绵羊MyoG基因外显子的单核苷酸多态性群体遗传学分析

Analysis on Single Nucleotide Polymorphisms of Exon of MyoG Gene in Different Sheep Breeds

采用PCR-SSCP技术分析了肌细胞生成素(MyoG)基因外显子1、2在蒙古羊、无角陶赛特羊、德国肉用美利奴羊和白萨福克羊这4个绵羊品种的多态性。结果表明在在外显子1(exonⅠ)所扩增的片段中存在3种基因型(AA型、AB型和BB型),在外显子2(exonⅡ)所扩增的片段中不存在多态性。对于exonⅠ扩增片段,4个绵羊品种均检测到AA和AB基因型;BB基因型只在蒙古羊、陶赛特羊和白萨福克羊中检测到。在4个绵羊品种中,蒙古羊的AA基因型频率最高,而其它3个品种羊是AB基因型频率高;A等位基因频率明显高于B等位基因频率。exonⅠ的多态性片段测序分析表明:MyoG基因第305处发生了单碱基突变(T→C),并导致了所编码氨基酸由半胱氨酸变为精氨酸。

The polymorphisms of myogenin gene in Mongolian sheep, Poll Dorset sheep, German meat Merino sheep and Suffolk sheep were analyzed by PCR-SSCP. The results indicated that there were three genotypes （AA, AB and BB）detected by exon Ⅰ , and there weren＇t polymorphism in exon Ⅱ. To amplify fragments by exon Ⅰ , AA and AB genotypes were detected in four sheep breeds. BB genotype was detected in Mongolian sheep, Poll Dorset sheep and Suffolk sheep. Frequency of AA genotype in Mongolian sheep was the highest , but frequency of AB genotype in other three breeds was high. Frequency of A allele was obviously higher than frequency of B allele in four sheep breeds. The polymorphic fragments amplified by exon Ⅰ were cloned and sequenced, and the sequencing results showed that there was one single nucleotide mutation ：T→C at cDNA 305 of myogenin gene in sheep, and this mutation resulted in an amino acid change. cysteine→arginine.