Teil eines Buches,
Modelling the self-assembly of the plant microtubule cortical array
Abstract Book of the XXIII IUPAP International Conference on Statistical Physics, Genova, Italy, (9-13 July 2007)
Zusammenfassung
Filamentous proteins, making up the cytoskeleton of cells, assemble into a rich variety of structures, essential for the maintenance, growth and division of the
cell. The specific spatial patterning of these cytoskeletal structures is achieved by as yet only partially understood self-organisation mechanisms. Unravelling these mechanisms is a challenge both for cell biological experiments and physical modelling. In plant cells, the significant orientational ordering of microtubules, in a structure known as the cortical array, is crucial to sustain their characteristic anisotropic growth. During this growth phase, the microtubules are confined to a thin layer of cytoplasm just inside the cell membrane. The microtubules are seen to align with an orientation transverse to the growth axis of the cell. In vivo the microtubules appear to adhere to the membrane confining them to a two-dimensional system. This motivates a two-dimensional model of this self-assembling system. Using a mean field approach we build a dynamical model of the plant microtubule cortical array in which each term is based on known physical and biological factors. Specifically, we include microtubule nucleation, polymerisation, depolymerisation and interactions between microtubules. The latter are derived from recent experimental observations of angle-dependent effects in collisions between microtubules (crossing, zippering or catastrophe induction). Using a linear stability analysis of the homogeneous isotropic stationary phase, we determine which regions of parameter space correspond to in vivo observed patterns of GFP-labelled microtubules and explore the phase diagram with MC simulations.
