title: Magnetosome chain arrangement and stability in magnetotactic cocci.
abstract: We have studied the disposition of chains of magnetosomes inside magnetotactic cocci with light and electron microscopy. Light microscopy of isolated cocci indicated that the chains of magnetosomes are disposed on opposite sides of the cell. Electron spectroscopic imaging of whole unprocessed bacteria, showed the magnetosome chains in the cells. Freeze-etching of the cell surface allowed the observation of the close association of the chain with the cell surface. During the replication process of the freeze-etching, the magnetosome chains remained attached to the replicas, which indicates that chains were very close to the cell surface before freezing. We provide evidence that the large area of the contact faces between magnetosomes in a chain may provide an extra mechanical stability that helps keep the magnetosomes in chains even after isolation from the bacteria. Comparison with pointed magnetosomes from different cocci present in the same samples showed that the maintenance of linear chains is more difficult to be achieved because of the geometry of the crystals.
authors.affiliation: Departamento de Microbiologia Geral, Instituto de Microbiologia Professor Paulo de Góes, Universidade Federal do Rio de Janeiro, 21941590, Rio de Janeiro, R.J., Brasil. ulins@micro.ufrj.br
authors.forename: Ulysses
authors.initials: U
authors.lastname: Lins
authors.forename: Marcos
authors.initials: M
authors.lastname: Farina
mesh_terms: D001938:Brazil; D002465:Cell Movement / Q000502:physiology*; D005613:Freeze Etching; D006090:Gram-Negative Bacteria / Q000166:cytology* / Q000378:metabolism; D008280:Magnetics; D008854:Microscopy, Electron; D015388:Organelles / Q000378:metabolism / Q000648:ultrastructure*; D012623:Seawater / Q000382:microbiology