The inter-tissue metabolic responses to hypoxia were determined in lungfish (Protopterus aethiopicus), and trout (Salmo gairdneri). Lungfish respond to hypoxia with a reduction in metabolic rate. It was intended to determine which tissue, or tissues exhibit decreased metabolic rates during hypoxia, and then compare the results with the metabolic reactions observed in trout, which are not reported to reduce metabolic rate during hypoxia. The metabolic potentials of the heart, brain, white muscle and liver in the African lungfish were estimated using enzymatic data. Metabolic effects of a 12 hr submergence were monitored using metabolite measurements. Heart was the most oxidative tissue, but also showed the greatest anaerobic potential. The brain displayed relatively low oxidative capabilities. White muscle remained almost inert. Although high energy phosphate concentrations in brain and heart did not fall during submergence, glycolysis was activated as indicated by cross-over plots, depletion of endogenous glycogen stores, and lactate accumulation. Blood-tissue lactate and glucose gradients indicated (1) that the heart and brain released lactate throughout submergence, (2) that after 12 hr of submersion the brain and heart were probably obtaining all their required glucose from the blood (3) that the liver released glucose throughout submergence, and (4) the white muscle was metabolically isolated from the rest of the body during submergence. The lack of measurable changes in white muscle metabolite concentrations coupled with the low enzyme activities leads to the suggestion that the most significant adaptation to hypoxia in these fishes may not be the capacity for increased anaerobic energy production. Instead, it is likely that the ability of the muscle to prevent the activation of glycolysis during hypoxic dysoxia is the key to the animal's survival. Histochemical and ultrastructural studies were done on the axial musculature of the lungfish. The small wedge of red coloured muscle evident upon gross examination was shown by histochemical demonstrations of lactate and succinate dehydrogenases, of adenosine triphosphatases, and of lipid to be composed of a mosaic of red and intermediate fibres. Respectively, these fibres measured 23.6 and 34.3 microns in average diameter. The bulk of the myotome is composed of white fibres having an average diameter of 67.3 microns. Mitochondrial density, capillarity and lipid content were very low for all fibres. These data suggest that the axial musculature is geared primarily for anaerobic function. The relatively large percentage of white muscle indicates that the overall metabolic rate of the axial muscle is low. The capacity of the muscle to exist with a reduced rate of ATP turnover (as was suggested above) may be related to the large proportion of white fibres present in the myotome. Tissue metabolites were measured in a hypoxia sensitive organism, the Rainbow trout (Salmo qairdneri), before and after exposure for 3 hr to inspired oxygen tensions of 20 torr (at 4°C). There were small changes in the brain but the energy status was maintained. The red muscle was the least affected. White muscle creatine phosphate was depleted. Various data indicate that the white muscle is the major user of glycolytic substrates and the major producer of lactate. The heart is stressed as indicated by a decline in glycogen, ATP, CrP, and the total adenylate pool. The liver exhibited declines in every indicator of metabolic homeostasis. The liver concentrations of glycogen did not decline. The fact that anaerobic glycolysis has been activated in the white muscle, while the muscle remains in metabolic communication with the other tissues via the blood, supports the suggestion that the metabolism of the white muscle will have a pronounced effect on the metabolic status of the whole animal. The trout is maintaining its rate of oxygen uptake while activating anaerobic glycolysis in the attempt to maintain 'normal' rates of energy utilization. The turnover rates of glucose and lactate were measured in trout subjected to the same hypoxic stress as above. Glucose turnover did not change while lactate turnover increased from 2.8 ± 0.4 µmoles/min./kg to 20.6 ± 6.8 µmoles/min./kg. The lack of increase in glucose turnover was attributed to the observation that liver glycogen concentrations do not change and so there is no increase in glucose flux. The increase in lactate turnover emphasizes the fact that anaerobic glycolysis is activated and that some tissues are oxidizing lactate. The problem of when a cell becomes hypoxic and the reactions of the cell to that stress is addressed. The cell (tissue, organ, animal) has two options if oxygen supply drops to a level which prevents oxidative metabolism from supplying all of the requirements for ATP synthesis. The cell may exhibit a decline in requirements, in which case the rate of ATP production need not be as high as in the oxidative state or, conversely, anaerobic energy production may increase in the attempt to maintain ATP production rates. The lungfish muscle appears to be capable of the former, thus preserving substrates for other tissues and reducing the rate of end-product formation. The trout white muscle, on the other hand, exerts a major influence upon the other tissues when the animal is stressed with hypoxia. The term 'energy conformer' is applied to animals which do not maintain oxygen uptake in the face of a declining supply, and which allow ATP production to decline concomittantly by not activating glycolysis to a marked degree. An energy regulator would activate glycolysis in the attempt to maintain oxidative rates of ATP production. The trout is more of an energy regulator than is the lungfish with the main difference in this capacity being in the white muscle. / Science, Faculty of / Zoology, Department of / Graduate

