TEMPORAL INDUCTION-PATTERN OF HEPATIC CYTOCHROME-P450 1A IN THERMALLYACCLIMATED DAB (LIMANDA-LIMANDA) TREATED WITH 3,3',4,4'-TETRACHLOROBIPHENYL (CB77)

Mature male dab (Limanda limanda) acclimated at 10 degrees and 16 degr ees C were orally administered a single dose of 0.5 mg/kg 3,3',4,4'-te trachlorobiphenyl (CB77). At both temperatures, levels of cytochrome P 450 1A (CYP1A) protein and 7-ethoxyresorufin O-deethylase (EROD) activ ity showed a two to six fold induction 40 days after CB77 treatment co mpared to control groups. Maximum responses of both EROD activity and CYP1A protein for the warm-acclimated fish were observed at 5 days aft er treatment. For the cold-acclimated fish a slow, progressive elevati on for both EROD activity and CYP1A protein was observed and maximum r esponses were measured 40 days after treatment. Absolute EROD activity and CYP1A protein levels of fish from both temperatures were equally high at 40 days after treatment. Since in the control groups EROD acti vity and CYP1A protein levels were higher in the cold-acclimated fish, the magnitude of induction was higher in the warm acclimated ones. Th e highest concentrations of CB77 in muscle of fish from both temperatu res were found at 5 and 10 days after treatment. The liver somatic ind ex (LSI) showed 1.5 fold significantly higher values for the fish accl imated at 10 degrees C. Copyright (C) 1996 Elsevier Science Ltd