A compass needle made by a Magnetoreceptor and assisted by Cryptochromes
Here it is: In yellow, a polymer made of five molecules of the protein termed Magneto-Receptor (MagR) - five loops hosting iron. It is surrounded by cryptochrome proteins
Credit: S. Qin et al. Nature Mater. http://dx.doi.org/10.1038/nmat4484 (2015).
"Together with Cry, it forms a nanoscale ‘needle’: a rod-like core of CG8198 (MagR) polymers with an outer layer of Cry proteins that twists around the core (see 'Protein biocompass')."
"Using an electron microscope, Xie’s team saw assemblies of these rods orienting themselves in a weak magnetic field in the same way as compass needles."
"Many birds have a compass in their eyes. Their retinas are loaded with a protein called cryptochrome, which is sensitive to the Earth’s magnetic fields. It’s possible that the birds can literally see these fields, overlaid on top of their normal vision. This remarkable sense allows them to keep their bearings when no other landmarks are visible."
Following the experiments of Researcher Lauren Foley from the University of Massachusetts Medical School we can create artificial magnetic fields resembling the Earth's field and place for instance the fly food always in the south. Flies would learn to go to the south to find food. Transgenic flies that do not have cryptochromes in their retinas could not find the south. When the human gene was inserted in their genome, their capacity to find the pole with the food was restored.
Excerpts from an article by The Guardian
“The nanoscale biocompass has the tendency to align itself along geomagnetic field lines and to obtain navigation cues from a geomagnetic field,” 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.”
“It has been well documented that cryptochromes, which are crucial to the compass proposed in this new paper, may harness significant quantum effects to convert the Earth’s weak magnetic field into a signal in the animal’s brain. This is a tantalising possibility since the new UK quantum technology hubs are focusing about a quarter of their £150M on sensor systems. It would be remarkable if we can learn some tricks from Mother Nature in this highly-advanced field of physics,” he added.
3 examples from The Guardian
Enzymes: "enzymes make use of a remarkable trick called quantum tunnelling to accelerate biochemical reactions. Essentially, the enzyme encourages electrons and protons to vanish from one position in a biomolecule and instantly rematerialise in another, without passing through the gap in between – a kind of quantum teleportation."
Photosynthesis: "Energy packet was not hopping haphazardly about, but performing a neat quantum trick. Instead of behaving like a localised particle travelling along a single route, it behaves quantum mechanically, like a spread-out wave, and samples all possible routes at once to find the quickest way."
European robin: "an internal chemical compass that utilises an astonishing quantum concept called entanglement, which Einstein dismissed as “spooky action at a distance”. This phenomenon describes how two separated particles can remain instantaneously connected via a weird quantum link. The current best guess is that this takes place inside a protein in the bird’s eye, where quantum entanglement makes a pair of electrons highly sensitive to the angle of orientation of the Earth’s magnetic field, allowing the bird to “see” which way it needs to fly."
Specialised/Mechanistic article Magnetoreception and the radical pair mechanism:
The discovery of magnetite (Fe3O4) in the human brain in 1992 by Dr. Joesph Kirschvink at CalTech
Using an ultrasensitive superconducting magnetometer in a clean-lab environment, we have detected the presence of ferromagnetic material in a variety of tissues from the human brain. These magnetic and high-resolution transmission electron microscopy measurements imply the presence of a minimum of 5 million single-domain crystals per gram for most tissues in the brain and greater than 100 million crystals per gram for pia and dura.
Biogenic magnetite in the human brain may account for high-field saturation effects observed in the T1 and T2 values of magnetic resonance imaging and, perhaps, for a variety of biological effects of low-frequency magnetic fields.
Another study by Dr. Joesph Kirschvink
Magnetite Minerals in the Human Brain: What Is Their Role?
Production of single-domain magnetite throughout life by sockeye salmon, Oncorhynchus nerka.
Similar results in humans