Rainbow trout (Salmo gairdneri) from two wild stocks native to British Columbia, and a non-native domestic strain were reared under varying conditions to examine effects of growth rate and body size, genetic stock, and photoperiod on the incidence and timing of testis development. The ratio of gonad weight to body weight (Gonadosomatic index) was found to be useful for separating mature and immature male fish and for determining the onset of gonadal development. In Premier lake fish testis development began one year before the expected date of spawning. At this time, signs of maturation were evident primarily among males that reached a body weight of between ten and twenty grams, whereas most of the fish smaller than this "critical" size remained immature (i.e. no testis developmment). Apparently, this critical size must be reached by a certain time of the year. Thus, a time 'window' exists wherein fish achieving a certain size begin preparation for spawning the following year. Altering photoperiod regime during the time window had no effect on the incidence of sexual precociousness, but did delay spermatogenesis by an undetermined length of time. / Science, Faculty of / Zoology, Department of / Graduate

M.Sc. (Zoology) / Aphanomyces invadans is an oomycete associated with epizootic ulcerative syndrome (EUS). It affects more than a 100 freshwater and estuarine species of fish and is a serious threat to aquaculture and natural aquatic ecosystems. Currently, cases of EUS have been reported across Asia, Australia, North America and more recently Southern Africa. Outbreaks occur mostly during periods of sudden temperature change, such as heavy rainfall or change of seasons. These conditions favour sporulation of A. invadans, and low temperatures have been shown to delay the inflammatory response of fish to oomycete infection. Diagnosis of A. invadans is usually based on clinical signs and confirmed by demonstrating the presence of mycotic granulomas in histological section. Further diagnosis of EUS is made by isolation of A. invadans from internal tissues. Demonstrating typical asexual characteristics by inducing sporulation allows identification of the oomycete to the genus level. After inducing sporulation, the zoospores can be isolated for use in clinical infection of fish through subcutaneous injection or bath challenge systems. Standard molecular techniques such as polymerase chain reaction (PCR) have also been development for the fast and reliable diagnosis of the disease. The aim of this study was to perform different infection trials on EUS in two susceptible fish species, three-spot gourami, Trichogaster trichopterus, and rainbow trout, Oncorhynchus mykiss. Through initial trials, three-spot gourami was established as a suitable positive control species. Subsequently, hyphae were successfully re-isolated from infected fish and demonstrated as A. invadans, which was used in a further inoculation trial. Rainbow trout were challenged with A. invadans through intramuscular inoculation revealing varying degrees of susceptibility at different water temperatures. Detection of fungal hyphae and mycotic granulomas in tissue sections was achieved through histopathological examination, including the use of birefringence and fluorescents. Confirmation of A. invadans DNA in the various infection trials was done through PCR analyses. A histological grading system is proposed which will allow simplification of large scale qualitative microscopic analyses and identification of histological trends within a data set when analysing suspected cases of EUS. It is recommended that similar infection trials be applied to endemic species in Southern Africa to investigate their susceptibility to EUS.

