Regensburg 2010 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 37: Biomaterials

BP 37.7: Vortrag

Freitag, 26. März 2010, 12:00–12:15, H43

Using microtubules to measure actin viscoelasticity — Felix Zörgiebel¹, •Marcel Bremerich¹, Frederick C. MacKintosh², and Christoph F. Schmidt¹ — ¹III. Physikalisches Institut, Georg-August-Universität, 37077 Göttingen — ²Department of Physics & Astronomy, Vrije Universiteit, 1081 HV Amsterdam

In conventional active and passive microrheology techniques, micron-sized particles are embedded in biological samples for probing their viscoelastic properties. These methods are not always well suited for investigating the interior of living cells because the probe particles can perturb their neighborhood and because surface interactions can occur. Such problems can be elegantly circumvented by using natural constituents of the cellular system as local probes. The thermal bending fluctuations of microtubules, for instance, intrinsically carry information about the mechanical properties of the surrounding medium. It turns out that one can investigate local shear moduli and stress fluctuations in biopolymer networks by a detailed analysis of the spatial and temporal bending fluctuations of just one point of a microtubule, largely without introducing probe artifacts. To test this new method, we sparsely seeded an in vitro network of filamentous actin with microtubules which were again sparsely labeled with nanometer-sized gold particles. The displacements of these particles were then tracked by laser interferometry using an optical trap. Knowing the microtubule elastic properties, the observed bending dynamics allowed us to estimate the complex shear modulus of the surrounding actin network.