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Query: UMLS:C0026936 (Mycoplasma)
 14,761 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Several virion and nonvirion DNAs were tested for the ability to activate endogenous type C virus in BALB/c-derived mouse cells using the calcium precipitation technique. The DNAs from all herpesviruses tested activated xenotropic type C virus synthesis. These included DNAs from herpes simplex virus types 1 and 2, Epstein-Barr virus, human cytomegalovirus, SA8 virus, infectious bovine rhinotracheitis virus, pseudorabies virus, and herpes saimiri virus (M-DNA). In contrast, DNAs from vaccinia virus, simian virus 40, primate cells, bacteria, mycoplasma, and salmon sperm showed no ability to activate type C virus when tested under the same conditions. Several herpesviruses and vaccinia virus, which were highly infectious for the BALB/c cells used, were tested for their ability to activate type C virus after UV irradiation. All herpesviruses tested were positive, while vaccinia virus was negative. Unirradiated simian virus 40 also showed no ability to activate type C virus. Activation of type C virus by DNA from herpes simplex virus was observed after shearing or sonication of the DNA to an average size of 3 x 10(6) daltons, but was not observed with DNA sonicated to an average size of 1 x 10(6) daltons. Alkali denaturation of DNA from herpes simplex virus or treatment with DNase, but not RNase, destroyed its ability to activate type C virus, as did crosslinking of the DNA with 4,5',8-trimethylpsoralen (psoralen) and light.
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PMID:Activation of endogenous type C virus in BALB/c mouse cells by herpesvirus DNA. 21 61

Matings of genetically marked derivatives of Mycoplasma pulmonis resulted in the exchange of chromosomal DNA and the appearance of doubly marked transconjugants. Transposons Tn916 and Tn4001, and a series of integrative plasmids derived from their cloned antibiotic resistance genes, were used to construct antibiotic-resistant mycoplasmal derivatives to examine this phenomenon at the molecular level. Genetic exchange occurred on agar surfaces at frequencies ranging from 3.3 X 10(-4) to 6.4 X 10(-8) transconjugants per CFU. Examination of chromosomal DNA from transconjugants by hybridization revealed that the transposons or integrated plasmids were in the same chromosomal locations as in the parental strains, indicating that exchange involved the transfer of chromosomal DNA and homologous recombination. Transfer was not affected by DNase, polyethylene glycol, EDTA, or calcium chloride but was affected by treatment of either parent with trypsin. Mixing of mating strains before plating had no effect on mating frequencies, but mating did occur in liquid media. The ability to exchange chromosomal markers was limited to selected strains of M. pulmonis; mating did not occur with Acholeplasma laidlawii or M. gallisepticum. Heat and UV inactivation studies revealed that nonviable cells could act as donors in matings. The evidence presented supports a conjugationlike mechanism involving specific trypsin-sensitive membrane components.
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PMID:Genetic exchange of transposon and integrative plasmid markers in Mycoplasma pulmonis. 215 66

A Mycoplasma fermentans-derived high-molecular-weight material (MDHM) is described which causes differentiation of concanavalin A-stimulated CBA/J or C57BL/6 mouse thymocytes to cytolytic effector T cells (CTLs). The effect of MDHM was inhibited by addition of monoclonal anti-interleukin-6 (IL-6) antibody. It could also be abolished after removal of adherent cells. However, adherent cell-depleted thymocytes could still form CTLs after addition of IL-6. The action of MDHM could thus be explained by the capacity of MDHM to stimulate IL-6 release from adherent cells. MDHM was active on macrophages from CBA/J and C3H/HeJ endotoxin nonresponder mice and was also capable of stimulating IL-6 release from human monocytes. On gel chromatography, MDHM had an apparent molecular size of 1.5 x 10(6) daltons. Treatment with RNase and DNase had no effect on either size or biological activity. Proteinase K did not abolish activity but reduced the apparent molecular size of MDHM. MDHM production by M. fermentans required either coculture with eucaryotic cell lines in RPMI 1640 medium with fetal calf serum or addition of eucaryotic cell sonic extracts to this medium. The biological activity of MDHM is not identical to that of a mitogen for murine spleen cells derived from M. arthritidis; MDHM caused only slight proliferation in this system compared with the mitogen from M. arthritidis, and the latter did not elicit IL-6 release from macrophages. The results are discussed in relation to mycoplasmas as putative etiological agents for rheumatoid arthritis, since high IL-6 titers were reported for synovial fluid from patients with this disease.
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PMID:Mycoplasma fermentans-derived high-molecular-weight material induces interleukin-6 release in cultures of murine macrophages and human monocytes. 232 16

