APPLICATION OF THE DNA ALKALINE UNWINDING ASSAY TO DETECT DNA STRAND BREAKS IN MARINE BIVALVES

DNA alkaline unwinding methods were used to detect DNA strand breaks in tissues of marine bivalves following field and laboratory exposures and subsequent recoveries in the laboratory. Field deployments of mussels (Mytilus edulis) or oysters (Crassostrea virginica) into two highly contaminated urban estuaries (New Bedford Harbor, Massachusetts, and Elizabeth River, Virginia, respectively) resulted in significantly increased DNA strand breaks in gill tissues. DNA strand breaks did not persist in tissues from oysters that were deployed in the Elizabeth River and then allowed to recover in the laboratory for 7-10 days. Laboratory studies were conducted to characterize the sensitivity and specificity of the DNA unwinding method to defect DNA strand breaks in bivalve tissues. Increased DNA strand breaks resulted from acute exposures to sublethal concentrations of the genotoxic agent N-methyl-N'-nitro-N-nitrosoguanidine, but were not persistent for