2006 APS March Meeting
Monday–Friday, March 13–17, 2006;
Baltimore, MD
Session D5: Catalysis and Complexity: Ken Hass Memorial
2:30 PM–4:54 PM,
Monday, March 13, 2006
Baltimore Convention Center
Room: 309
Sponsoring
Unit:
FIAP
Chair: Willes Weber, Caltech
Abstract ID: BAPS.2006.MAR.D5.3
Abstract: D5.00003 : From Condensed Matter Theory to Complex Biological Structures
3:42 PM–4:18 PM
Preview Abstract
Abstract
Author:
Anders Carlsson
(Washington University)
Condensed matter theory has given us many successful examples of
the combination of analytic theory and numerical modeling in
treating microscale and nanoscale physical phenomena. The
methods of condensed-matter theory are increasingly being applied
to biological problems. We will describe recent work modeling
the growth of actin networks in biological cells. Actin, an
abundant intracellular protein, polymerizes into semiflexible
filaments which are important for many processes, including cell
motion and shape changes. The growth of the filaments is
regulated by intracellular proteins that can, for example, cap
the growing ends of filaments, cause new branches to grow on
existing filaments, or sever filaments. These activities generate
a dynamic actin filament network at the cell edge. The
filaments' growth can generate forces large enough to move the
cell and change its shape. The talk will describe
Brownian-dynamics simulations of the growth of single filaments
against an obstacle, and stochastic-growth modeling of the growth
of the actin network. The single-filament growth simulations show
that even filaments attached to an obstacle can grow and push it
forward, at rates comparable to free-filament growth rates. This
result is consistent with experimental observations of
filament-obstacle attachments. The network-growth simulations use
a minimal stochastic growth model including capping, branching,
and severing. Simulation studies of this model yield a network
structure quite similar to that seen by electron microscopy.
Surprisingly, the growth velocity of the network is almost
independent of the opposing force. Analytic theory shows that
this effect is due to the autocatalytic nature of the branching
route to filament generation. Studies of the polymerization
dynamics of this model reveal a ``branching explosion'' in which
large clusters of branched filaments form at short times, but the
filaments are nearly unbranched at long times.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2006.MAR.D5.3