Genotoxic hazard of pollutants in cetaceans: DNA damage and repair evaluated in the bottlenose dolphin (Tursiops truncatus) by the Comet Assay

Single cell gel electrophoresis (or Comet Assay) was used for evaluation of the in vitro genotoxicity of hydrogen peroxide (used as a positive control ), polychlorinated biphenyls is (PCBs) (Aroclor 1254) and methyl mercury ch loride, in isolated bottlenose dolphin leukocytes. Results showed that hydr ogen peroxide and methyl mercury induced DNA strand breakage in a dose-depe ndent manner, while PCBs did not induce a clear dose-effect response at the Iom doses investigated. Efficiency in repairing DNA breakage induced by me thyl mercury was also evaluated. Findings demonstrated that dolphin cells c ure characterized by higher efficiency in DNA repair when compared to human leukocytes. The observed resistance to methyl mercury toxicity in dolphins was hypothesized to be a defence strategy developed to combat high dietary exposure and compensate for limited capacity to excrete persistent polluta nts. (C) 2001 Elsevier Science Ltd. All rights reserved.