Molecular cloning of an elongation factor 1α and its mRNA localization in testis of the Nile tilapia Oreochromis niloticus

During spermatogenesis, many proteins are synthesized in the testis prior to the completion of sperm maturation. Many components are involved in the testicular protein synthesis and one of the components that is implicated in the polypeptide chain elongation is elongation factor 1α. In the present study, the molecular cloning of elongation factor 1α (EF-1α) was conducted from a testis cDNA library of the Nile tilapia. The cDNA for tilapia EF-1α (tEF-1α) contains a complete open reading frame encoding 462 amino acids. The predicted amino acid sequence of EF-1α shows an approximate 90% similarity to those identified in other teleost fish, such as medaka, sea bream and zebrafish. Northern blotting revealed that the gene is expressed in all of the examined tissues and in ovulated eggs. The results of in situ hybridization indicate that the gene is expressed specifically in Leydig cells in testis, suggesting the involvement of EF-1α as an actin-binding protein in the cluster formation of Leydig cells. In the ovary, the gene is expressed in the perinucleolus stage of oocytes, suggesting that EF-1α is also implicated in oocyte growth.