Potential Use of Superoxide Dismutase As A Biomarker of Metal Pollution In Two Species of Freshwater Snails Lymnaea Natalensis And Helisoma Duryi.
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Date
2013-03-12
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Abstract
Toxic metals such as lead and cadmium are widely found in our environment. Humans and animals are exposed to these metals from numerous sources through contaminated air, water, soil and food. Exposure to these metals has been shown to cause an increase in the production of reactive oxygen species (ROS) such as hydroxyl radical COIr), superoxide anion radical C02-) or hydrogen peroxide (H202). These ROS are toxic to the cell and usually cause apoptosis. A number of enzymes are responsible for the removal of these ROS and include superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX) and quinone oxidoreductase (QOR). At times exposure to metals results in the induction, repression or inhibition of these enzymes. We have prevsiously reported on the effect of metals on CAT, GPX and QOR. However, it has been shown that SOD can be induced as a result of exposure to metals. This study was therefore conducted to assess the possibility of using metal exposure related induction of SOD as a potential biomarker of water pollution. The study was performed using two species of aquatic snails found in Southern Africa, namely Lymnaea natalensis and Helisoma duryi. Adult snails reared in outdoor cement aquaria were exposed daily for three days to three concentrations (0.01 ppm, 0.1 ppm and 1.0 ppm) of copper (Cu), cadmium (Cd), lead (Ph) or zinc (Zn) individually. SOD activity was measured in post-mitochondrial fractions. Although not statistically significant, our data indicates a trend in hoth species of snails where Cu, Cd and Pb caused dose related increases in SO..p activity. However, Pb caused a dose related change only in L natalensis and not in H. ~ryi. The activity was increased several fold at 1 ppm while the lower concentrations seemed to have little or no effect. These results suggest that metal exposure results in an increased SOD activity in aquatic invertebrates. Furthermore, induction of SOD activity as a result of exposure to metal is a potential biomarker of water pollution. However, further studies are required using other metals and a wider concentration range in order to test the reliability of this enzyme as a biomarker.
Description
Presented at the Southern African Society of Aquatic Scientists Conference in 2004.
Keywords
Superoxide Dismutase, Metal Pollution, Snails, Lymnaea Natalensis, Helisoma Duryi