DNA strand breaks, cytochrome P-450-dependent monooxygenase system activity and levels of chlorinated biphenyl congeners in the pyloric caeca of the seastar (Asterias rubens) from the North Sea

Seastars (Asterias rubens L.) were collected at sampling locations in different areas along transects radiating into the southern North Sea, representing areas impacted by contaminants to different degrees. Strand breakage in DNA isolated from tissue of the pyloric caeca was measured by the alkaline unwinding assay, modified to allow for the isolation of highly intact DNA. The interpretation of the results is based on the incidence of DNA strand breaks (expressed as the double : total DNA ratio or F value, indicating the degree of double-strandedness). The cytochrome P-450 concentration and the benzo [a] pyrene (BaP) hydroxylase activity were measured in microsomal fractions of the pyloric caeca. The chlorinated biphenyl (CB) congeners in tissue samples from the digestive gland were determined by temperature-programmed gas-chromatography, with a CPSil8 capillary column as the stationary phase, hydrogen as the carrier gas and Ni-63-electron capture detection. Areas where seastars showed different DNA integrity could be described. The highest integrity (0.75 < F < 0.85) was found in the off-shore reference sites of the Dogger Bank and Southern Bight. The mean F value in seastars from most sampling locations varied between 55 and 75%. The lowest DNA integrity (0.35 < F < 0.55) was found in specimens obtained from sampling locations near the river Rhine delta, along the Dutch coast and at two expected uncontaminated offshore areas. The BaP hydroxylase activity was relatively high near the mouth of the rivers Rhine and Scheldt, but also at a supposedly clean site near Dogger Bank. The concentration of CB congeners in the pyloric caeca of seastars decreased along transects radiating into the southern North Sea from the coastal areas of the Netherlands; the highest concentrations were in the nearby coastal areas and the lowest were in the open sea sampling locations. The data indicate that there might be a relationship between pollution from the Rivers Rhine, Meuse and Scheldt and the incidence of DNA strand breaks and/or BaP hydroxylase activity.