Detection of micronuclei in haemocytes of zebra mussel and great ramshorn snail exposed to pentachlorophenol

The frequency of micronuclei (MN) induced by pentachlorophenol (PCP) in haemocytes of zebra mussel, Dreissena polymorpha Pall. and great ramshorn snail, Planorbarius corneus L. was determined over a 14 days of exposure (sampling after 4, 7 and 14 days) under laboratory conditions. PCP doses for zebra mussel ranged from 10 to 150 microg/l, and for ramshorn snail from 10 to 450 microg/l. Micronuclei were detected after bisbenzimide fluorescent staining. Positive responses were observed in both species. The mean MN frequencies in treated mussels ranged between 0.69 and 7.50 per thousand, and between 2.07 and 13.80 per thousand in treated snails. The spontaneous MN levels in mussels averaged from 0.5 to 2.75 per thousand, and in snails from 1.56 to 2.00 per thousand. Our results suggest that haemolymph of both species represent an appropriate test tissue in environmental genotoxicity assessment.