Abstract

Migratory birds and other animals possess a physiological magnetic compass that helps them to find directions, but the biophysical mechanism underlying this ability remains a mystery. One currently much discussed hypothesis is that light-induced magnetically sensitive radical pair reactions may provide the first step of a magnetic signal.

While this mechanism is well understood in principle, generic radical pairs require magnetic fields about an order of magnitude above the geomagnetic field for effects to be observed. We will discuss what factors optimize sensitivity of radical pairs and address experimental support for the radical pair hypothesis.

A candidate molecule is the blue-green light photoreceptor cryptochrome. We will present recent attempts to observe magnetic field effects on in vivo read outs of cryptochrome activity in biological cells as a step towards an elucidation of magnetic signal transduction and, possibly, magnetogenetic approaches.