Magnetite in a fish nasal cell. Image: The Scientist from Herve Cadiou, University of Cambridge
In a prior blog, we talked about different animals that are able to sense the Earth's magnetic field. The mystery of how fish, and perhaps other animals, do this may be solved. Animals use the magnetic field like a compass. This is an important skill especially to migratory species who don't have the benefit of Google Maps. It is sort of a built-in GPS system.
Dr. Michael Walker from the University of Auckland discovered that brain cells connected to the nasal cavity of fish can be stimulated by magnetic fields. Further research showed that nasal tissue collected from yellowfin tuna actually contained magnetite.
In new research, Dr. Michael Winklhofer from the University of Munich and his colleagues isolated nasal cells from rainbow trout and exposed these cells to magnetic fields. His team found that only one to four out of every 10,000 cells actually responded to the magnetic field. Inside the cells, they found a chain of magnetite that acted like a compass needle following the magnetic field around. Cells in animals aren't able to spin around freely like they do in culture, rather the motion of the magnetite likely causes changes in the cell membrane allowing charged particles to move in or out if the cell. This change could then activate electrical impulses that are sent to the brain. The researchers are now looking at whether or not calcium plays a role in this potential signaling mechanism.
Dr. David Keays from the Research Institute of Molecular Pathology in Vienna is building on this research in an effort to find magnetic cells in pigeons, whose location is currently under debate. He will be exploring the eyes, ears and nose of pigeons in his search.
Source:
Edera SHK, Cadioub H, Muhamadb A, McNaughtonb PA, Kirschvinkc JL, Winklhofera M. Magnetic characterization of isolated candidate vertebrate magnetoreceptor cells. PNAS. July 9, 2012.
DOI: 10.1073/pnas.1205653109
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Given the weakeness of earth's magnetism (now growing weaker every year as we swing ever closer to the next pole-flip) one can truly say that this is not an 'intense field' of study.....