Matsui S I, Weinfeld H, Sandberg A A
J Cell Biol. 1979 Feb;80(2):451-64. doi: 10.1083/jcb.80.2.451.
RNA synthesis almost ceases in mitosis. It is ambiguous whether this temporal, negative control of RNA synthesis is solely because of the nature of chromosomes per se, (i.e., their condensed state), or to a physical loss of RNA polymerases along with other nuclear proteins which have been shown to pass into the cytoplasm in mitosis, or to their combined feature. Aside from such regulatory considerations, a question has also been raised as to whether RNA polymerases are constituents of metaphase chromosomes. To clarify these aspects of RNA polymerase-chromatin interaction in mitosis, the enzymes in chromosomes were quantitated and their levels compared to those in interphase nuclei and cells at various phases of the cell cycle. The results show that the amounts of form I, form II, and probably form III enzymes bound to a genome-equivalent of chromatin stay constant during the cell cycle. Thus, the mechanism for the negative control of RNA synthesis in mitosis appears to exist in the chromosomes per se, but not to be directly related to the RNA polymerase levels. This quantitative conservation of chromatin-bound RNA polymerases implies that they may persist as structural components of the chromosomes in mitosis.
RNA合成在有丝分裂过程中几乎停止。RNA合成这种暂时的负调控是仅仅由于染色体本身的性质（即它们的凝聚状态），还是由于RNA聚合酶与其他已被证明在有丝分裂时进入细胞质的核蛋白一起物理性丢失，抑或是由于它们的综合特性，目前尚不清楚。除了这些调控方面的考虑，还提出了一个问题，即RNA聚合酶是否是中期染色体的组成成分。为了阐明有丝分裂过程中RNA聚合酶 - 染色质相互作用的这些方面，对染色体中的酶进行了定量，并将其水平与间期细胞核和细胞周期各阶段细胞中的酶水平进行了比较。结果表明，与基因组当量染色质结合的I型、II型以及可能的III型酶的量在细胞周期中保持恒定。因此，有丝分裂中RNA合成负调控的机制似乎存在于染色体本身，但与RNA聚合酶水平没有直接关系。染色质结合的RNA聚合酶的这种定量守恒意味着它们可能在有丝分裂中作为染色体的结构成分持续存在。
