Ultrastructure and Ribosomes of Mycoplasma gallisepticum

Abstract

The ultrastructure of M. gallisepticum strain-A5969 has been studied by electron microscopy (thin-section and negative staining), ultra-centrifugation, 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 ribo-nucleic-acid-protein ratio of 0.68, and an uncorrected sedimentation coefficient of 70.2S. The 70.2S particle can be broken into 49.3S and 32.4S particles. Ribosomal arrays were found filling the intra-cytoplasmic 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.