【作者】 姬爱国；

【导师】 周忠孝； 刘文忠；

【作者基本信息】 山西农业大学 ， 动物遗传育种与繁殖， 2004， 硕士

【摘要】 采用胸腺核苷、氨甲蝶呤以及5-溴尿嘧啶核苷同步化外周血淋巴细胞培养法,以染色体核型,G-、C-带和Ag-NORs 技术,对德国肉用美利奴、南非肉用美利奴、道赛特、萨福克、夏洛莱、考力代、南×(夏×考)杂种羊和小尾寒羊8 个种群绵羊共32 只羊(每个种群4 只,公母各2 只)的染色体核型及其似近系数聚类,G-带、C-带,以及Ag-NORs 多态性聚类进行了分析。结果表明:8 个绵羊种群的二倍体染色体数为2n=54,公羊核型为54,XY;母羊核型为54,XX。26 对常染色体中,1-3 号染色体为大的中着丝粒染色体,4-26 号染色体为端着丝粒染色体;X 染色体为最大端着丝粒染色体,Y 染色体为最小中着丝粒染色体。测量染色体长度,计算相对长度,并进行单因素方差分析表明,绵羊各常染色体的相对长度之间存在一定的差异;对性染色体进行Duncan′s 多重比较,种群间X 染色体差异较小;Y 染色体种群间不但存在形态差异,且在相对长度上差异极显著(P<0.01),这与品种的起源和形成过程有关。按核型似近系数λ的大小进行聚类,采用DA/NJ 法绘制聚类图。将8个种群按亲缘关系或培育程度分为四大类,小尾寒羊为最原始类型,其次是德国肉用美利奴羊,南×(夏×考)杂种羊、夏洛莱羊、南非肉用美利奴羊和道赛特羊为高度选育类型,萨福克羊和考力代羊是处于相近水平的中间类型。G-带分析表明,绵羊各种群间除Y 染色体以外的所有染色体对的带型基本一致。根据8 个种群G-带带型共同特点,绘制了绵羊染色体G-带带型模式图,共计带纹329 条(n)。C-带分析表明,阳性带分布于所有常染色体的着丝粒部位,另见萨福克公羊的1 号染体近两端表现插入性C-带;X 染色体均呈阴性,Y 染色体除德国肉用美利奴公羊呈阴性外,其它种群呈阳性。C-带分布的部位虽然相似,但其形状和大小在种群间具有多态性。绵羊Ag-NORs 位于1、2、3、4、21、25 号染色体上。萨福克羊1 号染色体两臂上除着丝粒银染外,其长臂近端也有1-2 个Ag-NORs。X~2独立性检验表明,绵羊Ag-NORs 分布频率具有丰富的多态性。同时对Ag-NORs 的分布频率进行聚类分析,采用D_S/NJ 法绘制聚类图。另外,还观察到三倍体、四倍体和姐妹染色单体交换(SCE)等正常绵羊体细胞染色体畸变类型,这些畸变类型的频率除道赛特较高外,其它种群均较低。SCE 仅见于南×(夏×考)杂种羊.更多还原

【Abstract】 The high-resolution peripheral blood lymphocyte culture method, chromosomal karyotypic with TdR (Thyinidine), MXT(Methotrexate) and 5′-BudR (5`-Bromo-2-Deoxyuridine). Banding techniques were used to study the chromosomal karyotypes, the cluster analysis of Karyotype Resemblance-Near coefficients, G-band ,C-band , and the polymorphism and cluster of Ag-NORs for GMM, SAMM, Suffolk, Dorset, Charolais, Corredale, SCC and Xiaoweihan yang. The high-resolution G-band ideogram was constructed. The result showed that the number of diploid chromosomes of seven breeds and one crossed sheep was 2n=54 (male 54, XY; female 54, XX). Among the total homologous pairs of autosome,1～3 chromosomes were metacentic chromosomes ; 4-26 homologous pair of autosome chromosomes were acrocentic chromosomes; X chromosome was the longest acrocentic chromosome, The Y chromosome was the smallest metacentic chromosme. The results of measuring chromosome and one-way ANOVA analysis showed that the relative length of all autosomes was different among the sheep breeds.The X chromosomes were similar and the Y chromosomes were different not only in relative length (p<0.01) but also in morphology. The result of the clustering analysis of eight breeds′karyotype resemblance-near cofficient and neighbor-joining method, NJ indicated that the eight breeds could be classified into four classes , according to the relationship and the terms of selection . Xiaoweihan yang was the oldest breed, the second was GMM; Dorset,SAMM, Charolais and SCC were the highly selected breeds; However, Suffolk and Corredale were in the middle station. The analysis of high-resolution G-banding illustrated that the appearance of banding patterns of all the chromosomes except for the Y chromosome were basically similar among the eight sheep breeds. Each pair of chromosomes could be identified by their characteristic bands. In this paper the G-bands ideogram of sheep were constructed. Total G-bands were 329(n). The analysis of C-banding showed that there was polymorphism among breeds. All of the autosomes gave positive C-bands. There was inserted C-bands on long arm of chromosome No.1 in Suffolk. The X chromosome showed negative C-bands . The Y chromosomes among eight breeds were positive except for GMM. Although the C-bands were located on the similar regions, they had polymorphism in shape and size.更多还原