Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 90-97).

Thesis (M.Sc.)--York University, 2005. Graduate Programme in Biology. / Typescript. Includes bibliographical references. Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url%5Fver=Z39.88-2004&res%5Fdat=xri:pqdiss &rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR11935

Electrophoretic techniques were utilized for the demonstration of variation in 22 proteins from 24 natural populations of four species ( G. bursarius, G. pinetis, G. arenarius and G. personatus ) of the Geomys complex of pocket gophers. Of the 24 structural loci , 19 were considered to be polymorphic. Five of the six esterases contributed greatested to the polymorphism while non-esterase proteins generally showed low values. In the GeoMys complex of pocket gophers in this study,selection appeared to be the most important influence on genetic structure with some evidence of random drift in two of the four species. Populations of G. arenarius and G. personatus had the highest average interspecific genetic similarities to G. bursarius and . pinetis was the most divergent. Biochemical evidence supports the phylogeny of Geomys based on morphological and fossil data.

Small molecules have played an important role in defining the functions and identities of numerous proteins involved in fundamental biological processes as well as pathways involved in disease. Chemical genetics represents the formalization of this process into a defined field desiring to achieve the breadth and specificity of classical genetics. In order to gain full advantage of a small molecule's ability to perturb the cell for novel or desired phenotypes, a complete understanding of the molecule's mechanism of action must be achieved. Identification of the biological targets of a molecule represents the most direct approach to attaining this knowledge. In our strategy to find novel mechanisms to target cancers with oncogenic RAS mutations, we have used small molecules to probe specific weaknesses of this cancerous network through synthetic lethal screening. One molecule identified in these screens, RSL3, attracted interest as a candidate for target identification studies because of its potent lethality and potentially unique mechanism of action. We used an affinity chromatography approach to directly isolate binding partners of RSL3 by modifying the molecules structure to incorporate various affinity tags. Through these experiments we ultimately identified a number of interesting candidate targets. Investigations validating these targets suggest that multi-targeted modulation of antioxidant and prostaglandin networks may be a mechanism for selectively killing cancers with oncogenic RAS. The identification of biological targets of small molecules poses a difficult challenge to the field of forward chemical genetics. Thus, we attempted to optimize a unique method for target identification, the yeast three-hybrid system (Y3H), which detects small molecule-protein interactions through a transcriptional assay in vivo. We created a version of our Y3H system that incorporated a covalent anchor and compared it with the existing state-of-the-art, which uses a high affinity non-covalent anchor. Transcriptional assays indicated our new system was functional, but surprisingly could not improve upon the original Y3H system. These results highlight the complexities of manipulating ligand-receptor interactions in vivo.

Insects have evolved various physiological responses to cope with stressors such as pathogens, toxins and environmental factors. It is known that the responses resulting from infection or DNA damage share some of the same pathways. Exposure of Drosophila melanogaster and the dung beetle Euoniticellus intermedius to stress led to changes in the expression of proteins involved in metabolism, development, protein degradation, mRNA processing and stress responses. Stress responses in D. melanogaster are well characterised. However, the role played by Drosophila p53 (Dmp53) and a member of the retinoblastoma binding protein 6 (RBBP6) family, Snama, are unknown. Snama has been proposed to play a role in Dmp53 regulation. Following DNA damage we investigated the role of Dmp53 and Snama. Flies recovering from camptothecin treatment display a glycolytic flux, involving a metabolic shift, different to that observed in cancer cells. Camptothecin treatment leads to an increase in the mortality of both sexes. Furthermore, females show a specific decrease in fecundity which is due to an increase in Dmp53 dependent apoptosis in the ovaries and is accompanied by a depletion of Snama and an increase in Dmp53 transcripts. Expression data indicated that Dmp53 activity may be largely regulated at the protein level. Bypassing glycolysis through methyl pyruvate supplementation led to differential expression of Dmp53 and Snama and improved reproduction and embryonic development. These results highlight differences between the metabolic strategies used by cancerous and non-cancerous cells which may be exploited in future chemotherapies. While immune responses amongst insect orders are evolutionarily conserved, many remain uncharacterised. To investigate the immune system of an organism that lives in a microbe rich environment, E. intermedius was infected with the fungal pathogen Beauveria bassiana. This resulted in decreased lifespan and fecundity. Homologs of proteins involved in the immune response of insects were identified in E. intermedius, including a member of the Toll family of proteins, an insect defensin (present in the hemolymph) as well as a homolog of the serine protease Persephone. These results show that immune signalling pathways are conserved in this dung beetle.

Includes bibliographies and indexes / xvi, 832 p. : / Title page, contents and abstract only. The complete thesis in print form is available from the University Library.

Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Hong Kong, 2010. / Includes bibliographical references (leaves 149-163). Also available online.

Thesis (Ph. D.)--University of Hong Kong, 2010. / Includes bibliographical references (leaves 149-163). Also available in print.