Berlin 2012 – scientific programme

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BP: Fachverband Biologische Physik

BP 17: Posters: Physics of Cells

BP 17.5: Poster

Wednesday, March 28, 2012, 17:30–19:30, Poster A

Mechanical properties of filopodia quantified by photonic force microscopy — •Felix Kohler and Alexander Rohrbach — University of Freiburg, Germany

Filopodia are highly dynamic protrusions of the cell surface that are filled with tight bundles of actin. They can extend and retract on a timescale of seconds to minutes. We use photonic force microscopy (PFM) to investigate the mechanical concepts of the filopodial retraction. An optically trapped bead is attached to a tip of a filopodium. During retraction the motion of this bead is tracked interferometrically in 3D with nanometer precision at a microsecond timescale. We have measured F-actin dependent steps inside living cells during filopodial retraction likely belonging to actin-based molecular motors [1]. The high forces a filopodium can exceed as well as the retraction dynamics indicate that coordinated molecular motor movement controls filopodial mechanics. Experimental results are shown together with a Morkov chain model, which describes the cooperative behavior of molecular motors in biological systems like filopodia.

[1] Kress, H. et al.,"Filopodia act as phagocytic tentacles and pull with discrete steps and a load-dependent velocity", pnas ,Vol.104, 2007, 11633-11638