Using maps, compasses, and sextants, mariners in the early 1500's developed the first methods to navigate the open sea; heralding an age of exploration as humanity set sail for thehorizon. Yet long before this time evolution had equipped life on the planet with a biological global positioning system that was far superior to those early navigational tools – the Magnetic Sense. While there is unequivocal behavioural evidence demonstrating that this faculty exists, it is the least understood of all senses. It is a classic scientific mystery: the location of the primary sensors, the underlying biophysical mechanisms, and the neurological basis of the sense are unknown. Currently, there are three ideas that aim to explain how magnetosensation might work: (1) magnetite based magnetoreception; (2) a light sensitive radical pair based model; and (3) electromagnetic induction. We are testing these concepts with a focus on a light-based mechanism that relies on the cryptochrome CRY4, and an inductive mechanism that exploits a highly sensitive calcium channel CaV1.3. Our goal is to identify the molecules, cells and circuits that underlie the magnetic sense in pigeons. To achieve this objective we employ pigeons as model system, and exploit an array of advanced methods in neuroscience including: whole brain iDISCO clearing, 2-photon calcium imaging, RNA sequencing, neuronal tracing, and magnetic activation assays.
Hochstoeger et al. The biophysical, molecular, and anatomical landscape of pigeon CRY4: A candidate light-based quantal magnetosensor. Sci Adv. 2020 Aug 12;6(33):eabb9110.
Nimpf S, et al. A putative mechanism for magnetoreception by electromagnetic induction in the pigeon inner ear. Curr Biol. 2019 Dec 2;29(23):4052-4059.e4
Treiber, CD., et al. (2012). Clusters of iron-rich cells in the upper beak of pigeons are macrophages not magnetosensitive neurons. Nature. 484(7394):367-70.
Prof. Erik Schleicher (University of Freiburg)
Dr Jeremy Shaw (University of Western Australia).