Oxidative stress and macromolecular damage caused by pollutants and repair of oxidised DNA in the gill of \(Mytilus\) \(edulis\)

Mussels (\(Mytilus\) \(edulis\)) are able to bioaccumulatc many chemicals including potential genotoxicants in their soft tissues. Certain genotoxicants damage DNA and other macromolecules via production of reactive oxygen species. Genotoxicants can also interfere with DNA repair processes in the cell. This project examined the potential of such agents to produce oxidative damage in gill of mussels both under laboratory and field exposures. Indigenous mussels from a polluted (New Brighton) and a reference (Llandudno) estuary were collected in 2005-2006 and were examined for DNA damage, lipid peroxidation, glutathione depletion and effects on repair of DNA damage (8-oxo-deoxyguanosine). From the parameters tested, 8-oxodeoxyguanosine levels (assessed using the formamidopyrimidine glycosyJasemodified comet assay) were higher in mussels from the polluted site only during summer whereas repair (cutting) of 8-oxo-deoxyguanosine in DNA was lower in the polluted site at most collection times. Lipid peroxidation varied according to season. Subsequent maintenance of mussels under clean laboratory conditions for one month abolished the differences between sites in most cases for all the parameters. \(In\) \(vivo\) exposure of mussels to the metals hexavalent chromium and cadmium also verified DNA damage via reactive oxygen species and the suppression of DNA repair mechanisms (towards either 8-oxo-deoxyguanosine or ethenoadenosine) was shown to be a potential contributor to genotoxicity. Overall, mussels were shown to be sensitive to the genotoxic potential of different aquatic pollutants. The study emphasises the need to measure specific oxidative DNA lesions rather than a simple measurement of frank DNA strand breaks and supports the strategy of "recovery" experiments to determine recoverable, field-induced damage to DNA and other macromolecules