Altered Esterase Activity Due To Pesticide Exposure In The Aquatic Snail Physa Acuta.

Presented at the first meeting of Federation of African Societies of Biochemistry & Molecular Biology in 1998.,The effect ofpesticides on the xenobiotic metabolising enzymes of the aquatic snail Physa acuta was studied. Adult snails reared in the laboratory were exposed daily for three days to the following pesticides: 2,4-dichlorophenoxyacetic acid, deltamethrin, endosulphan, malathion and pirimiphos-methyl. Cytosolic fractions prepared from the snails showed that pesticide exposure had no effect on the glutathione or glutathione dependent enzyme activities. General esterase activity using two different substrates was reduced significantly by exposure to the organophosphate pesticides malathion and pirimiphos. Exposure to the other pesticides did not cause any substantial changes in the esterases activities. The nature of this inhibition is not yet apparent. It is likely, however, that the changes are due to a competitive type inhibition by the pesticides for the active site of the enzyme.,Federation of African Societies of Biochemistry & Molecular Biology (FASBMB