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Characterization of Moraxella bovis Aspartate Transcarbamoylase

Description: Aspartate transcarbamoylase (ATCase) catalyzes the first committed step in the pyrimidine biosynthetic pathway. Bacterial ATCases have been divided into three classes, class A, B, and C, based on their molecular weight, holoenzyme architecture, and enzyme kinetics. Moraxella bovis is a fastidious organism, the etiologic agent of infectious bovine keratoconjunctivitis (IBK). The M. bovis ATCase was purified and characterized for the first time. It is a class A enzyme with a molecular mass of 480 to 520 kDa. It has a pH optimum of 9.5 and is stable at high temperatures. The ATCase holoenzyme is inhibited by CTP > ATP > UTP. The Km for aspartate is 1.8 mM and the Vmax 1.04 ┬Ámol per min, where the Km for carbamoylphosphate is 1.05 mM and the Vmax 1.74 ┬Ámol per min.
Date: December 2001
Creator: Hooshdaran, Sahar

Comparative Mitochondrial DNA Sequence Diversity in Isolated and Open Populations of Southern Flying Squirrels

Description: Three populations of Southern flying squirrels were studied in the Ouachita Mountains of Arkansas to assess the impact of population subdivision-due to island formation--on the population genetics of Glaucomys volans. One island, one mainland, and one open population were investigated. A 367 nucleotide hypervariable region of mitochondrial DNA was sequenced in individuals from each population. Individuals and populations were compared to assess relatedness. Higher sequence diversity was detected in the open and island populations. One island individual shared characters with both the island and mainland populations. Results support the hypothesis that the mainland population may have reduced gene flow. Also, the island population may have been originally founded by at least two maternal lineages.
Date: August 1999
Creator: Cook, Melaney Birdsong

Novel Role of Trypsin in Zebrafish

Description: It has been shown previously in our laboratory that zebrafish produce trypsin from their gills when they are under stress, and this trypsin is involved in thrombocyte activation via PAR2 during gill bleeding. In this study, I investigated another role of the trypsin that is secreted from zebrafish. This investigation has demonstrated a novel role of trypsin in zebrafish. Not only did this investigation demonstrate the role of trypsin in zebrafish behavior, but also it showed that PAR2 might be the receptor that is involved in trypsin-mediated behavioral response. In addition, we have shown that Gq and ERK inhibitors are able to block the trypsin pathway and prevent the escaping behavior. Finally, the results of this investigation suggest that the cells that respond to trypsin are surface cells, which have an appearance similar to that of neuromast cells.
Date: May 2013
Creator: Alsrhani, Abdullah Falleh