【作者】 李婧；

【导师】 潘玉春；

【作者基本信息】 东北农业大学 ， 动物遗传育种与繁殖， 2003， 硕士

【摘要】 按照系统保种理论，一个品种确定保种目标之后即应实行目标保种。但对目标保种如何才更有效，迄今尚无充分研究。为此，本文即以民猪作为研究对象、以高繁殖性能作为保种目标，探讨分子遗传辅助进行目标保种的新方法，并用以指导民猪的保种实践。具体工作如下： 1、采用PCR-SSCP法检测了4个重要产仔候选基因——雌激素受体(ESR)基因、促卵泡素β亚基(FSHβ)基因、催乳素受体(PRLR)基因、表皮生长因子(EGF)基因的多态性，以在分子水平上重新认识民猪的种质遗传特性及其变化动态。结果表明在民猪中，4个候选基因中仅ESR基因的基因型分布达到哈代温伯格平衡状态。与2000年的ESR和FSHβ基因分布情况作比较显示，群体遗传结构已经发生明显变化。说明即使ESR基因、FSHβ达到了平衡状态也不能保证其基因频率、基因型频率在下一代保持不变。 2、针对动物实验的客观实际，运用BLUP的基本原理，提出了动物候选基因基因型效应的混合模型分析法，包括单基因模型、多基因无互作模型及多基因合并基因型逐步剥离模型。应用提出的多基因分析法对民猪产仔数4个候选基因的基因型效应进行分析，结果表明：①在不考虑基因互作的情况下，4个候选基因效应均不显著(p＞0.05)。②考虑互作时，ESR基因与FSHβ基因和PRLR基因的互作效应对民猪头胎总产仔数影响显著(p＜0.05)，其中，ESR与FSHβ基因的合并基因型中AABB型为最佳合并基因型；ESR与PRLR基因的合并基因型中AABB型也为最佳合并基因型；ABAB和AAAB分别为ESR与FSHβ基因、ESR与PRLR基因的合并基因型中的劣质基因型。其它基因效应均不显著(p＞0.05)。 3、为了指导基因型辅助选配，运用BLUP的基本原理，提出了候选基因的遗传作用模式分析法，并分别采用单个候选基因效应分析模型、不剖分上位效应的分析模型和剖分上位效应的模型对民猪的产仔数资料进行了分析。结果表明：①只考虑单个候选基因，FSHβ基因的显性效应与PRLR基因的加性效应显著(p＜0.05)，即FSHβ基因杂合型的头胎总产仔数显著低于平均值，PRLR基因的AA型为优良基因型，其它各项效应均不显著。②当同时考虑4个候选基因但不剖分上位效应时，FSHβ基因的加性效应也达到显著(p＜0.05)，即FSHβ基因的AA型母猪经产活产仔数显著低于平均值；③剖分上位效应时，发现不同基因对猪产仔数的作用模式不同。 本研究所提出的相关统计分析方法丰富了候选基因研究的理论，有关民猪的分析结果可以作为民猪优良基因的监测和分子标记保护的参考依据，进而指导民猪保种实践，因而既具理论意义，也具实践意义。更多还原

【Abstract】 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.更多还原