Glycogen Synthase Kinase-3αß is an enzyme that is involved in cell cycle regulation by promoting the degradation of cyclin D1 and cycling D3 in cells. Special emphasis is placed in its regulatory role in B cells, as there it is evidence that suggests that this protein is inhibited during germinal center formation, where B cells undergo proliferation, somatic hypermutation and class switch recombination. By inducing DNA recombination via the Cre/lLxP recombination system and utilizing tamoxifen as a Cre activity inducer, B cells were culture in 40LB cells to form induced germinal center in vitro. Flow cytometry analysis suggests that in the absence of GSK-3 αß B cells proliferate extensively in germinal centers and being the process of class switch recombination. Although the results of this study are in accord with current theory, more experiments and research need to be made to validate the conclusions set forth in this study.

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Most studies of insect Malpighian tubules (MTs) have examined transport of monovalent ions (K^+, Na^+, Cl^-). Isolated Drosophila melanogaster MTs also transport Ca^2+ from bath to lumen and transport is stimulated by cAMP. The lower segment of the MTs transports Ca^2+ at a higher rate per unit length than does the main segment known to produce the primary urine. This study examines both whole animal calcium regulation in larvae, pupae and adults and the mechanisms of Ca^2+ transport by isolated MTs. Drosophila melanogaster appears to regulate its calcium content and haemolymph calcium level. Calcium content of the whole fly only increased 10% with a 6.2-fold increase in dietary calcium. Anterior MTs can contain as much as 50% of the whole animal calcium content. The difference in MTs accumulation is due primarily to the enlarged initial segment of the anterior MTs. This segment, absent from the posterior MT, contains calcium-containing concretions. Whole fly calcium content does not increase continuously with the age implying that calcium is eventually being excreted. Haemolymph calcium concentrations do not change in response to changes in dietary calcium, suggesting that calcium concentration is regulated either by the rate of absorption or by the rate of excretion. The midgut and the enlarged initial segment of the anterior MTs may play important roles in haemolymph calcium regulation. Isolated MTs show sensitivity to both Ca^2+ channel blockers and Ca^2+ -ATPAse inhibitors on the basolateral and apical membranes respectively. Voltage-gated calcium channels appear to mediate calcium movement from bath to cell. A ruthenium red sensitive Ca^2+ -ATPAse may be used to transport calcium against the electrochemical gradient from cell to lumen. Lastly, the dissolution of luminal concretions plays a large role in net calcium secretion. / Thesis / Master of Science (MSc)

Multiple antibiotic resistant bacteria continue to be a threat to the health of the world's population. Glycopeptide antibiotics are one type of drug that are used to treat these serious pathogens. Increased usage over the years has led to the emergence of bacteria which are resistant to these glycopeptide antibiotics and now the need for altered antibiotics with an increased effectiveness has arisen. 𝘚𝘵𝘳𝘦𝘱𝘵𝘰𝘮𝘺𝘤𝘦𝘴 𝘵𝘰𝘺𝘰𝘤𝘢𝘦𝘯𝘴𝘪𝘴 NRRL 15009 produces the glycopeptide antibiotic A47934. Here, the biosynthetic gene cluster for A47934 was sequenced in its entirety. All enzymes encoded by assigned open reading frames were analyzed and functions assigned where possible. The resulting biosynthesis cluster encodes all the enzymes necessary to produce A47934, as well as confer resistance and regulate the resistance response. In addition to sequencing the biosynthetic gene cluster, enzymatic studies were attempted on the two-component regulatory system (VanR and VanS) which confers resistance to A47934. Finally, inactivation of 𝘴𝘵𝘢𝘓 was attempted. Overall, the results presented here should help us to further understand how these chemically complex glycopeptide antibiotics are made and lend further insight into how we can attempt to produce new semi-synthetic versions. / Thesis / Master of Science (MSc)

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Many consumers seem to be uncomfortable or unwilling in making online transactions. This lack of trust stems in part from the online exchange process itself where consumers are deprived of many traditional cues that they would use to evaluate this process. This research focuses on consumer perceptions of regulatory governance in online exchanges and how signals of governance might act to increase consumer trust in online transac-tions. An experimental methodology was used to examine the effects of different types of structures on consumer perceptions and to provide direction for public policy makers as well as online businesses and private regulatory entities. / Ph. D.

Self-handicapping has been conceptualized as an identity-based strategy motivated by impression management and, more recently, as an avoidance coping strategy. However, additional evidence suggests that self-handicapping can provide a short-term performance boost (with detriments accruing over the long-term). I use a resource conservation perspective to suggest that this boost in performance may be attributed to an individual's motivation to conserve resources, particularly when there is reason to believe that resources spent now may be better used later. The current study tests if handicapping situations (similar to ones created following the choice to self-handicap) encourage an individual to conserve their resources (e.g., reducing effort), allowing them to spend those resources on later tasks. It was hypothesized that individuals in a handicapping situation would show greater resource conservation (evidenced by decreased effort) as well as improved performance on a follow-up resource-dependent task, compared to those not in a handicapping situation. Additionally, I hypothesize that individuals in a handicapping situation will show greater conservation and greater subsequent performance on a resource-dependent task when there is anticipation for that follow-up task. Effort was also hypothesized to mediate the relationship between group assignment and subsequent performance differences. Finally, it was hypothesized that these relationships would be moderated by neuroticism, conscientiousness, and self-handicapping tendencies (traditional moderators of SH). Prior to an in-lab study, participants (N = 162 undergraduates) completed on-line measures of self-handicapping (SHS), neuroticism, and conscientiousness. Participants were then brought to the lab individually for a study supposedly testing the effects of sound on performance. They were randomly assigned to one of three groups differing in the information given regarding: (1) the level of distraction a stimulus would produce and (2) whether a follow-up task was anticipated after the noise-based task (i.e., Distraction-Anticipation, Distraction-No Anticipation, No Effect-Anticipation). All participants were first given a series of geometric tracing designs allegedly assessing their spatial reasoning ability (series contained 4 solvable designs and 2 impossible designs) and were provided with noncontingent success feedback. Then, participants were asked to complete a new series of tracing designs (eight solvable, one impossible) while a tone was playing. Participants in the distraction conditions (i.e, Distraction-Anticipation and Distraction-No Anticipation) were led to believe that the tone had the ability to significantly impair performance, while participants in the No Effect condition believed the tone had no impact on performance. Following this task, all participants were given a series of logic questions that served as an assessment of regulatory depletion. Results supported the two primary hypotheses. When participants believed that the tone was distracting, and when they anticipated a third task, they were more accurate on the part three logic task (F(2,159) = 7.69, p<.01) compared to both those in the No Effect-Anticipation and the Distraction-No Anticipation conditions. The relationship between group assignment and part three logic performance was mediated by effort during part two (quitting r2 = .14; F(2, 105) = 8.43, p<.001; indirect effect b = -.05, SE = .03, 95% CI [-.12, -.01]). No theoretically meaningful moderators were found. The findings provide initial evidence for resource conservation as a new and unique motivation for self-handicapping. Implications for future research are discussed. / Ph. D.