Lecturer: Jean-François Joanny, Collège de France and Institut Curie, Paris
Abstract:
Many biological systems use the beating of cilia either to propel themselves or to induce fluid flow
around them. Recent experiments in the group of Pascal Martin at Institute Curie study the beating
of self-assembled actin bundles anchored on a solid surface induced by myosin motors, which can
be considered as artificial cilia. In addition to the beating pattern of each cilium, the experiment
images a wave of myosin motors along the cilium.
Classical theories describe the beating cilium as a bending slender beam immersed in a viscous fluid dissipation being due to the external hydrodynamic drag of the viscous fluid. The beating is created by an active mechanism internal to the cilium and due to molecular motors.
I will present in this talk a very generic theory of cilia beating that includes the various types of
external and internal dissipation and of active forces propelling the cilium and that explicitly
considers the molecular motor distribution along the cilium. The theory is based on the entropy
production on the cilium and the various dissipative forces are obtained from Onsager force-flux
relations. The active forces are related to myosin motor densities along the cilium obtained from
binding and unbinding kinetics for the motors.
A simple version of this theory in two dimensions provides a quantitative description of the
experiments on artificial cilia done in the group of Pascal Martin.