Application of the DNA Alkaline Unwinding Assay to Detect DNA Strand Breaks in Marine Bivalves

摘要

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 characterize the sensitivity and specificity of the DNA unwinding method to detect DNA strand breaks in bivalve tissues. Increased DNA strand breaks resulted from acute exposures to sublethal concentrations of genotoxic agent N-methyl-N'-nitro-N-nitrosoguanidine, but were not persistent for more than 48 h. Acute or chronic (continuous 7-day) exposures of mussels to sublethal concentrations of copper (not generally considered to be genotoxic) did not result in increased DNA strand breaks.