新疆肉羊18号染色体上与后臀肌发育相关基因的多态性分析

Polymorphism Analysis of Genes Associated with Hindquarters Muscular Development on Chromosome 18 in Xinjiang Meat Sheep

通过对新疆肉羊18号染色体与后臀肌发育相关基因的多态性分析,试图找到与新疆肉羊后臀肌性状发达相关基因,为肉羊分子标记辅助选择提供理论线索。运用PCR-SSCP、PCR-RFLP方法,对陶赛特和萨福克两个肉羊品种群体及其与本地细毛羊杂交1代和2代群体Callipyge(CLPG)基因的多态性进行分析,结果表明:位于18号染色体内的DLK1和GTL2间的103 849 bp处没有发现PCR-RFLP多态性,表明新疆肉羊后臀肌过度发育与CLPG基因无关。随后,实验进一步对18号染色体Meg3.9位点158 520处进行PCR-SSCP分析,发现扩增片段存在着多态性;Meg3.9扩增片段多态性位点在肉羊群体中的基因型有AA、AB和AC,以AA型为主。其中AA、AB基因型与新疆肉羊后臀肌肉发达的表型无关,AC基因型与新疆肉羊后臀肌肉发达的表型相关。在陶赛特与本地细毛羊杂交1代群体中,AC基因型的屠体重和屠宰率与AA、AB基因型差异显著(P<0.05),但3种基因型的各月龄体重没有差异(P>0.05)。通过以上分析可以推断,引起新疆肉用绵羊后臀肌过度发育的性状不是CLPG基因内9571-268.3位点突变导致,可能还存在其他基因或与其连锁的多个QTL的共同作用。

Through polymorphism analysis of genes associated with hindquarters development on chromosome 18 in Xinjiang meat sheep, we sought genes that are associated with increased hindquarters musculature in the hope to provide theoretical guidance to molecular marker-assisted selection of meat sheep. The polymorphism of Callipyge （CLPG） gene was analyzed by PCR-SSCP and PCR-RFLP in populations of Dorset and Suffolk breeds and their F1 and F2 crosses with local Xinjiang Fine Wool sheep. Results showed that there was no PCR-RFLP polymorphism at 103849 bp in the region between DLK 1 and GTL2 on chromosome 18, which suggested that hindquarters over-development was not controlled by the callipyge gene （CLPG） in Xinjiang meat sheep group. In addition, single nucleotide polymorphisms （SNPs） were detected at the Meg3.9 locus on chromosome 18 by PCR-SSCP. Based on the polymorphism, three genotypes AA, AB and AC could be discerned in this locus, with AA being the major one. The relationship between the genotypes and hindquarters hypertrophy was also investigated in the same group. Results indicated that the AC genotype had a significant impact on the hindquarters hypertrophy while the other two were not related to the muscling trait. In F1 crosses between Dorset and local fine wool sheep breeds, there was a significant difference in carcass weight and slaughter rate between the AC genotype and the other two genotypes （ P〈0.05）, but there was not significant difference in the monthly live weight among the three genotypes （P〈0.05）. Based on the above, we found the muscling trait did not result from the mutation in at the 9571-268.3 site of the CLPG locus. Thus it may be under the influence of other genes or multiple linked QTL.