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Query: UNIPROT:Q9NRP7 (fused)
 58,367 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Protoplasts of Bacillus megaterium, incubated at 50 degrees C for 120 min, lost the ability to revert to bacillary form. Such heat-inactivated protoplasts, however, produced recombinants when fused by polyethylene glycol treatment with normal protoplasts. Although this differential inactivation effect is not yet fully reproducible, reciprocal inactivations of the parental protoplasts in genetic crosses have clearly shown that for protoplast fusion (i) either of the parents may serve as the viable recipient for markers coming from the heated parental protoplasts, and (ii) either of the parents may be rendered nonviable and yet, when fused with a viable partner, contribute to formation of a recombinant. Heat inactivation seems to provide a way to counterselect when few markers are available and one of the parents is prototrophic.
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PMID:Polyethylene glycol-induced fusion of heat-inactivated and living protoplasts of Bacillus megaterium. 9 76

In previous studies of bacterial protoplast fusion, only the frequencies of cell wall regeneration and of bacterial recombination were determined. In this work the frequency of the heterozygous fusion products is measured by prophage complementation. Two multiply marked nonsuppressing strains of Bacillus subtilis, each lysogenic for a different Sus mutant of the phage phi 105, were induced by mitomycin C, protoplasted, fused, and, after dilution in hypertonic broth, incubated until plating with phi 105-sensitive indicator bacteria. When cell lysis was avoided, the frequency of the heterozygous fused cells could be determined from the number of infectious centers produced. The very high frequencies observed are in good agreement with those determined directly, with nonlysogenic strains, by electron microscopic examination of the fused protoplasts (C. Frehel, A. M. Lheritier, C. Sanchez-Rivas, and P. Schaeffer, J. Bacteriol. 137:1354--1361, 1979). Evidence is presented that fusion occurs in two steps, one polyethylene glycol dependent, the other energy requiring. The bacterial growth medium affects the ability of the protoplasts to fuse and to regenerate a cell wall. When experiments using different growth media were compared, an inverse relationship between these abilities was observed, and a direct relationship appeared between the heterozygotes (corrected for wall regeneration) and the recombinant bacteria that were found.
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PMID:Bacterial fusion assayed by a prophage complementation test. 10 45

When protoplasts derived from sporulating cells of Bacillus subtilis were fused by exposure to polyethylene glycol (PEG) and fixed immediately thereafter, protoplasts with two enclosed prespores could be seen by electron microscope. The number of fusion events was greatly increased, and multiply fused protoplasts appeared, when the PEG-treated suspension was diluted in hypertonic broth and reincubated before fixation. This post-PEG incubation effect is taken to indicate a fusion mechanism of two steps: a short, PEG-dependent step of membrane activation, followed by a slow, metabolism-requiring step completing fusion. When prespore-bearing protoplasts from two genetically different strains were mixed and fused, the extent of fusion could also be followed by counting clones of recombinant bacteria. Maximal from the start, their number (1% of each parent type protoplast present) was unaffected by post-PEG incubation. Fusion in this case is apparently completed after plating on the wall-regeneration medium. After optimal post-PEG incubation, the majority of the protoplasts were seen to participate in fusion, and the cytological fusion observed, corrected for wall-regeneration frequency, accounted quantitatively for the prototrophic bacteria eventually recovered. These results are in good agreement with those obtained independently by Sanchez-Rivas and Garro (J. Bacteriol. 137:1340--1345, 1979).
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PMID:Electron microscopic study of Bacillus subtilis protoplast fusion. 10 47

A clone of Vero cells was isolated and shown to be totally unable to synthesize interferon and insensitive to the toxic effect of poly(rI).poly(rC) treatment. Cells of this clone and mouse L cells were fused by treatment with polyethylene glycol or Sendai virus. Hybrid cell clones were isolated following selection in medium containing hypoxanthine, thymidine and ouabain. The hybrids were sensitive to the antiviral effect of poly(rI).poly(rC) and synthesized mouse, but not primate, interferon. It is proposed that in Vero cells, the gene for interferon synthesis is defective or absent.
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PMID:Regulation of the interferon system: evidence that Vero cells have a genetic defect in interferon production. 11 94

Mitotic CHO cells and mouse testicular cells were fused with polyethylene glycol. Several types of prematurely condensed chromosomes were observed. From chromosome morphology it was possible to determine that most of the PCC represented mouse cells. Labeling of either the CHO cells in vitro or the testicular cells in vivo with 3H-TdR prior to fusion also demonstrated that the PCC were derived from the mouse cells. In some PCC, 20 chromosomes could be counted, the haploid number for mouse. It is assumed that these PCC were induced in mouse spermatid nuclei.
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PMID:Induction of prematurely condensed chromosomes from testicular cells of the mouse. 11 94

