ISOLATION AND CHARACTERIZATION OF A CDNA-ENCODING AN ACTIN GENE FROM SEA SCALLOP (PLACOPECTEN-MAGELLANICUS)

Two full-length complementary DNAs (cDNA) were isolated from a sea sca llop adductor muscle-specific cDNA library and sequenced completely. B oth clones encode the same open reading frame of 376 amino acid residu es. The amino acid sequence is highly homologous to other invertebrate actin sequences, and as in other invertebrates, the N-terminal sequen ces are much more similar to the nonmuscle actin of higher vertebrates than to their muscle actin. Results suggest that this is the primary actin gene expressed in adductor muscle. The size of the actin gene fa mily in this species is approximately 12-15, determined through Southe rn hybridization. An actin gene probe may also be useful as a genetic marker because it reveals polymorphisms in sea scallop in at least thr ee loci. Strong signals were obtained when DNA digests from several sh ellfish and fish were probed with an actin coding region probe, indica ting that this clone will be useful in genetic studies of other fish a nd shellfish species.