LARGE-SCALE CHROMATIN STRUCTURAL DOMAINS WITHIN MITOTIC AND INTERPHASE CHROMOSOMES INVIVO AND INVITRO
LARGE-SCALE CHROMATIN STRUCTURAL DOMAINS WITHIN MITOTIC AND INTERPHASE CHROMOSOMES INVIVO AND INVITRO
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DOI：
10.1007/bf00291049
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发表时间：
1989-08-01
期刊：
影响因子：
1.6
通讯作者：
AGARD, DA
中科院分区：
文献类型：
--
作者：
BELMONT, AS;BRAUNFELD, MB;AGARD, DA
在通过与活细胞内染色体进行光学显微镜比较确定能保持染色体形态的缓冲条件下，观察到宽度约为130纳米的高阶染色质结构域是黑腹果蝇和人类有丝分裂染色体的显著组成部分。在同等条件下制备的间期核中，大小相似的空间离散染色质结构域也是显著组成部分。对后期 - 末期转换过程中染色体的观察表明，染色体主要通过这些大规模染色质结构域的逐渐伸直或解旋而去浓缩。对末期核中这些高阶结构域大小分布的定量分析表明，平均宽度为126±36纳米。利用0.5微米厚切片的染色体和间期核的立体对进行的三维观察表明，这些大规模染色质结构域由30纳米纤维紧密折叠成更大的线性纤维状元件组成。在两种不同的缓冲系统中，体外降低多胺或二价阳离子浓度会导致这些较大规模结构域的丧失，在20 - 30纳米纤维以上没有明显的高阶染色质组织。在这些条件下，有丝分裂染色体和间期核内的DNA分布相对于活细胞内通过光学显微镜观察到的，或者通过电子显微镜在未经缓冲液透化直接固定的细胞内观察到的情况，显得明显弥散。这些结果表明，这些大规模染色质结构域是体内染色体结构的基本要素。
Higher-order chromatin structural domains approximately 130 nm in width are observed as prominent components of both Drosophila melanogaster and human mitotic chromosomes using buffer conditions which preserve chromosome morphology as determined by light microscopic comparison with chromosomes within living cells. Spatially discrete chromatin structural domains of similar size also exist as prominent components within interphase nuclei prepared under equivalent conditions. Examination of chromosomes during the anaphase-telophase transition suggests that chromosomes decondense largely through the progressive staightening or uncoiling of these large-scale chromatin domains. A quantitative analysis of the size distribution of these higher-order domains in telophase nuclei indicated a mean width of 126 .+-. 36 nm. Three-dimensional views using stereopairs of chromosomes and interphase nuclei from 0.5 .mu.m thick sections suggest that these large-scale chromatin domains consist of 30 nm fibers packed by tight folding into larger, linear, fiber-like elements. Reduction in vitro of either polyamine or divalent cation concentrations within two different buffer systems results in a loss of these larger-scale domains, with no higher-order chromatin organization evident above the 20-30 nm fiber. Under these conditions the DNA distribution within mitotic chromosomes and interphase nuclei appears significantly diffuse relative to the appearance by light microscopy within living cells, or, by electron microscopy, within cells fixed directly without permeabilization in buffer. These results suggest that these large-scale chromatin structural domains are fundamental elements of chromosome architecture in vivo.