Dresden 2009 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 34: Invited Talks Winklhofer / Zabow

MA 34.1: Hauptvortrag

Donnerstag, 26. März 2009, 14:00–14:30, HSZ 04

The biophysics of geomagnetic-field reception in animals — •Michael Winklhofer — LMU Munich, Germany

I will give an overview of the recent progress towards understanding the physical basis of the magnetic sense of animals. Research into magnetic field reception is currently driven by two hypotheses. One proposal relies on the presence of molecules that undergo magnetically anisotropic chemical reactions due to transient formation of a spin-correlated radical pair. Lately, the proposed chemical compass mechanism has been corroborated in principle by in-vitro experiments on artificial radical-pair systems. Specifically designed behavioral experiments suggest the involvement of radical-pair molecules in the compass sense of birds, but the biological structures hosting such molecules remain elusive. The second hypothesis builds on specialized sensory structures that contain ferrimagnetic particles and assumes that the magnetic input energy is converted into mechanical output energy to be transduced into a nerve signal by means of strain-sensitive ion channels. Magnetite has indeed been identified in sensory nerve structures, with stable magnetic single-domain particles in fish and micrometer-scale clusters of superparamagnetic nanocrystals in birds. While it is straightforward to explain the basic compass sense with the magnetite-based transduction mechanism, it is still a challenge to explain its sensitivity, which in some animals has been reported to be lower than 100 nT. Funding by the German Science Foundation (DFG Wi1828/4-1) and HFSP (RGP 45/2008) is gratefully acknowledged.