Formation and persistence of DNA adducts in the liver of brown bullheads exposed to benzo[a]pyrene.

The formation and persistence of benzo[a]pyrene (BP)-DNA adducts in the liver of brown bullheads (Ictalurus nebulosus) treated with the hydrocarbon (20 mg/kg body wt, i.p.) was investigated using the 32P-postlabeling assay. The highest level of covalent binding of BP to liver DNA (188 fmol BP adducts/mg DNA) was observed 25-30 days following treatment. After 70 days, the adduct level in liver DNA had declined to approximately 26% of the maximum adduct level. One major BP-DNA adduct and several minor ones were detected in the liver. The major adduct co-chromatographed with anti-BP-7,8-diol-9,10-epoxide-deoxyguanosine (anti-BPDE-dGuo) adduct. The data suggest that brown bullheads metabolically activate BP by the same mechanism as the mammalian systems susceptible to carcinogenic effects of the hydrocarbon.