Metabolites analysis, metabolic enzyme activities and bioaccumulation in the clam Ruditapes philippinarum exposed to benzo[a]pyrene

• We measured the contents of five B[a]P metabolites in gills and digestive glands.
• B[a]P could activate metabolic system except GST in the clams.
• B[a]P entering the body of clam tended to accumulate rather than being metabolized.
• Both digestive gland and gill played important roles in B[a]P metabolism.
• More B[a]P and its metabolites accumulated in digestive glands than in gills.

A study was performed on clams (Ruditapes philippinarum) exposed to 0.03, 0.3 and 3 μg/L benzo[a]pyrene (B[a]P) for 21 days. B[a]P metabolite contents, activities of aryl hydrocarbon hydroxylase (AHH), 7-ethoxyresorufin O-deethylase (EROD), epoxide hydrolase (EH), dihydrodiol dehydrogenase (DD), glutathione-S-transferase (GST), sulfotransferase (SULT) and uridinediphosphate glucuronyltransferase (UGT) and B[a]P bioaccumulation were assayed in gills and digestive glands. Results showed that the order of B[a]P phase I metabolite contents was 9-hydroxy-B[a]P>B[a]P-1,6-dione>B[a]P-7,8-dihydrodiol, and the concentration of B[a]P-7,8-dihydrodiol sulfate conjugates was higher than that of B[a]P-7,8-dihydrodiol glucuronide conjugates. B[a]P accumulation and the activities of AHH, EROD, EH, DD, SULT and UGT increased first and then reached equilibrium. GST activity was induced first and then depressed. The concentration of B[a]P was far higher than that of its metabolites. Besides, there were no significant differences between enzyme activities in gills and those in digestive glands. These results provided information on B[a]P metabolic mechanism in bivalve and scientific data for pollution monitoring and food security.