Quantifying Energy Fluxes in a Cell

Cells are out of equilibrium systems that use energy to drive a myriad of processes necessary for life. We aim to quantify what the energetic costs of these processes are and how energy is partitioned between them focusing on spatiotemporal patterns of glycolytic activity in the cell While the temporal dynamics have been studied, the spatial dynamics of glycolysis rates are largely unknown. Here, we use oocytes of the bat star Patiria miniata as a model system to address this question. With a recently developed probe that gives a fluorescence signal in the presence of a glycolysis intermediate, whose concentration is known to be directly proportional to glycolytic flux in a large number of systems, we employ techniques from fluorescence microscopy to quantify this signal in different regions of the cell with high spatiotemporal accuracy. We show that there is a significant increase in signal at the boundaries of the cells and in the nucleus, which gradually increases throughout meiosis, suggesting a spatially varying glycolytic rate. Combined with targeted perturbations and other single cell imaging techniques, this work will help us take a peek into the metabolism of a single cell, and is a step towards a roadmap elucidating the energy budgets of various cellular processes.