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BP: Fachverband Biologische Physik

BP 20: Regulation and Signaling

BP 20.8: Vortrag

Donnerstag, 28. Februar 2008, 11:45–12:00, C 243

Mechanisms of sperm chemotaxis — •Benjamin M. Friedrich and Frank Julicher — Max-Planck Institute for the Physics of Complex Systems, Nöthnitzer Straße 38, Dresden

Sperm cells swim towards the egg propelled by a flagellum which beats regularly. In many species sperm show chemotaxis, i.e. they move upwards a gradient of chemoattractant molecules released by the egg. Sperm cells sample the local chemoattractant concentrations with receptors on the surface of their flagellum. A signaling cascade within the flagellum transduces the concentration stimulus and elicits a swimming response by changing the flagellar beat [1,2]. We propose an effective description of this signaling cascade and derive consequences for experiments. In the limit of low chemoattractant concentrations, the concentration stimulus is Poissonian shot noise since the binding of chemoattractant molecules to the receptors is a discrete process. We therefore study also the influence of fluctuations in the concentration stimulus on the chemotaxis mechanism and derive measures for the fidelity of chemotaxis.

[1] B. Kaupp et. al.: NCB 5, 109 (2003)

[2] B.M.F., F.J.: PNAS 109 (2007)