Fig. 2: Simulation of dynamic microtubules reproduces patterning into bands and gaps.

a Design of ten-banded cells: microtubules (black lines) are simulated to undergo dynamics on the surface of cylindrical cells. Ten bands (pink) separated by gaps were distributed evenly over the cell surface. The separation phase runs from T = 0 h (left) to 3 h, followed by a 2 h maintenance phase (T = 5 h, right). b Degree of separation for four different nucleation modes. Lines and margins represent medians ± 16% and 84% percentiles from more than 100 individual simulation runs. c Improved design using ten, independent ‘single-band’ models: single bands including their gap environment with a total length of 6 µm at T = 0 h (left) and T = 5 h (right). All other parameters remained as in a. d Degree of separation for ‘reconstituted’ structures for four different nucleation modes. Lines and margins represent medians and 16% and 84% percentiles, respectively, for more than 100 ‘reconstituted’ structures comprised ten unique single-band models obtained from 2000 independent simulations. e–i Top row: schematic representations of the five different nucleation modes: isotropic (e), isotropic with threefold higher nucleation rate and 2 µm-wide bands (f), parallel (g), branched (h) and redistributed nucleation (i). A microtubule is depicted as a grey rod with plus and minus ends. Arrows indicate the direction of polymerization from a nucleation site. Elliptic areas depict orientation bias for branched nucleation of ~35° relative to the microtubule axis. Redistributed nucleation involves determination of nucleation site as with parallel nucleation, followed by a shift of a random integer times the length of the repeating unit (d_band + d_gap) leading to global redistribution of the nucleation sites, while maintaining relative position to the nearest band centre. Lower row of panels shows snapshots of representative simulations for each nucleation mode.