Math-Sci Seminar

Speaker:  Prof. Enzo Orlandini ,  Dept. of Physics, University of Padova, Italy


Title: Dynamics of fibers growing inside soft vesicles

Date: Thu 28 Sep, 2006
Time: 16:45
Place: Science Building, Room Z42

Abstract:

We present 3-dimensional dynamical computer simulations of the
growth of a semiflexible polymer fiber inside a fluctuating
tethered vesicle. This situation is often encountered in cell
biology, however our main emphasis here is on fibers polymerizing
inside red blood cells  in vivo. We find three distinct
regimes. Very stiff fibers stall soon and lock the membrane into a
strongly deformed prolate shape reminiscent of sickle red blood
cells. Fibers of intermediate stiffness buckle and form a toroidal
configuration which distorts the membrane into an oblate
shape. The kinetics in this regime resembles the process of
microtubule growth and consequent membrane reshaping in the
marginal band of developing erythrocyte cells. Finally, more
flexible polymers -- with genome-like rigidity -- form massive
spool-like condensates with toroidal domains, much as DNA when
packaged in bacteriophage heads, while the vesicle inflates
isotropically.

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