FORMATION OF DNA-ADDUCTS IN THE GILL TISSUE OF MYTILUS-GALLOPROVINCIALIS TREATED WITH BENZO[A]PYRENE

The formation of DNA adducts was evident after treatment of spawned or resting Mediterranean mussels (Mytilus galloprovincialis Lmk.) with 0 .5-100 mu g/l of benzo[a]pyrene for 2 and 3 days. Reference DNA sample s, in vitro radiolabelled with 0.5, 5, 50 mu M H-3-anti (+/-)-B[a]P-di ol-epoxide, were initially used to compare two DNA purification proced ures. Following a standard four-step extraction starting with phenol, in comparison to a simplified single-step extraction without phenol, w e obtained lower yields of bound radioactivity in the reference DNA sa mples. After simplified DNA purification and nuclease P1 enhanced P-32 -postlabelling assay we detected a reproducible dose-dependent increas e of a specific spot in gills of mussels treated with B[a]P, although this spot was present in low amounts. Short (2 days) and prolonged (27 days) pretreatment of mussels with a polychlorinated biphenyl mixture , Aroclor 1254, did not increase the levels of B[a]P-related adducts. On the whole, these results indicate the formation of detectable amoun ts of DNA reactive intermediates in gills of mussels treated with B[a] P. Although the pathway of formation and the molecular identity of the specific adducts remain unclear, their presence suggests that polycyc lic aromatic hydrocarbons may cause genetic damage in marine mussels.