Bonn, August 12, 2020. The sense of direction in pigeons is fascinating. How do carrier pigeons manage to cover hundreds of kilometers and yet arrive at their destination with maximum precision? Their navigational skills are based on a special power: they orient themselves to the magnetic field of the Earth.
Yet, until now, a lot about this magnetic sense remains unexplained. The location inside the pigeon’s body and the molecular identity of the magnetic compass are disputed. For decades, scientists suspected that cryptochromes, a class of special molecules in the pigeon's eye, are responsible for the magnetic sense. Unfortunately, up until now, there had been no clear evidence to support this. Moreover, it remained unknown on how the signals of cryptochromes are transmitted to the pigeon’s nervous system.
Now, an international group of researchers led by Prof. David Keays (Research Institute of Molecular Pathology, Vienna), involving caesar scientist Pascal Malkemper, has discovered new evidence on the importance of cryptochromes in magnetic orientation.
Cryptochromes are proteins found in the retina of the eye that have been shown to react to magnetic fields. Previous studies had already demonstrated that the pigeon's magnetic sense is dependent on light. Combining these clues, the research team obtained new data that points to cryptochrome 4 (cry4) as the light-dependent magnetoreceptor of the pigeon. The scientists were able to show that cry4 is located in synapses of the retina, where likely interacts with photoreceptors of the pigeon retina via glutamate receptors, when perceiving magnetic fields.
The scientists’ work provides strong evidence for the hypothesis that one of the cryptochromes in the pigeon's eye is actually responsible for the perception of magnetic fields. It also opens the field for further exciting experiments. Cryptochromes are not only found in birds, but also in the eyes of other animal species, and even humans. Whether we too can unconsciously perceive the Earth's magnetic field has yet to be explored.
The study appears today in the renowned journal "Science Advances" (https://advances.sciencemag.org/content/6/33/eabb9110).