Biological effects of contaminants: Measurement of DNA adducts in fish by 32P-postlabelling

This document describes in detail the 32P-postlabelling method and its application to fish. Several recent studies have shown that the 32P-postlabelling method can be used to detect and measure the levels of DNA modified by large, hydrophobic aromatic compounds in teleosts. Moreover, the levels of hepatic DNA adducts in wild fish positively correlate with the concentrations of polycyclic aromatic compounds (PACs) present in marine sediments in several cases, and a strong positive correlation has been observed between sediment concentrations of PACs and the prevalence of neoplastic lesions in liver of marine flatfish. Laboratory studies with model PACs and sediment extracts also have shown that the PAC-DNA adducts formed are persistent and have chromatographic characteristics similar to DNA adducts detected in wild fish. These findings suggest that the levels of hepatic DNA adducts found in fish tissues can function as molecular dosimeters of exposure to potentially genotoxic environmental contaminants, such as high molecular weight PACs. The 32P-postlabelling assay has been used as a marker of exposure to potentially genotoxic contaminants in environmental monitoring studies, such as NOAA's National Status and Trends (NS&T) Program and in the Bioeffects Surveys of NOAA's Coastal Ocean Program.