【作者】 刘宁；

【导师】 赵有璋； 吴登俊；

【作者基本信息】 甘肃农业大学 ， 动物遗传育种与繁殖， 2005， 博士

【摘要】 测定了饲养在中国的11个家养山羊品种(包括4个引进品种)72个个体的线粒体DNA(mtDNA)控制区(D-环)全序列,结果表明控制区全序列长度为1,212bp或1,213bp,共检测到276个变异(突变)位点,占分析位点总数的22.56%,其中简约信息位点175个,单一多态位点81个,所有这些突变均为两核苷酸间的变异;同时,本次试验在中国本地山羊的序列中也检测到T?C,G?A颠换的发生。颠换发生的频率在0.0825%(简阳大耳羊)～0.66%(昭通山羊)之间,其中,马头山羊、榕江小香羊的核苷酸序列的颠换发生率均为0.413%,与作为外群参与分析的野生山羊(Capra aegagrus和Capra falconeri)的颠换发生频率(0.436%)相似。在碱基的1,075位有一个核苷酸的插入/缺失。所有序列的Tajima D中性检验结果不显著(P > 0.10或0.05 < P < 0.10),说明序列均为选择性中性,同时也表明中国南方山羊品种在过去没有出现群体扩张。无论国内家养山羊,还是引进品种均表现出了较高的核苷酸多样度(Pi)和单倍型多样性(H)。整个家山羊群体的平均核苷酸差异数为19.475,核苷酸多样度为(1.608±0.09)%,这些差异共定义了60种单倍型,单倍型多样性为0.977。其中,中国家养山羊7个品种有40种单倍型,引进的4个品种有20种单倍型。中国南方山羊的单倍型多样性(0.973)比引进品种(0.903)高,但引进品种的核苷酸多样性(1.731%)、单倍型间的平均距离(0.0187)、单倍型间的平均核苷酸差异数(19.475)高于中国南方山羊品种(分别为1.531%、0.0151和18.554),但差异均不显著(P>0.05)。表明中国家养山羊的遗传多样性较为丰富,且品种间表现出弱的遗传结构。将本研究测定的73条mtDNA的D环全序列与文献报道的76条家山羊序列、2种野山羊(角猾羊和捻角山羊)的D环序列结合分析发现,文献报道的单倍型仅有3种在中国南方地方山羊品种中存在。各家养山羊品种间平均核苷酸差异数为19.475(7.50~30.42),平均核苷酸差异率为1.607%(0.619%~2.512%)。品种间的Kimura双参数距离变异较大(0.0008~0.0315)。许多品种都具有独特的单倍型类型,只有2种单倍型在品种间有共享。各单倍型在品种间和品种内的分布和频率也不平衡,显示出山羊mtDNA控制区(CR,D-loop)序列具有较为丰富的遗传多样性,尤其是在国内地方山羊品种(系)中,D-loop序列的核苷酸单倍型之间没有共享性,大多数为各品种(系)所特有的单倍型。更多还原

【Abstract】 In the study, complete sequence of mitochondrial DNA (mtDNA) control region(CR,D-loop) was sequenced in 73 individuals from 11 domestic goat breeds (strains) raised in China (include 4 foreign breeds). The complete sequence of mtDNA CR is 1,212 or 1,213bp (base pair).Polymorphic sites were 276 (22.77% in 1,212) with 175 parsimony informative polymorphic sites, 81 singleton polymorphic sites. All polymorphic sites were two nucleotide variants. Transversions among nucleotide pairs were identified within the Chinese indigenous species (strains).The frequencies of transversion were from 0.0825%(JYL)~0.66%(ZT).The frequencies of transvertion in Matou goat (MT) and Rongjiang goat (RJ) were 0.413%,it is alike with the frequencies of the wild goat (Capra aegagrus and Capra falconeri) (0.436%) which were used as out-group. Only one insertion/deletion site were identified in 1075 sites among all species (strains).Tajima’s test of selective neutrality was not significant (P > 0.10 or 0.05 < P < 0.10).It revealed that all sequences of domestic goats were selective neutrality and that goat population did not undergo expansions. High nucleotide diversity(Pi=0.987)and haplotype diversity(H=1.768%)were manifested either in Chinese goat or in foreign goat populations. All sequence polymorphic sites defined 60 haplotypes with 20 haplotypes within 4 foreign breeds, 40 within 7 Chinese breeds. Chinese local-raised goats showed higher haplotype diversity (0.973) than foreign breeds (0.913), while nucleotide diversity pairwise distance and average number of nucleotide differences among haplotypes were higher than foreign breeds.These results suggested richer genetic diversity within Chinese goat populations. The hierarchical components of mtDNA variation computed under the analysis of molecular variance(AMOVA) framework showed that smaller but not significant percentage existed among breeds(24.22%;P>0.05) .The AMOVA results revealed that there were no significant divergence and far weaker genetic structure among breeds.Only 3 haplotypes existed in common with Chinese goat populations by analyzing 152 sequences in the study, combined with 18 introduced domestic goat species and 2 wild goats(Capra aegagrus and Capra falconeri) reported in documents. The average number of nucleotide differences, average number of nucleotide subs. Per-site be tween breeds were 19.475(7.50~30.42) and 1.607% (0.619%~2.512%), respectively. The Kimura 2-parameter distance between breeds varied from 0.0008 to 0.0315. Many breeds had its unique更多还原