Abstract
The ultrastructure of a new isolate of Pyrodictium abyssi, obtained from the Midatlantic Ridge at a depth of 3600 m, was studied by scanning and transmission electron microscopy using cryopreparation techniques. Scanning electron microscopy revealed an extensive three-dimensional network, consisting of cells and extracellular tubules. Cells are inter-twined with the tubules. The presence of 10-nm ...
Abstract
The ultrastructure of a new isolate of Pyrodictium abyssi, obtained from the Midatlantic Ridge at a depth of 3600 m, was studied by scanning and transmission electron microscopy using cryopreparation techniques. Scanning electron microscopy revealed an extensive three-dimensional network, consisting of cells and extracellular tubules. Cells are inter-twined with the tubules. The presence of 10-nm thin flagella was verified by low-angle shadowing, freeze etching, and negative staining. In scanning electron microscopy and in ultrathin sections in transmission electron microscopy, cells are highly irregular with ultraflat areas. Transmission electron microscopy studies showed that the tubules are hollow cylinders, made of helically arrayed protein subunits, with an outer diameter of approximately 25 nm. The tubules often conglomerate into large bundles. Sections of high-pressure-frozen, freeze-substituted cells revealed many new details: the cytoplasm is homogenous and densely packed, occasionally containing regular structures of unknown nature in ribosome-free areas; the cell envelope consists of a cytoplasmic membrane, a periplasmic space, containing lightly stained material, and a zigzag-shaped surface-layer protein. The subunits of the surface layer are arranged on a p6 lattice with a center-to-center spacing of 21 nm.
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