<div>Background: Natural resistance associated macrophage protein 1 (Nramp1) is a relatively conservative gene that plays a crucial role in swine immune response and disease resistance.&nbsp; 
 
Methods: We identified the polymorphisms and gene variations in the exon 2 of Nramp1 using polymerase chain reaction&ndash;restriction fragment length polymorphism and investigated the correlation between the polymorphisms and piglet diarrhea in four pig breeds (Bamei, Duroc, Landrace, and Large White pigs).&nbsp; 
 
Result: The results showed that two alleles (A and B) were identified in all the pig breeds, three genotypes (AA, BB, and AB) were detected in Bamei and Large White breeds, and two genotypes (AA and AB) were detected in Landrace and Duroc breeds. Allele A and genotype AB were dominant in Bamei, Large White, and Landrace breeds, whereas genotype AA was dominant in Duroc pigs. A moderate polymorphism was observed in Landrace and Large White pigs, and polymorphism was abundant in Bamei pigs and low in Duroc pigs. The Chi-square test for Hardy&ndash;Weinberg equilibrium disclosed that the exon 2 of Nramp1 in the four breeds of pigs did not deviate from the Hardy&ndash;Weinberg balance (P&gt;0.05). The results of association analysis showed a significant correlation between breed and piglet diarrhea (P&lt;0.05), and the diarrhea score of Bamei pigs was much lower than those of the other breeds. The study could supply theoretical references for further functional research on Nramp1 gene and for screening genes related to disease-resistance breeding.</div>

<div>Polymorphism of Nramp1 Gene and Its Association with Diarrhea in Pigs</div>

The Nramp1 gene is an important factor associated with susceptibility to infectious diseases caused by intracellular pathogens. The objective of this study was to determine the structures and sequences of Nramp1 in Tibetan, Gansu Black, Large White, Yorkshire, and Duroc pigs. Sequence analysis of the Nramp1 gene in the five pig breeds revealed the presence of 11 nucleotide variants in intronic regions, 2 nucleotide variants in the control region, 10 nucleotide variants and one deletion in the 3&rsquo; non-coding region, and 15 nucleotide variants in the exons. However, only 4 nucleotide variants resulted in amino acid changes. Further analysis predicted that the Tibetan pig Nramp1 protein harbors 10 transmembrane domains. The analysis also predicted 10 serine phosphorylation sites, 3 threonine phosphorylation sites, and 4 tyrosine phosphorylation sites in the Nramp1 protein of Tibetan pigs. Predictions of the Tibetan pig Nramp1 tertiary structure revealed 7 putative a -helices and 5 putative b-sheets. Predictions of the Yorkshire pig Nramp1 protein revealed significant differences compared with the Tibetan pig Nramp1 protein. The results indicated that differences in transmembrane domains and tertiary structures of the Nramp1 protein of the Tibetan and Yorkshire pig breeds could explain differences in the disease resistance of these two breeds

Nucleotide variants of the Nramp1 gene in pigs and their effects on disease resistance

The present study aimed to explore polymorphisms at exon X-XI, encompassing two potential N-linked Glycosylation sites (GLY, GLY), complete transmembrane domain 8 (TM8) and one conserved &lsquo;Consensus Transport Motif&rsquo; (CTM) of buffalo (Bubalus bubalis) SLC11A1 (formerly NRAMP1) gene by PCR-RFLP and automated DNA sequencing. PCR&ndash;RFLP genotyping of animals (n=150) from three Indian buffalo breeds viz., Murrah, Surti, and Mehsana by Alu I, Taq I, Hae III, Rsa I, Pst I and Mva I reveals monomorphic pattern. Sequence comparisons demonstrate no change at nucleotide level among the buffalo breeds. However, results of this study show three nucleotide changes in buffaloes as compared to that of B taurus (NM_174652): one transition (CT at amino acid position 349) and two transversion (CA at amino acid position 321 and CG at amino acid position 356). Transversion CA and CG, resulting in deduced amino acid exchange Asp321 &ndash;Glu321 and Pro356 &ndash; Ala356, respectively has been identified. The non-synonymous single nucleotide variation (nsSNV) (CA at amino acid position 321), observed in all the three buffalo breeds under study, leads to the loss of a potential N-glycosylation motif of SLC11A1 gene and therefore may alter the property of the protein. A comprehensive study of this N-glycosylation motif of SLC11A1 gene in different species followed by structural analysis of the protein is required to better understand the functional impact of nsSNV.

Polymorphism of Nramp1 Gene and Its Association with Diarrhea in Pigs

Nucleotide variants of the Nramp1 gene in pigs and their effects on disease resistance

Genetic analysis of glycosylation sites, TM 8 and consensus transport motif of buffalo SLC11A1 gene