Immunochemical investigation of CYP 1A and Mn-SOD in Scapharca inaequivalvis exposed to benzo[a]pyrene

Benzo[a]pyrene among PAHs is the most pollutant investigated for its toxicity and carcinogenicity. In vertebrates, the CYP1A subfamily members represent the main forms of P450 associated with exposures to PAHs and the P450 dependent oxidative metabolism of B[a]P leads to the production of ROS (mostly O2 -). About this, SOD represents an appropriate response to oxidative injury as a mechanism of protection against increasing ROS levels. This research was focused on the study of the induction of CYP 1A and Mn-SOD, involved in detoxification processes, in hepatopancreas of Scapharca inaequivalvis (Adriatic bivalve) exposed to B[a]P. Scapharca specimens were exposed to 0.44 mg B[a]P. Samples were taken at 0 (control), 12, 24, 36 h of exposure. The B[a]P concentration were analyzed in samples in soft tissues of pooled animals by HPLC. CYP 1A1 and Mn-SOD, were detected in hepatopancreas, by western blot analysis after SDS-PAGE. Immunopositive bands were semi-quantified by Quantity One Software. B[a]P content showed rapid increase (12 h) followed by a similar rapid decrease. CYP 1A (49 kDa) showed major levels after 36 h of B[a]P exposure. The Mn-SOD imunopositive band (26 kDa) were less significantly expressed after 36 h of exposure only with respect to the control group. In conclusion the increase of CYP 1A levels in Scapharca suggests an active biotrasformation mechanism due to the MFO system. The decrease in Mn-SOD expression might be associated with the disease processes. The induction of CYP 1A in presence of B[a]P might be a reliable and sensitive biomarker of PAH exposure in aquatic organisms. (Supported by MIPAF contr. No. 6C66) Phagocytic