occurs very late in reprogramming. To further test this, we purified the SSEA1+ population directly from a reprogramming culture that represents a state where the pluripotency marker Nanog is already active but the Xi is not yet reactivated. We show from these intermediates that the promoter region of Nanog is demethylated. However, promoter regions of Xi-linked genes from these intermediates are still completely methylated. Together, our results identify new late stages of reprogramming to iPSCs.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Pathak, Chintan
- Description:
- Microarray data can be used to derive an understanding of the relationships between the genes involved in various biological systems of an organism, given the availability of web applications and databases of gene expression measurements from the complete spectrum of experimental conditions and materials (Lee et al., 2009). However, there have been no reports, to date, of a web application that can perform comprehensive gene expression correlation analysis. Here, I describe an integrated approach to analyzing gene expression correlation and molecular pathway associated with them. This will also address some commonly asked questions in querying and analyzing gene expression data to facilitate target ID / validation activities. Also, in the future this will help project teams to explore gene expression data for relevant pathways. Furthermore, this approach assists in elucidating relationships between genes and genetic disorders. Until now, researchers used methods that required more effort to gather results and deduce relationships among genes (Janes et al., 2008). I built a web application called Gene-AP to address this problem. Gene-AP can use a "query" gene, along with parameters set by the investigator, from pre- developed microarray gene expression correlation data. The parameters to be considered may include a correlation score and data limit. Gene-AP can also perform statistical analyses of biological relationships between query genes and theoretically connected pathways using functional enrichment analysis using Cytoscape which is integrated in this web application. This utility has been tested on a particular set of data using ESR1 (estrogen receptor gene as the query gene). I found various pathways such as intracellular trafficking and ion binding to be associated with the ESR1 gene products. These results are similar to those found in earlier wet-lab experiments. I intend to improve upon this strategy which will facilitate better interpretation of gene expression correlation data and allow exploration of additional developmental pathways.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Kuppers, Rudolf
- Description:
- Sarcoma 180, a mouse ascites tumor, was examined ultrastructurally using transmission electron microscopy. Its general fine structure, and the cell surface interactions occurring as a result of agglutination were examined. Three types of agglutinins were used, Concanavalin A (Con A), an ascites "factor", and manganese ion. Ultrastructurally, Sarcoma 180 had the features of many tumors: A large heterochromatic, multilobate nucleus with numerous nucleoli, reduced amounts of endoplasmic reticulum, and numerous microvilli on the cell surface. The mitochondria were somewhat pleomorphic. Large lipid droplets were seen in addition to several other large, darkly stained bodies in the cytoplasm. Cell surface interactions between untreated cells were not commonly seen. Three surface interactions were seen after agglutination: 1) Microvillous associations characterized by the interaction of villi with adjacent cell surfaces; 2) intermediate associations in which adjacent cell membranes were approximately parallel, crosslinked by patches of lightly stained material, and separated by greater than 100A; and 3) close association in which the cells were separated by less than l00A, commonly 20A, and resembled gap junctions. All three types of associations were seen after Con A agglutination. The intermediate association may represent actual crosslinking by Con A aggregates. The close associations, it was argued, resulted from interactions between cell surface components. Microvillous associations were most commonly seen, though their significance was not clear. The ascites "factor" at high concentration induced pinocytosis and vacuolization. Agglutination resulted from large aggregates of flocculent material crosslinking the cells. At lower concentration, intermediate associations were seen, small aggregates of "factor" possibly crosslinked the cells together. Manganese ion produced a very rapid agglutination mediated totally by villous interactions. Points of interaction were very tight, with no obvious gap between membranes. It was thought that ionic bridging, or denaturation of surface components was involved.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology
- Creator:
- Hoover, Malachia
- Description:
- Stem cells are necessary for proper development, tissue homeostasis and regeneration while dysregulation of their activity leads to diseases such as diabetes, neurodegeneration and cancer. Yet, the molecular and cellular mechanisms that drive stem cell mediated regeneration remain to be fully elucidated. We hypothesized that the stem cell marker, Cripto (or TDGF1), is a regulator of tissue regeneration. Using the zebrafish model of caudal fin wound healing, we show that expression of the zebrafish Cripto homolog, one-eyed pinhead (or oep), is increased at 96 hours post amputation within a previously established window of stem cell enrichment in this model. We further demonstrate that Cripto is necessary and sufficient for stem cell mediated regeneration in this in vivo model as well as in an in vitro wound healing assay. We identified non-muscle myosin II's (MYH9/10) as novel Cripto binding proteins using co-immunoprecipitation (Co-IP) and mass spectrometry and confirmed the interaction between these proteins via Co-IP/Western blot from mammary epithelial cells and endogenous immunofluorescence co-localization in mesenchymal stem cells, a key cell type that contributes to wound healing in zebrafish and mammals. Notably, the effects of Cripto and MYH9/10 inhibitors on regeneration of wounded zebrafish caudal fins were not additive suggesting Cripto and MYH9/10 have overlapping functions and mechanisms of action. Cripto and its homologs are cell-surface GPI-anchored glycoproteins that can be released via GPI anchor cleavage by phospholipases. We previously demonstrated that tissue-specific stem cell functions of Cripto depend upon its soluble secreted form and this led us to test whether MYH9/10 function may be required for transporting Cripto to the cell surface or mediating release of soluble Cripto from the cell surface. Indeed, we find that cell-surface localization of Cripto in and its release as a soluble factor from mammalian cells requires MYH9/10 function. Using Bio-Grid proteomics, we discovered Rab11A, an endosomal and exosomal marker, to be a co-binder of GRP78 and Myosin IIs. We then pharmacologically inhibited Myosin IIs using Blebbistatin or Rho Kinase (ROCK) inhibitors in mesenchymal stem cells transfected with wild-type, constitutively active, and dominant negative Rab11A constructs. Our results show that the expression of Rab11A regulates Cripto and Myosin II binding interactions, suggesting a possible role for Rab11A in the endosomal and exosomal trafficking of Cripto. Based on our findings, we propose a new model whereby MYH9/10/Rab11A-mediated Cripto transport enables cells to generate a pool of extracellular Cripto that can subsequently function in autocrine and/or paracrine pathways to promote stem cell mediated regeneration and wound healing.
- Resource Type:
- Thesis
- Campus Tesim:
- Northridge
- Department:
- Biology