Modeling dividing actomyosin droplets as colloids in liquid crystal

Biopolymer networks are often organized into oriented bundles both in reconstituted in vitro situations and in the cell. Motivated by dividing fluid droplet-like bundles of actomyosin observed in experiments, we propose a theoretical mechanism for division of a droplet of liquid crystal material induced by a colloidal particle. The preferred alignment of actin filaments at the droplet surface and that at the motor cluster, modeled as a colloidal inclusion wet by the droplet, together result in a deformed droplet having minimal free energy. The dynamics of the model are illustrated by continuum simulations which show droplet deformation and pinching off into two equal daughter droplets. While colloidal inclusions are widely known to induce defects in a surrounding bulk liquid crystal, we predict here that the colloid can in principle deform and divide droplets of liquid crystal. Our description of these liquid crystal droplet dynamics, where the active forces of molecular motors is accounted for effectively through aligning interactions, explores the physical aspects of complex fluid phase separation in biology and suggests that self-assembly of motors may occur through interactions mediated by ordered biopolymers.