藏绵羊基因OLA-DQA2第2外显子多态性分析

 【目的】针对藏绵羊腐蹄病所带来的死亡现象,选择与该病相关的基因OLA-DQA2为研究对象,分析群体中该基因的遗传多态性及变异特征,为进一步寻求抗病分子育种提供依据。【方法】采用PCR-SSCP检测216只表型正常和患病藏绵羊OLA-DQA2基因第2外显子的多态性,克隆、测序群体内变异产生的各等位基因序列,构建系统发育树以明确藏绵羊OLA-DQA2基因等位基因之间的遗传关系。【结果】藏绵羊DQA2基因第2外显子中表现了15个基因型。发现藏绵羊群体中OLA-DQA2基因第2外显子有8个新等位基因,分别命名为OLA-DQA2*H、*I、*J、*K、*L、*M、*N和*O,使绵羊基因库中该座位的等位基因数量从23个增加到31个。序列分析中发现71个核苷酸多态位点,这些多态位点主要由点突变形成,其中转换39个(占54.9%),颠换23个(占32.4%)。【结论】藏绵羊DQA2基因第2外显子具有丰富的遗传多态性,群体中可能蕴藏着更多的抗性遗传资源。

Polymorphisms of the Gene OLA-DQA2 Exon 2 in Tibetan Sheep

【Objective】 There is a foot-rot disease in the population of Tibetan sheep, which leads to the loss of sheep on death. Gene OLA-DQA2 is associated with foot-rot disease. The polymorphism and variation of gene OLA-DQA2 exon 2 was investigated in order to find the best alleles for foot-rot resistance in the further observation by means of phenotype and genotype. 【Method】 Fragments of DNA containing OLA-DQA2 exon 2 were amplified using PCR. Single-strand conformational polymorphism (SSCP) analysis and DNA sequence analysis were employed to detect genetic variation in 216 Tibetan Sheep (including ones with foot-rot). 【Result】 Fifteen nucleic acid sequences were identified. Eight novel alleles were found for the first time, respectively named OLA-DQA2*H, *I, *J, *K, *L, *M and *N. Thus the number of alleles identified is increased from 23 to 31. Seventeen-one nucleotide polymorphisms were found in the analysis of gene sequences, which mainly came from point mutation, including transition of 39 (54.9%) and 23 of transversion (32.4 %). 【Conclusion】 Tibetan sheep DQA2 gene exon 2 has high level of sequence polymorphism. The population may have strong resistance to genetic resources. The best alleles will be found by further observation from phenotype and genotype of the DQA2 gene in the near future. Consequently, the plan of disease resistance will be carried out in sheep breeding practice.