Studies of the Ultrastructure and Ribosomal Arrangements of the Pleuropneumonia-Like Organism A5969

Maniloff, Jack; Morowitz, Harold J.; Barrnett, Russell J.

doi:10.1083/jcb.25.1.139

Cited by 58 publications

(30 citation statements)

References 23 publications

(20 reference statements)

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“…Under these circumstances, the smaller of the two ribosomal subunits, when it can be distinguished, is observed to lie closer to the polysomal axis than the larger one. Double rows of ribosomes are often seen in tissue sections (22,2,4,13,17), and this arrangement with the smaller subunit in the center may be associated with a very efficient packing of asymmetric ribosome units along a linear axis. On the other hand, in positively contrasted preparations, a more extended array is found, possibly because of decreased support from the staining medium.…”

Section: Resultsmentioning

confidence: 99%

An Electron Microscopic Study of Large Bacterial Polyribosomes

Slayter

Kiho

Hall

et al. 1968

The Journal of Cell Biology

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Section: Resultsmentioning

confidence: 99%

An Electron Microscopic Study of Large Bacterial Polyribosomes

Slayter

Kiho

Hall

et al. 1968

The Journal of Cell Biology

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“…In particular, mycoplasma ribosomal and transfer RNAs contain many kinds of modified bases, but in smaller amounts than reported for other prokaryotes (1,4,5).…”

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confidence: 99%

“…A review of the biochemical and biophysical studies of the mycoplasmas concluded that, in general, their biology is qualitatively similar to that of other prokaryotes, the only differences being quantitative ones due to the limited size of the mycoplasma cell and genome (1). In particular, mycoplasma ribosomal and transfer RNAs contain many kinds of modified bases, but in smaller amounts than reported for other prokaryotes (1,4,5).…”

mentioning

confidence: 99%

Phylogenetic analysis of the mycoplasmas.

Woese¹,

Maniloff²,

Zablen³

1980

Proc. Natl. Acad. Sci. U.S.A.

324

198

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The phylogenetic relationships between the mycoplasmas and bacteria have been established from a comparative analysis of their 16S rRNA oligonucleotide citalogs. The genera Mycoplasma, Spiroplasma, and Atholeplasma arose b degenerative evolution, as a deep branch of the subline of costridial ancestry that led to Bacillus and Lactobacillus.Thermoplasma has no specific relationship to the other mycoplasmas; it belongs with the archaebacteria.Mycoplasma is the general name for a group of prokaryotes that do not have cell walls; each cell is bounded by a single lipoprotein membrane (for reviews, see refs. 1 and 2). The various isolates have been placed in the class Mollicutes, order Mycoplasmatales and classified into the genera Mycoplasma (containing about 50 currently recognized species), Acholeplasma (6 species), Ureaplasma (1 species), and Spiroplasma (1 species). In addition, the class Mollicutes contains two genera of uncertain taxonomic position: Anaeroplasma (two species) are obligate anaerobes and Thermoplasma (one species) is an acidophilic thermophile. The taxonomy and characteristics of these genera have been reviewed recently by Tully (3). All mycoplasmas, except Acholeplasma and some Anaeroplasma isolates, require sterol for growth. The genome size of the Mycoplasma and Ureaplasma is about 0.5 X 109 daltons, that of the Acholeplasma, Spiroplasma, and Thermoplasma about 1.0 X 109 daltons. The G.C content of the cell DNA is: Mycoplasma, 23-41%; Acholeplasma, 29-35%; Ureaplasma, 28%; Spiroplasma, 26%; Anaeroplasma, 29-34%; and Thermoplasma, 46% (2).A review of the biochemical and biophysical studies of the mycoplasmas concluded that, in general, their biology is qualitatively similar to that of other prokaryotes, the only differences being quantitative ones due to the limited size of the mycoplasma cell and genome (1). In particular, mycoplasma ribosomal and transfer RNAs contain many kinds of modified bases, but in smaller amounts than reported for other prokaryotes (1, 4, 5).The origin of and relationships among mycoplasmas have been controversial for many years. Their small genome sizes and general simplicity led some workers to suggest that they might be descendants of a primitive type of organism that preceded the typical bacteria in the evolutionary progression (6). However, mycoplasmas may merely be degenerate forms. If so, there is still the question of whether mycoplasmas constitute a separate and major branch of the bacteria, as the name Mollicutes connotes, or whether they represent a diverse collection of wall-less forms derived from many different branches of bacteria.In the studies presented here, we have examined the question of mycoplasma genealogy through comparative analyses of their 16S rRNA sequences. This technique, rRNA cataloging, has been used successfully in determining the phylogenetic structure of a variety of bacterial groups (7,8). We find that the mycoplasmas are not a phylogenetically coherent group in the sense that all derive from a common ancestor, itself a mycopl...

