Dresden 2014 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 4: Membranes and Vesicles I

BP 4.7: Vortrag

Montag, 31. März 2014, 16:45–17:00, HÜL 386

On the dynamic properties of giant unilamellar vesicles under flow - towards a model for shear force transduction in cells — •Bernhard Sebastian, Tobias Favero, and Petra Dittrich — ETH Zürich, Schweiz

We present a novel method for the study of external shear force transduction through vesicle membranes and their effect on the dynamics of the enclosed lumen in 3D using defocusing fluorescence microscopy.

Blood cells and endothelial cells are frequently exposed to mechanical strain induced by external flow, hence shear stress. External forces are transferred to the intracellular lumen through a process called mechanotransduction. We used giant unilamellar vesicles (GUVs) as a model system to investigate the effects of shear force induced mechanotransduction on the dynamics of the vesicle membrane as well as inside the lumen. Vesicles were trapped on a microfluidic chip. Fluorescent beads enclosed inside GUVs were used as flow tracer particles. A novel 3D tracking program allowed for visualization of the bead movement and its analysis in three dimensions at high spatial resolution using conventional fluorescence wide-field microscopy.

We observed bead movement along the GUV membrane in a bi-hemispheric pattern including rare crossing events between the hemispheres, independent of external flow speed. Detailed analysis of the bead trajectories revealed regions of high and low velocity that spatially depend on the magnitude of external flow. Flow in the GUV membrane was found to differ from that inside the lumen.