DNA adducts in perch ( Perca fluviatilis) from a creosote contaminated site in the River Ångermanälven, Sweden

Abstract

Levels of hepatic DNA adducts, analysed by 32P-postlabelling, histopathological lesions and organosomatic indices, were measured in perch ( Perca fluviatilis). The fish were caught at five sites in the river Ångermanälven, Sweden: one site known to be contaminated with creosote, sites downstream from the contaminated site and a reference site upstream. Perch were also caught at a long-distance reference site. The level of DNA adducts in fish from the creosote-contaminated site was 6.8±4.1 nmol mol −1 nucleotides compared to 0.21±0.21 nmol mol −1 nucleotides in fish from the long-distance reference site. The adduct level was also significantly increased compared to adduct levels in fish from the local reference site. Hepatocellular degeneration and macrophage aggregates were observed but did not correlate with a specific site in the river. No effects on organosomatic indices that correlated with distance from the contaminated site were observed. In the laboratory, perch were exposed to an organic solvent extract prepared from sediment collected at the creosote-contaminated site or to benzo(a)pyrene (BaP) by oral administration. Perch treated with the extract had adduct patterns very similar to those observed in perch from the contaminated field site. Two diagonal zones including 10–12 adduct spots were observed on the autoradiograms. One adduct was tentatively identified by co-chromatography with a 32P-labelled standard of 7 R,8 S,9 S-trihydroxy, 10 R-( N 2-deoxyguanosyl 3′-phosphate)-7,8,9,10-tetrahydrobenzo(a)pyrene (BaPDE-dG-3′p) in two different solvent systems. Autoradiograms derived from the BaP-exposed perch showed one major adduct and several less intense spots. The major BaP adduct had the same chromatographic properties as the standard BaPDE-dG-3′p adduct. This study shows that 32P-postlabelling analysis of DNA adducts in perch can be used as a sensitive indicator of exposure to genotoxic polycyclic aromatic hydrocarbons, and that comparison of DNA adduct patterns of fish exposed in the field and laboratory can be used to determine the responsible source of pollutants.