Please read the abstract in the section 00front of this document / Thesis (PhD (Food Science))--University of Pretoria, 2006. / Food Science / unrestricted

Two trial were conducted to determine the possible effects of season, protein supplementation, age and birth status on the reproduction rate (ovulation rate and rate of twinning) of ewes. In Trial 1 the weight, age and birth status if ewes were recorded. 144 ewes were randomly allocated in two treatment groups (urea and mix protein group) synchronised, mated and the number of corpora lutea, foetuses observed, lambs born per ewe and the mass of the ewe after lambing were also recorded. Lambing status or the 1-year-old (0.993 ± 0.316) and 2-year-old (1.233 ± 0.134) ewes were lower (p < 0.05) than that of the 6- year-old ewes (1.897 ± 0.248). The lambing status and the number of corpora lutea of the single born ewes (1.179 ± 0.131; 1.274 ± 0.138) were lower (p < 0.0001) than that of the twin born ewes (1.614 ± 0.139; 1.782 ± 0.147), within the urea treatment. In Trial 2, 75 ewes were randomly allocated in four treatment groups (raw lupins, cooked lupins, cottonseed oil-cake and Fescue grass), synchronised and the number of corpora lutea were recorded. The weight, age and birth status of the ewes were also recorded. The number of corpora lutea from the cooked lupin group (1.815 ± 0.184) was significantly higher than that from the cottonseed oilcake group (1.048 ± 0.209), within the twin born ewe group. It was concluded that season, protein supplementation, age and birth status influenced the reproduction rate of ewes. Copyright / Dissertation (Msc)--University of Pretoria, 2009. / Animal and Wildlife Sciences / unrestricted

Currently a grate emphasis is being put on accurate and early diagnosis of Alzheimer's disease (AD), which is important for the introduction of treatments that could postpone the onset of the disease. Antibodies against tau protein appear to be suitable biomarkers for early diagnosis of AD. Therefore, this work deals firstly with preparation of human recombinant tau protein in bacteria and its subsequent use in determining levels of antibodies in blood serum of patients with AD and in normal older persons. A preparation of the tau protein in sufficient purity was achieved for the antibodies measurment by ELISA method and results were statistically analyzed using nonparametric methods. Results were compared with data from Mgr. Jany Švarcové obtained by measuring antibodies in serum of patients with AD and normal elderly using an commercial bovine tau protein. According to the analysis there are differences between the data obtained from human and the bovine tau protein. It was proven that patients with AN have lower levels of antibodies against tau protein than healthy seniors. Recombinant human tau protein was also used to immunize rabbits. The ELISA method confirmed the creation of antibodies against human tau protein in rabbits.

The synthesis of iron-sulfur clusters is an essential cellular process, which depends on complex biosynthetic pathways. In model eukaryotes, these pathways are the ISC pathway in the mitochondria and the CIA pathway in the cytosol. A recent genome and transcriptome analysis showed, that an amitochondriate protist Monocercomonoides exilis lacks the canonical ISC pathway, which has been replaced by a bacterial SUF pathway. A close free-living relative of M. exilis, Paratrimastix pyriformis possesses a mitochondrion-related organelle, yet also possesses a SUF pathway instead of ISC. The acquisition of the SUF pathway has been suggested as the primordial cause for mitochondrial loss in M. exilis, which is the first documented eukaryotic organism without a mitochondrion. The SUF pathway has been the subject of numerous studies in bacteria, however, its role as the core provider of iron-sulfur clusters for eukaryotic cells has been reported in merely a handful of eukaryotes and was based predominantly on genomic data. This thesis focuses on the putative ATPase SufC and the putative scaffold protein SufB. Both proteins were successfully produced in recombinant forms. SufC has been found to possess ATPase activity in vitro, which was increased upon interaction with SufB. The conditions for theATPase...

>Magister Scientiae - MSc / Retinoblastoma Binding Protein 6 (RBBP6) is a 200 KDa multi-domain protein that has been shown to play a role in mRNA processing, cell cycle arrest and apoptosis. RBBP6 interacts with tumour suppressor proteins such as p53 and pRb and has been shown cooperate with Murine Double Minute 2 (MDM2) protein in catalyzing ubiquitination and suppression of p53. Unpublished data from our laboratory has suggested that RBBP6 and MDM2 interact with each other through their RING finger domains. RBBP6 has also been shown to have its own E3 ubiquitin ligase activity, catalyzing ubiquitination of Y-Box Binding Protein 1 (YB-1) in vitro and in vivo. YB- 1 is a multifunctional oncogenic protein that is generally associated with poor prognosis in cancer, tumourigenesis, metastasis and chemotherapeutic resistance. Unpublished data from our laboratory shows that RBBP6 catalyzes poly-ubiquitination of YB-1, using Ubiquitin-conjugating enzyme H1 (UbcH1) as E2 ubiquitin conjugating enzyme. We have furthermore shown that the zinc knuckle of RBBP6 interacts specifically with the Ubiquitin-associated domain (UBA) domain of UbcH1.

