褪黑激素受体1A基因外显子2与小尾寒羊高繁殖力的关联

Association between exon 2 of melatonin receptor 1A gene and prolificacy in Small Tail Han sheep

以褪黑激素受体1A(melatonin receptor 1A,MTNR1A)基因为候选基因,通过2种限制性内切酶(MnlⅠ、RsaⅠ),采用PCR-RFLP技术检测MTNR1A基因第2外显子主要序列在高繁殖力绵羊品种小尾寒羊中的单核苷酸多态性,同时研究该基因对小尾寒羊高繁殖力的影响。结果表明,MTNR1A基因外显子2的605位碱基处表现出MnlⅠ酶切多态性,在小尾寒羊中检测到3种基因型:MM(236 bp/236 bp)、Mm(236 bp/303 bp)、mm(303 bp/303 bp),MM和Mm基因型频率明显高于mm基因型频率。MTNR1A基因外显子2的604位碱基处表现出RsaⅠ酶切多态性,在小尾寒羊中检测到3种基因型:RR(267 bp/267 bp)、Rr(267 bp/290 bp)、rr(290 bp/290 bp),RR和Rr基因型频率明显高于rr基因型频率。复合基因型MMRR、MMRr、MmRR、MmRr的频率明显高于MMrr、mmRR、mmRr的频率,没有检测到mmrr复合基因型。小尾寒羊产羔数在MnlⅠ和RsaⅠ酶切复合基因型之间没有显著差异,但至少携带一个拷贝等位基因M的小尾寒羊比不携带M的具有稍微较高的产羔数,基因型为mm的小尾寒羊产羔数比其他基因型的小尾寒羊平均低0.26只。

The exon 2 of melatonin receptor 1A （MTNR1A） gene was amplified and a uniform fragment of 824 bp was obtained in 137 Small Tail Hart ewes. The 824 bp PCR product was digested with restriction endonucleases MnlⅠ and RsaⅠ , and genetic polymorphisms were detected by PCR-RFLP. Polymorphic MnlⅠ site was detected at base position 605 of the exon 2 of MTNR1A gene. Three genotypes MM （236 bp/236 bp）, Mm （236 bp/303 bp） and mm （303 bp/303 bp） were found in Small Tail Han sheep. Frequency of MM genotype and Mm genotype was obviously higher than that of mm genotype. Polymorphic RsaⅠ site was detected at base position 604 of the exon 2 of MTNR1A gene. Three genotypes RR （267 bp/267 bp）, Rr （267 bp/290 bp） and rr （290 bp/290 bp）were found in Small Tail Hart sheep. Frequency of RR genotype and Rr genotype was obviously higher than that of rr genotype. Frequencies of combined genotypes MMRR, MMRr,MmRR,MmRr were obviously higher than those of combined genotypes MMrr,mmRR,mmRr, No combined genotype mmrr was detected in Small Tail Han sheep. Litter size was not significantly associated with MTNR1A combined genotype in Small Tail Han sheep. Ewes that carried at least one copy of M had slightly larger litters than those that did not. Ewes of genotype mm had approximately 0. 26 fewer lambs per ewe lambing than ewes of other genotypes.