FIGURE 6:

Sensitivity of centrosome positioning to external cues, modulated by internal properties. (A, B) The centrosome is initially placed in the center of the cell and is decentered. The cell has a radius of 10 μm and contains 300 randomly positioned cytoplasmic dyneins. MT rigidity is set to 15 pN/μm². (A) Simulations in which MT pivoting and gliding are not allowed (top) and MT pivoting and gliding are allowed (bottom). Left, simulations (400 s) in which different numbers (5, 130, 400, and 800) of cortical dynein have been added on a 60° crescent at the bottom part of the cell. Right, trajectories of centrosomes, in a color representing the number of dyneins in the cell from 0 (green) to 1000 (red). The position of the cortical crescent was shifted to make it possible to distinguish the different trajectories on a single plot. (B) Left, schematic representation of MT network configuration when MT pivoting and gliding are not allowed (blue) and when both are allowed (purple). Cortical dynein molecules are represented in black. Right, final distance of centrosome to cell center according to the number of cortical dyneins placed on the crescent when gliding and pivoting are not allowed (blue) and allowed (purple). The black horizontal dashed line indicates the threshold above which we considered the centrosome to be off center. Colored vertical dashed lines represent threshold number of motors necessary to be decentered in each case.