Sponsored by
[ Events ]

Activity Search
Sort out
NCTS Seminar on Mathematical Physiology
10:30 - 12:00, July 12, 2024 (Friday)
Room 505, Cosmology Building, NTU
(臺灣大學次震宇宙館 505室)
A First-Principles Geometric Model for Dynamics of Motor-Driven Centrosomal Asters
Yuan-Nan Young (New Jersey Institute of Technology)

The centrosomal aster is a mobile and adaptable cellular organelle that exerts and transmits forces necessary for tasks such as nuclear migration and spindle positioning. Recent experimental and theoretical studies of nematode and human cells demonstrate that pulling forces on asters by cortically anchored force generators are dominant during such processes. Here, we present a comprehensive investigation of a first-principles model of aster dynamics, the S-model (S for sto- ichiometry), based solely on such forces. The model evolves the astral centrosome position, a probability field of cell-surface motor occupancy by centrosomal microtubules (under an assumption of stoichiometric binding), and free boundaries of unattached, growing microtubules. We show how cell shape affects the stability of centering of the aster, and its transition to oscillations with increasing motor number. Seeking to understand observations in single-cell nematode embryos, we use highly accurate simulations to examine the nonlinear structure of the bifurcations, and demonstrate the importance of binding domain overlap to interpreting genetic perturbation experiments. We find a generally rich dynamical landscape, dependent upon cell shape, such as internal constant-velocity equatorial orbits of asters that can be seen as traveling wave solutions. Finally, we study the interactions of multiple asters, which we demonstrate an effective mutual repulsion due to their competition for surface force generators. We find, amazingly, that centrosomes can relax onto the vertices of platonic and non-platonic solids, very closely mirroring the results of the classical Thomson problem for energy-minimizing configurations of electrons constrained to a sphere and interacting via repulsive Coulomb potentials. Our findings both explain experimental observations, providing insights into the mechanisms governing spindle positioning and cell division dynamics and show the possibility of new nonlinear phenomena in cell biology.
Meeting number (access code): 2511 487 9615
Meeting password: paVgtK7Ys75
Organizer: Tai-Chia Lin (NTU)


back to list  
(C) 2021 National Center for Theoretical Sciences