Comparative studies of hepatic xenobiotic metabolizing and antioxidant enzymes in different fish species

Seven marine and five freshwater fish species were compared in terms of their activities of eight liver xenobiotic and oxyradical metabolizing enzymes namely those of the mammalian [Ah] gene battery, viz. cytochrome P450 1A (7-ethoxyresorufin-O-deethylase-EROD), glutathione S-transferase, UDP glucuronosyl transferase, DT-diaphorase, aldehyde dehydrogenase, and the antioxidant enzymes catalase, glutathione peroxidase and Superoxide dismutase. A number of these enzyme activities are in use or have been proposed for use as biomarkers for aquatic pollution. Inter-species variations were observed in all enzyme activities. EROD exhibited the greatest variation (> 300-fold), followed by putative DT-diaphorase (20–100-fold). In most other enzyme activities the interspecies variations were in the order of 5- to 10-fold. The data from this comparative study of biomarker enzymes in different fish species provide a valuable basis for future enzyme regulation studies and biomonitoring investigations.