MOLECULAR CHARACTERISTICS AND THE EXPRESSION OF TRANSFERRIN GENE IN CHINESE SOFT SHELL TURTLE

Transferrin has a variety of biological functions such as iron transportation, anti-microbial, and immunoregulation. In this study, we isolated the full length cDNA of transferrin of Chinese soft shell turtle (Pelodiscus sinensis) from the constructed liver cDNA library. The cDNA sequence consisted of 2359 bp, including an open reading frame (ORF) of 2094 bp which could encode a 674-aa peptide. The genomic DNA of transferrin consisted of 19100 bp and contained 17 exons and 16 introns, with a structure similar to that of other vertebrates. Using the online software we predicted the molecular characteristics of transferrin. The results indicated that the N-lobe of transferrin had a signal peptide of 19 amino acids; this gene was composed of two similar domains with a similarity of 37%. There were 2 N-linked glycosylation sites in the N-lobe, and 11 disulfide bonding formation areas in amino acids peptide. The quantitative PCR results showed that the expression of transferrin was the highest in liver in the normal group. The results also showed that after the infection with Aeromonas hydrophila the expression of this gene was first increased and then decreased in liver, spleen, kidney and heart, and the increase was particularly high in liver and spleen. Moreover, we applied western-blot to testify the prokaryotic expression of transferrin of Chinese soft shell turtle. This study could provide insights into the biological functions of transferrin in non-specific immune responses.