Isolation, characterization, and expression analysis of three actin genes in the New Zealand black-footed abalone,...

Three actin genes -- H. irisA1, H. irisA2, and H. irisA3 -- from the mollusc Haliotis iris (New Zealand black-footed abalone) were isolated by polymerase chain reaction (PCR). The genes were similar to molluscan (84.1% to 94.9%) and vertebrate (84.5% to 86.6%) actins. The sequence similarity between the genes ranged from 88.5% to 93.2%. The greatest disparity, 32.3%, was found over a 99-nt region located at nt 808-906 of H. irisA1, corresponding to amino acids 212-244 of the three actins. The H. iris actin gene family contains at least eight members. Reverse transcription (RT)-PCR analysis of the three genes showed H. irisA1 and H. irisA2 were expressed at low levels in fertilized eggs and blastula stages and at high levels in trochophore and veliger larvae. H. irisA3 was detected in fertilized eggs; it was not detected in the blastula stages and at high levels in the trochophore and veliger larvae. The structure and expression of the three actin genes are discussed.