The full length cDNA cloning and expression of elongation factor 1δ from the Chinese mitten crab(Eriocheir sinensis)

Elongation factor (EF) is a protein factor which plays roles in the peptide chain elongation in the process of protein synthesis, including elongation factor 1( EF-1) and elongation factor 2(EF-2). Elongation factor 1 consists of four subunits α, β, γ and δ, and plays a key role in protein translation process. In this study, we cloned EF-1δ gene from Eriocheir sinensis using reverse transcriptase polymerase chain reaction (RT-PCR) and rapid-amplification of cDNA ends (RACE), and primers were designed according to the conserved sequence of elongation factor-1 δ from Xenopus laevis. The full-length cDNA sequence of EF-1δ is 933 bp which codes 263 amino acid residues. And comparison results showed that the nucleotide homology of EF-1δ was 70% similar to Xenopus laevis and amino acid homology of EF-1δ was 54% similar to Danaus plexippus, using BLASTN and BLASTX software. The phylogenetic analysis based on amino acid sequence shows that EF-1 δ has highest similarity with EF-1δ of Lepeophtheirus salmonis. The expression of the gene in different tissues and stages of E. sinensis was analyzed by real-time fluorescent quantitative PCR. The result showed the EF-1δ mRNA was mainly detected in muscle and small amount in testis, hepatopancreas and trace in heart, ovary, stomach, intestine, gill. EF-1δ mRNA was detected with high level in muscles compared to hepatopancreas and gill in different developmental states of the crab, and displays significant difference at P<0.05. It also has significant difference at P<0.05 between muscles in different developmental states, and it was detected the highest expression in precocious crab, followed by mature crab and by a lower expression of crablet; And there is no significant expression difference between hepatopancreas and gill tissues in different developmental states.