Animals' 'sixth sense' is more widespread than previously thought

Researchers from the Universities of Manchester and Leicester, with assistance from the National Physical Laboratory, used fruit flies in a study that raised the possibility that more animals than previously believed are capable of sensing a magnetic field.

Our knowledge of how animals perceive and react to magnetic fields in their surroundings has significantly improved as a result of the article, which was published in today's issue of Nature.

The creation of new measurement instruments that use magnetic fields to specifically trigger the activity of biological cells, possibly even human cells, may also be made possible by this new information.

The team demonstrates for the first time how a chemical called flavin adenine dinucleotide, or FAD for short, which is found in all living cells, can, in sufficient quantities, give a biological system magnetic sensitivity.

The use of the earth's magnetic field by species like the monarch butterfly, dove, turtle, and other creatures for long-distance navigation is already known to scientists. The finding, however, may indicate that all living things—to varying degrees—possess the biological molecules necessary to detect magnetic fields.

Professor Richard Baines, a co-lead investigator and a neuroscientist from The University of Manchester, said, "It is well known how we perceive the outside world, from visual and sound to touch, taste, and scent. On the other hand, it is unclear which creatures are capable of detecting and reacting to a magnetic field. The knowledge of how animals perceive and react to exterior magnetic fields—a hotly debated and active field—has significantly advanced as a result of this research."

The study team tested their theories by manipulating gene expression in the fruit fly (Drosophila melanogaster). The fruit fly has been used in numerous studies as a model to understand human biology despite having an extremely distinct nervous system from ours on the outside.

The sixth sense, magnetoreception, is much harder to discern than the more common five sensations of sight, smell, hearing, touch, and taste.

Dr. Adam Bradlaugh, co-lead scholar and a neuroscientist from The University of Manchester, explains that this is due to the fact that a magnetic field has very little energy compared to sound or light pulses used by the other senses, which are much more powerful.

Nature has used quantum mechanics and cryptochrome, a protein that is light-sensitive in both plants and mammals, to get around this.

A member of the team and quantum chemist from the National Physical Laboratory, Dr. Alex Jones, stated, "Due to quantum physics, the movement of an electron within the protein caused by the cryptochrome's absorption of light can produce an active form of the protein that can exist in one of two states. The respective populations of the two states are affected by the magnetic field's existence, which in turn affects the protein's "active-lifetime.""

Added Dr. Bradlaugh, "One of our most surprising discoveries, and one that contradicts conventional wisdom, is that cells can continue to "feel" magnetic fields even in the presence of a very tiny amount of cryptochrome. This demonstrates that cells can detect magnetic fields in other ways, at least in an experimental setting."

Added he, "By demonstrating that a fundamental molecule found in all cells can, in sufficient quantities, confer magnetic sensitivity without any component of cryptochromes being present, we uncover a potential "other method." The light sensor that typically attaches to cryptochromes to promote magnetosensitivity is this molecule, known as flavin adenine dinucleotide (or FAD for short)."

The results, according to the experts, are crucial because they help us better understand how ambient variables, such as electromagnetic noise from telecoms, may affect creatures that depend on a magnetic sense to live.

Since cryptochrome appears to have developed to take advantage of magnetic field effects on this pervasive and physiologically old metabolite, the magnetic field effects on FAD in the lack of cryptochrome also offer a hint as to the evolutionary beginnings of magnetoreception.

Professor Ezio Rosato, a co-author from The University of Leicester, stated, "We may be able to better understand the impacts of magnetic field exposure on people as a result of this research. This new knowledge may also open up new study directions into using magnetic fields to influence the activation of target genes because FAD and other parts of these molecular machinery are present in many cells. As an instrument for experimentation and perhaps ultimately for therapeutic use, that is regarded as the golden grail."