Molecular cloning and expression analysis of a beta-thymosin homologue from a gastropod abalone, Haliotis diversicolor supertexta.

The beta-thymosins are a family of highly conserved small peptides with multiple functions. In this study, we isolated the full-length cDNA of a beta-thymosin homologue from a gastropod abalone Haliotis diversicolor supertexta which we named ab-TMSB. The full-length cDNA of ab-TMSB consists of 499 bp with an ORF encoding a 43 amino acids protein. The deduced amino acid sequence of ab-TMSB shows 61-76% identity to other beta-thymosins and shares a conserved actin-binding domain. The phylogenetic analysis revealed that ab-TMSB was branched with Sycon raphanus beta-thymosin and clustered with Strongylocentrotus purpuratus beta-thymosin. Quantitative real-time PCR showed that ab-TMSB was ubiquitously expressed in abalone and highly expressed in hemocyte. Moreover, the expression level of ab-TMSB in hemocyte was upregulated after LPS challenge. Taken together, these results indicate that ab-TMSB is a beta-thymosin homologue and may be involved in the immune response of abalone H. diversicolor supertexta.