title: Ultrastructure of a magnetotactic spirillum.
abstract: The ultrastructure of a magnetotactic bacterium (strain MS-1) was examined by transmission, scanning, and scanning-transmission electron microscopy. The organism resembled other spirilla in general cell morphology, although some differences were detected at the ultrastructural level. Electron-dense particles within magnetotactic cells were shown by energy-dispersive X-ray analysis to be localizations containing iron. A non-magnetotactic variant of strain MS-1 lacked these novel bacterial inclusion bodies. A chain of these particles traversed each magnetotactic cell in a specific arrangement that was consistent from cell to cell, seemingly associated with the inner surface of the cytoplasmic membrane. Each particle was surrounded by an electron-dense layer separated from the particle surface by an electron-transparent region. The term "magnetosome" is proposed for the electron-dense particles with their enveloping layer(s) as found in this and other magnetotactic bacteria.
mesh_terms: D002462:Cell Membrane / Q000648:ultrastructure; D002467:Cell Nucleus / Q000648:ultrastructure; D002473:Cell Wall / Q000648:ultrastructure; D003593:Cytoplasm / Q000648:ultrastructure; D005407:Flagella / Q000648:ultrastructure; D002479:Inclusion Bodies / Q000648:ultrastructure; D008280:Magnetics; D008854:Microscopy, Electron; D009940:Organoids / Q000648:ultrastructure; D012270:Ribosomes / Q000648:ultrastructure; D013139:Spirillum / Q000648:ultrastructure*