Includes bibliographical references (leaves 89-94). / The abalone Haliotis midae is a gastropod mollusc which is of commercial importance in South Africa due to its high export value. During this study the genetic structure of farmed Haliotis midae was investigated in order to determine whether microsatellite DNA analysis could be used to separate farmed abalone into phenotypically different groups with respect to growth rate. Microsatellites display high levels of variability and this makes them suitable for a wide variety of applications in aquaculture, particularly where genetic differentiation between population groups may be limited. This study investigates the genetic composition of 120 individuals from 2 spawning events that had been classed as either fast or slow growing by the farm managers. Three highly polymorphic microsatellite loci were selected and used to determine the extent of the genetic diversity which exists amongst the 120 individuals tested from the lacobsbaai abalone farm. Additionally, these microsatellite loci were used to determine whether abalone classed as either fast or slow growing could be differentiated into specific genetic population groups. Neighbour-joining trees constructed using genetic distance data obtained for all three loci demonstrated that a distinct separation between the fast and slow growing abalone was evident. It was also found that there has been a loss of genetic diversity on the lacobsbaai abalone farm in terms of heterozygosity. This has been attributed to the high levels of inbreeding as evidenced by the high Fis values. All population groups were found to deviate significantly from Hardy-Weinberg equilibrium and this is most likely due to the occurrence of non-random mating on the lacobsbaai abalone farm. This study has successfully demonstrated that a combination of micro satellite loci with high allelic diversity can potentially be employed as a tool for distinguishing between fast and slow growing farmed abalone. This study needs to be validated by testing larger sample sizes and the use of additional farms.

Includes bibliographical references. / The first part of this project attempted to develop a method for the specific detection of the SMV G1 strain. The techniques were based on nucleotide sequence differences in that part of the SMV genome that spans the mid-region of the coat protein gene to the end of the non-coding region (NCR), and in the CI protein-coding region of the genome.

Includes abstract. / Includes bibliographical references. / Previous studies have shown that over-expression of nuclear respiratory factor (NRF)-1 in mice increases glucose transporter (GLUT)-4 and myocyte enhancer factor (MEF-) 2A content, but the mechanisms have not been elucidated. Because NRF-1 has a binding site on the mef2a gene, and MEF2A binds the glut4 gene as a MEF2A-MEF2D heterodimer, the aims of this study were to determine whether NRF-1 over-expression a) enhanced GLUT4 expression indirectly via MEF2A and b) alters MEF2A-MEF2D dimer formation in C2C12 myotubes.

Includes abstract. / Includes bibliographical references (p. 49-52). / Custom antigen arrays offer a platform to assay the serological response of cancer patients to at set of selected cancer testis antigens in order to infer a diagnosis value or to assess the patient responses to particular treatments. However, the acquisition of the array data is subject to bias and noise. Therefore, array data processing and analysis is required to clear the data from bias, reduce noise and learn from the data. This study aims to address the issues of normalization and sample qualitative clustering for custom protein arrays.

In order to conduct proteomic analysis on the hydrated root tissues of the resurrection plant, Xerophyta viscosa Baker, aeroponically grown plant roots were subjected to various proteomic techniques. Three protein extraction methods were investigated, of which one method, was the most suited in isolating total protein from the root tissues of X. viscosa.

Bibliography: leaves 86-97. / Low environmental nutrient concentration is the main factor limiting natural production and success of Gracilaria gracilis cultivation in Saldanha Bay, South Africa and nitrogen is the single element of all the nutrients required by seaweeds that is most frequently limiting to growth. Biomass, relative growth rate, the concentration of nitrogen in the growth medium, the mean nitrogen uptake rate of the plant and the amount of nitrogen in the thallus were determined for nitrogen enriched and nitrogen deprived G. gracilis cultures grown in the laboratory.

Includes bibliographical references (leaves 77-84). / This study demonstrates high level expression of L2, 25 mg.kg⁻¹of leaf material, is achievable. Interestingly, expression was best when coded for by a mammalian codon-optimized form of the L2 gene as opposed to the wildtype or plant codon-optimized (plantized) genes. Moreover, real time PCR revealed limited levels of transcript when coded for by the plantized gene in comparison to the other genes. A set of vectors which target the protein to the cytoplasm, the endoplasmic reticulum (ER), chloroplast or apoplastic space were Expression of HPV -16 L2 in Plants used and it was found that targeting of the protein had no effect on its expression levels.

Includes bibliographical references. / A deficiency of water is a common stress experienced by plants. Dehydration of plant tissue results in altered protein and lipid ultrastructure responsible for membrane stabilisation leading inevitably to the death of the plant. Some plants known as resurrection plants have evolved with the ability to survive dehydration to less than 2% water content, a property known as desiccation tolerance. Recently a polyphenol extracted from the leaves of a common African resurrection tree Myrothamnus flabellifolius Welw. has been isolated and characterised as 3,4,5-tri-O-galloylquinic acid. This study has investigated the role which this polyphenol may play in desiccation tolerance.

Includes bibliographical references. / The linker histone HI binds to the nucleosome and is essential for the organization of nucleosomes into the 30-nm filament of the chromatin. This compaction of DNA has a well-characterized effect on DNA function. In Saccharomyces cerevisiae, HHO 1 encodes a putative linker histone with very significant homology to histone HI. In vitro chromatin assembly experiments with recombinant Hho 1 p have shown that it is able to complex with the dinucleosomes in a similar manner to histone HI. It has also been reported that disruption of HHOl has little affect on RNA levels. A longstanding issue concerns the location of Hho 1 p in the chromatin and studies have shown using immunoprecipitation technique with anti-HA antibody, that Hho 1 p shows a preferential binding to rDNA sequences. In this project we have tried to confirm the above results in wild type cells, using immunopurifi ed anti rHho 1 p antibody.

Word processed copy. / Includes bibliographical references (leaves 54-69). / The preservation of yeast viability and vitality during storage in the desiccated state is fundamental as several industrial processes utilise this technology. The significance of the stress response protein and putative hydrophilin, Hsp 12p, was therefore examined in vivo under desiccation conditions.