Bioaccumulation and detoxification responses in the scallop Chlamys farreri exposed to tetrabromobisphenol A (TBBPA)

• TBBPA accumulation in gill and digestive gland was measured.
• TBBPA significantly inhibited AhR pathway and Pgp-mediated transport.
• CYP3A and CYP4 showed time-dependent responses to TBBPA exposure.
• GST and UGT play essential role in phase II metabolism of TBBPA.
• SULT may only react on the intermediate active substances of TBBPA produced by phase I metabolic process.

Tetrabromobisphenol A (TBBPA) is currently the most widely used brominated flame retardant (BFR). In this study, the bioaccumulation of TBBPA and its consequent detoxification responses were examined in the scallop Chlamys farreri over 10 days’ exposure. Chemical analysis showed that C. farreri absorbed TBBPA rapidly and an approximate steady state was achieved within 6 days. The mRNA expression levels of three important genes involved in aryl hydrocarbon receptor (AhR) pathway were down-regulated upon TBBPA exposure. Both CYP3A and CYP4 showed time-dependent responses to TBBPA exposure. Glutathione-S-transferase (GST) activity and gene expression level, and UDP-glucuronosyltransferase (UGT) activity were increased in time- and dose-dependent manners, confirming their role in the phase II metabolism of TBBPA. The TBBPA-elicited down-regulation of the P-glycoprotein (Pgp) gene was observed in all treatments. This study provides a preliminary basis for studying TBBPA detoxification mechanisms of marine bivalves.