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

Attachment of washed Mycoplasma gallisepticum cells to glass was quantified with organisms in which membrane lipids were labelled with 3H. Siliconization of the test tubes decreased attachment, while centrifugation increased it. Attachment increased with temperature, decreased with increasing pH and ionic strength of the attachment mixture, but was unaffected by Ca2+, Mg2+ and EDTA. This suggests that ionic bonds, but not salt bridges, participate in the attachment process. Glycophorin, the major receptor responsible for M. gallisepticum attachment to erythrocytes, partially inhibited the attachment of the organisms to glass. However, bovine serum albumin also decreased attachment. Extensive pretreatment of the organisms with trypsin decreased their ability to attach to glass by about 35 to 40%. Trypsin and pronase failed to detach the organisms already bound to glass, suggesting that external mycoplasma cell components, other than membrane proteins, also participate in attachment of the organisms to glass.
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PMID:Adherence of Mycoplasma gallisepticum to glass. 3 84

The human pathogen Mycoplasma pneumoniae adheres to a variety of cells, including erythrocytes. A hemadsorption technique was developed to quantitate adherence by photometric measurement of lysates of erythrocytes that attached to sheets of M. pneumoniae grown in cups of Linbro plates. Attachment of sheep erythrocytes (SE) increased with higher ionic strength, was unaffected by minor pH variations (6 to 9), and was blocked by anti-M. pneumoniae antiserum, but was not inhibited by a variety of sugars, amino acids, and bovine serum albumin. The reaction was time and temperature dependent. The temperature curve showed peaks at 14 and 28 degrees C with untreated SE but only one peak at about 38 degrees C with glutaraldehyde-treated SE. The temperature dependence indicated involvement of either metabolic or membrane activities in the binding process. Trypsin treatment of the M. pneumoniae sheet abolished adherence of SE but was only partially effective with human erythrocytes and noneffective with rabbit erythrocytes. The binding capacity of the mycoplasma cells for SE was restored by incubation in growth medium for 3 to 4 h; this restoration was inhibited by 10 mug of chloramphenicol per ml. Neuraminidase treatment of SE removed their attachment capacity but had no effect on attachment of rabbit erythrocytes and only a slight effect on attachment of human erythrocytes. Pretreatment of M. pneumoniae with neuraminic acid partially blocked the adherence of SE, whereas rabbit erythrocyte attachment was not affected. Attached SE could be detached by trypsin, but not by neuraminidase. For human and rabbit erythrocytes, the results suggest binding mechanisms other than the interaction between neuraminidase-sensitive receptors and protein-containing binding sites shown for SE.
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PMID:Adherence of erythrocytes to Mycoplasma pneumoniae. 3 34

Mycoplasmas adhere closely to the central region of the surface of mouse peritoneal macrophages in vitro. They do not appear connected to each other or the macrophage membrane, and they induce no change in the surface of the cell. After addition of antimycoplasma antibody, mycoplasmas show interconnections and the cell shows an increase occurrence of ruffled membrane and folding over the mycoplasmas. Large and small lacunae appear in the membrane at sites other than those taking in organisms, and the cell develops a diffusely granular appearance. These changes are associated with an increase in pinocytosis of horseradish peroxidase that is 85% above controls. Five minutes after addition of antibody, the macrophage appears contracted and engorged and has persistent membrane changes consisting of pits, openings, and membrane folds. Trypsin causes slow ingestion of surface mycoplasmas without the obvious membrane folding over organisms but with evidence of a predominantly invaginating process of phagocytosis. The macrophage surface has numerous microprojections, but is does not have the granular appearance seen after addition of antibody. Trypsin and Mycoplasma pulmonis antigen do not enhance macrophage pinocytic rates. (Am J Pathol 87:347-358, 1977).
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PMID:Attachment and ingestion of mycoplasmas by mouse macrophages. II. Scanning electron microscopic observations. 85 Nov 71