1. The cholesterol content of hen erythrocytes was modified by treating the cells with phospholipid liposomes. 2. Depletion of cellular cholesterol, by using liposomes of dipalmitoylglycerophosphocholine or phosphatidylcholine from hen erythrocytes, had no effect on the susceptibility of the cells to fusion induced by oleoylglycerol, but markedly decreased fusion induced by Sendai virus. 3. By contrast, enrichment of cellular cholesterol by using liposomes of dipalmitoylglycerophosphocholine and cholesterol increased cell fusion induced by oleoylglycerol, poly(ethylene glycol) and Sendai virus. 4. Virus-induced cell fusion of guinea-pig erythrocytes, which were enriched in cholesterol by feeding a cholesterol-rich diet to the animals, was also enhanced. 5. Hen erythrocytes that were treated with liposomes prepared from egg phosphatidylcholine contained increased quantities of phospholipid phosphorus and fused readily on incubation with retinol, independently of their cholesterol content. 6. It is suggested that cholesterol may enhance cell fusion by acting to facilitate a phase separation of protein-free areas of lipid bilayer, which subsequently provide the sites for cell fusion.
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PMID:Membrane cholesterol and cell fusion of hen and guinea-pig erythrocytes. 19 60

Spontaneous mitotic cells of the mouse leukemic cell line GF7 are preferentially included in cell fusion products after treatment with polyethylene glycol (PEG). This implies a unique configuration of the natural mitotic membrane which is particularly vulnerable to induction of fusion by PEG. Colcemid-arrested GF7 mitotic cells, however, are excluded from PEG-induced cell fusion products, suggesting that colcemid reverses the membrane configuration which is susceptible to the action of PEG. When Sendai virus is used as the fusogenic agent, both colcemid-arrested and spontaneous mitotic cells are selectively fused. There must, therefore, be an essential membrane-fusogen reaction which is characteristically different for each of these agents.
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PMID:Increased polyethylene glycol-mediated fusion competence in mitotic cells of a mouse lymphoid cell line. 19 53

Multinucleate cells are found frequently in rheumatoid synovium. In this study, polyethylene glycol was used to fuse rabbit synovial fibroblasts. Approximately 40% of the cells developed more than one nucleus in a 24 hour period, during which time cell membranes had increased permeability. In cultures containing multinucleate cells, 3H-thymidine incorporation was depressed for 24 hours although 3H-leucine incorporation into TCA precipitable material was unaffected; autoradiography showed that depression of 3H-thymidine continued for at least 4 days. Collagenase production by cultures containing fused cells was increased more than 10-fold over control cultures during a 28 day period.
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PMID:Collagen production by cultures containing multinucleated cells derived from synovial fibroblasts. 21 86

Previous work had demonstrated the coupling of a beta-adrenergic receptor on an erythrocyte with the adenylate cyclase [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] of a tissue culture cell when the two cells were fused by Sendai virus. The validity of this finding for animal tissues in general, for membrane preparations, and for peptide hormone receptors could hitherto not be assessed. Available fusion procedures worked efficiently only with certain intact cells from tissue culture and with erythrocytes. In the present work a membrane fusion method was developed that causes the transfer of the glucagon receptor from purified rat liver membranes to Friend erythroleukemia cells; even direct transfer to a membrane fraction prepared from Friend cells became feasible. It can therefore be concluded that a peptide hormone receptor in a normal tissue membrane has properties similar to those demonstrated for a beta-adrenergic receptor in an erythrocyte: it exists in the membrane as a dissociable independent unit that can readily couple with the adenylate cyclase of a foreign cell. The efficiency of the membrane fusion procedure is due to the combined action of polyethylene glycol, phospholipids, stearylamine, and ATP in a salt medium. The method promises to be applicable to membranes of various cells and tissues, and it can probably be used to analyze hormone receptors and adenylate cyclase systems in states of malfunction by transfer to their respective counterpart in a normal cell membrane. Studies in biochemical hybridization of membrane components need not be limited to hormone activation of adenylate cyclase. With the aid of the membrane fusion method, this approach could be applied to any dissociable multicomponent system in biological membranes.
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PMID:Transfer of glucagon receptor from liver membranes to a foreign adenylate cyclase by a membrane fusion procedure. 22 Jun 8

A whole-cell microtechnique for the determination of complementation of human metabolic disorders is presented. This procedure permits the isolation of individual multinucleate cells produced by cell fusion for the quantitative evaluation of complementation. Mutant fibroblasts with a deficiency of propionyl-CoA carboxylase activity (EC 6.4.1.3) that had been mapped to complementation groups pcc and bio were used to evaluate the microtechnique. Complementation was monitored by the determination of [14C]propionate incorporation into cellular macromolecules. Single cells or a small number of cells were isolated from plastic film dishes after radioactive incubation by cutting out the portion of the plastic film holding the desired cells. Isotope incorporation was linear in 10-50 unfused cells and in 10-50 fused normal cells containing five or more nuclei. There was also a direct correlation between the nuclear content of cells and the amount of isotope incorporated. Three pcc and two bio mutants were fused in pairwise combinations by means of polyethylene glycol and complementation was determined by isotope incorporation in sets of 50 multinucleate cells, each cell isolated individually. The results agreed with autoradiographic data for both complementing and noncomplementing strains. The method is quantitative and gives severalfold higher sensitivity than current procedures. The method can be applied to the complementation analysis of a wide variety of inherited disorders of intermediary metabolism.
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PMID:Analysis of genetic complementation by whole-cell microtechniques in fibroblast heterokaryons. 29 39


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