  Cell signaling, gene expression, and metabolism are affected by cell-cell
heterogeneity and random changes in the environment. The effects of such
fluctuations on cell signaling and gene expression have recently been studied
intensively using single-cell experiments. In metabolism heterogeneity may be
particularly important because it may affect synchronisation of metabolic
oscillations, an important example of cell-cell communication. This
synchronisation is notoriously difficult to describe theoretically as the
example of glycolytic oscillations shows: neither is the mechanism of
glycolytic synchronisation understood nor the role of cell-cell heterogeneity.
To pin down the mechanism and to assess its robustness and universality we have
experimentally investigated the entrainment of glycolytic oscillations in
individual yeast cells by periodic external perturbations. We find that
oscillatory cells synchronise through phase shifts and that the mechanism is
insensitive to cell heterogeneity (robustness) and similar for different types
of external perturbations (universality).
