  In stable environments, cell size fluctuations are thought to be governed by
simple physical principles, as suggested by recent findings of scaling
properties. Here, by developing a microfluidic device and using E. coli, we
investigate the response of cell size fluctuations against starvation. By
abruptly switching to non-nutritious medium, we find that the cell size
distribution changes but satisfies scale invariance: the rescaled distribution
is kept unchanged and determined by the growth condition before starvation.
These findings are underpinned by a model based on cell growth and cell cycle.
Further, we numerically determine the range of validity of the scale invariance
over various characteristic times of the starvation process, and find the
violation of the scale invariance for slow starvation. Our results, combined
with theoretical arguments, suggest the relevance of the multifork replication,
which helps retaining information of cell cycle states and may thus result in
the scale invariance.
