In stable environments, cell size fluctuations are thought to be governed by simple physical principles, as suggested by recent finding of scaling properties. Here we show, using E. coli, that the scaling concept also rules cell size fluctuations under time-dependent conditions , even though the distribution changes with time. We develop a microfluidic device for observing dense and large bacterial populations, under uniform and switchable conditions. Triggering bacterial reductive division by  switching to non-nutritious medium, we find evidence that the cell size distribution changes in a specific manner that keeps its normalized form unchanged; in other words, scale invariance holds. This finding is underpinned by simulations of a model based on cell growth and intracellular replication . We also formulate the problem theoretically and propose a sufficient condition for the scale invariance.  Our results emphasize the importance of intrinsic cellular replication processes in this problem, suggesting different distribution trends for bacteria and eukaryotes.
In stable environments, cell size fluctuations are thought to be governed by simple physical principles, as suggested by recent findings of scaling properties. Here we show, using E. coli, that the scaling concept also emerges with respect to cell size fluctuations under abrupt starvation , even though the distribution changes with time. We develop a microfluidic device for observing dense and large bacterial populations, under uniform and switchable conditions. Triggering bacterial reductive division by abruptly switching to non-nutritious medium, we find that the cell size distribution changes in a specific manner that keeps its normalized form unchanged; in other words, scale invariance holds. We also find that the normalized distribution depends slightly on the growth condition before starvation. These findings are underpinned by simulations of a model based on cell growth and cell cycle . We also formulate the problem theoretically and propose a sufficient condition for the scale invariance. Finally, we numerically show the range of validity of the scale invariance over various characteristic times of the starvation process, revealing the number of multifork replications is crucial for the scale invariance. Our results emphasize the importance of intrinsic cellular cycle processes in this problem, suggesting different distribution trends for bacteria and eukaryotes.
R
finding
findings
R
rules
emerges with respect to
R
time-dependent conditions
abrupt starvation
A
abruptly
D
evidence
R
This finding is
We also find that the normalized distribution depends slightly on the growth condition before starvation. These findings are
R
intracellular replication
cell cycle
A
Finally, we numerically show the range of validity of the scale invariance over various characteristic times of the starvation process, revealing the number of multifork replications is crucial for the scale invariance.
R
replication
cycle