Community composition and distribution of macroinvertebrates in the Umzimvubu River,South Africa: a pre-impoundment study

This paper presents baseline biological data on aquatic macroinvertebrates and water quality in the Umzimvubu River and selected tributaries, Eastern Cape Province, South Africa, prior to the construction of proposed large-scale water resource developments. Sampling was conducted seasonally at 14 sites between 1996 and 1998. The macroinvertebrate community composition was strikingly similar (±70%) across sites. Faunal diversity was low (104 taxa in total), but many taxa found were sensitive to water quality change (ASPT 5.0 to 9.6), indicating good water quality, which is attributed to the currently undeveloped nature of the catchment. Concentrations of water quality variables fell within a narrow range, except for total suspended solids, which at times was very high (up to 8 532mg l^–1). The highly variable concentration of the total suspended solids and its potential effects on biodiversity need to be investigated further. It is likely that bilharzia will spread and that pest blackflies may become a problem to livestock if the water resources become developed as is proposed. We suggest that more flow gauging weirs are needed to measure flows better for future management and also that the implications of the proposed developments on the estuary need to be investigated.     

Combined effect of 3-aminobenzamide and N-acetylcysteine on HIV replication in chronically infected U937 cells

Summary

The existence of a close relationship between apoptosis associated with oxidative stress and the increase of viral progeny in chronically HIV-infected cells has been previously reported. The possibility of modulating both phenomena by using an antioxidant such as N-acetylcysteine (NAC) has also been demonstrated. The present investigation was designed to study the role of the nuclear enzyme poly-(ADP-ribose)-polymerase (PARP) when HIV- infected cells are treated with tumour necrosis factor alpha (TNFα), a cytokine capable of inducing both apoptosis and intracellular oxygen free radical production. PARP overexpression may result in a rapid drop of intracellular NAD⁺ and ATP concentration, thus contributing to cellular redox imbalance. We have used the specific PARP inhibitor 3- aminobenzamide (3-ABA), alone or in a combination with NAC. 3-ABA was only partially capable of inhibiting viral replication and apoptosis induced by TNFα. In contrast, the combination of NAC and 3-ABA led to an inhibition of apoptosis as well as to a marked decrease in viral particle production, with a parallel replenishment of intracellular reduced glutathione content. The results reported here confirm the potential role of antioxidant drug treatment in specific phases of HIV infection.