The effect of mutation at M307 in FUT1 gene on susceptibility of Escherichia coli F18 and gene expression in Sutai piglets.

Escherichia coli F18 (ECF18) is a common porcine enteric pathogen. The pathogenicity of ECF18 bacteria depends on the existence of ECF18 receptor in the brush border membranes of piglet's small intestinal mucosa. Alpha (1) fucosyltransferase gene (FUT1) has been identified as the candidate gene controlling the adhesion to ECF18 receptor. The genetic variations in the position of M307 nucleotide in open reading frame of FUT1 have been proposed as a marker for selecting resistant pigs. The piglets were divided into three groups, AA, AG and GG, according to the genotypes present at M307 of FUT1. Small intestinal epithelium cells of piglets with AA, AG and GG genotypes were selected to test the adhesion capability of the wild type E.coli expressing F18ab fimbriae, the recombinant E. coli expressing F18ac fimbriae or the recombinant E. coli secreting and surface-displaying the FedF subunit of F18ab fimbriae, respectively. Here, we examined the distribution and expression of porcine FUT1 mRNA in different tissues in Sutai pigs using real-time PCR. The results showed that piglets with AA genotype show resistance, whereas piglets with GG or AG genotypes are sensitive to the pathogenic E. coli F18 in Sutai piglets. FUT1 was expressed in all the tissues that were examined, and the gene's expression was highest in the lungs. There was no significant difference in expression level among the three genotypes in the liver, lung, stomach and duodenum, where the gene expression was relatively high. The present analysis suggested that mutation at M307 in FUT1 gene determines susceptibility of small intestinal epithelium to E. coli F18 adhesion in Sutai piglet and the expression of FUT1 gene may be regulated by other factors or the mutation was likely to be in linkage disequilibrium with some cis-regulatory variants.

[cDNA microarray on differently expressed genes in duodenum in porcine sensitive or resistant to Escherichia coli F18].

Based on the paired full-sib individuals selected from the established resource populations of Sutai pig that were characterized as resistant or sensitive to ETEC F18, Agilent double labeled cDNA microarray was used to identify the gene expression profiles in duodenum on purpose of investigating the genes related to Escherichia coli F18 receptor, which may cause edema disease and post-weaning diarrhea in piglets, as well as exploring the molecular mechanism about the differences involved in two different lineages. The results showed that thirteen differently expressed genes were found in one matched group including sensitive ones with GG genotype comparing with resistant ones with AA genotype at a two-fold filter, where there were 6 up-regulated genes and 7 down-regulated genes. In the other matched group composed of sensitive ones with AG genotype, 4 up-regulated genes and 2 down-regulated genes, 6 in total were screened out. GO analy-sis revealed that the differently expressed genes participated in many biological processes, such as immune response, ex-tracellular region, bacterial binding, response to external stimulus and so on. Meanwhile, these genes were mainly related to the Glycan Biosynthesis and Metabolism and Immune System pathways. Actually, the roles that they may play in edema disease and post-weaning diarrhea need further study and verification.

[Isolation of new alleles of the swine TLR4 gene and analysis of its genetic variation].

Using the PCR-SSCP method, the genetic variation in exon 1 of the TLR4 gene was detected among 893 animals, including Asian wild boars, 3 imported commercial and 10 Chinese indigenous swine breeds. This was conducted to analyze the polymorphisms of exon 1 of TLR4 gene in native and foreign pig breeds and aimed at providing a theoretical foundation for further research on the role that TLR4 gene played in immune and defense system. New alleles were isolated for exon 1 of the swine TLR4 gene for the first time, There were 6 genotypes and 3 alleles, in which the Duroc appeared AA, BB, CC, AB, AC and BC genotypes; Sutai pig, which has Duroc pig origin, were detected to be BB, CC, and BC genotypes; Yorkshire and Landrace were detected to be CC and BC genotypes. Wild boar and all 10 Chinese native pig breeds appeared highly conserved in exon 1 of TLR4 gene, with only CC genotype. Among the 3 homozygous genotypes, the CC genotype matches the sequence in GenBank, while a G93C synonymous mutation and a G194A nonsense mutation were found in the BB and AA genotypes, respectively. The correlation between these two mutation points of TLR4 gene with resistance to stress and disease is worthy of further study.