Intracellul�re Bewegungsorganellen der Myxobakterien

Effects of drugs that influence eucaryotic motile processes on motility of Cystobacter fuscus (Myxobacterales)

Cytochalasin B, dbcAMP and EGTA were found to inhibit the motility of Cystobacter fuscus completely whereas colchicine and cAMP only reduced velocity of movement.

Intracellular, periodic structures in the gliding bacterium Myxococcus xanthus

Electron microscopic observations of thin sections of Myxococcus xanthus vegetative cells revealed the presence of cytoplasmic bundles of 4- to 5-nm-diameter filaments running longtitudinally below the cell membrane and terminating in association with the envelope near one pole. Part of each bundle demonstrated a herringbone-like periodicity (approximately 12-nm spacing). This structure was observed in cells from shake cultures and in gliding cells fixed by several methods. It is proposed that the structure may be attached to the envelope near both poles in gliding cells and that the motive force for motility may be provided by its contraction and relaxation. In one of four nongliding mutants examined, the periodicity was indistinct or lacking. In this mutant another structure, comprised of linearly arrayed beads, was observed in association with the filamentous bundle. Another structure, characterized by major, transverse bands (approximately 34 nm apart), occurred in patches that may traverse the diameter of the wild-type cells in which the structure was observed.

The fine structure of a microplate-microtubule array, microfilaments and polyhedral body associated microtubules in several species of Anabaena

A microplate-microtubule array was observed in Anabaena sp. (B-378). This structure consists of an arched plate, about 8 nm thick, and various microtubules, 12 nm in diameter and 50 nm long, arranged in rows. The microtubules project at right angles from one side of the plate into the cytoplasm or towards the plasma membrane. Up to twelve microplate-microtubule arrays were observed in a single section of a cell. Microfilaments, about 2.8 nm in diameter and of undetermined length, were observed in four isolates of Anabaena. The microfilaments were always found in bundles, nwhich varied in size, up to 0.63 mum across and 0.91 mum long. Microtubules, 10 nm in diameter and about 150 nm in length, were observed associated with one facet of polyhedral bodies in 8 out of 20 isolates of Anabaena. The microtubules occurred in groups of up to 20 or more, and were always oriented with the long axis parallel to the facet of a polyhedral body. In cross section, the microtubules had an electron transparent lumen 5 nm wide and a wall 2.5 nm thick. These structures are compared to previously described microtubules and microfilaments.

On the structure of the peptidoglycan of cell walls from Myxobacter AL-1 (myxobacterales)

Basically the peptidoglycan of Myxobater AL-1 consists of alternating beta-1,4-linked N-acetylglucosamic-N-acetylmuramic acid chains. After splitting the aminosugar backbone with a specific algal enzyme three subunits arise: a monomer, a dimer and a timer. Investigation of the monomer with specific enzymes and comparison of the degradation products to standards derived from other bacterial peptidoglycans suggest the following structure of the monomer peptide: L-alanyl-D-glutamic-L-meso-diaminopimelic-D-alanine. A D-alanyl-D-meso-diaminopimelic acid bond is the bridgebond between the peptides of the subunits.

Surface structure of gliding bacteria after freeze-etching

Ultrastructural studies of gliding bacteria demonstrate 10- to 11-nm beads on the inner surface of the outer bilayer of Cytophaga columnaris. These were not found in Myxococcus xanthus. On treatment with glutaraldehyde and ethanol, the beads appear in linear arrays.