Upper Midwest Environmental Sciences Center
Acetylcholinesterase inhibition in the threeridge mussel (Amblema plicata) by chlorpyrifos: implications for biomonitoring
Doran, W. J., Cope, W. G., Rada, R. G., and Sandheinrich, M. B., 2001, Acetylcholinesterase inhibition in the threeridge mussel (Amblema plicata) by chlorpyrifos: implications for biomonitoring: Ecotoxicology and Environmental Safety, v. 49, p. 91-98.
The effects of chlorpyrifos, an organophosphorus insecticide, were examined on the activity of the nervous system enzyme acetylcholinesterase (AChE) in the threeridge mussel Amblema plicata in a 24-day laboratory test. Thirty-six mussels in each of seven treatments (18 mussels per duplicate) were exposed to chlorpyrifos (0.1, 0.2, 0.3, 0.6, and 1.2 mg/L), a solvent (acetone), and a solvent-free (well water) control for 12, 24, or 96 h. The activity of AChE was measured in the anterior adductor muscle of eight mussels from each treatment after exposure. To asses potential latent effects, six mussels from each treatment were removed after 24 h of exposure and transfered to untreated water for a 21-day holding period; AChE activity was measured on three mussels from each treatment at 7 and 21 days of the holding period. The activity of AChE in chlorpyrifos-exposed mussels did not differ from controls after 12 or 24h of exposure (t- test, P>0.05), but was significantly less than controls after 96 h (t-test, P=0.01). AChE activity did not vary among mussels at 24 h of exposure (i.e., Day 0 of holding period) and those at Day 7 and Day 21 of the holding period. Overall changes in AChE activity if mussels during the test were unrelated to individual chlorpyrifos concentrations and exposure times (repeated measure ANOVA; (P=0.06). A power analysis revealed that the sample size must be increased from 2 to 5 replicates (8 to 20 mussels per time interval and test concentration) to increase the probability of detecting significant differences in AChE activity. This calculated increase in sample size has potential implications for future biominitoring studies with chlorpyrifos and unionid mussels.
acetylcholinesterase, chlorpyrifos, biominitoring, mussel, unionidae