BIOTRANSFORMATION ENZYMES AND THEIR INDUCTION BY BETA-NAPHTHOFLAVONE DURING EMBRYOLARVAL DEVELOPMENT IN SALMONID SPECIES

Biotransformation enzymes were studied in vitro in subcellular fractio ns from early life stages of Arctic charr (Salvelinus alpinus), whitef ish (Coregonus lavaretus) and grayling (Thymallus thymallus). Each spe cies showed an increase in 7-ethoxyresorufin O-deethylase (EROD), NADP H-cytochrome c reductase and glutathione S-transferase (GST) throughou t embryolarval development. Significant increase in enzymatic activiti es seemed to occur around hatching period in the three species, especi ally for EROD activity. Interspecies comparison led to different resul ts depending on how activities were expressed (specific, per individua l, or normalized with respect to the size of individual). Arctic charr embryos and eleuteroembryos exposed for 72 h to 0.12 ppm beta-napthof lavone showed a sixfold induction of EROD activity whereas NADPH-cytoc hrome c reductase and GST activities were not modified.