Induction and Entrainment of Glycolytic Oscillations in Single Yeast Cells

Oscillations are widely distributed in nature and synchronization of oscillators has been described at the cellular level (e.g. heart cells) and at the population level (e.g. fireflies). Yeast glycolysis is one of the best known oscillatory systems. However, it has been studied almost exclusively at the population level, and observations have thus been limited to average behavior in synchronized cultures. To determine the mechanisms behind oscillations, cell-cell interactions and synchronization, and to investigate the role of cell-cell heterogeneity, oscillations have to be studied on the single-cell level. In this work, we developed and combined a suite of methods to induce and study sustained glycolytic oscillations in individual yeast cells. These methods include optical tweezers for cell positioning, microfluidics for precise environmental control, and fluorescence microscopy as readout for metabolite concentration. Using this methodology, we identified the precise conditions required for oscillations to emerge in individual cells and elucidated the mechanism behind oscillations. We also investigated the mechanism behind cell-cell synchronization, its robustness to cell-cell heterogeneity, and its universality with respect to different types of external perturbations.