During sporulation of Bacillus subtilis, the cell cycle is reorganized to generate separated prespore and mother cell compartments, each containing a single fully replicated chromosome. The process begins with reorganization of the nucleoid to form an elongated structure, the axial filament, in which the two chromosome origins are attached to opposite cell poles, with the remainder of the DNA stretched between these sites. When the cell then divides asymmetrically, the division septum closes around the chromosome destined for the smaller prespore, trapping the origin-proximal third of the chromosome in the prespore. A translocation pore is assembled through which a DNA transporter, SpoIIIE/FtsK, transfers the bulk of the chromosome to complete the segregation process. Although the mechanisms involved in attaching origin regions to the cell poles are quite well understood, little is known about other aspects of axial filament morphology. We have studied the behavior of the terminus region of the chromosome during sporulation using time-lapse imaging of wild-type and mutant cells. The results suggest that the elongated structure involves cohesion of the terminus regions of the sister chromosomes and that this cohesion is resolved when the termini reach the asymmetric septum or translocation pore. Possible mechanisms and roles of cohesion and resolution are discussed.

中文翻译：

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枯草芽孢杆菌孢子形成早期姐妹染色体末端的结合。

在枯草芽孢杆菌的孢子形成过程中，细胞周期被重组以产生分离的前孢子和母细胞区室，每个区室包含一个完全复制的染色体。该过程从重组类核开始，形成一个细长的结构，即轴丝，其中两个染色体起点连接到相反的细胞两极，其余 DNA 在这些位点之间拉伸。当细胞随后不对称分裂时，分裂隔膜围绕着前往较小前孢子的染色体关闭，将染色体的起源近端三分之一困在前孢子中。组装易位孔，DNA 转运蛋白 SpoIIIE/FtsK 通过该孔传输大部分染色体以完成分离过程。尽管将起源区域连接到细胞极的机制已经很清楚了，对轴向细丝形态的其他方面知之甚少。我们使用野生型和突变细胞的延时成像研究了孢子形成过程中染色体末端区域的行为。结果表明，细长结构涉及姐妹染色体末端区域的内聚，并且当末端到达不对称隔膜或易位孔时，这种内聚被解决。讨论了凝聚力和分辨率的可能机制和作用。结果表明，细长结构涉及姐妹染色体末端区域的内聚，并且当末端到达不对称隔膜或易位孔时，这种内聚被解决。讨论了凝聚力和分辨率的可能机制和作用。结果表明，细长结构涉及姐妹染色体末端区域的内聚，并且当末端到达不对称隔膜或易位孔时，这种内聚被解决。讨论了凝聚力和分辨率的可能机制和作用。