Effects of BαP and TBBPA on multixenobiotic resistance (MXR) related efflux transporter activity and gene expressions in gill cells of scallop Chlamys farreri.

The multixenobiotic resistance mechanism (MXR) provides aquatic organisms with the capacity to adapt to polluted environments, which can be inhibited by chemosensitizers. In the present study, the effect of two typical marine persistent organic pollutants, benzo(a)pyrene (BaP) and tetrabromobisphenol A (TBBPA), on the most relevant ABC transporters, ABCB1, ABCC1, and ABCG2 of scallop Chlamys farreri was tested. MXR transporter efflux activity of cultured gill cells of the scallops was evaluated by measuring the intracellular fluorescent intensity of Calcein-AM and rhodamine 123 with flow cytometry. The results showed that ABCB1 and ABCC1 transporters demonstrated increased activity compared with ABCG2 in mediating MXR efflux activity. BaP and TBBPA were able to suppress the efflux transporter activity of ABC transporters significantly, of which BaP revealed block effects by acting on the ABCB1 transporter. Additionally, exposure of BaP and TBBPA only significantly upregulated the expression level of ABCC1 gene. This study demonstrated the promising utility of efflux transporter activity in conjunction with biomarkers such as mRNA levels in identification of chemosensitizer.