32P-postlabelling analysis of hepatic DNA of benthic fish from European waters

Specimens of bottom-feeding dabs (Limanda limanda) were caught at several sites in the North Sea and English Channel. DNA was isolated from their livers and analysed by 32P-postlabelling using butanol extraction or nuclease P1 digestion to enhance sensitivity. From South West Patch (North Sea), 5/12 samples showed evidence of adducts with chromatographic properties on PEI-cellulose tic plates similar to those of adducts formed by aromatic carcinogens. Areas of radioactivity were also observed on chromatograms of 2/6 samples from Sylt I (North Sea). In contrast, 6 DNA samples from fish caught in the Channel showed no evidence of adducts. Liver DNA samples from sole (Solea sp.) from another site, Liverpool Bay, exhibited areas of radioactivity which were not evident in samples from a less-polluted area. Sea water from several sites war pumped through XAD resin columns; retained material was eluted with acetone and tested in the sublethal hydroids bioassay for the presence of toxic microc ontaminants. Only the samples from Liverpool Bay showed significant toxic effects. Supported, in parts, by a grant from the European Science Foundation.