QLS seminar (in person) by Subhadip Ghosh on 2 February 2022 at 14h00 CET
Quantitative Life Sciences
qls at ictp.it
Thu Jan 27 09:45:18 CET 2022
Dear All,
On Wednesday, 2 February at 14h00 CET, Dr Subhadip Ghosh (Theoretical
Physics Department, Faculty of Science, Zagreb University, Croatia) will
give a seminar titled:
*Activity driven pattern formation in microtubule network and cell membrane
*
Abstract:
Self assembly of different globular and filamentous proteins in the
eukaryotic cell throughout the entire cell cycle is ubiquitous and helps
a cell to perform various tasks such as migration from one place to
another, intake of food from the outside world, cell division, etc. The
organization of individual microtubule filaments into bundles during the
formation of the mitotic spindle is an example of such a phenomenon when
a cell enters mitosis. At the beginning of prometaphase, experimentally
it is found that at the midplane of a vertically oriented spindle,
microtubules form a mist-like distribution which transits to well-formed
droplet like structures as time progresses. We construct a free energy
description of this system using the density of microtubules and
cross-linking proteins as field variables considering attractive and
repulsive interactions between them. Further, dynamical equations
governing the time evolution of density fields are obtained by
minimizing the free energy and incorporating a non-equilibrium process
of microtubule polymerization and depolymerization. Linear stability
analysis shows that the system transits from homogeneous distribution of
microtubules to a phase consisting of multiple bundles of microtubules
once the density of cross-linking proteins crosses a threshold and the
bundles do not collapse into a single large bundle over time.
On the other hand, pattern formation on the cell membrane is linked
with the contractile active force generated by the actomyosin cortex
beneath it and outward push coming due to polymerization of filamentous
actin attached to the membrane surface. Membrane associated proteins act
as the nucleating centers of actin polymerization, and the proteins
couple to the membrane surface in a curvature dependent manner modifying
the local bending modulus of the membrane. These competing equilibrium
and non-equilibrium forces acting on cell membrane allow a cell to
deform, and mediate cell motility and division. We use coupled evolution
of fields to perform linear stability analysis and numerical
calculations. As activity overcomes the stabilizing factors such as
surface tension and bending rigidity, the spherical membrane shows
instability towards pattern formation, localized pulsation, and running
pulsation between poles.
The seminar will be held in person in the Common Area, second floor, ex
SISSA building (Via Beirut, 2)
Indico page http://indico.ictp.it/event/9858/
Best regards,
Erica
--
Erica Sarnataro
Group Secretary
Quantitative Life Sciences
The Abdus Salam International Centre for Theoretical Physics (ICTP)
Trieste, Italy
Tel. +39-040-2240623
www.ictp.it/research/qls.aspx
e-mail:qls at ictp.it
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