中文摘要：

核小体定位是指DNA双螺旋相对于组蛋白八联体的位置.核小体定位通过限制蛋白结合位点参与基因转录调控.本文利用实验检测的人类CD4＋T细胞核小体定位数据,研究了核小体定位在转录因子结合位点（TFBS）和转录起始位点（TSS）附近的分布模式,并分析了在TFBS和TSS周围,核小体定位与DNA甲基化之间的关系.结果表明,在休眠和激活的人类CD4＋T细胞中,部分TFBS和TSS周围的核小体定位在动态改变,即在定位和缺失两种状态之间切换.在TFBS周围,核小体定位和DNA甲基化存在一种互补模式,核小体定位与DNA低甲基化相联系;而在TSS周围,两者呈现同步模式,DNA高甲基化伴随高核小体水平.而且,在TFBS和TSS周围,DNA甲基化位点的分布呈周期模式.CD4＋T细胞被激活时,较少的转录因子启动了较多的基因.

英文摘要：

Nucleosome positioning refers to the position of a DNA helix with respect to the histone core.Positioning plays roles in gene transcription regulation by limiting the accessibility of DNA sequences.Using experimentally-determined nucleosome data,patterns of nucleosomes in the vicinity of transcription start sites（TSS） and transcription factor binding sites（TFBS） are investigated in CD4 ＋ T cell.And the relationship between DNA methylation and nucleosome positioning is also studied.The results indicate that the nucleosomes around some TSS and TFBS switch dynamically in resting and activated T cells.The nucleosome distribution and DNA methylation site distribution show an anticlastic mode near TFBS.Namely,the low DNA methylation is associated with the high nucleosome level.However,in the vicinity of TSS,the two distributions show a synchronous mode.Moreover,around TFBS and TSS,a periodical feature is observed.In activation of CD4 ＋ T cell,less transcription factors regulate more genes.