Magnetosome

Magnetospirillum gryphiswaldense cells that contain chains of intracellular magnetite crystals (top). Magnetite crystals formed
by M. gryphiswaldense (below).
(Electron microscope images)

A magnetosome is a magnetic particle in the cells of living beings. This cell organelle forms a basis for orientation in magnetic fields, especially in the earth's magnetic field , and consequently also for the magnetic sense of some types of bacteria and animals.

Magnetosomes consist of crystals of magnetite (Fe ₃ O ₄ ) or greigite (Fe ₃ S ₄ ), which are produced by biomineralization . They have a diameter of 40–90 nm and are surrounded by a monolayer of phospholipids , proteins and glycoproteins . This simple envelope structure differs from the so-called biomembrane , which is based on a double lipid layer.

The shape of the magnetosomes varies greatly between biological species. It can be cube-shaped to cuboid and also nail-shaped or teardrop-shaped. Each cell contains several magnetosomes that form chains in it.

Occurrence

Magnetosomes are found in both prokaryotic and eukaryotic organisms. Examples of prokaryotes are the bacteria Magnetospirillum gryphiswaldense and Magnetospirillum magnetotacticum . Every tiny crystal in the magnetosome is a weak permanent magnet that alone cannot align the cell. That is why the cytoskeleton lines up 15 to 30 particles linearly in the middle of the cell. The cytoskeleton is also responsible for uniform distribution and transport during cell division.

Examples of magnetosomes in eukaryotes can be found in algae of the genus Anisonema . Magnetic particles in cells or tissues in connection with magnetotaxis / magnetoreception have also been detected in other eukaryotes . B. Termites , honey bees ( Apis mellifera ) butterflies , trout , salmon (genus Oncorhynchus ), eels , dolphins , migratory birds, carrier pigeons . But in these organisms the presence of magnetosomes as defined above, i. H. as structured, membrane-bounded cell compartments, not secured.

However, the term magnetosome is e.g. B. has been proposed for the magnetic organs of salmon.

genetics

Magnetosomes are complex organelles whose biosynthesis and organization are responsible for more than 30 genes. These are arranged in a "magnetosome island" in the genome of M. gryphiswaldense . By genetically engineering the gene group, it was possible to trigger an excess of magnetosomes.

literature

R. Blakemore: Magnetotactic bacteria. In: Science . Volume 190, No. 4212, pp. 377-379, October 24, 1975.
DL Balkwill, D. Maratea, RP Blakemore: Ultrastructure of a Magnetotactic Spirillum. (PDF; 3.1 MB). In: Journal Of Bacteriology. Volume 141, No. 3, March 1980, pp. 1399-1408.
JL Kirschvink, A. Kobayashi-Kirschvink, BJ Woodford: Magnetite biomineralization in the human brain. In: PNAS . Volume 89, 1992, pp. 7683-7687
German translation published in Blick durch die Wissenschaft on October 6, 1992

