Regensburg 2007 – scientific programme
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BP: Fachverband Biologische Physik
BP 24: Cell Mechanics (in vivo)
BP 24.9: Talk
Thursday, March 29, 2007, 12:15–12:30, H44
Physical description of mitotic spindle orientation during cell division — •Andrea Jiménez-Dalmaroni1, Manuel Théry2, Victor Racine2, Michel Bornens2, and Frank Jülicher1 — 1Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Str. 38, 01187 Dresden, Germany — 2Institut Curie, CNRS UMR144, Compart. et Dynamique Cellulaire, 26 rue d'Ulm 75248, Paris, France
During cell division, the duplicated chromosomes are physically separated by the action of the mitotic spindle. The mitotic spindle is a dynamic structure of the cytoskeleton, which consists of two microtubule asters. Its orientation defines the axis along which the cell divides. Recent experiments on dividing cells, which adhere to patterned substrates, show that the spindle orientation depends on the spatial distribution of cell adhesion sites. Here we show that the experimentally observed spindle orientation can be understood as the result of the action of cortical force generators acting on the spindle microtubules. We assume that the local activity of force generators is controlled by the spatial distribution of cell adhesion sites determined by the particular geometry of the adhesive substrate. We develop a simple physical description of the spindle mechanics, which allows us to calculate the torque acting on the spindle, as well as the energy profile and the angular distribution of spindle orientation. Our model accounts for the preferred spindle orientation, as well as the full shape of the angular distributions of spindle orientation observed in a wide variety of patterns. We conclude that, based on a few simple assumptions, we can provide a quantitative description of the spindle orientation.