Includes bibliographical references (p.143-164). / In the field C. wilmsii (homoiochlorophyllous) and X humilis (poikilochlorophyllous) plants do not experience drought longer than two and six months, respectively. In this study longevity of dry C. wilmsii and X. humilis plants was investigated for up to 10 months under four different sets of conditions. Some conditions resembled those under which the two species would experience drought in the field, but also included those that resemble the accelerated aging conditions used in seed studies.

Includes bibliographical references (leaves 61-70).

Includes abstract. Includes bibliographical references.

Includes abstract Includes bibliographical references

Includes bibliographical references (leaves 43-56). / The G-box is a plant DNA cis-acting element involved in the regulation of gene expression in response to a range of environmental signals including anaerobiosis, dehydration and light as well as by abscisic acid (ABA). Basic leucine zipper (bZIP) transcription factors have been shown to specifically bind and activate transcription from G-boxes in a dimerized form. A 1.5 kb cDNA for a bZIP class transcription factor, designated EnGBF1, was cloned from a desiccation-tolerant grass, Eragrostis nindensis by degenerate RT-PCR.

Bibliography: leaves 153-170. / In order to understand the role of linker histones in the formation of the 30-run chromatin fibre as well as their role in transcriptional repression, it is essential to know their location on the nucleosome. In this study, we have modelled the location of the globular domain of chicken linker histone HS (GHS) on the nuc1eosome. The primary DNA binding site of GH5 was modelled by homology to the co-crystal structure of the E. coli CAP-DNA complex.

Includes abstract. / Includes bibliographical references (p. 112-116). / Haliotis midae is an important marine gastropod that is commercially farmed along the South African coastline. The demand for the edible foot of the abalone far exceeds the supply, as such monitoring the health status of commercially farmed abalone is important if the demand is to be met. In farming conditions, bacterial infections can spread rapidly leading to mass mortalities amongst the abalone population. In order for treatment to be effective, there needs to be an effective monitoring system in place that can assess the health status of the abalone. This study sought to address these issues by identifying a candidate gene that could be an ideal biomarker with respect to a bacterial stress.

Includes bibliographical references. / Myo-inositol I-phosphate synthase (INO 1) catalyses the conversion of glucose-6-phosphate to myo-inositol I-phosphate, which is subsequently dephosphorylated to myo-inositol. Myo-inositol is a precursor for a number of important metabolites that include membrane components, storage molecules, phytohormones and a variety of osmoprotectants. Xerophyta viscosa Baker (Family Velloziaceae) is a monocotyledonous angiosperm which has the ability to resume full physiological function after desiccation. The full-length cDNA for INO1 from X viscosa was isolated using the RACE technique.

Includes bibliographical references (p. 102-112). / The diverse microbiota of the human gastrointestinal tract plays a major role in the general health of humans. A number of bacterial strains with distinctive properties have been isolated and used commercially as probiotics in order to harness these health benefits and offer them to unhealthy hosts. There are set criteria that have to be followed before new probiotics can be introduced into the market. Five Bifidobacterium isolates with extremely high sucrase activity were randomly selected from a faecal sample from a healthy donor for further characterisation as potential probiotics with the ability to utilize fructo- oligosaccharide substrates in the gut. Phylogenic identification of the isolates to the species level was carried out using sequences of the 16S rRNA gene, 16S-23S rRNA gene spacer region, the heat shock protein (hsp60) and Elongation factor Tu (tuf).

Includes abstract. / Includes bibliographical references (leaves 80-89). / Although South Africa is the second largest producer of abalone outside Asia, the sustainability of the industry could be threatened by infectious diseases (Troell et ai., 2006). Probiotics are increasingly being viewed as an alternative to chemical and antibiotic treatments (Balcazar et al., 2006), and have been shown to improve the health of the South African abalone, Haliotis midae (Macey and Coyne, 2005). In order to establish better health management systems, and to implement alternative therapies such as probiotics, a better understanding of how the abalone immune system functions, and specifically how it responds to stimulation, is necessary. Two genes of the electron transport system, cytochrome b and cytochrome c oxidase III, were found to be upregulated in a cDNA microarray experiment performed on haemocytes from immunestimulated abalone (Arendze-Bailey, unpublished). The current study sought to confirm these results by semi-quantitative PCR and to further elucidate the roles of these genes, and thus the electron transport system, in the abalone immune response.