Persistence of atrazine impact on aneuploidy in Pacific oysters, Crassostrea gigas

The widespread use of the herbicide atrazine has incited much research on its toxicity in aquatic systems where it is routinely detected due to runoff from cultivated fields. Moreover, the determination of the genotoxic effect of such pollutants in the marine environment has become a major requirement for ecosystem protection. In the Pacific oyster, Crassostrea gigas, hypodiploid aneuploid cells have regularly been reported. There is a negative correlation between this phenomenon and growth as well as evidence for a genetic basis. A positive relationship between atrazine and aneuploidy was previously demonstrated in C. gigas adults and juveniles. To evaluate the persistence of this impact, our study examined the offspring of the same adult population previously treated with different atrazine doses (10 μg/l representing a peak value found in a polluted environment and 100 μg/l) and a sweater control. We observed that these offspring exhibited significantly higher aneuploidy levels when their parents had been exposed to atrazine (14.9 to 16.9% in comparison with the control where the levels ranged from 11.4 to 12.8%). In addition, the present study examined the aneuploidy level of a sample of juveniles, previously exposed for three and a half months to the same doses of atrazine, then replaced in non polluted conditions for an additional period of two and a half months and this aneuploidy level remained significantly different between the treatments applied. These results demonstrate the persistence of atrazine impact on Pacific oyster aneuploidy in time within and between generations, indicating that this widely used compound may represent an important factor causing at least medium term damage to genetic material.