He Xiaoyun, Zhang Zhuangbiao, Liu Qiuyue, Chu Mingxing
Key Laboratory of Animal Genetics, Breeding and Reproduction of Ministry of Agriculture, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China.
Reprod Domest Anim. 2019 Oct;54(10):1400-1410. doi: 10.1111/rda.13538. Epub 2019 Aug 13.
Previous researches have shown that MTNR1A plays an essential role in sheep reproduction. However, most researches focused more on the reproductive seasonality of sheep, and few scientists had studied the association of polymorphisms of the MTNR1A gene with ovine litter size and reproductive seasonality. Therefore, we chose MTNR1A gene to detect its novel sequence polymorphisms and population genetics and analyse their association with seasonal reproduction and litter size in ewes. The mRNA expression level in hypothalamus, pituitary and ovary was also detected. In this study, five polymorphisms (g.15118664G > T, g.15118683C > T, g.15118756C > T, g.15118774C > T and g.15118951G > A) were identified in exon 2. Most importantly, the g.15118683C > T and g.15118951G > A were significant difference between year-round oestrous sheep and seasonal oestrous sheep (p < .01), and g.15118756C > T had a great effect on litter size of Small Tail Han sheep (p < .05). In addition, the mRNA expression level of MTNR1A in the hypothalamus of polytocous Small Tail Han sheep was significantly higher than that in monotocous Small Tail Han sheep (p < .01) and the expression of MTNR1A in the hypothalamus of year-round oestrous sheep was significantly higher than that in seasonal oestrous sheep (p < .01). Polymorphisms in exon 2 may regulate the reproductive seasonality and litter size of ewes by influencing gene expression to regulate the reproductive seasonality and litter size of ewes. Our studies provided useful guidance in marker-assisted selection of the litter size in Small Tail Han sheep.
以往的研究表明，MTNR1A在绵羊繁殖中起着至关重要的作用。然而，大多数研究更多地集中在绵羊的繁殖季节性上，很少有科学家研究MTNR1A基因多态性与绵羊产羔数和繁殖季节性之间的关联。因此，我们选择MTNR1A基因来检测其新的序列多态性和群体遗传学，并分析它们与母羊季节性繁殖和产羔数的关联。同时还检测了下丘脑、垂体和卵巢中的mRNA表达水平。在本研究中，在外显子2中鉴定出5个多态性位点（g.15118664G>T、g.15118683C>T、g.15118756C>T、g.15118774C>T和g.15118951G>A）。最重要的是，g.15118683C>T和g.15118951G>A在常年发情绵羊和季节性发情绵羊之间存在显著差异（p<.01），而g.15118756C>T对小尾寒羊的产羔数有很大影响（p<.05）。此外，多胎小尾寒羊下丘脑MTNR1A的mRNA表达水平显著高于单胎小尾寒羊（p<.01），常年发情绵羊下丘脑MTNR1A的表达显著高于季节性发情绵羊（p<.01）。外显子2中的多态性可能通过影响基因表达来调节母羊的繁殖季节性和产羔数。我们的研究为小尾寒羊产羔数的标记辅助选择提供了有用的指导。