Clinical isolates, cell-culture contaminants, and the type strain PG21 of Mycoplasma hominis were examined for attachment to erythrocytes and human cell cultures. Strain 13428 (from blood, postpartum fever) and strain 1184 (cell culture) attached to human and guinea pig erythrocytes, but there were no differences in attachment activities between these strains. However, five M. hominis strains isolated from different tissue sites showed quantitative differences in attachment to human WiDr (intestinal carcinoma cell cultures), MRC-5 (human embryonic lung fibroblasts) and HeLa (carcinoma of cervix) cell cultures. The relative attachment activities were, in descending order: strain 1184 (cell culture), strain 11932 (cervix), strain 13428 (blood, postpartum fever), 13408 (nongonococcal urethritis), and type strain PG21 (multiple passage, originally from human rectum). Trypsin and pronase treatment of M. hominis strain 1184 markedly reduced attachment, suggesting that surface proteins play a role in M. hominis attachment to mammalian cells. In subsequent studies, strain 1620 (septic arthritis) showed the highest attachment activity, whereas strain 1652 (surgical skin flap) and L01888 (cell culture) showed attachment activity similar to cell culture strain 1184. The differing attachment activities of these M. hominis strains isolated from different infected sites of patients with a variety of diseases may be relevant to the virulence of these strains.
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PMID:Attachment of Mycoplasma hominis to human cell cultures. 331 97

In contrast to mycoplasma virus L1 and L2 circular DNA, mycoplasma virus L3 linear DNA is not biologically active in polyethylene glycol-mediated transfection. Electroporation of Acholeplasma laidlawii, however, leads to plaque formation after incubation with L3 DNA. The efficiency of electroporation-mediated transfection is 1/10 that of polyethylene glycol-mediated transfection as estimated with L1 DNA. Trypsin treatment of cells before DNA addition increases the efficiency of DNA uptake.
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PMID:Electroporation-mediated transfection of Acholeplasma laidlawii with mycoplasma virus L1 and L3 DNA. 339 73

Haemadsorption-negative mutants of Mycoplasma pneumoniae were isolated which varied in their capacity to adsorb erythrocytes of various animal species suggesting adherence to erythrocytes is mediated by different binding mechanisms. Trypsin treatment of the wild-type strain resulted in loss of haemadsorbing activity; several polypeptides, some of which regenerated with haemadsorbing activity following further incubation, were also trypsin sensitive. The haemadsorption-negative mutants could be divided into two groups according to their polypeptide pattern. In the first group (11 mutants) the PAGE pattern was identical to that of the wild-type strain. The second group comprised 7 mutants which differed from the wild-type by lack of one or more polypeptides with molecular weights of 190 000, 90 000 or 40 000. During growth attachment to glass was weak or absent in the mutants. Surface hydrophobicity as measured by hydrophobic-interaction chromatography was nearly comparable in mutants and parent strain.
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PMID:Analysis of polypeptides of mutants of Mycoplasma pneumoniae that lack the ability to haemadsorb. 640 87

Four antigens of Mycoplasma hyorhinis GDL were defined by murine monoclonal antibodies. Components of broth-grown mycoplasmas were separated under reducing conditions by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and subsequent protein blots were stained with individual antibodies. Each antibody reacted with a distinct component with relative molecular weights of 120,000, 73,000, 51,000, and 38,000, respectively (termed p120, p73, p51, and p38). Trypsin treatment of protein blots specifically abrogated binding of antibodies, suggesting that the epitopes recognized were associated with proteins. By using indirect immunofluorescence and immunoferritin techniques, mycoplasmas colonizing the surface of chronically infected BW5147 murine T-lymphoblastoid cells were selectively stained with antibody to p120, indicating the localization of the corresponding epitope at the mycoplasma surface. Protein blots of mycoplasmas derived from BW5147 cell cultures were stained with antibody to p120, revealing a component identical to that observed with broth-grown organisms. These results establish the identity of a surface protein antigen of M. hyorhinis GDL expressed at the surface of organisms during their colonization of host cells.
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PMID:Mycoplasma hyorhinis GDL surface protein antigen p120 defined by monoclonal antibody. 660 27