Juvenile rainbow trout (Salmo gairdneri Richardson) from the Lardeau River in southeastern British Columbia were studied in both their natural environment and stream tanks. In the river, highest densities of recently emerged trout occurred in areas with overhanging cover, shallow depth and minimal current. Older, underyearling trout were generally found in regions with smaller bottom particle size than yearlings; both age classes avoided fast current areas. Young trout migrated from the Lardeau River to Kootenay Lake during spring and summer. Except during these seasons trout were larger and more abundant in the upper versus the lower river; this was probably a result of better rearing habitat and higher biological productivity in the upper river. Trout fed almost exclusively on drifting organisms. Lake origin drift was an important food to riverine trout during summer; kokanee (Oncorhynchus nerka) eggs and fry were significant during fall and spring respectively. In stream tanks, where it was possible to manipulate prey populations, live prey were consumed significantly more than the same species when dead, suggesting that prey body movement was an important prey characteristic. In both the field and stream tanks, trout consumed prey within a discrete size range with larger fry generally consuming bigger prey than smaller fry. Further work is suggested which would improve our understanding of the feeding ecology of stream rearing trout. / Science, Faculty of / Zoology, Department of / Graduate

This thesis investigates the effects of alanine on rainbow trout’s glucose metabolism at the organismal and molecular levels. Rainbow trout is an important aquaculture species that belongs to the salmonid family. As a carnivorous fish, the requirement of protein/amino acids in trout’s diet is high. In contrast, rainbow trout are poor utilizers of carbohydrates. One prevalent hypothesis suggests that high levels of dietary amino acids could indeed contribute to the poor utilization of carbohydrates in this species. In mammals, there is evidence supporting the importance of alanine as a gluconeogenic precursor. However, a recent study found that alanine stimulates hepatic AMP-activated protein kinase (AMPK) to lower circulating glucose levels in mice. Alanine levels are high in all tissues in rainbow trout. The role of alanine in gluconeogenesis is less clear in trout and there is no evidence, to our knowledge, regarding its effects on glucose kinetics. Therefore, the main goal of the study was to investigate the impact of the continuous infusion of exogenous alanine for 4h on glucose fluxes and to identify potential mechanisms in tissues that could interpret the observed changes in glucose fluxes in vivo. Glucose turnover, appearance and disposal, Rt, Ra and Rd, respectively, were measured to determine the impact of alanine on glucose fluxes. The expression and/or activity of key genes in glucose transport, utilization and gluconeogenesis were assessed in liver and muscle. An additional goal was to assess whether alanine activates AMPK in trout. The levels of phosphorylated AMPK and other signaling proteins known to interact with the latter were quantified. Results show that alanine reduced plasma glucose levels and inhibited Ra and Rd glucose, consistent with previously observed effects of insulin in rainbow trout. The reduction in the expression of a paralogue of glut4, a key gene in glucose transport, and the activity of hexokinase (HK), a key enzyme in glucose utilization, in muscle can partially explain the observed reduction in Rd glucose. Together, these results suggest that glucose was not a preferred substrate under conditions of increased alanine availability and that alanine was probably oxidized to provide energy. Alanine failed to activate AMPK in trout, contrary to mammalian findings. However, it increased AKT (also known as protein kinase B) phosphorylation in muscle, similar to the effect of insulin in trout. In conclusion, my results suggest that alanine mediated at least some of the observed effects by stimulating insulin secretion given the similarities between the effects of exogenous alanine and insulin in rainbow trout as discussed above. Future studies are warranted to investigate the hypothesis that alanine is an insulin secretagogue in rainbow trout.

