CHARACTERIZATION OF GENE-EXPRESSION OF A P53 HOMOLOG 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 analysi s reveals that p53, in this population, is a single copy gene. A 1.7 t o 1.9-kb p53 mRNA was detected at very low levels in normal adult gona dal tissue. This transcript is similar in size to that of vertebrate p 53 genes. RNAs were harvested from several tissues, including individu al clam gonads during gametogenesis. These were hybridized in ribonucl ease (RNase) protection assays to a p53 antisense probe designed from the clam p53 cDNA sequence. RNase protection profiles indicate that p5 3 mRNA is expressed in adductor muscle, gill, and gonads of both sexes . Although p53 mRNA is expressed throughout gametogenesis in mature ma le and female gonads, ovaries have significantly higher levels of expr ession. The significance of our findings to the study of normal clam g ametogenesis and to etiology of gonadal tumors is discussed.