THE APPLICATION OF THE P-32 POSTLABELING ASSAY TO AQUATIC BIOMONITORING

The aquatic environment is known to contain a variety of natural and a nthropogenic compounds that are capable of interacting with the geneti c material of aquatic organisms. The increases in the levels of these anthropogenic contaminants, associated with widespread industrialisati on, has led to the requirement for reliable methodologies to monitor t heir potential impact upon exposed aquatic organisms. Of the molecular techniques currently available, the P-32-postlabelling assay for the detection of DNA adducts offers considerable potential for the qualita tive and quantitative assessment of genotoxin exposure. Here we descri be several studies in which the technique was adapted for evaluation i n two marine bioindicator species the common mussel Mytilus edulis and the flatfish Limanda limanda. Laboratory studies in which M. edulis s pecimens were exposed to 2-aminofluorene and 4-nitroquinoline 1-oxide confirmed the species' capacity to form genotoxin-related adducts. How ever, in further studies, no exposure-related adducts could be detecte d in M. edulis specimens placed in mesocosms containing environmentall y realistic levels of anthropogenic contaminants. Biologically signifi cant levels of adducts were detected in L. limanda specimens exposed t o sediment bound contaminants under controlled conditions, although th e levels did not appear to be statistically significant. An in situ st udy in which adduct levels were determined in L. limanda specimens fro m two sites of contrasting contamination levels proved to be more conc lusive. The results were both biologically and statistically significa nt, suggesting that adduct levels could well be related to the levels of sediment-bound contaminants. Together the studies confirmed that th e determination of the levels of DNA adducts could be used as indicato rs of the exposure of aquatic organisms to environmental genotoxins. ( C) 1997 Elsevier Science B.V.