3. Electronic Theses and Dissertations (ETDs) - All submissions

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    The molecular basis of glycopeptide Resistence in two Clinical Isolates: Bacillus Lentus RSA1208 and Paenibacillus Thiaminolyticus RSA 1221
    (2006-10-25T08:10:34Z) Moodley, Arshnee
    The molecular mechanisms of glycopeptide resistance in two Gram-positive clinical isolates, Bacillus lentus RSA1208 and Paenibacillus thiaminolyticus RSA1221 were investigated. The glycopeptide resistance genotypes were determined by PCR. If van genes were detected, recombinant DNA techniques and sequencing were used to determine the gene sequence. The location of the resistance determinant was investigated using Southern hybridization techniques. To determine the 5’ and 3’ ends flanking the resistance operon, sub-genomic libraries were constructed. Transmission electron microscopy was used to assess possible structural changes of the B. lentus RSA1208 cell wall. B. lentus RSA1208 exhibits inducible, high-level resistance to both glycopeptides, but does not possess any known van resistance genes. Electron micrographs showed a visible increase in cell wall thickness in B. lentus RSA1208 grown in vancomycin compared to the isolate grown in vancomycin-free media. However, it remains to be confirmed as to whether this resistance is solely responsible for the high-level resistance phenotype. P. thiaminolyticus RSA1221 exhibits constitutive, high-level resistance to vancomycin only. It was found to possess a chromosomally-borne, vanA gene cassette. The vanA gene showed the highest amino acid identity to the vanA-like D-ala: D-lac gene found in P. thiaminolyticus PT-2B1 and Enterococcus faecium BM4147. All five genes of the vanA gene cluster (vanR, vanS, vanH, vanX, vanY) were amplified and sequenced. No vanZ gene was detected. The vanA operon in P. thiaminolyticus RSA1221 was found not to be associated with any known mobile elements. The observed constitutive expression of resistance maybe due to a two amino acid insertion in the VanSBpt1221 protein. v
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    Molecular metaphors taking on lives of their own: An investigation of metaphor in the conceptualisation of genetics and immunology
    (2006-02-09) Brom, Lauren Sylvan
    Genetics and immunology presently hold tremendous possibilities for changing the future through their biotechnological applications. To comprehend such complex subjects metaphor is generally employed. It is my contention that as these scientific concepts are repeatedly reinforced in both scientific and mass media representations, the metaphors suffuse our conceptual system to such an extent that they are no longer recognised as metaphors. Instead, they tend to be viewed as scientific ‘fact’. I have termed such pervasive metaphors, ‘concept metaphors’. I argue that the predominant concept metaphors regarding genetics and immunology are ‘information coding’ and ‘militarization’, respectively. Through this research, the origins of these concept metaphors as well as the extent to which they influence our current perceptions of life and health, become startlingly patent. I conclude by demonstrating how the utilisation of novel metaphors can significantly alter our conceptualisations and consequently, perceptions of these areas of molecular biology.
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