Investigation of EROD, CYP1A immunopositive proteins and SOD in haemocytes of Chamelea gallina and their role in response to B[a]P.

CYP1A sub-family represents themain form of cytochrome P450 involved in benzo[a]pyrene (B[a]P) detoxification, but there are no clear evidences about its presence in invertebrates. 7-Ethoxy resorufin O-deethylase (EROD) activity is strictly related to CYP1A presence, at the same time P450-dependent oxidative metabolism leads to reactive oxygen species (ROS) production, thought to be an importantmechanism of pollutant-mediated toxicity in aquatic organisms. Superoxide dismutases (SODs), EROD and CYP1A activities and/or expressionswere detected in haemocytes of pooled clams (Chamelea gallina) and cell-free haemolymph after 24 h, 7 and 12 days of exposure to 0.5 mg/L of B[a]P. After 24 h, B[a]P content was maximum in whole tissues. A 61 kDa band was recognized in haemocytes and cell-free haemolymph by polyclonal anti-fish CYP1A, while 53.5 and 63.8 kDa CYP1A immunopositive proteins were discriminate without differences of expression. Differently, EROD, MnSOD activity/expression and ECSOD expression decreased in haemocytes and haemolymph. C. gallina immune system presents an interesting response dose/time exposure of B[a]P and the 7 days condition highlights themajor effects of xenobiotic action. The identification of basal EROD levels supports the possible presence of the CYP1A, never identified in C. gallina andmore specifically never isolated in immune cells, as confirmedby CYP1A-immunopositive proteins identification.