Freeze-fracture confirmation of the presence of a core in the specialized tip structure of Mycoplasma pneumoniae.
The presence of a specialized terminal region in Mycoplasma pneumoniae was seen in thin sections viewed in an electron microscope. Actively growing cells were examined by the freeze-fracture technique in the absence of fixation to further establish the core as a significant structural entity. Cross fractures revealed a cytoplasmic matrix surrounding a central core structure of about 54 nm. This structure disappeared rapidly in aging cells. The convex protoplastic faces of the membrane around the core had characteristic 5- to 10-nm intramembrane particles evenly distributed across the cell surface, with no apparent difference in the region of the specialized tip. A periodicity previously noted in negatively stained preparations was clearly defined here in thin sections. Attachment of actively growing cells to sheep erythrocytes was seen primarily as a side attachment rather than attachment at the tip alone. This association between the mycoplasma and the sheep erythrocytes seriously deformed the sheep erythrocytes, but no membrane fusion could be detected.
D000268:Adhesiveness; D000818:Animals; D002462:Cell Membrane / Q000648:ultrastructure; D003593:Cytoplasm / Q000648:ultrastructure; D004912:Erythrocytes / Q000382:microbiology / Q000648:ultrastructure; D005614:Freeze Fracturing; D008854:Microscopy, Electron; D009177:Mycoplasma pneumoniae / Q000502:physiology / Q000648:ultrastructure*; D012756:Sheep / Q000097:blood