Understanding the variability of growth in single cells: from bacteria to mammalian cells

Noise analysis in biological systems has greatly increased our understanding of the underlying cellular processes. Noise in the cell division process is often assumed to be responsible for variability in cell cycle duration, and to underlie heterogeneous responses of bacteria to antibiotics, as well as of cancer cells to drugs. We show that variability of growth in bacteria can evolve under fluctuating environment. More generally, we ask whether we can differentiate between stochastic and deterministic control of cell division variability. Using long-term time lapse microscopy to follow thousands of divisions and tools from non linear dynamics analysis, we show that the variability in cell-cycle duration in mammalian cells, which at first glance seems dominated by noise, is in fact controlled by a deterministic factor.