Math-Sci Seminar

        (ATTENTION TO UNUSUAL DATE AND PLACE)

Speaker: Dr. Devrim Pesen, Royal Institute of Technology, Stockholm, Sweden
Title: Connecting Cellular and Molecular Mechanics
Date: Mon 25 Dec, 2006
Time: 16:45
Place: Science Building, Room Z24

Abstract:

The structure and dynamics of cell cortex are important for regulating not only cellular
mechanics (such as cell shape) but also for signal transduction. We studied the cortical
cytoskeleton of bovine pulmonary artery endothelial cells (BPAECs) using atomic force
microscopy (AFM) and confocal fluorescence microscopy (CFM). Our results show that
the contrast in AFM imaging of living cells depends on local mechanical properties.
AFM images of BPAECs revealed the local micromechanical architecture of their apical
surface at ~125 nanometers resolution. These local mechanics derive in large part from
the cytoskeleton, thereby allowing visualization of the cortical cytoskeleton. The cortex
in these cells is organized as a polygonal mesh at two length scales ; a coarse mesh with
mesh element areas ~0.5-10 µm2, and a finer mesh of unknown composition with areas
<0.5 µm2. These meshes appear to be intertwined, which may have implications for the
mechanical properties of the cell. Correlated AFM-CFM experiments and
pharmacological treatments reveal that actin and vimentin are components of the coarse
mesh, but microtubules are not mechanical components of the BPAEC apical cortex.
Further, the coarse mesh is highly dynamic and shows two modes of remodeling; intactboundary-
mode where mesh element boundaries remain intact but move at ~0.08 µm/min
allowing the mesh element to change shape; and altered-boundary-mode where
boundaries appear and disappear.


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