Quantifying Dissipation in Actomyosin Networks

Abstract

The self-organization of actomyosin networks is known to be intricately controlled by concentrations of filaments and associated proteins, however a general physical explanation of the emergence of different dynamical states (such as vortices in gliding assays) in these active matter systems has not yet been firmly established. It has been hypothesized that the dissipation of free energy by active matter systems is optimized during self-organization, leading to the emergence of more highly dissipative dynamical states, but this idea has not yet been evidenced in actomyosin systems. Here we establish a methodology for testing this hypothesis in actomyosin networks using MEDYAN, an agent-based simulation platform for studying active networks. We extend the capabilities of MEDYAN to allow quantification of the rates of dissipation resulting from chemical reactions and relaxation of mechanical stresses during simulation trajectories, and apply these methods here to characterize the trajectory of dissipation rates accompanying the self-organization of small disordered actomyosin networks at varying concentrations of myosin and cross-linkers, as well as the distributions of these dissipation rates. In the data presented here we do not observe network reorganizations that lead to increases in the total dissipation rate as predicted by the dissipation-driven adaptation hypothesis mentioned above, however we discuss possible future experiments utilizing this new methodology that could carefully test the applicability of this principle in actomyosin networks.