Stress Relaxation of Actin Networks and Solutions via Severing*

Actin Filaments are maintained in the cytoskeleton along with the monomeric actin in dynamic self-assembly. These biopolymers form highly dynamic networks that contribute to force generation and mechanical stability in the cytoskeleton. They undergo reactions such as polymerization, depolymerization, and severing, which play a crucial role in self-assembly and affect the rheology of the networks. Recent experiments and theory have identified novel stress relaxation due to severing. Inspired by prior studies, we focus on the effects of severing and its rheological implications in both solution and network limits. We develop computational models to predict specific signatures in stress relaxation due to severing in both limits. By introducing mechano-chemical feedback of stress on severing, we study its implications on the network topology and the effects on the onset of floppy to rigid transition based on the network connectivity and the applied shear strain.