Between 1982 and 1985 the cadavers of 50 Guillemots (Uria aalge), 41 Kittiwakes (Rissa tridactyla), 26 Herring Gulls (Larus argentatus) and 34 Black-headed Gulls (Larus ridibundus) were examined pathological, bacteriological and virological. The probable cause of death was established. Parasitosis were particularly prevalent in Herring Gulls (49%), where the main infection--as in Black-headed Gulls--was with Cestoides. In Kittiwakes and Guillemots mainly Spiruroideae were recorded. The commonest bacterium isolated in organs and intestinal tract was Escherichia coli, followed by Aeromonas hydrophila and Clostridium perfringens. Salmonella were found in the organs of 5% and in the intestinal tract of 3% of the birds. The species of Salmonella most frequently isolated was Salmonella typhimurium varieties copenhagen. Also recorded were Yersinia intermedia Serovar 0:17 (1x), Pseudomonas spp. (2x), bacteria of the Haemophilus-Pasteurella-Actinobacillus group (1x), Pasteurella multocida (2x), Moraxella septicaemiae (1x), Campylobacter spec. (1x), Mycoplasma spec. (6x), DNase positive Staphylococcus spec. (4x) and Streptococcus spec. (6x). Less in evidence among the birds examined were fungus diseases with Aspergillus spec. (4x) and Blastomyces spec. (4x). As for viruses one Guillemot was found to have an Adenovirus and another one to have a Paramyxovirus. From one of the Herring Gulls there also was isolated a Paramyxovirus, from a second one to a Reovirus. Three other species isolated have get to be identified. The chief cause of sickness and death in the Guillemots was oil-contamination. The majority of the examined Kittiwakes and Herring Gulls were victims of pathogenic agents. Many of the Black-headed Gulls died through traumata as gunshots or road traffic etc. In order to establish the causes of sickness and death in seabirds and to ascertain the importance of the various species as possible carriers of infectious diseases, a systematic series of investigation will be necessary. Without this it will not be possible to assess their epidemiological relevance for other wild birds, domestic poultry and humans.
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PMID:[The "diseased" or "dead" guillemots (Uria aalge), three-toed gulls (Rissa tridactyla), silver gulls (Larus argentatus) and laughing gulls (Larus ridibundus) found in the area of the German Bay, 1982-1985]. 275 34

We have previously described a monoclonal antibody (BU-1) to 5-bromo-2-deoxyuridine (BrdUrd) that is useful for measurement of cell cycle S-phase. BU-1 hybridoma supernatant reacted with incorporated BrdUrd after the cells had been ethanol fixed; without a requirement for acid or base denaturation. We have found that this reactivity is lost if purified antibody is used, if the culture supernatants are heated, or if a mycoplasma-free hybridoma line is isolated. The supernatant contained endogenous DNase activity that was a result of mycoplasma infection of the cell line. This DNase activity was required for staining the cells with BU-1 in the absence of other denaturation steps. The endogenous DNase could be substituted for by the addition of bovine pancreatic DNase I. The disruption of the double stranded DNA structure with an enzyme rather than with harsh chemical or heat treatments does not affect protein structure or cellular morphology and allows the detection of incorporated BrdUrd of morphologic or antigenic cell subsets. DNase pre-treatment may also be useful for detection of other 'hidden' DNA antigens.
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PMID:S-phase detection with an antibody to bromodeoxyuridine. Role of DNase pretreatment. 377 10

