Partial molecular characterization of the Nile tilapia (Oreochromis niloticus) alpha-cardiac muscle actin gene and its relationship to actin isoforms of other fish species

An alpha actin gene segment, isolated from Nile tilapia (Oreochromis niloticus), was characterized by nucleotide sequencing, predicted amino acid sequence and Southern blot hybridization. Genomic DNA amplification resulted in a 1063-bp fragment corresponding to a partial alpha-cardiac muscle actin gene containing exons 3 to 6. Southern blot analysis of the restriction-digested DNA revealed that the Nile tilapia genome contains multiple muscle actin isoforms. Although comparison of the nucleotide sequence, amino acid residues and exon-intron organization of the isolated actin gene with those of other vertebrates showed a high level of identity, diagnostic amino acid residues can still be correlated to distinct actin genes in fish species.