METABOLIC-ACTIVATION OF CARCINOGENIC AROMATIC-AMINES BY FISH EXPOSED TO ENVIRONMENTAL-POLLUTANTS

Activation of arylamines to mutagenic metabolites by hepotic S9 fracti ons has been evaluated as a biomaker of fish exposure to pollutants, u sing gilthead seabream (Sparus aurata), a valuable fish species from t he Spanish South Atlantic littoral, as model organism. To obtain maxim al sensitivity to the mutagenic action of aromatic amines, a strain of Salmonella typhimurium overproducing O-acetyltransferase was used. Fi sh were treated with Aroclor 1254, pesticides (malathion and dieldrin) , or copper(II), and compared to Aroclor 1254-treated rats. The promut agen activation capabilities of the S9 fractions were further characte rized by studying the effect of two monooxygenase inhibitors, alpha-na phthoflavone, a well known inhibitor of aromatic hydrocarbon-inducible forms of cytochrome P450, and methimazole, a substrate for the flavin monooxygenase (FMO) system. This study shows that 2-aminoanthracene ( 2-AA) and 2-acetylaminoflvorene (AAF) activation by gilthead liver is enhanced by treatment of fish with different xenobiotics. The catalyst responsible for this enhanced activation appears to be different for each promutagen and, at least for 2-AA, dependent on the type of xenob iotic. The data presented indicate further that treatment of gilthead with some compounds, such as malathion and dieldrin, enhances the acti vation of aromatic amines in liver, without inducing ethoxyresorufin-O -deethylase activity. The use of acetyltransferase-overproducing bacte ria appears to be a useful tool in the study of arylamine activation b y fish liver, where biotransformation capability is lower than in mamm als. (C) 1995 Wiley-Liss, Inc.