Scientists have discovered the elusive cells responsible for the sense of magnetoreception in trout noses.
Many animals, including pigeons, fish and honeybees, use magnetoreception to sense where they are — they orientated themselves along the Earths’ magnetic fields. This phenomenon has been widely studied, but the sensory physiology and specific cells involved have left scientists scratching their heads for over half a decade.
A research team led by Stephan Eder at Ludwig Maximilians University, Munich, have designed an elegant method of finding the cells responsible for magnetoreception. Their results, which have been published in the Proceedings of the National Academy of Sciences (PNAS) journal, show how these cells are capable of rapidly detecting small changes in external magnetic fields.
The researchers isolated cells from the nasal cavity of a trout because other studies have suggested that this region may contain magnetoreceptors — although no studies prior to this one had been able to prove it.
They found specific cells containing iron-rich deposits of magnetite — a naturally occurring magnetic mineral — giving each cell a magnetic dipole. These positive results indicated that they had found the magnetoreceptor cells, which have eluded scientists for decades.
The isolation technique used in the study was beautifully simple and can be reproduced easily. The researchers applied a moderately strong external magnetic field to a dissociated piece of trout nasal epithelium tissue. They found that the magnetite-based receptor cells would rotate with a frequency equal to that of the magnetic field they applied, making them easily recognisable and stand out from the rest of the tissue.
“We are able to unambiguously identify a cell as magnetic by its dynamic response to a rotating field,” asserted the researchers in their paper published in PNAS.
“This approach is certainly novel,” explained Jeremy Shaw from The University of Western Australia. “[It] provides an excellent way for scanning large volumes of tissue to alleviate what has been the classic needle in a haystack problem for years.”
Shaw mentioned one drawback to the technique, which is that the tissue must be dissociated in order to isolate the cells of interest. This makes it difficult to preserve the cells and study the finer cellular structures, which would be useful in understanding the biophysical mechanisms of magnetoreception. However, he feels this can be overcome easily enough in future studies.