Berlin 2008 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 8: Active Filament Networks

BP 8.9: Vortrag

Dienstag, 26. Februar 2008, 12:15–12:30, C 243

Three-dimensional preparation and imaging reveal intrinsic microtubule properties — Philipp J Keller, •Francesco Pampaloni, and Ernst H K Stelzer — Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, D-69117 Heidelberg, Germany

Microtubule dynamic instability has been studied for over two decades, employing two-dimensional experimental approaches and focusing on two dynamic states, microtubule growth and shrinkage. The role of a "third state", the microtubule pause, has not yet been investigated in detail, although microtubule pausing is often observed in interphase cells. We present a study of microtubule dynamic instability in three dimensions, performed with laser light sheet-based fluorescence microscopy (SPIM). In order to prevent any experimental bias due to surface proximity effects, we developed a three-dimensional (3D) assay employing transparent Teflon-based cylinders. Close-to-life conditions were ensured by the use of Xenopus laevis egg extract. We performed a three-dimensional quantification of all known states of microtubule dynamic instability, including a thorough investigation of microtubule pausing. The three-dimensional approach gives experimental access to the intrinsic microtubule dynamic properties and to microtubule population statistics in single asters. We obtain evidence for the stochastic nature of microtubule pausing and discovered a strong influence of microtubule pausing on the microtubule's dynamic properties. Moreover, our data rule out a simple GTP-cap model of microtubule stabilization for interphase Xenopus laevis extracts.