Analysis Of Selection Signatures Identify Genes Associated With Tail Type In Sheep

China has long history of sheep industry and a varies of sheep resources. However the production is relatively fall behand. sheep production linked with the income of farmers, herdsmen and the mutton demand for people in a particular region. the fat-tailed gradually lost its market value and economic value accompany with the people more and more focus on cardiovascular and cerebrovascular diseases. According to tail-type, chinese indigious sheep at least can be divided into four categories, namely thintail sheep, fat- buttock sheep, short- fat-tail sheep and long-fat-tail sheep. The fact that wild sheep is a thin-tail sheep illustrate that different tail type is the result of a special breeding in long husbandry practice. We can detection these selection signatues as the biotechnology and statistical method were development and then finding candidate genes associated with tail type for breeding and breed conservation. In this study, we choice two group sheep with extreme phenotypes, namely: the fat-tail group and thin-tail group. A total of 122 individuals were genotyped using Illumina Ovine 50 K SNP Chip. In order to understand the sheep population genetic structure in our country, we used NETVIEW to build fine mapping of 11 varieties of sheep before the selection signature analysis. The results from NETVIEW analysis suggest that the chinese indigious sheep can be divided into two groups, one is Tibetan sheep, another one is the Mongolian- kazakhstan group;UJI sheep have a direct genetic relationship with all of Mongolia group sheep except for Lop sheep and have indirect genetic relationship with LOP sheep. LOP sheep and KAZ sheep have closely genetic relationship, and KAZ sheep and DUL sheep exist distant genetic relationships. DIQ can be separated from Tibet group; and TIBT can be separated from Tibetan groups, TIBQ and TIBS can not be separated. NETVIEW can be as a tool to analysis population structure because it has the advantage of short time computation, reliable result, and well reflect histoy. UJI is the most ancient Mongolia sheep in this case, Tibetan sheep from different areas have the trendency of differentiation although it is not obviously. Then we use FST and hapFLK to detect selection signatures between fat-tail and thin-tail sheep. These two methods found six overlapping regions and 43 overlapping genes and pairwise FST methods was use to validate six overlapping areas. Candidate genes was identified by both methods. Pair-wise FST shows that in the overlap region, the peak selection signatures only exist in fattail and thin-tail sheep. This results showed that this overlap region 6 and several candidate genes, such as PBMP2, PPP1 CC,PROKR1, ETAA1, HOXA11, PDGFD may play an important role in tail type. We validate PDGFD gene using western blot, the result suggest that PDGFD protein expression level between three-month fetus and new-born fetus doesn’t have obviouse difference in tail adipose tissue and kidney but have obviouse difference in subcutaneous adipose tissue from three-month fetus and have obviouse difference in liver from new-born fetus. Although this result does not support PDGFD have an important role in tail type fomation, however we cannot deny its may affect the tail sheep fat deposition.