Project Details
Projekt
Bio-gene magnetite in organisms: its structure and putative function for orientation in the Earths magnetic field
Applicant
Dr. Stephan Eder
Subject Area
Biophysics
Sensory and Behavioural Biology
Mineralogy, Petrology and Geochemistry
Sensory and Behavioural Biology
Mineralogy, Petrology and Geochemistry
Term
from 2014 to 2017
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 255550953
The ferrimagnetic mineral magnetite (Fe3O4) occurs in the form of magnetosomes as intracellular biomineralization product in magnetotactic bacteria, where it provides the cells with the ability to swim along the Earths magnetic field lines. Since 1980, it has been suggested that magnetite also plays a key role as magnetoreception agent in the magnetic sense of higher organisms, particularly of migratory animals, which critically depend on a reliable sense of orientation. Indeed, magnetosome-like magnetite crystals were extracted from homogenized tissues of migratory fish species (salmon, tuna). However, it is still not clear whether these extracted magnetite crystals are involved in a magnetoreceptor structure, since the extraction technique used does not allow any interpretation on the cellular context of the magnetite crystals. Recently we succeeded in our efforts to gently extract and isolate intact cells with magnetic inclusions from the olfactory epithelium of rainbow trout. This method provides for the first time the possibility to study these candidate magnetoreceptor cells in more detail. In order to clarify the structure and function of these magnetic cells, we are planning to characterize the magnetic inclusions in terms of inner architecture, chemical composition and mineralogical nature with the aid of electron-micrographic techniques and micro-Raman-spectroscopy. In order to gain more insight into the magnetic structure of the inclusions, we will measure magnetic remanence curves of individual cells using alternating-field and pulse-field demagnetization techniques. Ferromagnetic resonance spectra will be used to screen tissue for magnetic signatures consistent with magnetosome structures in order to identify further candidate sites for magnetorceptor cells. Finally, we will investigate if magnetic field changes trigger physiological responses in these cells to test their putative magnetoreceptive nature. The information grained on the levels of structure, magnetism, and physiology, will be combined into a model of magnetite-based magnetoreception.
DFG Programme
Research Grants
International Connection
France
