Dear All,
Professor Roger Kamm, from the MIT Department of Mechanical Engineering,
is presenting a theoretical chemistry seminar TODAY (Wednesday, April
21) from 4:00-6:00pm in ROOM 56-154.
The title of his talk will be "Models for Cytoskeletal Rheology."
-- ABSTRACT --
Spanning a period of several decades, there have been several models
proposed for the elasticity or viscoelasticity of the cytoskeleton. In
addition, there have been numerous experiments using cells and
reconstituted actin gels, with or without cross-linkers and motor
proteins, designed to characterize the rheology of actin networks under
various conditions. Still, debates continue regarding the contributions
of various potential mechanisms (filament bending stiffness, thermal
fluctuations, filament extensional stiffness, cross-linker stiffness,
cross-link binding and unbinding) to cell viscoelasticity, and which
model (semiflexible polymer network, tensed network, cellular solids) is
best able to capture the measured characteristics. Here, we use a
computational model of a thermally-active cross-linked,
three-dimensional network to probe the important factors and discuss
these in the context of the different models. We conclude that thermal
fluctuations are not important at normal actin concentrations in the
cytoskeleton, in contrast to the semiflexible polymer network theory.
But both the cellular solids and tensed network models fail to capture
some of the salient mechanical features. For cross-linked networks under
prestress, the tensed network model appears most consistent with the
results of our simulations. However, currently no single model
satisfactorily captures viscoelastic behaviors of actin networks over a
wide range of conditions. Our simulation scheme provides a basis for
delineating multiple mechanisms involved in this complex system.
Thanks!
Lee-Ping
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