DNA STRAND BREAKS, CYTOCHROME P-450-DEPENDENT MONOOXYGENASE SYSTEM ACTIVITY AND LEVELS OF CHLORINATED BIPHENYL CONGENERS IN THE PYLORIC CECA 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. Str and breakage in DNA isolated from tissue of the pyloric caeca was meas ured by the alkaline unwinding assay, modified to allow for the isolat ion of highly intact DNA. The interpretation of the results is based o n the incidence of DNA strand breaks (expressed as the double : total DNA ratio or F value, indicating the degree of double-strandedness). T he cytochrome P-450 concentration and the benzo [a] pyrene (BaP) hydro xylase activity were measured in microsomal fractions of the pyloric c aeca. The chlorinated biphenyl (CB) congeners in tissue samples from t he digestive gland were determined by temperature-programmed gas-chrom atography, with a CPSil8 capillary column as the stationary phase, hyd rogen as the carrier gas and Ni-63-electron capture detection. Areas w here seastars showed different DNA integrity could be described. The h ighest integrity (0.75 < F < 0.85) was found in the off-shore referenc e sites of the Dogger Bank and Southern Bight. The mean F value in sea stars from most sampling locations varied between 55 and 75%. The lowe st DNA integrity (0.35 < F < 0.55) was found in specimens obtained fro m sampling locations near the river Rhine delta, along the Dutch coast and at two expected uncontaminated offshore areas. The BaP hydroxylas e activity was relatively high near the mouth of the rivers Rhine and Scheldt, but also at a supposedly clean site near Dogger Bank. The con centration 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 near by coastal areas and the lowest were in the open sea sampling location s. The data indicate that there might be a relationship between pollut ion from the Rivers Rhine, Meuse and Scheldt and the incidence of DNA strand breaks and/or BaP hydroxylase activity.