Mycoplasma pulmonis has substantial DNase activity exposed on the cell surface. At least part of this activity is attributable to an endonuclease. The activity is destroyed at 56 degrees C and inhibited by either 5 mM EDTA or 10 mM zinc chloride. It can also be eliminated by treatment of intact organisms with trypsin and is regenerated by incubation of the treated organisms in a medium that supports protein synthesis. DNase exposed at the cell surface constitutes 20% of the total DNase activity present in M. pulmonis extracts.
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PMID:Identification and preliminary characterization of external membrane-bound nuclease activities in Mycoplasma pulmonis. 394 Oct 2

DNA isolated from Mycoplasmatales viruses MVL51 and MVGs51 was infectious when mixed with Acholeplasma laidlawii BN1-Na1(R) 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 dose-response 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 10(5) virus equivalents of DNA.
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PMID:Transfection mediated by Mycoplasmatales viral DNA. 450 32

Following our previous demonstration that both viable and heat-killed Mycoplasma orale induce selective tumor cell killing by murine peritoneal macrophages, further investigations reported here showed that also macrophages from a continuously proliferating cell line established from long-term cultures of murine bone marrow explants can effectively be induced by the heat-killed mycoplasmas to express cytolysis. The use of single-cell suspensions of M. orale from a 0.45-micron filtrate or following either sonication or treatment with DNase did not significantly affect the level of cytolysis. Minute quantities of M. orale acted synergistically with ineffectively low levels of either lymphokines (LK) or lipopolysaccharide (LPS) to produce killing. The exceptional resistance of M109 lung adenocarcinoma cells to macrophage-mediated killing induced by LK and LPS, as previously reported by us, could not be overcome by the addition of M. orale. These data appear to indicate a mechanism of macrophage activation by M. orale similar to that caused by LPS.
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PMID:Studies on the mechanism of macrophage-mediated tumor cell lysis induced by Mycoplasma orale. 651 64

Extracts of the Mollicutes Acholeplasma equifetale, Acholeplasma laidlawii B, Mycoplasma arthritidis. Mycoplasma pulmonis, and Mycoplasma pneumoniae had DNase and endonuclease activity. A. laidlawii B had at least two peaks of DNase activity in sucrose gradients with sedimentation coefficients of 3.1S and 4.3S. These fractions also had endonuclease activity with different substrate specificities. A. laidlawii B may have more than two peaks of endonuclease activity in sucrose gradients.
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PMID:Properties of the nucleases of mollicutes. 681 65

Phenol-extracted DNA from mycoplasma virus L2 was able to transfect Acholeplasma laidlawii in the presence of polyethylene glycol. Transfection was sensitive to DNase and was most efficient with 36% (wt/vol) polyethylene glycol 8000 and cells in logarithmic growth. Virus production by the transfected cells was similar to that of the cells infected by intact virus. L2 DNA transfected A. laidlawii with a single-hit dose-response curve, reaching saturation at high DNA concentrations. Optimum transfection frequencies were about 10(-7) transfectants per L2 DNA molecule and 10(-4) transfectants per CFU. When DNA was present in saturating amounts, the number of transfectants increased linearly with the number of CFU present in the transfection mixture, suggesting that DNA uptake does not occur by a mechanism involving cell fusion. The cleavage of the superhelical mycoplasma virus L2 genome with restriction endonucleases that cleave the DNA molecule once reduced the transfection frequency. Host cell modification and restriction of transfecting L2 DNA were similar to those for infecting L2 virions.
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PMID:Polyethylene glycol-dependent transfection of Acholeplasma laidlawii with mycoplasma virus L2 DNA. 687 42


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