IMPLICATIONS FOR THE PRESENCE OF TRANSFORMING GENES IN GONADAL TUMORSIN 2 BIVALVE MOLLUSK SPECIES

Studies were initiated on oncogene activation in two bivalve species w ith high frequencies of histologically identifiable gonadal neoplasms. Pathological assessments identified epizootic seminomas and dysgermin omas in softshell clams (Mya arenaria) from three Maine estuarine site s contaminated by herbicides and in hardshell clams (Mercenaria) from the Indian River in Florida, an area of potential citrus agrochemical exposure. NIH3T3 transfection assays were used to examine DNA isolated from these molluscan tumors for the presence of activated oncogenes. DNAs isolated from advanced tumors in both species were able to transf orm NIH3T3 cells in a standard focus assay. These same cells were also able to form colonies in low concentrations of serum and induce tumor s in athymic mice. Cells expanded from isolated foci demonstrated anch orage-independent growth in soft agar. The results of these studies in dicate that DNA from the clam tumors is able to transform mouse fibrob lasts, which suggests that a transforming gene is present in these tum or cells. Studies are under way to identify the gene(s) detected by th ese assays.