Studies On Single Nucleotide Polymorphisms Of Ob Gene And The Association With Partial Economic Traits In Songliao Black Pig

Candidate genes are selected on the basis of known relationship between physiological or biochemical processes and traits.In this study,we selected obese gene as the gene affecting litter size performance and meat traits in pig.We detected the polymorphisms of ob gene by PCR-RFLP(Polymerase Chain Reaction-Restrain Fragment Length Polymorphism)and Bi-PASA(Bidirectional PCR amplification of specific alleles)in random population of Songliao Black pig,and analyzed the genetic correlation between the polymorphisms and litter size performance and meat traits of ob gene by SPSS in Songliao Black pig.The trial made use of public resources NCBI database and NAGRP Pig Genome Coordinat Search Program website so as to search ob gene sequences and SNPs in pig,and reference to a large number of research literature reports about association between SNPs of ob gene and performance.With screen ob gene of candidates SNP,we detect three mutation site in G1112A site,T3469C site and G3714T site by RFLP-PCR and Bi-PASA.We predicted that one transcription factor binding sites was inserted at 1112A in intron 2 with TFSEARCH program, which may lead to insert an additional transcription factor RORalp.The analysis of the condon usage frequence was made to the synonymous mutate of T3469C locus and G3714T locus in extron 3 of ob gene in pig by codon usage database.The results show that the mutation in 3714 locus occurred T→G change which lead codon GCU into GCG. GCU of codon usage frequency(17.0) was that of GCG(8.6);the mutation in 3469 locus occurred T→G for subversion which lead codon GCU into GCG. But the CUU of codon usage frequency(11.5) is about one-fourth of that of the CUG(46.0).A chi-square analysis suggested that the allele frequencies and genotype frequencies of Songliao Black pig for G1112A locus,T3469C site and G3714T site were in Hardy-Weinberg equilibrium(P>0.05).G1112A site of the G allele,T3469C site of the T allele and G3714T site of the G allele in allele frequencies are very high,they are dominant allele in groups.For G1112A site and G3714T site,Songliao Black pig had intermediate polymorphism(0.5>PIC>0.25),but for T3469C site ,Songliao Black pig had low polymorphism(PIC<0.25).The software SHEsis was also used to make haplotype analysis.there was a weak linkage disequilibrium between G1112A and G3714T. 0b gene were detected in the four different haplotypesin Songliao Black breeds,in which Haplotype G-T-G is dominance .Generalized linear model,independent variables of which including genotypes of ob locus and population was resolved with GLM program of SPSS version 10.0 for association with partial economic traits.The preliminary result of meat and carcass traits in Songliao Black pig show that TT genotype of T3469C was significant associated with backfat thickness and lean meat percentage(P<0.05),in which the backfat thickness of TT homozygotes was smaller than that of heterozygotes,but the lean meat percentage of TT homozygotes was bigger than that of heterogotes.GG genotype of G3714T was significant associated with lean meat percentage(P<0.05),in which the lean meat percentage of GG genotype was bigger than both GT genotype and TT genotype.The preliminary result of litter size traits in Songliao Black pig show that CT genotype of T3469C was significant associated with total number of piglets born(P<0.05),in which the total number of piglets born of CT heterozygotes was bigger than that of TT homozygotes.TT genotype of G3714T was significant associated with total number of piglets born and 20 day weight of litter size(P<0.05),in which the total number of piglets born of GT genotype was bigger than both GG genotype and TT genotype,and the 20 day weight of litter size of TT genotype was bigger than both GT genotype and GG genotype.This study indicates ob gene perform effects on production and carcass quality traits,which would provide theory basis for the improvement of relative traits.