Ultrastructure and Ribosomes of Mycoplasma gallisepticum

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Abstract
Maniloff, Jack (Yale University, New Haven, Conn.), Harold J. Morowitz, and Russell J. Barrnett . Ultrastructure and ribosomes of Mycoplasma gallisepticum . J. Bacteriol. 90: 193–204. 1965.—The ultrastructure of Mycoplasma gallisepticum strain A5969 has been studied by electron microscopy (thin-section and negative staining), ultracentrifugation, and chemical analysis. The list of ultrastructure is: membrane, nuclear material, ribosomes, ribosomal structures, infra-bleb region, and blebs. The nuclear material, containing the cell's deoxyribonucleic acid, appears as an unbounded region containing 30-A fibrils. The ribosomes have a diameter of about 140 A, a ribonucleic acid-protein ratio of 0.68, and an uncorrected sedimentation coefficient of 70.2 S . The 70.2 S particle can be broken into 49.3 S and 32.4 S particles. Ribosomal arrays were found filling the intracytoplasmic space between the nuclear material and the membrane. Under certain conditions, these arrays formed cylindrical arrangements of ribosomes. The infra-bleb region is composed of a granular material, although little internal structure could be found. The bleb was highly structured.