Animals' "Sixth Sense" More Common Than We Thought

A study of fruit flies by researchers from the Universities of Manchester and Leicester, supported by the National Physical Laboratory, has revealed that the animal world's ability to detect magnetic fields may be greater than previously thought.

A paper published today (Feb. 22, 2023) in the journal Nature has significantly advanced our understanding of how animals sense and respond to magnetic fields in their environment.

This new knowledge may also allow the development of new measurement tools in which the activity of biological cells, including potentially human cells, can be selectively stimulated by magnetic fields.

The team showed for the first time that large enough amounts of a molecule called flavinadenine dinucleotide (FAD), found in all living cells, can make a biological system magnetically sensitive.

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Scientists already know that species such as the monarch butterfly, pigeons, turtles and other animals use the Earth's magnetic field to travel long distances.

But the discovery may indicate that the biological molecules needed to detect magnetic fields are present to a greater or lesser extent in all living things.

The research was funded by the Biotechnology and Life Sciences Research Council.

Lead researcher and neuroscientist Professor Richard Baines of the University of Manchester said: "How we perceive the outside world, from sight, sound to touch, taste and smell, is well understood."

"However, it is still unknown which animals can sense and how they react to the magnetic field.

"This research is a significant advance in understanding how animals perceive and respond to external magnetic fields, a highly active and controversial field."

To do this, the research team used the fruit fly (Drosophila melanogaster) to manipulate gene expression to test their ideas.

The fruit fly has a nervous system that, although outwardly very different, works like ours and has been used in countless studies as a model for understanding human biology.

Magnetic reception, as the sixth sense is called, is more complex than the five more familiar senses: sight, smell, hearing, touch and taste.

Manchester University lead researcher and neurologist Dr. According to Adam Bradl, this is because the magnetic field carries very little energy, unlike the photons of light or sound waves used by other senses. a fist

To solve this problem, nature used quantum physics and the light-sensitive protein cryptochrome, which is found in animals and plants.

Dr. Alex Jones, a quantum chemist at the National Physical Laboratory and also a member of the team, said: "The absorption of light by cryptochrome causes an electron to move inside the protein, which, thanks to quantum physics, can create an active cryptochrome form that occupies one of two states.

"The presence of a magnetic field affects the relative population of the two states, which in turn affects the ' active life' of this protein."

Dr Bradlaugh said: "One of our most surprising findings, which goes against existing understanding, is that cells continue to 'sense' magnetic fields when only a very small amount of cryptochrome is present."

"This suggests that cells can detect magnetic fields in other ways, at least in the lab."

He added: "We have discovered a possible 'other way' by showing that a nuclear molecule present in all cells can confer sufficiently high magnetic sensitivity without any part of the cryptochromes."

"This molecule, flavinadenine dinucleotide (FAD), is a light sensor that normally binds ~~to cryptochromes~~ to maintain magnetic sensitivity."

According to the researchers, the findings are important because understanding the molecular mechanism that allows a cell to sense a magnetic field allows us to better understand how environmental factors (such as electromagnetic noise from telecommunications) can affect animals that depend on the field. A magnetic sense of life.

The magnetic field effect on FAD in the absence of cryptochrome also provides insight into the evolutionary origins of magnetoception, as cryptochrome likely evolved to exploit the magnetic field effect in this ubiquitous and biologically ancient metabolite.

Co-author Professor Ezio Rosato of the University of Leicester said: "This study may eventually allow us to better assess the effects of magnetic field exposure on humans."

"Furthermore, because FAD and other components of these molecular machines are found in many cells, this new knowledge may open new avenues of research into the use of magnetic fields to manipulate target gene activation."

"It is considered an experimental tool and perhaps the holy grail for clinical use."

Citation: Bradlaugh AA, Fedele G, Munro AL, et al. The main elements of the radical pair of magnetosensitivity in Drosophila . Nature _ 2023. doi: 10.1038/s41586-023-05735-z

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