Molluscan Esterase Activity As a Biomarker of Aquatic Pollution Caused By Monocrotophos.

Naik, Yogeshkumar S. (2013) Molluscan Esterase Activity As a Biomarker of Aquatic Pollution Caused By Monocrotophos. UNSPECIFIED.

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Presented at the ANCAP(African Network for Chemical Analysis of Pesticides)Conference in August 2004.,There are many analytical protocols for detecting levels of agrochemicals~inaquatic systems. Methods of analytical chemistry can provide information of the exact concentrations in water samples. However they do not provide information on the potentially harmful effects on the organisms in the aquatic environment as biological markers have been shown to. Biomarkers of environmental quality should be tested under field situations if they are to be accepted outside academic circles and become part of national policies in environmental monitoring programs. We have previously shown that exposure of Lymnaea natalensis to organophosphates caused dose and time dependent inhibition of esterase activity. Here we report on the effects of monocrotophos on esterase activity in L. natalensis under field simulated conditions.Juvenile snails reared outdoors were exposed to single dose (5, 12, 15, 20 and 25ppb) of monocrotophos dissolved in either Matopos (pristine) or Umguza (polluted)dam water for 1, 7 or 14 days. Water was not changed for the duration of exposure. Post mitochondrial supernatants of whole snail homogenates were used to measure esterase activity. Cholinesterase activity was measured using acetylcholine iodide while carboxylesterase activity was measured using a-naphthyl acetate and 4nitrophenyl acetate. Esterase activity was significantly reduced in a dose responsive manner for aIr substrates. The degree of inhibitioll. varied depen,ding on the water source. Our results also indicated a decrease with time in degree of inhibition of esterase activity, suggesting a recovery with time of the snails from pesticide poisoning. On comparing data from the two dams higher inhibitions were observed in snails exposed to Matopos dam water than those exposed to Umguza dam water. Umguza dam water is highly contaminated with industrial effluents and therefore expected to have a higher microbial load and increased pesticide decomposition rate when compared to Matopos dam water, which is relatively pristine. Our results have shown that esterase activity is very sensitive to presence of organophosphates with inhibitions of up to 92 % observed within 24 hours of exposure. Altered esterase activity therefore has a potential use as a biomarker for detecting organophosphatepollution in water samples.,African Network for Chemical Analysis of Pesticides

Item Type: Other
Uncontrolled Keywords: Molluscan Esterase,Water Pollution,Monocrotophos
Divisions: Universities > State Universities > National University of Science and Technology
Depositing User: Mr. Edmore Sibanda
Date Deposited: 30 Nov 2015 22:31
Last Modified: 30 Nov 2015 22:31

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