Biochemical Evidence that Winter Flounder (Pseudopleuronectes americanus) have Induced Hepatic Cytochrome P-450-Dependent Monooxygenase Activities

Livers from winter flounder (Pseudopleuronectes americanus) captured near Mount Desert Island, Maine, showed marked variation in hepatic benzo[a]pyrene hydroxylase (AHH; from 0.04 to 8.8 FU∙min−1∙mg protein−1) and 7-ethoxyresorufin deethylase activities (7-ERD; from < 2 to 1165 pmol∙min−1∙mg protein−1), and a dichotomy in the effect of 7,8-benzoflavone (ANF) added in vitro on AHH activity. Based on this ANF effect, the flounder could be divided into two groups. One group had high 7-ERD activity and high AHH activity which was inhibited by ANF; the other group had low 7-ERD activity and low AHH activity which was enhanced by ANF. Sex, weight, length, liver weight, gonad weight/body weight ratio, and liver/body weight ratio explained only a small part of the variability in hepatic AHH activities. Electrophoretograms of hepatic microsomes from flounder treated with 1,2,3,4-dibenzanthracene (DBA) or 5,6-benzoflavone (βNF) showed a novel or enriched polypeptide species present near 57 000 daltons, in the molec...