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AKB: Biologische Physik

AKB 3: Cell Motility I

AKB 3.5: Vortrag

Montag, 27. März 2006, 12:45–13:00, ZEU 255

A self-organized simple swimmer driven by molecular motors — •Stefan Guenther and Karsten Kruse — Max-Planck-Institut für Physik komplexer Systeme, 01187 Dresden, Germany

Microorganisms often use flagella or cilia to move in an aqueous environment. In eukaryotes these hair-like appendages are internally driven by molecular motors. Spontaneous oscillations of the motors lead to two- or three-dimensional beating patterns of the appendage, which propels the organism. Due to the complicated structure of cilia and flagella our understanding of the swimming mechanism is still far from complete.

Here, we study a simple self-organized swimmer, that is based on elements thought to be important for the beating of flagella. The swimmer consists of three spheres arranged in a line. Two adjacent spheres are coupled by an active joint containing molecular motors. These joints are similar to sarcomeres, the elementary contractile units of muscle, and can oscillate spontaneously. Taking the hydrodynamic interactions between the spheres into account, the system moves directionally along its long axis. We calculate the swimming speed as a function of the fluid’s viscosity and find a critical value above which there is no net motion. For parameters appropriate for sarcomeres, swimming speeds are in the order of µm/min and should be experimentally observable.