Supplemental Materials
This article contains the following supporting material:
- Supplemental Materials
- Movie 1 - Movie S1. Simulation of Nf=600 MTs in the cortical pulling model (see section 2.1 of the supplementary materials), where the MTs reaching to the cell periphery (cortex) are captured by cortically bound dynein motors and are pulled upon while simultaneously depolymerized. The MTs are color-coded with respect to the local tension; red, blue and white colors denote compressional, extensional, and no forces respectively. The same coloring scheme is used in all the movies and figures. Since MTs are largely under extensile load, they undergo very small deformations and remain relatively straight. Proper centering and rotation of pronuclear complex is achieved in this model --for the choice of model parameters given in section 2.1 of the supplementary materials -- within a physiologically reasonable time (10 min).
- Movie 2 - Movie S2. Simulation of Nf=600 MTs in the cortical pushing free-sliding submodel (see section 2.2 of supplementary materials). In this model cortical repulsive forces are applied to the MTs reaching to the cell cortex only in the normal direction to the cortex (pointing inwards), so that plus-ends cannot penetrate the boundary. Nevertheless, MTs are allowed to grow or slide freely tangential to the boundary. As a result (as it can be seen in the movie), a large number of MTs that reach to the boundary bend and continue to grow tangentially. While centering of PNC is achieved after 15 min, the rotation of PNC and alignment with AP axis is not observed in this submodel after 240 min. In this simulation fmin=0.10 s^-1 (see section 2.2 of supplementary materials for details).
- Movie 3 - Movie S3. Simulation of Nf=600 MTs in the cortical pushing no-sliding submodel (see section 2.2 of supplementary materials). In this model, once MTs reach closer than a minimum distance to the cell cortex, the position of MT plus-ends are fixed (hinged) on the cortex as long as they are in the growing state. As a result, unlike the free-sliding model, MTs cannot grow or slide tangential to the boundary. Instead, as we see in the movie, MTs are buckled to continue growing against the boundary. The choice of fmin=0.20 s-1 results in the centering (after 10 min) and the alignment of centrosomal axis with the AP-axis (after 30 min).
- Movie 4 - Movie S4. Simulation of Nf=600 MTs in the cytoplasmic pulling model (see section 2.3 of supplementary materials), where minus-end directed cargo-carrying cytoplasmic dyneins walk on the MTs and apply a pulling force on them towards their plus-end. We assume that cytoplasmic dynein motors are uniformly attached to the MTs, so that the PNC moves in the direction of the longest MTs ( with the largest number of dynein motors). In this simulation the number of dyneins per unit length of MTs is taken as ndyn=0.02 μm-1. Since the MTs are under extension, their deformations are small. As the exntensile load is length-dependent in this model, the tension increases from zero at the plus-ends towards the minus-ends that are clamped to the PNC (note the transition from white at the plus-ends to dark blue at the minus-ends). Both centering and rotation of PNC is obtained within a physiologically reasonable time (10 min).
- Movie 5 - Movie S5. Simulation of Nf=600 MTs in the cortical pushing no-sliding submodel. In contrast to Movie S3 (fmin=0.20 s-1), we take takefmin=0.10 s-1, which effectively doubles the turnover time of the MTs interacting with the cell cortex with respect to Movie S3. As a result, MTs are substantially more buckled. While this change of parameter does not substantially change the centering time, it reduces the rotation time to half of the time of the simulation with fmin=0.20 s-1.