Laboratoire de Physique Théorique
Toulouse - UMR 5152

The cytoskeleton is constituted of rigid filaments, actin and microtubules, that interact with molecular motors introducing filament sliding and active reorganization. Experimentally it has been shown that reconstituted cytoskeleton solutions are able to self-organize into many different filament patterns like asters, vortices, bundles, etc. I will discuss recent modelings of this structure formation process involving filaments, motors and passive crosslinks. In the second part I will present a simple model describing how cells (or simpler cell fragments) can use active processes, namely actin polymerization and motor-induced contraction to move on a substrate. The model consists of a simplified version of the orientational filament dynamics, coupled to a phase-field description of the cell membrane. This model successfully reproduces the primary phenomenology of cell motility : discontinuous onset of motion, diversity of cell shapes, as well as the possibility of complex shape oscillations and stick-slip motion.

1) D. Smith, F. Ziebert et al. ’Molecular motor-induced instabilities and crosslinkers determine biopolymer organization’, Biophys. J. 93, 4445(2007). 2) F. Ziebert, I.S. Aranson and L. S. Tsimring ’Effects of crosslinks on filament-motor organization’ New J. Phys. 9, 421 (2007). 3) F. Ziebert, S. Swaminathan and I. S. Aranson, ’Model for self-polarization and motility of keratocyte fragments’, J.R. Soc. Interface 9, 1084 (2012). 4) F. Ziebert and I. S. Aranson, submitted (2012).