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“…All such studies require stable genetic markers; these have been extremely difficult to isolate in the mycoplasmas (23). The previously reported unsuccessful attempts to demonstrate DNA-mediated transformation in the mycoplasmas (2, 3) may reflect (a) the lack of different stable genotypes; (b) since it has been shown that transformation frequency is greatly reduced in lysogenic bacteria (24), and that the Acholeplasmas used for previous mycoplasma studies are carrying viruses (16) …”

Section: Dna-concentration Dependence For Transfectionmentioning

confidence: 99%

Transfection Mediated by Mycoplasmatales Viral DNA

Liss

Maniloff

1972

Proc. Natl. Acad. Sci. U.S.A.

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DNA isolated from Mycoplasmatales viruses MVL51 and MVGs51 was infectious when mixed with Acholeplasma laidlawii BNL-NaLR cells. Infectivity was destroyed by deoxyribonuclease but not by ribonuclease, Pronase, or specific antiserum to the virus. Host mycoplasma cells were only competent for transfection during late-log growth phase. The rates of the establishment of DNase insensitivity of viral DNA transfectants were similar to those of bacteriophage systems. The doseresponse curve for transfection suggested that an average of six molecules of DNA must interact with a cell in order to produce one infectious center. Mycoplasmatales virus DNA exhibited a low efficiency of infection; one infectious center required 4 X 106 virus equivalents of DNA.Mycoplasmas are a group of small prokaryotic cells (Order, Mycoplasmatales) bounded only by a single lipoprotein membrane. They are the smallest free-living cells: different mycoplasma species carry enough genetic information to only code for 600-1000 cistrons per cell (1). Previous attempts to study mycoplasma genomes have suffered from the lack of a system for performance of conjugation, transformation, or tranduction in these cells (2). Folsome (3) has reported that one mycoplasma species, Acholeplasma laidlawii A, was capable of binding in DNase-resistant form double-or single-stranded DNA of high molecular weight; however, the existence of transformation could not be demonstrated.Transfection, the infection of cells with isolated viral DNA, has been reported for several bacterial species: Escherichia coli (4, 5), Streptomyces kanamyceticus (6), Proteus (7), Bacillus species (8, 9), and Staphylococcus aureus (10). Infectious DNA has also been reported for many animal virus systems: polyoma (11), simian virus40 (12, 13), and Shope rabbit papilloma virus (14). This paper reports a transfection system in A. laidlawii by DNA from several Mycoplasmatales viruses. The lack of cell walls of the mycoplasmas means that this system may be similar to those of animal cells or bacterial protoplasts. MATERIALS AND METHODSCells and Media. The mycoplasma used for virus propagation and as an indicator strain was A. laidlawii BN1-Na1R (NaiR). It is a nalidixic acid-resistant mutant of a strain, A. laidlawii BN1 (15). The isolation of Na1R and the tryptose broth and agar media used in these studies have been described (16). Cells were assayed as colony-forming units (CFU/ml) (17).Virus Strains. The two Mycoplasmatales viruses used were MVL51, isolated from a spontaneous plaque on a NaiR lawn, and MVGs51, isolated from a lawn of Mycoplasma gallisepticum A5969. Both viruses plaque on NaiR, but are distinguishable by their different growth rates on NaiR and their different inactivation rates by antiserum against MVL51. The viruses were assayed as plaque-forming units (PFU) on NaiR lawns.Preparation of Viruses. Viruses were propagated as described (16). Lawns were started by plating an 18-hr culture, which had been diluted 1:1 with fresh medium. 6-hr Lawns of NaiR on tryptose-agar pl...

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Studies of the Ultrastructure and Ribosomal Arrangements of the Pleuropneumonia-Like Organism A5969

Cited by 58 publications

References 23 publications

An Electron Microscopic Study of Large Bacterial Polyribosomes

An Electron Microscopic Study of Large Bacterial Polyribosomes

Phylogenetic analysis of the mycoplasmas.

Transfection Mediated by Mycoplasmatales Viral DNA

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