Regensburg 2010 – scientific programme

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BP: Fachverband Biologische Physik

BP 32: Posters: Physics of Cells

BP 32.41: Poster

Thursday, March 25, 2010, 17:15–20:00, Poster B1

Measuring Cytoskeletal Orientation Distributions of Large Cell Populations by Digital Image Processing — •Norbert Kirchgeßner, Uta Zedler, Nico Hampe, Wolfgang Rubner, Bernd Hoffmann, and Rudolf Merkel — Institute of Bio- and Nanosystems 4: Biomechanics, Forschungszentrum Jülich GmbH, 52425 Jülich

Cell adhesion is vital for most cell types and supported by various proteins forming defined adhesion structures. These complex structures bind to both the cellular environment and to intracellular actin filaments. This direct interaction enables cells to actively sense and to respond to varying mechanical conditions. Cyclic stretch is such a mechanical signal with thereby induced cellular reorientations. Cell orientation given by the major axis of the cell shape is distinguished from cytoskeletal orientation defined by stress fibers. However, exact whole cell and cytoskeletal reorientation angles are difficult to determine.

Our approach applied the gradient based structure tensor method to bandpass filtered fluorescence microscopy data. In combination with a segmentation step this yielded accurate histograms of cytoskeletal orientations for individual cells. Subsequently, we obtained the predominant cytoskeletal orientation of each cell and intracellular orientation variations of stress fibers. Cellular orientations were determined as the major direction of the ellipse with equal normalized second central moment as the segmentation results for each cell. Application of these algorithms to large numbers of cells (n>200) yielded results with high statistical relevance.