中文摘要：

核小体定位是复制起始调控的重要因素，但是核小体定位是如何调控真核生物的复制起始，目前还不是很清楚。研究酵母Ⅲ号染色体上的不同活性复制起始序列形成核小体能力对探究真核生物DNA复制起始机制有着重要的生物学意义。酿酒酵母Ⅲ号染色体上的10个复制起始序列分为高活性和低活性两组复制起始序列，利用核小体体外组装技术，将回收纯化的高活性和低活性复制起始序列分别与组蛋白八聚体在体外进行梯度盐透析组装形成核小体，并进行Biotin标记检测，然后用ImageJ软件分析不同复制起始序列组装形成核小体能力的强弱。结果表明，用Image J软件对核小体组装能力强弱进行分析：ARS304〉ARS303〉ARS313〉ARS302〉ARS306〉ARS314，ARS305，ARS307，ARS309，ARS315。低活性复制起始序列较高活性复制起始序列更易形成核小体；复制起始位点偏好出现于核小体缺乏区。

英文摘要：

The regulation of DNA replication initiation sites has a guarantee for DNA replication and cell division. Nucleosome positioning is an important factor for the regulation of DNA replication initiation sites. But it is not clear that how nucleosome positioning regulates DNA replication initiation. It has important biological significance to understand the mechanism of DNA replication initiation. In the study, ten autonomously replicating sequences（ARS） of Saccharomyces cerevisiae YPH499 m chromosome were divided into efficient and inactivity groups. These aim sequences were amplificated by PCR, then recycled and purified using TIANgel Maxi Purification kit. A gradient salt dialysis method was employed to assemble nucleosome in vitro, then nucleosome depended on the purpose sequence were analyzed with Biotin labeling method. The ability of forming nucleosome was analyzed with Image J software. The result showed that nucleosome assembly strength which was analysised by Image J software is respectively 0.706, 1. 395, 2. 989, 0, 0. 031, 0, 0, 0. 714, 0 and 0 from ARS302 to ARS315. In other words, nucleosome assembly strength was as follows：ARS304 〉 ARS303 〉 ARS313 〉 ARS302 〉 ARS306 〉 ARS314, ARS305, ARS307, ARS309, ARS315. The results indicated the inactive ARS were more likely to form nucleosome than the efficient ARS; Replication initiation sites often show anucleosome- depleted region.