Thesis (M.S.)--University of Tennessee, Knoxville, 2004. / Title from title page screen (viewed Feb. 2, 2005). Thesis advisor: Reid R. Gerhardt. Document formatted into pages (xiii, 110 p. : ill., maps). Vita. Includes bibliographical references (p. 90-109).

Thesis (Ph.D.) - University of Queensland, 2004. / Program shared between two schools. Includes bibliography.

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Thesis (M.S.)--University of Wisconsin -- La Crosse, 1975. / Digitized and made available by the University of Wisconsin--La Crosse, Murphy Library. Includes bibliographical references (leaves 57-63). Online version of print edition.

Thesis (M.S.)--University of Wyoming, 2008. / Title from PDF title page (viewed on June 25, 2009). Includes bibliographical references (p. 47-51).

viii, 21 p. : ill. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / To determine the relative effects of rapid climate change on selection and drift in small populations, nine northern populations of the pitcher-plant mosquito, Wyeomyia smithii, were exposed to directional selection equivalent to 180 years of climate change, while control populations were maintained in their native climate. After three years, fitness had declined in the selected but not the control populations, indicating an adverse effect of climate change. When both selected and control populations were then reared in the selected climate, they showed no difference in fitness, indicating no genetic response to selection. Importantly, however, fitness was negatively correlated with accumulated inbreeding in both control and selected populations, pointing out that the effects of inbreeding and drift exceeded those of selection imposed by rapid climate change. Therefore, small northern populations at expanding edges of species' distributions should be most vulnerable to continued climate change. / Committee in Charge: Dr. William Bradshaw, Chair; Dr. Christina Holzapfel; Dr. Nathan Tublitz

PhD, Faculty of Science, University of the Witwatersrand, 1999

Bacillus thuringiensis subsp. israelensis (B.t.i.) produces a plasmid encoded parasporal crystalline protein which is larvacidal to mosquitoes carrying parasites for malaria and other infectious diseases. The purpose of this study was to construct a library of random fragments from the nine plasmids of wild type B.t.i. strain 402. The library was to be utilized in order to clone a 135kDa mosquitocidal polypeptide carried on a 108 kb B.t.i. plasmid.The library construction involved isolation of plasmid DNA by equilibrium density centrifugation, generation of random fragments of the nine plasmids by a partial Sau3A restriction digest, and ligation of these fragments into XbaI-BamHI restricted Lambda GEM-11 vector. Escherichia coli strain LE392 was infected by the packaged recombinant lambda and over 1000plaques were pooled to comprise the library. In order to verify construction of the library, both plaque screens of the library and Southern Analysis of restricted clones subjected to agarose gel electrophoresis were performed with labeled probes. The labeled probes were included: 1) radioactive end-labeled oligonucleotides constructed from published sequences of the B.t.i. 135 kDa toxic protein, 2) radioactive end-labeled random fragments from all nine plasmids of B.t.i., 3) radiolabeled entire plasmids of all nine plasmids of B.t.i., and 4) dioxigenin-labeled oligonucleotides. No homology between the lambda library digested DNA and the B.t.i. plasmid was observed. The results suggested that no lambda library of B.t.i. was constructed and, therefore, a lambda clone encoding the 135 kDa mosquitocidal polypeptide was not isolated. / Department of Biology

Culex mosquitoes, as well as being vectors of filariasis and Japanese encephalitis, are a world wide biting nuisance. Organophosphorus insecticides (OPs) have been widely used to control Culex populations. Resistance to OPs has occurred and is typically mediated by the increase in non-specific esterase activity. The two esterases involved are classified as 'A' and 'B' esterases with respect to their preference for the substrates α- or β- naphthyl acetate. The commonest phenotype involves two elevated esterases, A2 and B2, which occur in complete linkage disequilibrium. The over expression of esterase B1 is due to gene amplification. Initially, in order to further study the molecular biology of OP resistance, full length cDNAs coding for both A2 and B2 esterases were isolated and sequenced from an OP resistant Sri Lankan strain of Culex quinquefasciatus, PelRR. The B2 esterase cDNA was isolated with PCR using primers sharing homology with the B1 esterase cDNA and has 97.4% homology with esterase B1 at the amino acid level. This confirmed that the B esterases belong to an allelic series. Partial genomic sequences of B2 esterase from PelRR and four other OP resistant Culex strains were identical. This suggests that the initial B2 esterase amplification has occurred only once. However, the cDNA sequence of a B1 esterase cDNA isolated from an OP resistant Cuban strain of Culex quinquefasciatus, MRES, was different to that of the previously published B1 esterase gene sequence. At the genomic level, the haplotype of the Cuban B1 esterase gene, based on EcoRI endonuclease analysis, was also different, suggesting that the initial B1 esterase gene amplification event has occurred at least twice. AB esterase cDNA from an OP susceptible strain, PelSS, has also been partially sequenced. PelSS was derived from the same origins as PelRR but its B esterase cDNA sequence and haplotype of the gene are different. Thus, the B2 esterase gene conferring OP resistance, as well as being amplified, is only found in the resistant strain, PelRR. The A2 esterase cDNA was isolated by screening a PelRR cDNA expression library with an anti-A2 antiserum. The cDNA coded for a protein of 540 amino acids (the same as B2 esterase) and shared 47% amino acid homology with B2 esterase. This strongly suggests that the two genes arose from a duplication of an ancestral counterpart. Furthermore, screening of a PelRR genomic library with A2 and B2 esterase gene probes suggests that the two esterase genes, A2 and B2 are situated in tandem within the genome. PCR was used to amplify the coding region of the PelRR A2 esterase cDNA and this was co-transfected into the baculovirus expression system. The recombinant virus expressed an active A esterase.