Cytochrome P-450 levels and EROD activity in the Adriatic sturgeon (Acipenser naccarii, Chondrostei) and its induction by β-Naphthoflavone

The cytochrome P-450 enzyme system was studied in juvenile Acipenser naccarii (317.6+/-77 g initial live weight) reared at 23 degrees C and at a standard diet over a period of two month before using for experiments (final weight 546.3+/-148.8 g). While determining normal levels of cytochrome P-450 in liver tissue its induction was also studied under exposure to P-naphthoflavone (BNF; single dose at 80 mg/Kg body weight 52 hrs prior to sampling). Control fish showed total cytochrome P-450 levels in liver microsomes around 0.40+/-0.12 nmoles/mg proteins (n=12) while in BNF exposed fish the values increased significantly (0.55+/-0.11 nmoles/mg proteins; n=12). Ethoxyresorufin-O-deethylase (EROD) in control fish was 0.015+/-0.02 nmoles/mg proteins/min (n=12); it was found to be NADPH dependent and inducible by BNF. Western Immunoblotting and enzyme-linked-immunosorbent (ELISA) analyses of liver microsomes from untreated and BNF-exposed fish, using an antibody to rat cytochrome P-450 1A1 isoform (P-450 1A1)(Nelson et al.,1996) suggested the presence of a constitutive and BNF-inducible cytochrome P-450 homologous to rat P-450 protein. Measurement of cytochrome P-450-dependent EROD activity and P-450 1A1 expression levels in A. naccarii may be a useful parameter in monitoring environmental pollution.