Nonequilibrium Dissipation in Living Oocytes

Living organisms are inherently out-of-equilibrium systems. We employ recent developments in stochastic energetics and rely on a minimal microscopic model to predict the amount of mechanical energy dissipated during active vesicle motion in mouse oocytes. Our model includes complex rheological effects and nonequilibrium stochastic forces due to molecular motors. By performing active microrheology and tracking micron-sized vesicles in the cytoplasm of living oocytes, we quantify the spectrum of dissipated energy. We show that our model is consistent with the experimental data, and we use it to offer predictions for the injection and dissipation energy scales involved in active fluctuations in the oocyte cytoplasm.