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On the magnetostatic control of crystal orientation and iron accumulation in magnetosomes

Kirschvink, Joseph L. (1992) On the magnetostatic control of crystal orientation and iron accumulation in magnetosomes. Automedica, 14 . pp. 257-269. ISSN 0095-0963.

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Crystals of biogenic magnetite found in a variety of organisms exhibit consistent crystallographic orientations from particle to particle along magnetosome chains. typically with the [Ill] directions parallel to the chain length. In contrast to most biomineral systems where preferred crystal alignments are produced by organic matrix control, biophysical calculations presented here suggest that the common [Ill] alignment may arise spontaneously from magnetostatic interactions. A magnetosome chain produces relatively strong magnetic fields and field gradients in the surrounding space. particularly at the end where new crystals form. In this envtronment, the magnetocrystalline anisotropy of magnetite is enough to produce preferential crystal orientation for growing particles as small as 8.3 nm in size. Hence, the exceptional magnetic bacteria which do not produce such alignment must use some other form of biological control over crystal orientation. The unique magnetic environment surrounding magnetosome chains is not sufficient to cause the spontaneous accumulation of paramagnetic iron, but docs result in the exposure of most of a cell's biochemical machinery to unusually strong fields and field gradients. As this exposure has been present for much of the past 2 billion years since the evolution of the cukaryotic cell. high fields and gradients per se are unlikely to have deleterius biochemical effects.

Item Type:Article
Kirschvink, Joseph L.0000-0001-9486-6689
Additional Information:© 1992 Gordon and Breach Science Publishers. Received January 1990. This research was partially supported by NSF grants BNS83-00301, PY183-51370. NIH grant GM41635 and NIH BSRG award and by EPRI-RP2965-08. Contribution No. 4792 from the Division of Geological and Planetary Sciences, California Institute of Technology.
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Subject Keywords:Iron biomineralization, biogenic magnetite. magnetosomes. biomagnetism
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Caltech Division of Geological and Planetary Sciences 4792
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:47523
Deposited By: Ruth Sustaita
Deposited On:28 Jul 2014 21:04
Last Modified:03 Mar 2020 13:01

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