Berlin 2018 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 33: Cytoskeletal Filaments II

BP 33.6: Vortrag

Donnerstag, 15. März 2018, 16:30–16:45, H 1028

Bistability and oscillations in cooperative microtubule and kinetochore dynamics in the mitotic spindle — •Felix Schwietert and Jan Kierfeld — TU Dortmund University, 44221 Dortmund, Germany

In the mitotic spindle microtubules attach to kinetochores via catch bonds during metaphase. We investigate the cooperative dynamics of a one-sided spindle model consisting of a microtubule ensemble which is attached to a kinetochore via elastic linkers. The model includes the dynamic instability of microtubules, forces on microtubules and kinetochores from elastic linkers, and an external force on the kinetochore. We use a mean-field approach based on Fokker-Planck equations to analytically solve the one-sided spindle model, which establishes a bistable force-velocity relation of kinetochore motion. All results are in agreement with stochastic simulations. We derive constraints on linker stiffness and microtubule number for the occurrence of bistability. In the full two-sided spindle model, two such bistable systems are coupled in a tug-of-war. This leads to stochastic chromosome oscillations in metaphase (directional instability), which have been observed in several experiments. We also derive constraints on linker stiffness and microtubule number for metaphase chromosome oscillations. With certain modifications the model can be used to explain the effects of additional processes, e.g. microtubule poleward flux or polar ejection forces.