Hidden within many different organisms is an ability to navigate via an in-built compass that allows them to sense the Earth’s magnetic field, and not rely on a map as we mere humans do. This ability, called magnetoreception, is thought to be the driving force behind many different animals’ sense of direction. To everything from baby turtles using it to reach the sea, homing pigeons guiding themselves back to base, and dogs using it when out on the hunt, magnetoreception is incredibly important – but remarkably difficult to study.
Despite scientists knowing of its existence, magnetoreception has never been verifiably demonstrated in a lab – until now.
In a recent study published in the Proceedings of the National Academy of Sciences of the United States of America (PNAS), scientists from Japan have observed "live, unaltered cells responding to a magnetic field in real time". The findings could help us understand how many animals can utilize magnetic fields for navigation, and whether such fields may also play a role in human health.
“The joyous thing about this research is to see that the relationship between the spins of two individual electrons can have a major effect on biology,” said Professor Jonathan Woodward, Professor at the University of Tokyo and study co-author, in a statement.
To demonstrate magnetoreception in living cells is no easy feat, hence why it has taken decades of extensive work to reach this point. The researchers turned to molecules called cryptochromes, which have been shown in previous lab experiments to change depending on magnetic fields around them. Specifically, subunits of cryptochromes (called flavins) can glow when blue light is shone on them, a phenomenon called autofluorescence. Flavins are usually used by cells to detect light, but they also provided a fantastic opportunity for researchers to study magnetoreception. This is because varying conditions can alter how much light the flavins emit, including an altered magnetic field. When light shines on flavins, the molecule either emits light or produces radical electron pairs – the more electron pairs created, the lower the light intensity emitted.
Therefore, if you could make flavins fluoresce and then stimulate them with a magnetic field, the balance between radical pairs and fluorescence could be changed. Any differences in light intensity observed would demonstrate magnetoreception.
The researchers took this hypothesis to the lab, where they used HeLa cells – an immortal cervical cancer cell line famously derived from Henrietta Lacks – and made them fluoresce whilst waving a magnetic field over them. During stimulation with a magnetic field, the cells dimmed by a small but measurable 3.5%, before returning to normal without the magnet. This marks the first time living, non-engineered cells have shown such behavior in a lab setting.
“We’ve not modified or added anything to these cells. We think we have extremely strong evidence that we’ve observed a purely quantum mechanical process affecting chemical activity at the cellular level.” Woodward stated.
The findings suggest magnetic fields can have a direct impact on chemical reactions within cells, which could have large implications outside of navigation. It is possible that the Earth’s magnetic field, although weak, could have an impact on the health of human cells. Alongside this, magnetic fields may also become far more clinically relevant when studying cell behavior and interactions that present, and could also be involved in the medicine of the future.
However, the research is in its infancy, and far more study will be required to understand what role magnetoreception has in different cellular processes. The team now want to closely study cryptochromes and their interactions, as well as any potential consequences magnetic fields have on cells.