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Magnetite defines a vertebrate magnetoreceptor
C E Diebel1, R Proksch, C R Green
1Experimental Biology Research Group, School of Biological Sciences, University of Auckland, New Zealand. m.walker@auckland.ac.nz
Nature
|August 5, 2000
Summary
Rainbow trout possess a magnetite-based magnetic sense. Iron-rich crystals, identified as single-domain magnetite, are arranged in chains within receptor cells, explaining their magnetic detection capabilities.
Area of Science:
- Biophysics
- Sensory Biology
- Magnetoreception
Background:
- Magnetite-based magnetic senses are crucial for navigation and orientation in various species.
- Previous studies suggested a magnetite-based magnetic sense in rainbow trout (Oncorhynchus mykiss), but lacked direct cellular evidence.
- Candidate receptor cells containing iron-rich crystals were identified in trout olfactory lamellae.
Purpose of the Study:
- To investigate the magnetic properties of iron-rich crystals within candidate receptor cells in rainbow trout.
- To determine the structure and arrangement of these crystals within the receptor cells.
- To confirm a magnetite-based mechanism for magnetoreception in rainbow trout.
Main Methods:
- Confocal and atomic force microscopy (AFM) were used to map and visualize crystals within receptor cells.
- Magnetic force microscopy (MFM) was employed to detect magnetic dipoles associated with the crystals.
- Analysis of magnetic properties identified the crystal composition and structure.
Main Results:
- Iron-rich crystals within candidate receptors were confirmed to be magnetic, specifically single-domain magnetite.
- These magnetite crystals were arranged in chains approximately 1 micrometer long within individual, multi-lobed receptor cells.
- The observed crystal arrangement and properties are consistent with known mechanisms of magnetic intensity detection.
Conclusions:
- The study provides direct evidence for a magnetite-based magnetoreception mechanism in rainbow trout.
- The identified single-domain magnetite crystal chains within receptor cells explain the trout's behavioral and physiological responses to magnetic fields.
- This research elucidates the cellular basis of magnetoreception in a key fish species.
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