Berlin 2012 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 27: Posters: Cytoskeletal Filaments

BP 27.10: Poster

Donnerstag, 29. März 2012, 17:30–19:30, Poster A

Super-resolution study of paracrystalline actin in auditory receptor cells — •Valeria Piazza, Britta Weinhausen, Tim Salditt, and Sarah Köster — Institute for X-Ray Physics & CRC Physics, University of Göttingen, Germany

In most cell types microfilaments coalesce into networks and bundles with variable degrees of orientation and size. In statoacustical receptor cells, however, actin bundles inside stereocilia show an unusually "extreme" level of organization: thousands of filaments are tightly packed in a paracrystal array to form stiff cylinders (200-500 nm in thickness and with lengths ranging from 2 to 30 µm) with a supportive function for mechanotransduction. We study the peculiar packing symmetry and molecular composition of these cell protrusions by means of fluorescence nanoscopy and X-ray diffraction. With STED (STimulated Emission Depletion microscopy) coupled to immunofluorescence we test when and where each of the two actin isoforms - β and γ - is incorporated in cochlear stereocilia throughout development. Moreover, using spatially-resolved X-ray nano-diffraction we characterize the spacing of the actin filaments within individual stereocilia. The X-ray measurements are performed on hair cells that are chemically fixed in different conditions (for example, different developmental stages), to test whether the filament array changes or it is constantly maintained in one specific state. Eventually the imaging data will be combined with the X-ray analysis to correlate molecular composition to structure in discrete regions of stereocilia.