Biotechnology and pollution monitoring: Use of molecular biomarkers in the aquatic environment

Abstract

Abstract Metals and organic contaminants, present in the water‐column, sediment or food, are readily accumulated by aquatic organisms. Exposure to and toxic effects of contaminants can be measured in terms of the biochemical responses of the organisms—so‐called molecular biomarkers. The applications, advantages and limitations of such diagnostic and prognostic tests are discussed. The hepatic biotransformation enzyme cytochrome P4501A in fish and other vertebrates is specifically induced by organic contaminants such as aromatic hydrocarbons, PCBs and dioxins, and is used as a biomarker of exposure to organic pollution. Its induction is involved in chemical carcinogenesis via catalysis of the covalent binding of organic contaminants to DNA (DNA‐adducts). P4501A‐induction, measured as enzyme activity, enzyme amount, or mRNA, has been successively used in many field studies, involving some 27 fish species, in USA and Europe. Metallothioneins (MTs) bind and are specifically induced by metals such as Cd, Hg, Ag and Cu, and are used in both vertebrates and invertebrates as a biomarker for metal exposure. Bulky, hydrophobic DNA‐adducts are used as a biomarker for organic contaminant damage. MTs (measured at protein and mRNA levels) and DNA‐adducts ( 32 P‐postlabelling method) have been applied less extensively in the field than P4501A, but the results are similarly encouraging. Biomarkers should be used as part of an integrated programme of pollution monitoring, involving also general measurements of biological damage and animal health, and analysis of chemical contaminants in the biota and environment. Commercial availability of antibodies and mRNA probes will accelerate the widespread application of these molecular biomarkers.