GENOTOXICITY BIOMARKERS IN MYTILUS-GALLOPROVINCIALIS AS INDICATORS OFMARINE POLLUTANTS

Many substances pollute the marine environment. There is today a growi ng evidence on the increased risk of disease in marine organisms, espe cially fish, that inhabit contaminated waters. Different types of tumo urs have been evidenced in fish and shellfish populations. Different s hort-term biomarkers are available to predict the impact of carcinogen s on marine organisms. Their endpoints are different effects at the mo lecular and cellular level such as gene mutation, chromosome alteratio n and induction of DNA damage and repair. We have applied two differen t assays: alkaline elution to measure DNA single strand breaks and mic ronucleus assay as an index of a chromosomal damage. In order to selec t an aquatic organism as an indicator of water pollution by carcinogen ic agents, we have focused on the mussel. A program of validation of g enotoxicity was conducted in aquarium using DMBA. A time-dependence in crease of micronuclei was evident after the exposure to 100 ppb/animal . For alkaline elution the effect was 4 times the level of the control s. Experiments in the fields were conducted on adult specimens of Myti lus galloprovincialis collected from natural substrates. Our sampling stations were located in the La Spezia gulf, Ligurian sea. Genotoxic e ffects were evaluated in gill cells. A significant increment of the tw o parameters in polluted, in comparison with the unpolluted sites has been observed. High frequencies of micronuclei (the highest value was 42 +/- 13 with respect to control value 3 +/- 2) were scored in mussel s from polluted stations. The extent of DNA damage was also relevant w ith respect to clastogenic damage as revealed by micronucleus test. Th e greatest value of K (constant of elution) was 8-fold higher with res pect to the value of K obtained in the same tissue of mussel from refe rence areas. Evidence of DNA damage could reflect a recent pollution s tatus, since DNA strand breaks can be rapidly repaired by different me chanisms. On the contrary animals exposed to clastogenic compounds may exhibit elevated micronucleus frequency long after the exposure has c eased. The evaluation of both parameters could provide information of great significance about the pollution status of the water.