Studies On Candidate Genes Of Litter Size In Min Pig

Target conservation should be taken in action as soon as conservation target of some breed was confirmed according the systemic conservation theory. Hitherto, There has been few enough research about how to get target conservation more efficiently. So this thesis would make probing for the new methods on molecular assistant target conservation in order to conduct the conservation practice in min pig as min pig was taken as research object and excellent reproductive ability as conservation target. The specific works was as follows:(1) PCR-SSCP analysis was conducted on the four important candidate genes: the estrogen receptor (ESR),follicle-stimulating hormoneB(FSHB), prolactin recepter(PRLR) and epidermal growth factor(EGF) loci for litter size on min pig conservation population in order to recognized the genetic characteristic and variability tendency of min pig afresh in molecular level with molecular techniques. The results were as follows:Polymorphic sites were found in each candidate gene region. No frequency of alleles and genotypes of candidate gene was extremely. The frequencies of ESR fit Hardy-Weinberg equilibrium only. Compared with the distributions of ESR and FSH6 loci in 2000, the changes of genetic structure of the population were apparent greatly. And so that the frequencies of alleles and genotype are maybe variable in next generation although the frequencies of ESR and FSH was suit to the equilibrium.(2) BLUP was applied in animal candidate gene analysis to make statistic mode! of animal candidate gene research suit for the fact better, and the principle and computer method were described in particular and the effect of litter size candidate genes of min pig was estimated.The effect of each candidate genes was not significant (p>0.05) whereas no account of interacion between the genes. The statistic method: step-wise divest of compound genotypes was proposed. The results show that both the interactions between ESR and FSHB loci and that between ESR and PRLR loci were found significant associations between the polymorphism with litter size of min pig (p<0.05). And genotype AABB was the best in the combined genotypes between ESR and FSHB; AABB was also the best one in that between ESR and PRLR gene. The sows with combined genotypes not only ABAB between ESR and FSH , but also AAAB between ESR and PRLR have fewer littler size significantly, Others' effects were all not significant (p>0.05).(3) Principle of BLUP was combined with analysis of genetic model of candidate genes in this research to coduct the genotype-assistant assortative mating. Systemic statistic methods were given according different circumstances. And the data of litter size of min pig was dealed with single candidate gene model, the genetic model no account of epistasis effectand the model including epistasis effect respectively. As a result, the dominance effect of FSH and the additive effect of PRLR were found significant associations with the litter size of min pig(p<0.05) in single gene model.The sows with genotype AB of FSHfi have fewer litter size than average; genotype AA of PRLR is excellent. The additive effect of FSHB was also found significant .whereas all of four gene were put in same model no account of epistasis effect. Taking epistasis effect into account, all of additive effect and non-additive effect were found significant associations with the litter size of min pig with different genetic models.The statistic methods proposed in thesis make candidate gene research more abundant and make its pig. statistic theories more systemic, normative and rational. The result of this research can be used as reference for watch and detection of excellent gene or marker-assistant conservation, and then to guide the conservation work of min pig. To sum up, the research is significant not only in theory but also in practice.