Compass Discovered in the Fruit Fly

Ever wondered how animals such as fruit flies, whales or pigeons are able to navigate? The answer may lie in research published in Nature Materials this week by Professor Can Xie and colleagues at Peking University.

Many species are able to sense magnetic fields for the purpose of in order to navigate or for orientation. These include species such as monarch butterflies, salmon, lobsters, bats the mole rat and migratory birds. More unusual examples include the magnetic termite which can use magnetic information to guide and orient their bodies or inhabitant structures.  It has been widely accepted for a long while that animals are able to sense the earth’s magnetic field. However the outstanding mystery to this process was how the actual sensing was done.  One suggestion, proposed by Klaus Schluten was that animals sense geomagnetic fields through the strange quantum behaviour of the electrons produced when light falls cryptochromes (retinal proteins). However Xie questioned this hypothesis, suggesting that a compass based on cryptochromes alone is not enough to navigate.

The answer may instead lie in clumps of protein which align with the earth’s geomagnetic field and may then feed information to the nervous system creating the ability to navigate.   The team discovered these minuscule magnetic field sensors in the fruit fly (Drosophila melanogaster). However the same structures also form retinal cells in pigeons eyes and can form in butterfly,rat, whale and human cells (this was confirmed in follow up studies). Xie even suggested they could be a ‘universal mechanism for animal magnetoreception’ and could help to explain why some people have a good sense of direction.

The discovery was made via screening the fruit fly genome where they discovered a protein which they named MagR. MagR forms rod like clumps with cryptochrome proteins and the MagR-cryptochrome cluster formed behaves like a nanoscale compass.  Xie explained the system works via: having the tendency to align themselves ‘along geomagnetic field lines and to obtain navigation cues from a geomagnetic field”. Additionally, said Xie “We propose that any disturbance in this alignment may be captured by connected cellular machinery, which would channel information to the downstream neural system, forming the animal’s magnetic sense.”  This work may not only provide amazing insight into animal navigation but may also have implications in developing new technology such as map navigation in mobile phones.