Berlin 2008 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 27: Membrane Morphology and Adhesion
BP 27.2: Vortrag
Freitag, 29. Februar 2008, 10:45–11:00, C 243
Fluctuations of red blood cell membranes — •Thorsten Auth1,2, Nir S. Gov1, and Samuel A. Safran1 — 1Weizmann Institute of Science, Rehovot 76100, Israel — 2Forschungszentrum Jülich, IFF, 52425 Jülich, Germany
We model the red blood cell membrane by a lipid bilayer that is coupled to a polymerized membrane. Using experimental fluctuation spectra, this model allows us to determine the elastic constants and to quantify the active, ATP-driven fluctuations. The extensive experimental studies on and the easy availability of red blood cells make them especially attractive for setting up and testing theoretical models to quantitatively explain the experimental results. However, using a simple fluid-polymerized membrane model, several basic aspects regarding the mechanical properties of the cell membrane are not completely understood. On the one hand, static deformation experiments indicate that the cell is very stiff with a high shear modulus of the order of 10−3−10−2 kB T nm−2. On the other hand, the relatively large fluctuation amplitudes, observed in light scattering/video microscopy spectra at wavevectors, q ≈ 0.010 nm−1, indicate that the shear modulus is small. Furthermore, experiments that measure the fluctuation amplitude as a function of the position on the cell are — within the continuum theory — compatible only with a vanishing shear modulus. We have performed simulations of inhomogeneous membranes and find that localized fluctuations, due to irregularities of the cytoskeleton, are capable to explain both riddles.