KU Leuven, Department of Microbial and Molecular Systems (M²S), Faculty of Bioscience Engineering, 3001, Leuven, Belgium.
Microbial Sciences Institute, Yale University, West Haven, CT, USA.
Sci Rep. 2017 Aug 16;7(1):8473. doi: 10.1038/s41598-017-08660-0.
A growing bacterium typically divides into two genetically identical and morphologically similar sister cells and eventually gives rise to a clonal population. Nevertheless, significant phenotypic differentiation among isogenic cells frequently occurs, with the resulting heterogeneity in cellular behavior often ensuring population level growth and survival in complex and unpredictable environments. Although several mechanisms underlying the generation of phenotypic heterogeneity have been elucidated, the speed with which identical sister cells tend to phenotypically diverge from each other has so far remained unaddressed. Using Escherichia coli as a model organism, we therefore examined the timing and dynamics of phenotypic individualization among sister cells by scrutinizing and modeling microscopically tracked clonally growing populations before and after a semi-lethal heat challenge. This analysis revealed that both survival probability and post-stress physiology of sister cells shift from highly similar to uncorrelated within the first decile of their cell cycles. This nearly-immediate post-fission randomization of sister cell fates highlights the potential of stochastic fluctuations during clonal growth to rapidly generate phenotypically independent individuals.
一个不断生长的细菌通常会分裂成两个遗传上相同、形态上相似的姐妹细胞，最终形成一个克隆群体。然而，同基因细胞之间经常会出现显著的表型分化，从而导致细胞行为的异质性，这通常确保了在复杂和不可预测的环境中群体水平的生长和存活。尽管已经阐明了产生表型异质性的几种机制，但目前仍未解决相同姐妹细胞彼此之间表型分化的速度。因此，我们使用大肠杆菌作为模式生物，通过在半致死热冲击前后仔细观察和建模微观跟踪的克隆生长群体，研究了姐妹细胞表型个体化的时间和动态。这项分析表明，在细胞周期的前十分之一内，姐妹细胞的存活概率和应激后生理状态从高度相似转变为不相关。这种分裂后姐妹细胞命运的几乎即时随机化突显了克隆生长过程中随机波动的潜力，可以快速产生表型独立的个体。
