In Vitro Effects of Carbaryl and Dimethoate on Esterases of Lymnaea Natalensis.
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Date
2013-03-12
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Abstract
Agrochemicals have adverse biochemical and physiological effects on organisms and can ultimately cause disturbances in ecosystems. It is therefore important that sensitive techniques are available to monitor their presence and persistence in the environment be monitored. We are pursuing the possibility of developing modified esterase activity in aquatic snails as a potential biomarker for the detection of organophosphate and carbamate pesticides in contaminated waters. We have previously reported that exposure in vivo of the aquatic snail Lymnaea natalensis to a number of organophosphorus and carbamate pesticides causes inhibition of esterase activity to varying degrees in a pesticide and esterase substrate specific manner. Here we report on the effects of two commonly used pesticides, dimethoate and carbaryl in vitro, on the esterase activity of an aquatic snail L. natalensis. Post mitochondrial fractions were prepared from adult L. natalensis bred in outdoor cement aquaria. Esterase activity was measured in the presence of various concentrations of dimethoate or carbaryl. Our results showed a non-linear, but dose dependent, inhibition of esterase activity with both pesticides using 5 different substrates which were used to differentiate (choline and non-choline) esterase activity. Esterase activity was reduced significantly, depending on the substrate used, in the presence of both dimethoate (11 "10 - 78'Yo) and carbaryl (l5'Yo-93"1o). Both dimethoate and carbaryl showed similar IC50 values but variations were noted depending on the substrate used to determine esterase activity. Dimethote was, however, the mor'e potent of the two pesticides as shown by the its lower IC50 values when compared to carbaryl. Our data suggests there is a potential for the use of esterase activity in L. natalensis as a biomarker of organophosphorus and carbamate pesticides
Description
Presented in October 2002.
Keywords
Cabaryl, Dimethoate, Esterases, Lymnaea Natalensis, In Vitro Effect