Dresden 2003 – scientific programme

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DY: Dynamik und Statistische Physik

DY 16: Statistical physics in biological systems II

DY 16.4: Talk

Monday, March 24, 2003, 17:15–17:30, G\"OR/226

Time series analysis of beating sperm and the mechanics of cilia and flagella — •Ingmar Riedel and Jonathon Howard — Max Planck Institute of Molecular Cell Biology and Genetics Pfotenhauerstrasse 108, 01307 Dresden, Germany

Cilia and flagella are beating rods found in many eukariotic cells. The primary function of cilia is the movement of fluids over surfaces. That of flagella is the propulsion of single cells, such as sperm, through a fluid. Many different beating patterns of cilia and flagella can be found in nature.

Structurally, these objects are elastic filaments (microtubules in a 9+2 arrangement) driven by molecular motors (dyneins) distributed along the length of the filament. The motors force the microtubles to slide relative to each other. Due to structural constraints this is converted into local bending which leads to complex non-linear dynamics of the system.

In this study quantitatively analyzed time series of individual bull sperm at different temperatures are presented. The state of beating is characterized by digitization of the waveform of the sperm tail into an angle-arclength representation. From this representation, the sliding velocity of the filaments and hence the motor activity can be deduced along the tail over time.

We are particularly interested in how the beating characteristics, such as frequency and amplitude, depend on the temperature and how it might serve as a critical parameter controlling the dynamics of such a system.