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6206624 
Journal Article 
Electron microscope study of the structure of Escherichia coli ribosomes and CM-like particles††Abbreviation used: CM-like particles, particles somewhat similar to the abnormal type of ribosomes found in chloramphenicol-treated E. coli 
Bruskov, VI; Kiselev, NA 
1968 
Yes 
Journal of Molecular Biology
ISSN: 0022-2836
EISSN: 1089-8638 
37 
3 
367-377 
New techniques for making ribosome preparations have been worked out for electron microscope study; these methods ensure better preservation and reveal fine internal structure. Conditions have been found which allow high-quality negative staining of ribosomes with uranyl acetate without preliminary fixation by formaldehyde. When stained with uranyl acetate or sodium tungstate, the preparation shows the presence of a large number of ribosomes which have something like an opening in the border between the subparticles; these openings are penetrated by the stain and are seen in the micrographs as black spots. An analysis of the form and arrangement of the spots leads to the conclusion that some of them correspond to various projections of the through channel located on the border between the subparticles and intersecting the long axis of the particle. Sometimes this channel is penetrated by the stain from one or both sides. The outlines of the channel are also preserved in separate 50 s subparticles. When complete ribosomes are viewed along the channel, the 50 s subparticles usually have roundish configurations and resemble an arc. Sometimes 2 to 3 concentric half-rings can be seen in them. Roundish arc-like images are also found in separate 50 s subparticles. When ribosomes are viewed side-on (in the plane of separation of subparticles) perpendicular to the channel axis, they have a more or less rectangular configuration. Another type of rectangular particle corresponds, evidently, to the ribosome images observed in a direction perpendicular to the plane of separation of the subparticles. Peculiarities of the form and internal structure of ribosomes make it possible to present a morphological model of the 50 s subparticle in the form of an arc. This model offers a reasonable explanation of the form and the morphological features of the 50 s subparticles and, in particular, of the channel connected with the structure of the large subparticle. With the aid of the suggested model, almost all the particles can be interpreted in a straightforward and natural way. In investigations of protein-poor CM-like particles, it was possible to obtain good results by staining them with uranyl acetate. It was sometimes possible to observe the same characteristic types of images as those seen with ribosomes.