The Radical Pair Mechanism of Animal Magnetoreception

Animal magnetoreception is the phenomenon by which some night-migratory birds can make seasonal migrations by utilising a light-dependent response to the Earth’s magnetic field (MF) for directional information. At ~25-65µT, the geomagnetic field is generally considered impotent upon biological molecules [1]. Cryptochrome (CRY), a circadian regulator protein, is the proposed, a priori magnetoreceptor molecule. It is thought to generate spin-correlated radical pairs that can be modulated by an external MF; known as the ‘radical pair mechanism’ (RPM). Although relatively well-modelled in computational biophysics as a result [2,3], the biological mechanism of  ‘the avian compass’ in migrating birds is yet to be determined. By comparison of CRYs from disparate sources - avian, insect, mammalian and plant - and engineering variants in E. coli, the ultimate aim is to elucidate the role of cryptochrome in the mechanism of molecular magnetosensory processing. This can subsequently be instrumental in developing less invasive and phototoxic (magneto-)optogenetic therapies.