Characterization of gene expression of a p53 homologue in the soft-shell clam (Mya arenaria).

Expression of a clam p53 homologue was examined in tissues of the soft-shell clam, Mya arenaria, from Beal's Island, Maine. Southern analysis reveals that p53, in this population, is a single copy gene. A 1.7 to 1.9-kb p53 mRNA was detected at very low levels in normal adult gonadal tissue. This transcript is similar in size to that of vertebrate p53 genes. RNAs were harvested from several tissues, including individual clam gonads during gametogenesis. These were hybridized in ribonuclease (RNase) protection assays to a p53 antisense probe designed from the clam p53 cDNA sequence. RNase protection profiles indicate that p53 mRNA is expressed in adductor muscle, gill, and gonads of both sexes. Although p53 mRNA is expressed throughout gametogenesis in mature male and female gonads, ovaries have significantly higher levels of expression. The significance of our findings to the study of normal clam gametogenesis and to etiology of gonadal tumors is discussed.