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This study was designed to examine the influence of Cu deficiency on the binding, uptake, and degradation of apolipoprotein E-free high density lipoproteins (apo E-free HDL) in cultured rat hepatic parenchymal cells. The binding of apo E-free HDL during time course studies was slightly but significantly increased in cells derived from Cu-deficient rats. In saturation studies, the amount of surface-bound apo E-free HDL appeared to be saturable, although no difference was observed between Cu-deficient and adequate animals. The amount of total and specific cell-associated uptake of apo E-free HDL was significantly increased in hepatic parenchymal cells of Cu-deficient animals. The present data suggest that hepatic uptake of the HDL protein moiety may be increased in rats fed a diet deficient in copper.

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Currently, protocols for investigating the effects of chemical pollutants on periphyton communities under natural conditions are statistically flawed and/or potentially harmful to the ecosystems in which the studies are conducted. Toxicant-releasing substrates have been proposed to allow the delivery of different levels of chemical pollutants to replicate microbial communities in situ while minimizing the amount of toxicant released into the aquatic ecosystems under investigation. The purpose of this research was to compare the copper-induced responses of laboratory periphyton communities in artificial streams to those generated using standard, laboratory toxicity testing protocols during a summer and winter experiment. Chemical-releasing substrates were successfully used to deliver copper to periphyton communities in a predictable manner, over a broad range of doses, and at fairly constant rates during one week exposure periods. / Master of Science

Heavy metal accumulation in arable land as a result of mining activities, pesticides and fertilisers has become a global concern. Steinkopf and Concordia in the Northern Cape are well-known for subsistence farming, but just as well-known for the nearby copper mining industry. Very little research has been done on heavy metal toxicity in these areas, thus it was of importance to assess the wheat cultivars (Triticum aestivum) historically used in the study areas, to ensure the viability of wheat farming. The nine wheat cultivars screened were Flameks, Knoppies, Rooiwol, Rooigys, Yecoro Royo, Charchia, Witwol, Kariega and Losper. A comparative study was done by determining the concentration levels of Cu, Fe, Zn, Mn, K, Mg, Ca, Na, N and P in the roots and shoots of sensitive and tolerant wheat cultivars. It was established that Witwol and Rooigys were the most tolerant to these adverse conditions. Kariega and Rooiwol were most sensitive. Their tolerance was achieved by excluding copper from the roots and limiting the translocation of copper to the shoots. This trend to exclude copper uptake in Witwol and Rooigys, warrants further investigation on a molecular level to explain these adaptive mechanisms.

This research is designed to test how sublethal exposure to copper affects tadpole predator-escape behavior and how quickly tadpoles recover. After exposure, tadpoles were separated. Escape behavior was recorded for two-thirds of exposed tadpoles while one-third of the exposed population was measured weekly to determine growth and recovery. Control tadpoles were consumed within 15 minutes whereas those exposed to higher concentrations were consumed at a slower rate, which does not support the hypotheses. Although the rate of predation was lower, tadpoles exposed to higher Cu concentrations were on average, 1.47 cm in total body length. Those exposed to 0.93 mg/L averaged 0.86 cm. After being placed into clean water, treatment tadpoles recovered after 20 days.

Heavy metal accumulation in arable land as a result of mining activities, pesticides and fertilisers has become a global concern. Steinkopf and Concordia in the Northern Cape are well-known for subsistence farming, but just as well-known for the nearby copper mining industry. Very little research has been done on heavy metal toxicity in these areas, thus it was of importance to assess the wheat cultivars (Triticum aestivum) historically used in the study areas, to ensure the viability of wheat farming. The nine wheat cultivars screened were Flameks, Knoppies, Rooiwol, Rooigys, Yecoro Royo, Charchia, Witwol, Kariega and Losper. A comparative study was done by determining the concentration levels of Cu, Fe, Zn, Mn, K, Mg, Ca, Na, N and P in the roots and shoots of sensitive and tolerant wheat cultivars. It was established that Witwol and Rooigys were the most tolerant to these adverse conditions. Kariega and Rooiwol were most sensitive. Their tolerance was achieved by excluding copper from the roots and limiting the translocation of copper to the shoots. This trend to exclude copper uptake in Witwol and Rooigys, warrants further investigation on a molecular level to explain these adaptive mechanisms.