Blow J J, Laskey R A
CRC Molecular Embryology Research Group, Department of Zoology, Cambridge, UK.
Nature. 1988 Apr 7;332(6164):546-8. doi: 10.1038/332546a0.
In eukaryotes the entire genome is replicated precisely once in each cell cycle. No DNA is re-replicated until passage through mitosis into the next S-phase. We have used a cell-free DNA replication system from Xenopus eggs to determine which mitotic changes permit DNA to re-replicate. The system efficiently replicates sperm chromatin, but no DNA is re-replicated in a single incubation. This letter shows that nuclei replicated in vitro are unable to re-replicate in fresh replication extract until they have passed through mitosis. However, the only mitotic change which is required to permit re-replication is nuclear envelope permeabilization. This suggests a simple model for the control of DNA replication in the cell cycle, whereby an essential replication factor is unable to cross the nuclear envelope but can only gain access to DNA when the nuclear envelope breaks down at mitosis.
在真核生物中，整个基因组在每个细胞周期中精确复制一次。直到通过有丝分裂进入下一个S期，DNA才会再次复制。我们利用非洲爪蟾卵的无细胞DNA复制系统来确定哪些有丝分裂变化允许DNA再次复制。该系统能高效复制精子染色质，但在单次孵育中不会再次复制DNA。本文表明，体外复制的细胞核在进入有丝分裂之前，无法在新鲜的复制提取物中再次复制。然而，允许再次复制所需的唯一有丝分裂变化是核膜通透性增加。这提示了一个细胞周期中DNA复制控制的简单模型，即一种必需的复制因子无法穿过核膜，只有在有丝分裂时核膜解体时才能接触到DNA。
