Emergent dynamics in motor-free active contractile networks

Living cells exploit contractile structures in the cytoskeleton to achieve various functions such as cell division and motility. Here we show experimental and computational studies on a Ca²⁺-triggered contractile cytoskeletal network composed of cortical proteins from ciliates (Tetrahymena).

Our results demonstrate that this Ca²⁺-triggered network exhibits viscoelastic behaviors that under certain conditions can be reversed. We propose a unifying phase diagram for this calcium-driven contractile dynamics. We find that the microscopic parameters, such as diffusion coefficients, control both the morphology and contractility of the macroscopic network in different phases. Based on the simulation, we created a new phase experimentally combing the contractility and maintaining the micro-structure by pulsating energy input.

We demonstrate how this viscoelastic system can be useful in generating controlled active forces and could have potential in an artificial cytoskeletal network in synthetic cells.