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2C - Biomarkers (TUP/83) Acetylcholinesterase activity of Daphnia magna Straus pre-exposed to diazinon: multigenerational chronic exposure analysis. Sánchez, M.1, Ferrando, M.D.1, Andreu, E.1, 1 University of Valencia, Valencia, Spain, Spain ABSTRACT- Effects of pesticides and other xenobiotics on the acetylcholinesterase activity of Daphnia magna have been noted in several studies, however no data are available which reflect the influence of diazinon during exposure over this enzymatic activity of several generations of the selected cladoceran. Diazinon is widely used organophosphate insecticide which is used extensively to control several plagues in lawns and crop plants, and has frequently been detected in non-target aquatic environments. Given the ecological importance of limnic invertebrates, their high susceptibility to many pollutants, and their common use as test species, the present knowledge of biochemical effects of toxicants in these groups is desproportionately small. There is obviously an urgent need for a better undestanding of the biochemical aspects of toxicology in these invertebrates. Cholinesterases represent the site of action for organophsphorus and carbamate pesticides. In spite the relevance of aquatic invertebrates in the ′′good health′′ of freshwater ecosystems, in the last years there were some studies about the effects of pesticides on their AChE activity. The aim of this study was to investigate whether the toxicity of diazinon organophosphate towards acetylcholinesterase activity of D. magna increases during subsequent generations when multiple generations (F0, F1-1st brood and F1-3rd brood) are exposed to sublethal concentrations of diazinon, or whether the population achieves greater tolerance. D. magna was exposed to several sublethal diazinon concentrations (0.05, 0.1, 0.5, 0.75 ng/L) plus the blank and acetone control in a semi-static system for 5 days. AChE activity ( Key words: multigenerational, Acetylcholinesterase, diazinon, Daphnia magna |
mol/min⋅mg prot) was evaluated after 8, 24, 48, 72, 96 and 120 hours pesticide exposure. Daphnids enzyme activity decreased as concentration of diazinon increased, and during exposure time.