Cell size control driven by the circadian clock and environment in cyanobacteria

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Title: Cell size control driven by the circadian clock and environment in cyanobacteria
Authors: Martins, B
Tooke, AK
Thomas, P
Locke, JCW
Item Type: Journal Article
Abstract: How cells maintain their size has been extensively studied under constant conditions. In the wild, however, cells rarely experience constant environments. Here, we examine how the 24-hour circadian clock and environmental cycles modulate cell size control and division timings in the cyanobacterium Synechococcus elongatus using single-cell time-lapse microscopy. Under constant light, wild type cells follow an apparent sizer-like principle. Closer inspection reveals that the clock generates two subpopulations, with cells born in the subjective day following different division rules from cells born in subjective night. A stochastic model explains how this behaviour emerges from the interaction of cell size control with the clock. We demonstrate that the clock continuously modulates the probability of cell division throughout day and night, rather than solely applying an on-off gate to division as previously proposed. Iterating between modelling and experiments, we go on to identify an effective coupling of the division rate to time of day through the combined effects of the environment and the clock on cell division. Under naturally graded light-dark cycles, this coupling narrows the time window of cell divisions and shifts divisions away from when light levels are low and cell growth is reduced. Our analysis allows us to disentangle, and predict the effects of, the complex interactions between the environment, clock, and cell size control.
Issue Date: 27-Nov-2018
Date of Acceptance: 9-Oct-2018
ISSN: 0027-8424
Publisher: National Academy of Sciences
Start Page: E11415
End Page: E11424
Journal / Book Title: Proceedings of the National Academy of Sciences
Volume: 115
Issue: 48
Copyright Statement: © 2018 the Author(s). Published by PNAS. This open access article is distributed under Creative Commons Attribution License 4.0 (CC BY) (
Sponsor/Funder: Royal Commission for the Exhibition of 1851
Keywords: Science & Technology
Multidisciplinary Sciences
Science & Technology - Other Topics
cell size control
single-cell time-lapse microscopy
circadian clock
stochastic modeling
MD Multidisciplinary
Publication Status: Published
Open Access location:
Online Publication Date: 2018-11-08
Appears in Collections:Mathematics
Applied Mathematics and Mathematical Physics
Faculty of Natural Sciences

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