Philosophiae Doctor - PhD / The demise of apartheid presented South Africa with an opportunity to rebuild itself from its painful racist past to become a home to all those who live in it. This was done through a process of nation-building, which took the form of a multicultural civic nation, affectionately known as the Rainbow Nation, that embraces diverse cultures while affirming that individual citizens have equal rights. This thesis argues that the building of the Rainbow Nation has been somewhat successful, but more on a symbolic than institutional level, and that enduring forms of racial exclusion from socio-economic well-being pose the greatest threat to constructing a united, multicultural nation of civic equals.

After the abolition of apartheid, a process of healing and reconciliation was initiated in order for South Africa to move forward, grow and prosper. However, 25 years into democracy there is seemingly a lack of resolution. Instances of overt and covert racism, as well as anger and frustration have emerged increasingly, and repeatedly, as reflected in on-going recent events such as violent service delivery protests as well as the emergence of movements such as Fees Must Fall. Therefore, there is value in investigating the lived experiences of South Africans at this time in an attempt to understand the apparent discontent which calls into question the national narrative of reconciliation. The overall aim of this study was to explore the lived experiences of black South Africans with regards to the constructs of the ‘rainbow nation’ and ‘reconciliation’ following two-and-a-half decades of democratic rule. Situated within a phenomenological framework, the research process included in-depth interviews with black South Africans ages 40 and over. The focus on black participants was an attempt to fill the gap that is left by the dominance of content related to reconciliation focusing on the prejudice reduction of white people, prioritising white phenomena in the literature and otherwise. Data analysis was conducted through thematic analysis which allowed a number of themes to emerge. Themes included: loss; burden of blackness on identity and purpose; the problem of white privilege, lack of willingness to change and racism. Moreover, themes of theory versus reality and mistrust were also significant among the findings. From the themes that emerged it can be concluded that the black experience of the reality of living in South Africa is incongruent with the constructs of the ‘rainbow nation’ and ‘reconciliation’ that dominate the narrative of a democratic South Africa. The reality of post-apartheid South Africa is an unequal and divided country that requires more work, compromise and discomfort to attain the rainbow nation as it is envisioned. Hence, for these participants these constructs are more aspirational than reality-based. / Mini Dissertation (MA)--University of Pretoria, 2019. / Psychology / MA / Unrestricted

(English) The thesis deals with the knowledge interests and identity of environmental non governmental organization Hnuti Duha (Rainbow Movement). The aim is to identify the ideological concepts, values and interests represented by Rainbow Movement, by using cognitive approach to social movements. In addition, my goal is to thematize cognitive approach to social movements in the Czech Republic. I believe that it offers a valuable perspective for studying social movements, organizations and the civic sector. In the first part, I compiled the theoretical basis. I first concerned with the issues of civil society and NGOs, and then I introduced the cognitive approach and aspects of the environmental movement. In the practical section, I applied the cognitive approach to the analysis of the identity of the NGO Rainbow Movement. I used a qualitative research strategy - an analysis of interviews with employees of the Rainbow Movement. I described the motivation and basic dimensions of knowledge interests (cosmological, technological, organisational) of the Rainbow Movement. I tried to involve the current focus of the organization to influence political processes and to spread a positive vision that is perceived as a positive reform within a democratic society in order to move towards greater discretion...

A study was undertaken to investigate the application of tissue culture and histochemical banding techniques normally used in mammalian studies to fish cells and to examine the mechanisms of chromosome evolution and speciation in salmonids by comparing the chromosomes of the hybrid to those of the parental types. The application of banding techniques was generally unsuccessful in revealing bands, though quinacrine staining did reveal the presence of two fluorescent spots in the vicinity of the centromere. These were thought to be heterochromatic blocks, possibly related to the high incidence of centric fusion or fission in salmonids. Results of chromosome analysis showerd a higher incidence of acrocentric chromosomes in the hybrid than in either parental type which together with evidence for tetraploidization in salmonids is consistant with some of the requirements for species diversification. Conditions of divergence in chromosome evolution and changes which would have to occur in the hybrid for divergence from the parental types to take place are discussed. The results of a preliminary electrophoretic examination of LDH and esterase activity tended to confirm hybridization.

No description available.