Regensburg 2010 – scientific programme

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BP: Fachverband Biologische Physik

BP 15: Physics of Cells II

BP 15.4: Talk

Tuesday, March 23, 2010, 15:15–15:30, H43

Generating alternating bidirectional gradient fields for dynamic measurement of chemotactic response in living cells — •Börn Meier, Christoph Weber, Simon Youssef, Thomas Franosch, Joachim Rädler, and Doris Heinrich — Fakultät für Physik und CeNS, LMU München, Germany

Chemotactic response in eucaryotic cells is inherently probabilistic and measurements of single cell responses and population distributions help to advance quantitative understanding of underlying signalling pathways. Therefore we have designed a microfluidic function generator, creating time-varying but spatially homogenous chemical gradients of opposing direction. In a first step we monitored the migratory response of Dictyostelium discoideum cells to alternating cAMP-gradients with decreasing switching frequency. At low switching rates directed cell migration according to the applied chemotactic sequence appears. At frequencies above 0.01 Hz cellular motility is stalled, leading to trapped cells. We monitored the actin reorganization, underlying the cell response, identified by the Lim-Gfp fluorescence distribution in the cell. Cell polarization, reflected by the dipolar moment of the fluorescence distribution, expresses a delayed cell response, where two phases of opposing actin polymerization are intercepted by a phase of decreased actin polymerization.