Characterization and phylogeny of two β-cytoskeletal actins from Hemibarbus mylodon (Cyprinidae, Cypriniformes), a threatened fish species in Korea

Abstract

Complementary DNA and genomic sequences representing two different β-actins were isolated from a threatened freshwater fish species Hemibarbus mylodon. The β-actin 1 and 2 encoded an identical number of amino acids (375 aa), and shared 88.8 and 99.7% of identity at coding nucleotide and amino acid levels, respectively. Genomic open reading frame (ORF) sequences of both isoforms contained five translated exons interrupted by four introns with conserved GT/AG exon/intron boundary rule. Semi-quantitative RT-PCR showed that the two isoform mRNAs were ubiquitously detected in all tissues tested, but transcript levels were variable across tissues. Phylogenetic analysis showed that H. mylodon β-actin 1 and 2 were clustered into two distinct major and minor branches of Cypriniformes, respectively. Comparisons of the 5′-upstream region and 3′-UTR of H. mylodon β-actin 1 also showed a high degree of homology with those of the major teleost β-actins and warm-blooded vertebrate β-cytoskeletal actins, suggesting their more recent common origin.

• β-Actin isoforms
• gene structure
• phylogeny
• mRNA expression
• Hemibarbus mylodon

Acknowledgements

This study was supported by the Ministry of Environment, Korea.