Biomathematics Seminar: Cell Quakes: Mechanics and Microrheology in active gels and living cells
18 May 2010 14:15 in CM107
The mechanics of the in vivo cytoskeleton is controlled in part by the details
of its non-equilibrium steady-state. In this ``active'' material, molecular
motors (e.g. myosin) exert transient contractile stresses on the F-actin
filament network. Since microrheology traditionally relies of the linear
response properties of the soft materials in thermal equilibrium, this
departure from equilibrium has profound implications for the interpretation
of microrheological data from the interior of living cells and in vitro
active networks. In active networks, such as the in vitro systems of Mizuno et al.
[Science 315 (5810) pp. 370-373 (2007).] and in living cells, the
underlying theoretical foundation of the interpretation of microrheology
-- the Fluctuation-Dissipation theorem -- does not apply. New ideas are needed.
In this talk, review microrheology, and then discuss a new theoretical
interpretation of microrheology in active (i.e. molecular motor driven)
networks. I also explore how molecular motor activity can reversibly
control the elastic properties of these active gels. The cytoskeleton
points towards the development of new biomimetic materials whose
elastic properties can be tuned by controlling the material's non-equilibrium steady-state.