Vernon M. Mosley

Periodic structure in the flagella and cell walls of a bacterium.

Abstract Electron micrographs of a non-spore forming, gram-positive, motile bacterium show the peritrichous flagella to have an external contour of a counterclockwise double helix and the cell wall to have a rectangular periodic structure clearly visible on the inside surface. The flagella are about 150 A in a diameter and have a well-defined cross structure with a periodicity along the flagella axis of 155 A. The nearly constant angle (27 to 35 degrees) that the striae of this cross structure make with the normal to the flagellar axis requires the external contour of the flagella to be a double rather than a single counterclockwise helix. The periodic structure in the cell wall appears to be caused by a rectangular array of spheres or hemispheres having diameters of about 115 A. The outside of the cell wall shows only a faint suggestion of this periodicity.

Periodic structure in the flagella of Brucella bronchiseptica.

Abstract The flagella of the bacterium Brucella bronchiseptica have the external contour of a counter-clockwise of left-handed triple helix. The average periodicity along the length of the flagella was measured as 190 angstroms with the average diameter of the flagella measuring 139 angstroms.

Electron microscopy of ultraviolet irradiated bacteria and their interaction with bacteriophage.

Abstract Electron microscopic observation shows that most bacteria in a suspension of E. coli receiving doses of ultraviolet light many times that sufficient to reduce plate counts of viable organisms 10 5 fold can grow and multiply for some time after irradiation. Evidence of this residual metabolism diminishes with increased dose of radiation. Such bacteria are lysed by bacteriophage with yields of new bacteriophage that also diminish with increased irradiation.

X-ray microradiography of tissue sections with magnesium radiation.

Abstract Excellent contrast revealing detail within and between cells can be obtained in X-ray microradiographs of standard 6 μ sections of soft tissues when a magnesium target is used and photographs are made in vacuum.