Dresden 2009 – scientific programme

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BP: Fachverband Biologische Physik

BP 17: Poster II

BP 17.21: Poster

Wednesday, March 25, 2009, 17:15–19:45, P3

Rheology and Transport Processes in Living Cells — •Jean Mahowald, Delphine Arcizet, Joachim Oskar Rädler, and Doris Heinrich — Biophysics of Cell Dynamics Group, Lehrstuhl für Physik weicher Materie and Center of NanoScience (CeNS), Fakultät für Physik, Ludwig-Maximilians-Universität München, D-80539 München, Germany

Transport processes play a major role for the viability of cells. Living cells need to continuously uptake nutrients, which are engulfed in lipidic vesicles by endocytosis, and transported towards intracellular compartments. Transport throughout the cell consists of successive phases of diffusion phenomena (Brownian motion, subdiffusion or enhanced diffusion) and active transport along the microtubules by molecular motors.

We investigate the rheology and transport processes in Dictyostelium discoideum cells by magnetic tweezers, which are an interesting model organism due to their cytoskeleton simplicity and the variety of mutant strains available. Super paramagnetic micrometer beads engulfed by the cells are subjected to force pulses of 5 seconds and up to 200 pN. The recorded tracer path is providing real-time information about the transport phenomena. Our home-made algorithm allows us to dissect the bead path into phases of pure diffusion and directed active motion.

We observe that the average duration of diffusive transport events is significantly lowered by the application of an external force. Detailed information about the role of the different cell components in the active processes is obtained by modifying cytoskeleton properties.