Feasibility Analysis Of Of MUC4 And MUC13 Gene As E.coli Resistance Genetic Markers In Piglets

Mucin(mucins),also known as epithelial mucin,produced by epithelial cells,composed of membrane-bound and secreted glycoprotein of macromolecular protein family.It plays an extremely important role in the lubrication,protection of epidermal cells,and regulation of cell signal transduction.MUC4 and MUC13 as a principal member of the mucin family play an important role in the body's resistance to ETEC infection.Many scholars have shown that MUC4 and MUC13 are the most important candidate genes of ETEC F4 receptor.The 243 sites in intron 17 of the MUC4 gene and insertion deletion mutation in intron 2 of the MUC13 gene have been used as potential genetic markers of E.coli F4 resistance.On the one hand,this study are conducted to analyse the relationship polymorphisms of MUC4 and MUC13 gene with its mRNA expression,cytokine levels,production traits and reproductive performance with Yorkshire for the material from DNA and mRNA levels in order to assess feasibility as genetic markers of E.coli F4 resistance on basis of systematic analysis genetic effects of MUC4 and MUC13 genes.On the other hand,this study are conducted to analyse 35 days of Sutai and Meishan pigs MUC4 and MUC13 genes mRNA expression difference between resistant and sensitive individuals to discuss whether MUC4 and MUC13 are used as candidate gene of resistance to E.coli F18.The main experimental results were as follows:The polymorphism of g.243 A>G mutation in intron 17 of the MUC4 gene was analyzed by PCR-RFLP method.The results indicated that three genotypes and two alleles were identified,with A being the dominant allele in Large White pigs.Chi-square(?2)fitness analysis showed that polymorphisms in the Hhal restriction site of the MUC4 gene were in Hardy-Weinberg Equilibrium in Large White pigs(P>0.05).Association polymorphism of g.243 A>G mutation in intron 17 of the MUC4 gene with mRNA expression,vital cytokine levels,production traits and reproductive performance showed that IL-8,IL-10 levels and 100 kg weight day age were significantly higher in the GG genotype compared with the AA and AG genotypes(P<0.05),However,no significant differences were detected in IL-8,IL-10 levels and 100 kg weight day age of AA and AG genotypes;meanwhile,in the mRNA expression,the levels of other cytokine levels,other production traits and reproductive performance among the three genotypes(P>0.05).These observations indicated that selective molecular breeding based on the genotype will have no detrimental effects on the mRNA expression,resistance to disease,production traits and reproductive performance but might enhance the anti-disease capability and affect growth rate of the groups in Large White pigs.MUC4 gene mRNA expression analysis with different development stages in Sutai pigs showed MUC4 genes had different levels of mRNA expression in different tissues,meanwhile,MUC4 gene mRNA expression levels in liver,the spleen,stomach,thymus,duodenum and jejunum of 30 and 35 days old were significantly higher than 8 and 18 days of age(P<0.05).In addition,MUC4 gene mRNA expression had no significant difference in resistant and sensitive individuals of Sutai and Meishan pigs(P>0.05),indicating as the important candidate gene of E.coli F4 receptor,MUC4 gene might be not suitable for E.coli F18 receptor.Insertion deletion length polymorphism in intron 2 of the MUC.13 gene was analyzed by PCR product direct electrophoresis method.The results indicated that three genotypes defined as AA,AB,and BB was identified in Large White pigs,while B was dominant allele.Association polymorphism in intron 2 of the MUC13 gene with mRNA expression,vital cytokine levels,production traits and reproductive performance showed that the mRNA expression,vital cytokine levels,production traits,and the total number born,the number born alive,the number of piglets weaned from first to fourth parity all had no significant difference among three genotypes.These dates indicated that molecular markers of insertion deletion length polymorphism in intron 2 of the MUC13 gene could be applied to breeding practice with resistance to E.coli F4.MUC13 gene mRNA expression analysis with different development stages in Sutai pigs showed MUC13 gene had different levels of expression in different tissues,meanwhile,MUC13 gene mRNA expression levels in liver,stomach,duodenum and jejunum of 30 and 35 days old were significantly higher than 8 and 18 days of age(P<0.05).In addition,MUC13 gene mRNA expression had no significant difference in resistant and sensitive individuals of Sutai and Meishan pigs(P>0.05),indicating as the important candidate gene of E.coli F4 receptor,MUC13 protein played an role in protection and lubrication of gastrointestinal tract against pathogenic bacteria infection,while not directly involved in formation of E.coli F18 receptor.Therefore,MUC13 gene might be not suitable for E.coli F18 receptor.