Dynamic events of sister chromosomes in the cell cycle of Escherichia coli
Dynamic events of sister chromosomes in the cell cycle of Escherichia coli
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DOI：
10.1111/j.1365-2443.2007.01157.x
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发表时间：
2008-02-01
期刊：
影响因子：
2.1
通讯作者：
Hiraga, Sota
中科院分区：
文献类型：
--
作者：
Adachi, Shun;Fukushima, Toru;Hiraga, Sota
在各种条件下，在异步生长的大肠杆菌细胞中精确分析了涉及姐妹染色体分配的各种事件。为了研究姐妹染色体之间的凝聚力，我们分析了活细胞生长在各种条件下的复制起点（oriC）的数量通过流式细胞术和荧光显微镜的oriC焦点的副本。每个细胞的oriC病灶的平均数量显着小于每个细胞的oriC拷贝数，只有少数例外，这表明oriC姐妹拷贝的凝聚力。在mukB无效突变体细胞中，在某些生长条件下也观察到oriC姐妹拷贝的内聚现象。末端区（ter）的姐妹拷贝也被发现是内聚的。免疫荧光显微镜的新生DNA脉冲标记5-溴-2 '-脱氧尿苷（BrdU）表明，成对的复制叉双向复制的行为能够迁移到相反的方向进行复制过程中，在贫介质，然而，其中一些是密切相关的丰富的媒体。对MukB-GFP焦点的分析表明，MukB焦点的数量总是大于复制叉的数量。MukB-GFP灶的数量随着细胞长度的增加而增加。在生长的细胞中这些染色体事件的顺序已经被描绘出来。
Various events involving partitioning of sister chromosomes were precisely analyzed in asynchronously growing Escherichia coli cells in various conditions. To examine the cohesion between sister chromosomes, we analyzed living cells growing under various conditions for the number of the replication origin (oriC) copies by flow cytometry and the foci of oriC by fluorescence microscopy. The average number of the oriC foci per cell was significantly smaller than the number of oriC copies per cell with few exceptions, suggesting cohesion of oriC sister copies. Cohesion phenomenon of oriC sister copies was also observed in a mukB null mutant cells under some growth conditions. Sister copies of the terminal region (ter) were also found to be cohesive. Immunofluorescence microscopy for nascent DNA pulse-labeled with 5-bromo-2'-deoxyuridine (BrdU) indicated that paired replication forks acting on bidirectional replication were able to migrate toward opposite directions during ongoing replication in poor medium; however, some of them were closely associated in rich media. Analysis of the foci of MukB-GFP indicates that the number of MukB foci was always larger than the number of replication forks. The number of MukB-GFP foci increased together with cell length. The sequence of these chromosomal events in the growing cells has been depicted.