ABSTRACT
Pollution of environmental waters is a serious and growing problem all over the world. Fish accumulate pollutants directly from contaminated water and indirectly by ingestion of the contaminated organisms. Genotoxic pollutants induce DNA strand breaks and mutagenic lesions that proposed as genotoxicity biomarkers monitoring the fresh water environment. These lesions are believed to induce chemical carcinogenesis. In the present communication,the alkaline single cell gel electroplioresis,known as cornet assay, is a rapid,simple and sensitive technique measuring DNA strand breaks in individual cells. The genotoxic potential of the widely used pesticide [Malathion] was evaluated in clarias gariepinus erythrocytes. The cells were exposed to three sub-lethal concentrations of malathion [0.02, 0.3 and 0.5 micro g/ml]. Alkaline comet assay was performed on nucleated erythrocytes after 24,48 and 72hrs. The amount of DNA damage in cells was estimated from comet tail length as the extent of migration of the DNA damaged. DNA damage was observed to be increased with the increase of the concentration compared to the control [p<0.05]. The comet tail showed a concentration - time relationship. The maximum tail length at highest concentration and longest time was [8.62 micro m]. The present study indicated that comet assay applied on fish erythrocytes is a useful tool in estimating genotoxicity of chemical pollutants, such as malathion.