3. Electronic Theses and Dissertations (ETDs) - All submissions
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Item The behavioural ecology of bachelor male groups in the African striped mouse, Rhabdomys pumilio(2018) Kanyile, Sthandiwe NomthandazoMales in several animal species vary in traits which confer competitive ability. Younger and old, small and large males thus regularly make use of different behavioural tactics (i.e. alternative reproductive tactics, ARTs) in order to secure mates and increase their fitness. In the Succulent Karoo, males of the African striped mouse Rhabdomys pumilio adopt one of three main ARTs, i.e. philopatric, roaming, or territorial tactics; the tactic chosen is influenced by body mass. Additionally, the occurrence of bachelor groups (two or more males sharing a nest without any female) in striped mice has recently been observed. The present study was concerned with investigating the composition and function of these bachelor groups in striped mice, especially to assess whether they represent a fourth ART. For this, I used data collected from 2009 to 2016 to determine the season (breeding versus non-breeding) during which bachelor groups occurred and how they originated. At the start of the breeding season, I compared bachelor males with the known ARTs with regard to their scrotality, body mass, and age. I also determined the tactics of bachelor males before and after they were bachelors, and whether these tactic changes were associated to changes in body mass. My results indicate that bachelor groups are mainly formed by unrelated philopatric males which have dispersed from their natal groups. These groups most frequently occur in the breeding season, when population density is low to intermediate. Bachelor males occupy the intermediate position in the body mass spectrum in striped mice, being heavier than philopatrics but lighter than breeders, and do not differ in body mass from roamers. After the bachelor tactic, more males employed the roamer than the territorial breeding tactic. I hypothesise that the bachelor tactic is a “transitional tactic” which facilitates the change from a low fitness tactic (philopatric) to a higher fitness tactic (roaming or breeding) by allowing relatively small males to cooperate in social thermoregulation. These findings provide valuable insight on a phenomenon which has not been studied before in striped mice. Keywords: African striped mouse, alternative reproductive tactics, bachelor, behavioural plasticity, group-living, social flexibilityItem Calrentinin-Immunoreactivity during Odontogenesis in the Rat(2000-02-04) Mistry, DharmeshCalretinin is a 29kD calcium-binding protein that is abundantly expressed in the central and peripheral neural tissues. Calretini expression outside the nervous system has been less extensively characterised. The aim of this study was to determine the expression of calretinin during various stages of odontogenesis in the rat ( Rattus Norvegicus )Item The effect of creatine on the developing rat foetus(2004) Badenhorst, Frans HendrikCreatine is one of the most frequently or generally used ergogenic substances. It is used by professional and amateur athletes and the “man on the street”. Creatine is involved in energy production and protein synthesis in muscle. Although studies have been carried out on the effect of creatine on adults, no study has yet determined whether creatine would have an influence on the developing rat foetus if taken by a female during pregnancy. The aim of this study was thus to determine whether creatine had an effect on the developing foetusItem The amygdaloid modulation of adrenocortical function and habituation in rats(2015-09-09) Saling, Michael MartinThe relationship between amygdaloid damage and the intmperitoneal injection of betamethasone was studied with respect to the exploratory behaviour of male hooded rats. Amygdalaetomy produced attenuated longterm habituation of stimulus-specific and general exploratory behaviour. This habituation deficit was uninfluenced by betamethasone. Betamethasone also failed to influence long-tori. habituation in the intact animals. Although amygdalectomy did not alter short-term habituation, betamethasone accelerated the short-term habituation of general exploratory behaviour in both amygdalectomised and intact animals. On replication of the experiment betamethasone administration failed to influence exploration. It was tentatively concluded that amygdalectomy and betamethasone influence the habituation of exploratory activity under mutually exclusive circumstances. However, the failure to replicate the amygdalectomy- and betamethasone- induced changes in habituation could not be inteipreted within the context of the present experiment.Item Effect of dietary Terminalia sericea aqueous leaf extracts on high-fructose diet fed growing Wistar rats(2014) Lembede, Busisani WisemanSedentary lifestyles and poor dietary choices are the major cause of the global increase in the prevalence of obesity and metabolic dysfunction in children. The high cost and limited access to conventional drugs by poor communities make them depend on ethnomedicines. Terminalia sericea (T. sericea) contains phytochemicals that give its extracts hypolipidaemic and hypoglycaemic properties hence its use in ethnomedicine to treat diabetes mellitus. Using weanling Wistar rat pups fed a high fructose diet to model growing children exposed to high-sugar diets, this study sought to evaluate the effects of aqueous T. sericea leaf extracts on their growth performance, glucose homeostasis, visceral morphometry and their general health profile. Forty 21-day old male Wistar pups were randomly allocated to five treatment regimens. Each group had ad libitum access to a commercially supplied rat chow. Group 1 pups were given plain drinking water and plain gelatine cubes, group 2: 12% fructose solution and plain gelatine cubes, group 3: 12% fructose solution and gelatine cubes containing fenofibrate at a dosage of 100 mg.kg-1 per day, group 4: 12% fructose solution and gelatine cubes with a low dose (100 mg.kg-1 per day) of the T. sericea extract and group 5: 12% fructose solution and gelatine cubes with a high dose (400 mg.kg-1 per day) of the T. sericea extract. The pups were maintained on the regimens for 12 weeks after which they under went an oral glucose tolerance test. Fasting blood metabolite content was then determined after which the rats were killed and tissues collected for visceral morphometrical, linear growth and surrogate markers’ of health determinations. T. sericea extracts had no negative effect on growth performance (body mass and indexes of long bone growth) but rats given fenofibrate had lighter empty carcasses and shorter tibiae. vi The administration of T. sericea extracts neither improved glucose homeostasis nor caused derangement of glucose handling by rats given a high fructose diet following an oral glucose challenge. However, the administration of fenofibrate to rats given a high fructose diet resulted in decreased glucose handling following an oral glucose challenge. With the exception of the administration of fenofibrate which resulted in a significantly high (P < 0.05) fasting blood glucose concentration, treatment regimens had no effect on fasting blood glucose, triglyceride and cholesterol concentrations. Rats given fructose with either plain gelatine cubes or low T. sericea dose had significantly higher (P < 0.05) liver lipid content compared with the control treatment. Administration of T. sericea extracts to rats given a high fructose diet had no effect on the GIT, other abdominal viscera and markers of general health. The administration of fenofibrate to rats given a high fructose diet caused increased relative mass of GIT organs (stomach, small intestine and caecum), increased absolute mass of other viscera (liver and kidney); increased serum phosphorus and alkaline phosphatase concentration. Results from the study revealed that administration of a high dose of aqueous T. sericea leaf extracts has potent phytochemicals properties that has helped to prevent high fructose diet-induced deposition of fat in the in the liver (non-alcoholic fatty liver disease), without compromising growth, visceral morphometry and general health of growing Wistar rats.