Many pathogenic mycoplasmas are surface parasites, adhering to the epithelial linings of the respiratory and urogenital tracts. Since mycoplasmas lack cell walls their plasma membrane comes in close contact with that of their host, allowing exchange of components between the two membranes and possibly fusion. The tight association of the parasite with its host is illustrated in scanning electron micrographs of Mycoplasma pneumoniae and M. gallisepticum adhering to human red blood cells. Specialized structure at the tips of the mycoplasma cells appear to function as attachment organelles. Our main aim has been to chemically define the receptors on the host cell and the binding sites on the mycoplasma cells responsible for adhesion. Glycophorin (the major sialoglycoprotein of human red blood cells) serves as the main or sole receptor for M. gallisepticum whereas M. pneumoniae binds to additional receptors on human red blood cells. Trypsin treatment of M. pneumoniae cells abolishes their ability to attach to human red cells, suggesting the protein nature of the binding sites. M. pneumoniae membranes solubilized by detergents were subjected to affinity chromatography on glycophorin-Sepharose so that membrane components with high affinity for glycophorin could be isolated. The fraction isolated consisted of several proteins (relative molecular mass 25 000 and 45 000). The binding of this fraction to red cells was relatively low but appeared to be specific, as it was inhibited by glycophorin but not by its hydrophobic moiety. The possibility is discussed that the exposure of the binding sites on the mycoplasma cell surface is influenced by the electrochemical ion gradient across the membrane.
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PMID:Adhesion of mycoplasmas to eukaryotic cells. 679 Feb 54

The process of attachment of Mycoplasma hominis and M. orale to HAIN-55 cells, derived from normal embryonic human lung, was investigated quantitatively. The attachment reached its maximum within about 2-4 hr at 37 degrees C and increased linearly as a function of the number of organisms present in the system. The relative attachment efficiency of M. hominis was approximately 1% under our experimental conditions. Trypsin and EDTA were effective in detaching particles of M. hominis and M. orale from the surfaces of HAIN-55 cells. Therefore it was suggested that some proteinaceous substance and salt bridges might be involved in the attachment of these mycoplasmas to HAIN-55 cells.
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PMID:Attachment of Mycoplasma hominis and M. orale to human diploid lung fibroblasts. 679 14

Antibody-opsonized Mycoplasma pneumoniae cells with various radioactive markers were sedimented onto monolayers of guinea pig alveolar macrophages (AM). After 2 h of incubation, about 50% of the activity of [3H]palmitate-labeled mycoplasmas was associated with AM. Nonspecific attachment of the opsonized mycoplasmas to AM-free plastic surface areas was negligible. The occurrence of phagocytosis was proven by electron microscopy and monitoring of AM surface-bound antigen by 125I-labeled F(ab)2 fragments. The activity of [3H]palmitic acid-labeled mycoplasmas was only slowly released into the supernatant. About 55% of the activity remained AM-associated up to 70 h after phagocytosis. After phagocytosis of [3H]thymidine-labeled cells, about 70% of the radioactivity found non-precipitable by trichloracetic acid. 3H-amino acid-labeled protein was released to 50% within 8 h. Supernatants and AM were tested for M. pneumoniae antigen with enzyme-linked immunosorbent assay. Considerable amounts of antigenically active material could be found in the supernatant within 8 h. This antigen was totally inactivated by heat (80 degrees C). Trypsin treatment (1 mg/ml, 10 min) reduced the antigenicity by 80%. The results suggest a selective release of microbial material after phagocytosis.
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PMID:Release of Mycoplasma pneumoniae substances after phagocytosis by guinea pig alveolar macrophages. 680 91


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