DNA INTEGRITY AS A BIOMARKER OF MARINE POLLUTION - STRAND BREAKS IN SEASTAR (ASTERIAS-RUBENS) AND DAB (LIMANDA-LIMANDA)

DNA strand breaks in seastars and dab were measured by the time-depend ent partial alkaline unwinding of DNA followed by the determination of the double-stranded to total DNA ratio (F-value), Highest DNA integri ty (0.75 < F < 0.85) was found in seastars from offshore reference sit es, whereas lowest integrity (0.35 < F < 0.55) was identified in speci mens from the coastal zone and certain expected uncontaminated offshor e areas. A significant correlation existed between the fraction of dou ble-stranded DNA and the concentration of low chlorinated biphenyl con geners and with H atoms substituted in the meta and para position of t he biphenyl skeleton, Over 90% of double-stranded DNA was measured in dab obtained from pristine areas, with an average F-value in specimens from most sampling stations varying from 0.75 to 0.85, during August/ September 1991. Samples taken in May/June 1992 showed significantly lo wer DNA integrity (0.55 < F < 0.70 in most stations). A significant de crease of the integrity was established with increase in concentration of the congeners (tri to hepta chloro substituted and with or without a H atom substituted in the meta and para position).