FSHR And PDIA4 Candidate Genes SNP Analysis And Its Functions Research In Xiang Pigs

Follicle-stimulating hormone(FSH),a glycoprotein secreted from pituitary,can regulate ovarian function through the FSH receptor(FSHR).Protein disulfide iso-merase 4,member A(PDIA4)gene was higher in the mature ovarian cells content of pigs,can affect the development of follicles through changing downstream genes of estrogen receptor alpha(ER?)regulatory response by influencing the conformation of DBD area.To evaluate the effects of the FSHR gene and PDIA4 gene on the litter size of Xiang pig population,polymorphisms were detected by allele-specific polymerase chain reaction(AS-PCR)and sequencing methods,and the effect of polymorphisms on litter size traits in Xiang pigs was analyzed using the least square analysis.In eight candidate sites of FSHR gene,there were two polymorphic locus were detected out from Xiang pig population,which were rs322800083(C276T)and rs332115220(T601C).Moreover a new SNP novel 1(G-92A)was discovered.Four haplotypes were constructed between rs322800083 and rs332115220 sites,in which C-T was the main haplotype(45.0%)and presented closely linkage disequilibrium(r2=0.334)in Xiang pig population.Furthermore,the haplotype C-T corresponded to the highest total number born(TNB)at the second fetus of Xiang pigs,haplotype C-C to the lowest TNB.It was notified that haplotype C-T produced1.0 TNB of Xiang pigs more than haplotype C-C did(P<0.05).And the TNB at the third fetus was also the highest in haplotype C-T,which produced 1.6 TNB and 2.3 TNB more than haplotype T-C and C-C did(P<0.01).The genotypes of locus rs332115220 was weakly correlated with the third fetus of Xiang pig population(?<0.429).The research results suggested that haplotype C-T could be used as a molecular marker to assist selection for the litter size of Xiang pigs.In twenty-four candidate sites of PDIA4 gene,there were ten polymorphic locus were detected out from Xiang pig population,which were SNP2(rs81216657: C14 G and A14G),SNP3(rs325150081: G146A),SNP4(rs81216658: C176T),SNP5(rs343963559: C269T),SNP6(rs55618851: G443A),SNP7(rs334600072: G482A),SNP8(rs342384893: C700T),SNP9(rs694204126: T758C),SNP10(rs55618242: C816T)and SNP11(rs340066367:C817T).Moreover a new SNP novel 2(C-18G)was discovered.SNP4 loci was asynonymous mutation which encoded threonine(Thr).C allele frequency was the advantage allele in high production and low production of Xiang pigs,there was a significant difference in allele frequencies between those two group(P<0.05).And the site was biased towards the ACC cipher option,which had a codon bias.PDIA4 protein expression of genotype TT was at least by Western Blot measured,that codon bias was helpful in the expression of mRNA level and protein level.Four haplotypes were constructed between SNP4 and SNP6 sites,in which T-A was the main haplotype and presented highly close linkage disequilibrium(r2=0.854)in high production of Xiang pig population,but that was low level linkage disequilibrium(r2=0.485)in low production of Xiang pig.The linkage disequilibrium form in high production of Xiang pig was more approached to the large white pig,the T-A haplotypes frequencies in low production of Xiang pigs were extremely significant difference with high production of Xiang pigs and Large White pigs(P<0.01).So the research results suggested that haplotype T-A could be used as a molecular marker to assist selection for the litter size of Xiang pigs.