Thomas J O, Thompson R J
Cell. 1977 Apr;10(4):633-40. doi: 10.1016/0092-8674(77)90096-4.
We have used micrococcal nuclease as a probe of the repeating structure of chromatin in four nuclear populations from three tissues of the rabbit. Neuronal nuclei isolated from the cerebral cortex contain about 160 base pairs of DNA in the chromatin repeat unit, as compared with about 200 base pairs for nonastrocytic glial cell nuclei from the same tissue, neuronal nuclei from the cerebellum and liver nuclei. All four types of nuclei show the same features of nucleosomal organization as other eucaryotic nuclei so far studied: nucleosomes liberated by digestion with micrococcal nuclease give a "core particle" containing 140 base pairs as a metastable intermediate on further digestion and a series of single-strand DNA fragments which are mutiples of 10 bases after digestion with DNAase I. Nuclei from cerebral cortex neurons, which have a short repeat, are distinct from the others in being larger, in having a higher proportion of euchromatin (dispersed chromatin) as judged by microscopy and in being more active in RNA synthesis in vitro.
我们使用微球菌核酸酶作为探针，来研究家兔三种组织中四个核群体的染色质重复结构。从大脑皮层分离出的神经元细胞核，其染色质重复单元中含有约160个碱基对的DNA，而来自同一组织的非星形胶质细胞的神经胶质细胞核、小脑的神经元细胞核和肝细胞核，其染色质重复单元中约有200个碱基对。与迄今为止研究过的其他真核细胞核一样，所有这四种类型的细胞核都显示出相同的核小体组织特征：用微球菌核酸酶消化释放出的核小体，在进一步消化时会产生一个含有140个碱基对的“核心颗粒”作为亚稳中间体，以及一系列经DNA酶I消化后为10个碱基倍数的单链DNA片段。大脑皮层神经元的细胞核，其重复序列较短，在大小上、通过显微镜判断的常染色质（分散染色质）比例较高以及在体外RNA合成中更活跃等方面，与其他细胞核不同。
