No description available.

Genomic data has led to the realization that nearly one third of the bacterial genes discovered have unknown functions. Promising drug targets are no doubt among the conserved and essential genes, but drug development awaits an understanding of the basic physiological roles of the cryptic bacterial proteins they encode. The pressing need for novel antibiotics mandates investigation of these essential bacterial genes of unknown function. For a subset of such genes, it is becoming increasingly apparent that they may play critical roles in ribosome assembly or function in bacteria. One such essential gene, encoding the putative GTPase YihA in Escherichia coli has been highlighted as a target of particular importance for study (Galperin M.Y. and E.V. Koonin. (2004). 'Conserved hypothetical' proteins: prioritization of targets for experimental study. Nucleic Acids Res 32(18): 5452-63.). To study yihA's function, a strain with yihA under P_BAD control was generated and used to examine the impact of the loss of the gene product on ribosome assembly. Depletion of the YihA protein was found to cause accumulation of 30S and 50S subunits at the expense of 70S ribosomes, and the formation of long filamentous cells apparently incapable of dividing. Chemical genetic interactions were identified through chemical synthetic lethality screening with antibiotics which target the ribosomal A -site, and antibiotics which affect the bacterial cell wall. Finally, investigation of the importance of several patches of basic residues of YihA through mutagenesis and in vivo complementation shows the protein to be tolerant of mutation to non-catalytic residues. The inability of mutants with changes to amino acids important for nucleotide binding to complement represents the strongest evidence to date that the YihA protein relies on GTP binding and hydrolysis as part of its essential function in vivo. The findings of this study support a role for YihA in the poorly understood process of ribosome assembly in vivo, and represent important progress towards realization of this essential process as a source of novel antibiotic targets. / Thesis / Master of Science (MS)

No description available.

No description available.

published_or_final_version / Biochemistry / Doctoral / Doctor of Philosophy

published_or_final_version / Zoology / Master / Master of Philosophy

Levels of bacteria in excess of water quality standards for contact recreational designated use have been documented in Gilleland Creek, located in northeast Travis County, Texas. Stormwater monitoring showed increased bacteria levels after rainfall runoff events in Gilleland Creek, and analysis indicates the bacteria is of a nonpoint source origin. The objective of this research was to modify a flood control basin in an urban area in the upper part of the Gilleland Creek watershed to determine whether it is possible to substantially increase bacteria removal by retaining stormwater in the basin for 24 hours after a storm event. Bacteria reduction was predicted as a result of sedimentation and exposure to sunlight. The outlet of one flood control basin was retrofitted with an automated gate valve to control stormwater outflow and acted as the test basin. Another flood control basin, located approximately ¼ mile from the test basin, was unmodified and acted as the control basin. Stormwater monitoring at the inlet and outlet to both basins over the course of five storm events showed that neither the control nor the test basin exhibited a decrease in E. coli concentrations. Both basins were effective in decreasing the concentration of total suspended solids and showed varying performance for the treatment of nutrients. The dataset is limited by the small number of storm events that were sampled, and continued stormwater monitoring would offer additional insight into retrofit performance. / text

abstract / Biological Sciences / Doctoral / Doctor of Philosophy

No description available.

No description available.