Cell size is specific to each species and impacts cell function. Various phenomenological models for cell size regulation have been proposed, but recent work in bacteria has suggested an 'adder' model, in which a cell increments its size by a constant amount between each division. However, the coupling between cell size, shape and constriction remains poorly understood. Here, we investigate size control and the cell cycle dependence of bacterial growth using multigenerational cell growth and shape data for single Caulobacter crescentus cells. Our analysis reveals a biphasic mode of growth: a relative timer phase before constriction where cell growth is correlated to its initial size, followed by a pure adder phase during constriction. Cell wall labelling measurements reinforce this biphasic model, in which a crossover from uniform lateral growth to localized septal growth is observed. We present a mathematical model that quantitatively explains this biphasic 'mixer' model for cell size control.

中文翻译：

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双相生长动力学控制新月形杆菌中的细胞分裂。

细胞大小对每种物种都是特定的，并且会影响细胞功能。已经提出了用于调节细胞大小的各种现象学模型，但是细菌中的最新工作提出了“加法器”模型，其中细胞在每个分裂之间以恒定的量增加其大小。但是，细胞大小，形状和收缩之间的耦合仍然知之甚少。在这里，我们使用单代新月形细菌的多代细胞生长和形状数据研究细菌生长的大小控制和细胞周期依赖性。我们的分析揭示了一种双相生长模式：收缩期之前的相对定时器阶段，其中细胞的生长与其初始大小相关，紧随其后的是纯加法器阶段。细胞壁标记测量增强了这种双相模型，其中观察到从均匀的侧向生长到局部间隔生长的交叉。我们提出了一个数学模型，该模型定量地解释了用于细胞大小控制的这种双相“混合器”模型。