QLS seminar (in person) by Subhadip Ghosh on 2 February 2022 at 14h00 CET

[Quantitative Life Sciences]

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