Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Newcastle-upon-Tyne, UK.
Microbiologyopen. 2019 Oct;8(10):e876. doi: 10.1002/mbo3.876. Epub 2019 Jun 13.
Recent studies taking advantage of automated single-cell time-lapse analysis have reignited interest in the bacterial cell cycle. Several studies have highlighted alternative models, such as Sizer and Adder, which differ essentially in relation to whether cells can measure their present size or their amount of growth since birth. Most of the recent work has been done with Escherichia coli. We set out to study the well-characterized Gram-positive bacterium, Bacillus subtilis, at the single-cell level, using an accurate fluorescent marker for division as well as a marker for completion of chromosome replication. Our results are consistent with the Adder model in both fast and slow growth conditions tested, and with Sizer but only at the slower growth rate. We also find that cell size variation arises not only from the expected variation in size at division but also that division site offset from mid-cell contributes to a significant degree. Finally, although traditional cell cycle models imply a strong connection between the termination of a round of replication and subsequent division, we find that at the single-cell level these events are largely disconnected.
最近利用自动化单细胞时程分析的研究重新点燃了人们对细菌细胞周期的兴趣。有几项研究强调了替代模型，例如 Sizer 和 Adder，它们的主要区别在于细胞是否能够测量其当前大小或自出生以来的生长量。最近的大部分工作都是在大肠杆菌上完成的。我们着手在单细胞水平上研究特征明确的革兰氏阳性细菌枯草芽孢杆菌，使用准确的荧光标记进行分裂以及用于完成染色体复制的标记。我们的结果与快速和慢速生长条件下的 Adder 模型一致，与 Sizer 模型一致，但仅在较慢的生长速率下一致。我们还发现细胞大小的变化不仅来自于预期的分裂时的大小变化，而且来自于从细胞中部偏移的分裂位点也有很大的贡献。最后，尽管传统的细胞周期模型暗示一轮复制的终止和随后的分裂之间有很强的联系，但我们发现这些事件在单细胞水平上很大程度上是没有关联的。
