Active nematics: Topology in biology?

Active systems, such as bacterial suspensions and the cytoskeleton, driven by molecular motors, provide their own energy and hence operate out of thermodynamic equilibrium. Continuum models of active systems are closely related to those describing liquid crystal hydrodynamics, together with additional ‘active’ stress terms. I shall discuss recent results from simulations of dense active nematics and their relevance to cell motility and cell division. In particular I shall give examples where topological defects, which are important in the physics of liquid crystals, might be of relevance in biological systems.