Paper Number
BL23                         My Program 

Session
Biological, Living, Active, and Directed Systems

Title
In-silico rheology of passive asters

Presentation Date and Time
October 16, 2024 (Wednesday) 5:25

Track / Room
Track 3 / Waterloo 5

Authors (Click on name to view author profile)

  1. Varchanis, Stylianos (Flatiron Institute, Simons Foundation, Center for Computational Biology)
  2. Stein, David B. (Flatiron Institute, Simons Foundation, Center for Computational Biology)
  3. Shelley, Michael J. (Flatiron Institute, Simons Foundation, Center for Computational Biology)
    Shelley, Michael J. (New York University, Courant Institute of Mathematical Science)

Author and Affiliation Lines (in printed abstract book)
Stylianos Varchanis1, David B. Stein1 and Michael J. Shelley1,2
1Center for Computational Biology, Flatiron Institute, Simons Foundation, New York, NY 10010; 2Courant Institute of Mathematical Science, New York University, New York, NY 10012

Speaker / Presenter 
Varchanis, Stylianos

Keywords
biological systems; living systems

Text of Abstract
Asters are radiating arrays of microtubules associated with the centrosome organelle in dividing eukaryotic cells. These cytoskeletal structures play a critical role in the positioning and orientation of the mitotic spindle, pronuclear migration, and cell homeostasis [1-2]. During the cell cycle, cortical and cytoplasmatic forces create translational and rotational aster motions. Thus, determining the relationship between an applied force and the resulting aster motion is a central challenge. To this end, we develop a biophysical model that encapsulates important features of intracellular aster motion and conduct in-silico rheological experiments. We model the aster as a dense bed of thin, bendable, but inextensible fibers [3] attached to a rigid spherical core (the centrosome), immersed in the cytoplasm (assumed to be a linear Stokes fluid) and confined in a spherical shell mimicking the cell membrane. The system is simulated using an accurate and fast variational multiscale method specially designed for such fluid-structure interactions. We study the response of a single aster under small amplitude oscillatory translations/rotations to quantify the aster translational/rotational relaxation time and the related storage and loss moduli. Using large amplitude oscillatory translations/rotations, we determine the translational/rotational drag force on the aster. For all cases, we examine the effect of fiber density, fiber branching, and confinement. Our detailed rheological characterization provides valuable information about the mechanical properties of cellular asters that could contribute to understanding cytoskeletal conformations during mitosis.

[1] Dutta, Sayantan, et al. Nature Physics (2024): 1-9.
[2] Sami, Abdullah Bashar, and Jesse C. Gatlin., Molecular Biology of the Cell 33.11 (2022): br20.
[3] Stein, David B., and Michael J. Shelley., Physical Review Fluids 4.7 (2019): 073302.