BIOPHYSICAL THEORY AND MODELING |
Theoretical analysis of an iron mineral-based
magnetoreceptor model in birds
Ilia A Solov'yov 1* and Walter Greiner 1
1 Frankfurt Institute for Advanced Studies
* To whom correspondence should be addressed. E-mail: ilia{at}fias.uni-frankfurt.de.
Submitted on January 23, 2007
Revised on March 1, 2007
Accepted on 3 May 2007
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Abstract |
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Sensing the magnetic field has been established as an essential part of navigation and orientation of various animals since many years. Only recently a first detailed receptor concept for magnetoreception has been published on the basis of histological and physical results. The considered mechanism involves two types of iron minerals (magnetite and maghemite) which were found in subcellular compartments within sensory dendrites of the upper beak of several bird species. But so far a quantitative evaluation of the proposed receptor is missing. In the present paper we develop a theoretical model to quantitatively and qualitatively describe the magnetic field effects among particles containing iron minerals. The analysis of forces acting between these subcellular compartments shows a particular dependence on the orientation of the external magnetic field. The iron minerals in the beak are found in the form of crystalline maghemite platelets and assemblies of magnetite nanoparticles. We demonstrate that the pull or push to the magnetite assemblies, which are connected to the cell membrane, may reach a value of 0.2 pN - sufficient to excite specific mechanoreceptive membrane channels in the nerve cell. The theoretical analysis of the assumed magnetoreceptor system in the avian beak skin clearly shows that it might indeed be a sensitive biological magnetometer providing an essential part of the magnetic map for navigation.
Key Words:
avian orientation, iron mineral-based model, magnetic field effect, magnetite clusters, magnetoreception, magnetoreceptor system