Individual evidence

↑ Magnetospirillum is the microbe of the year 2019.
↑ Dirk Schüler, René Uebe: Nanocrystals for magnetic field orientation: biogenesis of magnetosomes. In: BIOspectrum. 25, 2019: 22-25.
↑ FF Torres De Araujo, MA Pires, RB Fraenkel, CEM Bicudo: Magnetite and Magnetotaxis in Algae . In: Biophys. J. Band 50 , 1986, pp. 375-378 , doi : 10.1016 / S0006-3495 (86) 83471-3 ( cell.com [PDF; 1.6 MB ]).
↑ Barbara A. Maher: Magnetite biomineralization in termites. In: Proceedings of the Royal Society, Biological Sciences. Vol. 265 (1397), pp. 733-773, April 22, 1998 PMC 1689035 (free full text)
↑ Deborah A. Kuterbach, Benjamin Walcott: Iron Containing Cells in the Honey-Bee ( Apis mellifera ) (PDF; 3.1 MB). In: J. exp. Bio. 126, 1986, pp. 375-387.
↑ ^a ^b S. Mann, NHC Sparks, MM Walker, JL Kirschvink: Ultrastructure, morphology, and organization of biogenic magnetite from sockeye salmon, Oncorhynchus nerka: implications for magnetoreception . (PDF; 5.6 MB). In: J. exp. Bio. 140, 1988, pp. 35-49.
↑ JL Kirschvink, MM Walker, S.-B.Chang, AE Dizon, KA Peterson: Chains of single-domain magnetite particles in the chinook salmon, Oncorhynchus tshawytscha. In: J. comp. Physiol. 157, 1985, pp. 375-38.
^ Robert C. Beason: Mechanisms of magnetic orientation in birds . (PDF; 120 kB). In: Integr. Comp. Biol. 45, 2005, pp. 565-573.
^ C. Walcott, JL Gould JL Kirschvink: Pigeons have magnets. In: Science . Volume 205, 1979, pp. 1027-1031.
^ Gregory C Nordmann, Tobias Hochstoeger, David A Keays: Magnetoreception: A sense without a receptor. In: PloS Biol. 15,10 , 2017, p. E2003234, PMC 5695626 (free full text)
↑ Anna Lohße, Isabel Kolinko, Oliver Raschdorf, René Uebe, Sarah Borg, Andreas Brachmann, Jürgen M Plitzko, Rolf Müller, Youming Zhang, Dirk Schüler: Overproduction of magnetosomes by genomic amplification of biosynthesis-related gene clusters in a magnetotactic bacterium. In: Appl Environ Microbiol. 82, 10, 2016, pp. 3032–3041, PMC 4959066 (free full text)

[1] Magnetospirillum is the microbe of the year 2019.

[2] Dirk Schüler, René Uebe: Nanocrystals for magnetic field orientation: biogenesis of magnetosomes. In: BIOspectrum. 25, 2019: 22-25.

[3] FF Torres De Araujo, MA Pires, RB Fraenkel, CEM Bicudo: Magnetite and Magnetotaxis in Algae . In: Biophys. J. Band 50 , 1986, pp. 375-378 , doi : 10.1016 / S0006-3495 (86) 83471-3 ( cell.com [PDF; 1.6 MB ]).

[4] Barbara A. Maher: Magnetite biomineralization in termites. In: Proceedings of the Royal Society, Biological Sciences. Vol. 265 (1397), pp. 733-773, April 22, 1998 PMC 1689035 (free full text)

[5] Deborah A. Kuterbach, Benjamin Walcott: Iron Containing Cells in the Honey-Bee ( Apis mellifera ) (PDF; 3.1 MB). In: J. exp. Bio. 126, 1986, pp. 375-387.

[oncorhynchus-6] S. Mann, NHC Sparks, MM Walker, JL Kirschvink: Ultrastructure, morphology, and organization of biogenic magnetite from sockeye salmon, Oncorhynchus nerka: implications for magnetoreception . (PDF; 5.6 MB). In: J. exp. Bio. 140, 1988, pp. 35-49.

[7] JL Kirschvink, MM Walker, S.-B.Chang, AE Dizon, KA Peterson: Chains of single-domain magnetite particles in the chinook salmon, Oncorhynchus tshawytscha. In: J. comp. Physiol. 157, 1985, pp. 375-38.

[8] Robert C. Beason: Mechanisms of magnetic orientation in birds . (PDF; 120 kB). In: Integr. Comp. Biol. 45, 2005, pp. 565-573.

[9] C. Walcott, JL Gould JL Kirschvink: Pigeons have magnets. In: Science . Volume 205, 1979, pp. 1027-1031.

[10] Gregory C Nordmann, Tobias Hochstoeger, David A Keays: Magnetoreception: A sense without a receptor. In: PloS Biol. 15,10 , 2017, p. E2003234, PMC 5695626 (free full text)

[11] Anna Lohße, Isabel Kolinko, Oliver Raschdorf, René Uebe, Sarah Borg, Andreas Brachmann, Jürgen M Plitzko, Rolf Müller, Youming Zhang, Dirk Schüler: Overproduction of magnetosomes by genomic amplification of biosynthesis-related gene clusters in a magnetotactic bacterium. In: Appl Environ Microbiol. 82, 10, 2016, pp. 3032–3041, PMC 4959066 (free full text)