There is much evidence in the recent literature that peptides may be intermediates in normal protein biosynthesis. This has also been inferred from certain disease states and other conditions under which protein biosynthesis is blocked at some point, e.g. cadmium, amino acid analogues or (in bacteria) antibiotics. The literature covering this concept will be presented. The present studies have been carried out on children, who because they are suffering from chronic protein malnutrition have very much lowered rates of protein synthesis and breakdown. In this unfortunate, but natural experiment, it was hoped that some factor or factors derived from protein synthesis might be found which influenced the synthetic mechanism as a whole. Evidence from the literature has been summarized which concludes that urine, apart from being convenient to collect, is the biological fluid most likely to contain high concentrates of peptides which are released during cellular metabolism.

Hypoalbuminaemia is an essential accompaniment of protein malnutrition. Yet the level of plasma albumin is usually regarded as a relatively crude reflection of a patient's nutritional status, reduction occurring only after prolonged or severe inadequacy of dietary protein. Brock recognized that a marginal degree of hypoalbuminaemia might be evidence of impending or early deficiency, and suggested that minor grades of "protein subnutrition" could conceivably exist with serum albumin levels still within the normal range. The work reported in this thesis developed originally out of an attempt to explore this possibility, and to characterize some of the changes in albumin metabolism that followed mild or early experimental protein deprivation in man and rabbits. Dynamic studies using albumin labelled with radioactive iodine revealed evidence of early adaptational changes, possibly occurring before alteration in the plasma albumin levels. While these studies shed some light on the response of albumin metabolism to experimental depletion, they failed to provide the hoped-for means by which subclinical protein malnutrition could be detected. From this work, however, it was but a short conceptual jump to the general problem of albumin homeostasis, a consideration of which forms the basis of this thesis. The first approach was a study of changes in albumin synthesis and catabolism in rabbits following limitation of dietary protein intake. Adaptive responses were then investigated in animals, provided with normal protein diets, after protein depletion induced by an alternative method - plasmapheresis - and, finally, after intravenous infusion of albumin solutions. Based on these and reported results, a tentative hypothesis has been adduced to account for the body's adaptation to variation in the plasma albumin pool, brought about by experimental manipulation or occurring spontaneously in disease.

No description available.

The studies presented in this thesis represent an attempt to characterise some aspects of the abnormalities of somatomedin physiology in protein-energy malnutrition. A suitable bioassay to study somatomedin was found in that of Van den Brande and Du Caju (1974) which makes use of uniform discs of cartilage punched from slices of immature porcine costal cartilage. The handling of the cartilage discs was made easy by the specially designed incubation rack. Preincubation increased sensitivity of the cartilage, and post incubation with radioactive tracer reduced the potential interference of varying sulphate content of assay samples. Serum samples were subjected to formal multipoint parallel line bioassay and data analysed by a computer programme designed to examine such assays. The bioassay was found to be sensitive to a concentration of serum of 5% and to have an index precision of less than 0.30 (and usually less than 0.20).

Doctor Scientiae / Living organisms are constantly being exposed to nanoparticles (NPs) in the environment via air, water, soil. Routes of exposure are usually in the form of industrial, occupational exposure, as well as therapeutic applications. This exposure could result in toxicity with potential harmful effects. The toxicity of nanoparticles depends on various factors such as surface interaction, shape, size, composition, aggregation and interaction with various cellular components. Nanotoxicity refers to the possible harmful effects of environmentally generated and man-made nanoparticles on biological and environmental system. Assessing potential toxicity is vital for the probable use and safety of nanoparticles as well as understanding the routes of entry into organisms and their mechanism of action. Proteomics is a developing field of science that is being explored to understand protein composition, structure and interaction at the cellular level. This helps in detecting the presence, quantity, alteration and regulation of proteins within the biological system. The proteome analysis brings an additional information as it enables measurement of wholeprotein (enzyme) expression levels, facilitating the construction of metabolic pathways and biomarker discovery for early disease diagnosis. Essentially, proteomic analysis reveals the consequence of stress on metabolic pathways necessary to maintain the energy homeostasis within the cells.