Phillips D M, Phillips S G
J Cell Biol. 1973 Jul;58(1):54-63. doi: 10.1083/jcb.58.1.54.
The reconstruction of the nucleolus after mitosis was analyzed by electron microscopy in cultured mammalian (L929) cells in which nucleolar RNA synthesis was inhibited for a 3 h period either after or before mitosis. When synchronized mitotic cells were plated into a concentration of actinomycin D sufficient to block nucleolar RNA synthesis preferentially, nucleoli were formed at telophase as usual. 3 h after mitosis, these nucleoli had fibrillar and particulate components and possessed the segregated appearance characteristic of nucleoli of actinomycin D-treated cells. Cells in which actinomycin D was present for the last 3 h preceding mitosis did not form nucleoli by 3 h after mitosis though small fibrillar prenucleolar bodies were detectable at this time. These bodies subsequently grew in size and eventually acquired a particulate component. It took about a full cell cycle before nucleoli of these cells were completely normal in appearance. Thus, nucleolar RNA synthesis after mitosis is not necessary for organization of nucleoli after mitosis. However, inhibition of nucleolar RNA synthesis before mitosis renders the cell incapable of forming nucleoli immediately after mitosis. If cells are permitted to resume RNA synthesis after mitosis, they eventually regain nucleoli of normal morphology.
通过电子显微镜对培养的哺乳动物（L929）细胞有丝分裂后核仁的重建进行了分析，这些细胞在有丝分裂之前或之后，核仁RNA合成被抑制3小时。当同步化的有丝分裂细胞接种到足以优先阻断核仁RNA合成的放线菌素D浓度中时，核仁在末期照常形成。有丝分裂后3小时，这些核仁具有纤维成分和颗粒成分，并具有经放线菌素D处理的细胞的核仁特有的分离外观。在有丝分裂前最后3小时存在放线菌素D的细胞，在有丝分裂后3小时没有形成核仁，尽管此时可检测到小的纤维状核仁前体。这些小体随后变大，最终获得颗粒成分。这些细胞的核仁外观完全正常大约需要一个完整的细胞周期。因此，有丝分裂后核仁RNA合成对于有丝分裂后核仁的组织不是必需的。然而，有丝分裂前核仁RNA合成的抑制使细胞在有丝分裂后不能立即形成核仁。如果细胞在有丝分裂后被允许恢复RNA合成，它们最终会重新获得形态正常的核仁。
