【作者】 牛华锋；

【导师】 陈玉林；

【作者基本信息】 西北农林科技大学 ， 动物遗传育种与繁殖， 2008， 硕士

【摘要】 为了进一步明确我国地方绵羊品种的起源、分类及遗传关系,本研究从中国甘肃、宁夏、陕西、山东、河南、新疆、青海等省、市自治区采集了兰州大尾羊(Lanzhou large tail sheep,LLT)、滩羊(Tan sheep,TS)、同羊(Tong sheep,TTS)、小尾寒羊(Small-tail han sheep,STH)、大尾寒羊(Large-tail han sheep,LTH)、阿勒泰羊(Aletail sheep,ALT)、西藏羊(Tibetan sheep,TBS)、多浪羊(Duolang sheep,DL)8个地方品种,并在陕西榆林采集了2个外来纯种萨福克绵羊(Suffolk sheep,SFK)和道塞特绵羊(Dorset sheep,DST)作为对照。本试验采用上游引物L15387 :5′AGCCCCACTATCAACACC3′和下游引物H16149:5′AAATAGTTACCCCCACAGTTAG3′。具体扩增序列位置是靠近tRNA pro一侧的D-loop 763 bp ,其中包含了D-loop上游50 bp。并通过测序分析D-loop高变区序列对我国的绵羊品种进行起源进化和多态性研究,结果如下:1.本试验所研究序列已提交GenBank,登录号:EF494774～EF494792,EF494802～EF494826,EF494875～EF600931,EF494842～EF600924,EF494866～EF600929,EF600912～EF600917。供试绵羊mtDNA D-loop HVI序列A、T含量占优势,其中国绵羊品种与外来品种mtDNAD-loop序列碱基组成没有明显的差异,说明了绵羊mtDNAD-loop为A、T富集区。2.供试绵羊mtDNA D-loop序列的长度范围为522 bp～683 bp,共有19种分子类型。这种长度变异除了少数碱基的缺失和插入之外,主要是由于D-loop区存在2～5个75 bp的串连重复序列所致。但这种序列长度的变异在单倍型中的出现是随机的,并不能作为单倍型的序列特征。3.本试验所获得的93条绵羊mtDNA D-loop序列,共发现了63种单倍型,共有73个变异位点,其中单一多态位点有30个,简约信息位点有43个。除了缺失和插入位点外,还包括22处碱基转换和1处碱基颠换,转换和颠换之比为14.8。说明绵羊线粒体碱基替换存在转换偏倚现象。4.本试验所获得的93条绵羊mtDNA D-loop序列单倍型多样度和核苷酸多样性分别为0.981、0.02900,平均核苷酸差异数K为9.309,反映了中国绵羊品种遗传多样性较贫乏。5.对D-loop区所测个体的所有单倍型利用MEGA 4.0进行NJ, UPGMA和ME聚类时,中国绵羊mtDNA D-loop单倍型序列聚类成A、B、和C三大支系。为了增加结果的可靠性,借用GenBank己发表的摩佛伦羊、赤羊、羱羊、盘羊和家绵羊的D-loop区序列与本研究中的所有序列一同聚类,结果摩佛伦羊聚在B单倍型组中,说明摩佛伦羊与家绵羊的关系较近。而赤羊自成一类,并没有出现在3个单倍型组中。说明现代家绵羊存在3个母系起源,且第三个母系起源地可能就在中国。更多还原

【Abstract】 In order to ascertain origin, sort and genetic relation of locality sheep breed in China, samples from 79 individuals of 8 different sheep breeds were collected from Gansu province(Lanzhou large tail sheep , LLT ), Ningxia province(Tan sheep , TS), Shanxxi province(Tong sheep , TTS),Shandong province(Small-tail han sheep , STH),Henan province(Large-tail han sheep,LTH), Xinjiang province(Aletail sheep,ALT; Small-tail han sheep,STH; Duolang sheep,DL),Qinghai province(Tibetan sheep,TBS) . And the Suffolk sheep and Dorset sheep from Yulin city in Shanxxi province as a control. Studying on the phylogeny evolution and population diversities among Chinese Domestic sheep breeds through analysising sequence of mtDNA D-loop HVI . the results showed that:1. All sequence data to GenBank,GenBank accession numbers:EF494774～EF494792,EF494802～EF494826,EF494875～EF600931,EF494842～EF600924,EF494866～EF600929,EF600912～EF600917。From the mean nucleotide compositions it could be concluded that there were enriched A and T in the mtDNA D-loop HVI .2. The length of the mtDNA D-loop sequences was considerable variable between 522bp and 683 bp, and nineteen molecule model. Except for minor insertions and deletions, the observed length variations were caused by different copy numbers of a 75 bp tandem repeat sequence. But it could not be considered as the characteristic sequence of haplotypes.3. The 93 individual sheep mtDNA D-loop HVI sequences found 63 haplotypes.and contained 73 variable sites, among them, singleton variable sites was 30, parsimony informative sites of two variants was 43. Except for insertions and deletions sites,the transition sites were 22 and transversion sites were 1, the ratio of transitions to transversions was 14.8,suggesting Chinese sheep has the high transition bias.4. The haplotype diversity and nucleotide diversity 93 individual sheep mtDNA D-loop HVI sequences were 0.981、0.02900.The average number of nucleotide differences variation was 9.309.The results indicate that the genetic diversity of Chinese sheep is very abundant.5. The NJ, UPGMA and ME phylogenetic trees was constructed by using MEGA 4.0 with goat as outgroup, three major lineages appeared in the 8domestic sheep, which termed A, B and C lineage. In order to improve the reliability of theresults, all the D-loop complete sequences were used to clustering which was O.musimon, O. vignei, O.aries from GenBank together with the sequences obtained in this study. The results showed that: the relationship between O.musimon and O.aries was nearer, because they were all in B lineage. All the analysis results indicated that the modern domestic sheep have the third maternal origin, and the genesis might be in China.更多还原