Effects of organophosphate and carbamate pesticides on acetylcholinesterase and choline acetyltransferase activities of the polychaete Nereis diversicolor.
A toxicity test for organophosphates (OP) and carbamates (C) was improved with the adult ragworm Nereis diversicolor. Animals were maintained in U-shaped glass tubes of 4-mm inner diameter fixed vertically on a plastic plate and placed in glass aquaria. Each tank was covered with glass in order to reduce evaporation and heat dissipation. Temperature varied between 15 and 16 degrees C and salinity was constant (34 per thousand) during the entire length of the experiment. Experiments were performed with a fixed day length of 12 h and seawater was gently aerated. The maintenance system allowed the administration of OP and C compounds via the seawater. An acclimatization period of 48 h was not sufficient to accomodate worms to their artificial burrows; accordingly, we chose to acclimate worms for a week before beginning the exposure. Choline acetyltransferase (ChAT) activity was very low and was not significantly modified by two OP compounds: malathion and parathion-ethyl. ChAT is not a target for these pesticides and should not be used for future studies about OP and C toxicity. On the other hand, inhibitory effects on acetylcholinesterase (AChE) activity were determined at concentrations of 10(-6) M for three OP compounds-malathion, parathion-ethyl, and phosalone-and a carbamate pesticide-carbaryl. We measured only short-term effects and no cumulative effect was determined, the maximum percentage of AChE activity inhibition being between 2 (carbaryl) and 7 (OP compounds) days after exposure and then remaining stable. Mortality occured only after a period of intoxication of 14 days. N diversicolor, which can be easily maintained at the laboratory, seems to be a good candidate for future laboratory studies to test the toxicity of other pollutants.
Scaps
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Laboratoire de Phylogénie moléculaire des Annélides, Université des Sciences et Technologies de Lille, Biologie Animale, Batiment SN3, 2ième Etage, F-59655 Villeneuve d'Ascq Cédex, France.
Demuynck
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Descamps
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Dhainaut
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D000818:Animals; D002219:Carbamates; D002795:Choline O-Acetyltransferase / Q000037:antagonists & inhibitors*; D002800:Cholinesterase Inhibitors / Q000633:toxicity*; D007306:Insecticides / Q000633:toxicity*; D009943:Organophosphorus Compounds; D011077:Polychaeta / Q000187:drug effects*; D018675:Toxicity Tests; D014874:Water Pollutants, Chemical / Q000633:toxicity*
D002219:Carbamates; D002800:Cholinesterase Inhibitors; D007306:Insecticides; D009943:Organophosphorus Compounds; D014874:Water Pollutants, Chemical; D002795:Choline O-Acetyltransferase