Molecular identification and expression analysis of natural resistance-associated macrophage protein (Nramp) gene from yellow catfish Pelteobagrus fulvidraco (Siluriformes: Bagridae).

Natural resistance associated macrophage protein genes (Nramp) is one of the important candidate genes responsible for regulating immune response against pathogen infection. The aim of the present was to quantify expression of Nramp gene in response to pathogen infection. Here, a Nramp was identified and molecularly characterized from Pelteobagrus fulvidraco (PfNramp). The obtained 3134 bp cDNA fragment of PfNramp comprised a 5'-untranslated region (UTR) of 81 bp, a 3'-UTR of 1403 bp and an open reading frame (ORF) of 1650 bp, encoding a polypeptide of 549 amino acids that contained a typical structural features of Nramp domain (Pfam01566). BLAST analysis exhibited that PfNramp shared sequence similarity to other organisms, in particular to Ictalurus furcatus (92%), Danio rerio (82%), and Homo sapiens (77%). Phylogenetic analysis revealed that PfNramp is close to Teleostei. Real-time quantitative reverse transcription-PCR (qRT-PCR) analysis showed that PfNramp was expressed in all examined tissues, with the highest abundance in liver. The mRNA expression of PfNramp was remarkably increased at different time points after lipopolysaccharide (LPS), and polyriboinosinic polyribocytidylic acid (poly I:C) challenge. These results suggest that PfNramp is an inducible protein in the innate immune reactions of P. fulvidraco and probably in other fish species.