Cloning and expression characterization of the serum transferrin gene in the Chinese black sleeper (Bostrichthys sinensis)

Abstract In this study, the gene encoding serum transferrin (STF) in the Chinese black sleeper ( Bostrichthys sinensis ) was cloned and sequenced. The full BsSTF cDNA is 2324 bp in length with an open reading frame (ORF) of 2067 bp encoding 688 amino acids and has 47.1%–65.7% identity with other fish homologues. The BsSTF genomic DNA is composed of 17 exons and 16 introns and is well conserved with respect to other vertebrate species in the number of exons and in the position of introns. The expression of the BsSTF mRNA was examined in all tissues tested including liver, blood, muscle, spleen, stomach, skin, intestine, brain, head kidney, fin, gill and gonad, with the highest expression levels found in the liver. Temporal transcriptional changes of BsSTF during embryonic development of the Chinese black sleeper were detected, and the results showed a substantial decrease in the early stages, from the cleavage stage to the blastula stage, reaching minimum levels at the blastula stage and increasing gradually until the pre-hatching stage, indicating that BsSTF is likely an important factor in early embryonic development. After infection with Vibrio harveyi , BsSTF expression was found to increase mainly in the liver and stomach, acting as a positive acute protein, suggesting that BsSTF is involved in the immune response.