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(W/MF137) Acetylcholinesterase activity in an intertidal copepod as a tool for environmental diagnosis. Synergistic effects of xenobiotics. Forget, Joëlle1, Bocquené, Gilles2, Pavillon, Jean-François 3, Leboulenger, François1, 1 2 3 ABSTRACT- In that study, we have purified a single form of acetylcholinesterase (AChE) from the copepod Tigriopus brevicornis (Crustacean) and used the AChE activity as an exposure biomarker to investigate the biological effects of contaminants present in two compartments of coastal ecosystems (seawater and sediment). Both a field and a laboratory study were conducted, the first one in the estuary of the river "Vilaine" (Britanny, France) and the second on dredged muds originating from various French harbours. The "Vilaine" estuary was selected for two essential reasons : 1/ the catchment area of this river drains one third of Brittany region which is primarily devoted to agriculture and subsequently heavely contaminated by pesticides ; 2/ Tigriopus brevicornis is present in intertidal pools all around the "Vilaine" mouth, thus allowing its use as contamination bioindicator. Measurements of AChE activity in Tigriopus and chemical analysis of trace compounds in water were carried out simultaneously during one year. The second study was led within the framework of the program PNETOX II. Eleven sites distributed on the North Sea, Atlantic and Mediterranean French coasts were sampled, and the contents of HAPs, PCBs, TBTs and heavy metals were measured in each sample of dredged muds. A very high sensitivity of the copepod AChE was observed. Significant differences between AChE activity level were measured according to stations localised in the "Vilaine" estuary and according to the sediments sampled in the French harbours. These activities were in good agreement with contamination levels. Synergistic effects were notable in a majority of multiple exposure cases, reducing the AChE activity by at least 50%. These studies enable us to propose AChE activity in Tigriopus brevicornis as an exposure biomarker useful to investigate possible synergy in neurotoxic effects of pollutants in the marine environment. Key words: Biomarker, AChE activity, Copepod, Synergistic effects |
