Biotransformation enzymes and their induction by beta-naphthoflavone during embryolarval development in salmonid species

Biotransformation enzymes were studied in vitro in subcellular fractions from early life stages of Arctic charr (Salvelinus alpinus), whitefish (Coregonus lavaretus) and grayling (Thymallus thymallus). Each species showed an increase in 7-ethoxyresorufin O-deethylase (EROD), NADPH-cytochrome c reductase and glutathione S-transferase (GST) throughout embryolarval development. Significant increase in enzymatic activities seemed to occur around hatching period in the three species, especially for EROD activity. Interspecies comparison led to different results depending on how activities were expressed (specific, per individual, or normalized with respect to the size of individual). Arctic charr embryos and eleuteroembryos exposed for 72 h to 0.12 ppm beta-napthoflavone showed a sixfold induction of EROD activity whereas NADPH-cytochrome c reductase and GST activities were not modified.