Regensburg 2010 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 32: Posters: Physics of Cells
BP 32.14: Poster
Donnerstag, 25. März 2010, 17:15–20:00, Poster B1
High-precision tracking of sperm swimming fine-structure provides strong test of resistive force theory — Benjamin M. Friedrich1,3, Ingmar H. Riedel-Kruse2,4, Jonathon Howard2, and •Frank Jülicher1 — 1Max Planck Institute for the Physics of Complex Systems, Dresden, Germany — 2Max Planck Institute for Molecular Cell Biology and Genetics, Dresden, Germany — 3Weizmann Institute of Science, Rehovot, Israel — 4Department of Bioengineering, Stanford University, Stanford, USA
Sperm cells are propelled in a liquid by regular bending waves of their whip-like flagellum. The shape of the flagellar wave determines the path along which a sperm cells swims. We have tested a simple hydrodynamic theory of flagellar propulsion known as resistive force theory: We conducted high-precision measurements of the head and flagellum motions during circular swimming of bull spermatozoa near a surface. We found that the fine-structure of sperm swimming represented by the rapid wiggling of the sperm head around an averaged path is, to high accuracy, accounted for by resistive force theory and results from balancing forces and torques generated by the beating flagellum. We determined the ratio between the normal and tangential hydrodynamic friction coefficients of the flagellum, to be 1.81±0.07 (mean±s.d.). We also determined how the coarse grained curvature of the swimming path depends on the average curvature of the beat pattern. The observed ratio of these curvatures can be accounted for by resistive force theory. Hence, this theory accounts both for the fine-structure of sperm swimming as well as for the circular motion on larger scales.