Abstract：Antimicrobial peptides (AMPs) were regarded as important components of the host innate immune system and play crucial roles in host defence against microbial invasion. Hepcidin was an antimicrobial peptide and iron regulatory molecule primarily in liver. A number of hepcidin AMPs had been isolated from teleosts. In this study, one hepcidin gene was amplified from the liver of yellow catfish(Pelteobagrus fulvidraco)by means of reverse transcription polymerase chain reaction(RT-PCR).The length of hepcidin cDNA fragment （GenBank accession number EU257703）was 282bp with an ORF ranging from 1st to 279thbp, which encoded a peptide of 93 amino acids. According to the blast result in GenBank database, the cDNA nucleotides and the deduced amino acid sequence of ORF share 80-82% and 69-71% identity with those of other species in Siluriformes.The prepropeptide contained a signal peptide (23 amino acids),a prodomain(45 amino acids) and a mature peptide(25收
amino acids).The predicted 25-amino acid hepcidin mature peptide included 8 conserved cysteine residues which were proposed to form four disulphide bonds. RT-PCR demonstrated that the hepcidin gene was expressed in a wide range of tissues of yellow catfish. And the hepcidin transcripts were highly abundant in liver,abundant in head kidney, intestine, muscle, brain, stomach, gill, heart, ovary, less abundant in skin, spleen and trunk kidney. Challenge of yellow catfish with Aeromonas hydrophila and Bacillus cereus significantly elevated hepcidin mRNA levels in liver. The new member of hepcidin discovered in this study could contribute to the research of immune function and mechanism in yellow catfish.
