Colloquium 5/23/2011

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Bela Mulder
Group Leader Theory of Biomolecular matter,
FOM Institute AMOLF, Amsterdam

Survival of the aligned: modeling the cortical microtubule array in plant cells

Plant cells typically elongate along a single growth axis. In order to sustain this anisotropy the cell requires spatially extended structures that encode the proper geometrical constraints. The most prominent of these structures is the so-called interphase cortical array. Its components are microtubules: long filamentous protein aggregates that exhibit an interesting intrinsic dynamics, in which they stochastically switch between periods of growth and shrinkage. In the cortical array the microtubules are attached to the inner side of the plasma membrane, effectively creating a 2D system, in which the only motion is caused by (de)polymerization. Because of the reduced dimensionality growing microtubules can now collide with pre-existing ones, giving rise to an angle dependent scattering events, in which the the colliding microtubule can either alter its course to grow along side the other microtubule, switch to the shrinking state, or simply slip over the obstacle. We address the question whether these interactions are sufficient to explain to explain the high degree of orientational alignment found in the cortical array. To that end we will present results both from event driven stochastic simulations and a coarse-grained dynamical model.