The magnetic sense: Why powerlines confuse the internal compass

July 10th, 2012
Migratory birds and fish use the Earth's magnetic field to find their way. LMU researchers have now identified cells with internal compass needles for the perception of the field – and can explain why high-tension cables perturb the magnetic orientation.

Although many animal species can sense the geomagnetic field and exploit it for spatial orientation, efforts to pinpoint the cells that detect the field and convert the information into nerve impulses have so far failed. "The field penetrates the whole organism, so such cells could be located almost anywhere, making them hard to identify," says LMU geophysicist Michael Winklhofer. Together with an international team, he has located magnetosensory cells in the olfactory epithelium of the trout.

The researchers first used enzymes to dissociate the sensory epithelium into single cells. The cell suspension was then stimulated with an artificial, rotating magnetic field. This approach enabled the team to identify and collect single magnetoresponsive cells, and characterize their properties in detail. Much to Winklhofer's surprise, the cells turned out to be more strongly magnetic than previously postulated - a finding that explains the high sensitivity of the magnetic sense.

Magnetite crystals show the way

The cells sense the field by means of micrometer-sized inclusions composed of magnetic crystals, probably made of magnetite. The inclusions are coupled to the cell membrane, which is necessary to change the electrical potential across the membrane when the crystals realign in response to a change in the ambient magnetic field. "This explains why low-frequency magnetic fields generated by powerlines disrupt navigation relative to the geomagnetic field and may induce other physiological effects," says Winklhofer.

The new findings could lead to advances in the sphere of applied sciences, for example in the development of highly sensitive magnetometers. In addition, they raise the question of whether human cells are capable of forming magnetite and if so, how much. "If the answer to the question is yes", Winklhofer speculates, "intracellular magnetite would provide a concrete physiological substrate that could couple to so-called electrosmog". (PNAS, 9. July)

Provided by Ludwig Maximilian University of Munich

This Phys.org Science News Wire page contains a press release issued by an organization mentioned above and is provided to you “as is” with little or no review from Phys.Org staff.

More news stories

Scientists develop pioneering new spray-on solar cells

(Phys.org) —A team of scientists at the University of Sheffield are the first to fabricate perovskite solar cells using a spray-painting process – a discovery that could help cut the cost of solar electricity.

SHERLOC to micro-map Mars minerals and carbon rings

(Phys.org) —An ultraviolet-light instrument on the robotic arm of NASA's Mars 2020 rover will use two types of ultraviolet-light spectroscopy, plus a versatile camera, to help meet the mission's ambitious ...

Ibuprofen relieves women's hurt feelings, not men's

(Medical Xpress)—For years, researchers have known that physical pain relievers such as ibuprofen can also help ease emotional pain, but new research suggests that ibuprofen has contrasting effects on men ...

Heavy metals and hydroelectricity

Hydraulic engineering is increasingly relied on for hydroelectricity generation. However, redirecting stream flow can yield unintended consequences. In the August 2014 issue of GSA Today, Donald Rodbell of ...