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Petry K, Siebenkotten G, Christine R, Hein K, Radbruch A. An extrachromosomal switch recombination substrate reveals kinetics and substrate requirements of switch recombination in primary murine B cells. Int Immunol 1999; 11:753-63. [PMID: 10330281 DOI: 10.1093/intimm/11.5.753] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Ig class switch recombination occurs in B lymphocytes upon activation, and is targeted to distinct switch (S) regions by cytokine-mediated induction of switch transcripts spanning the entire S region and the adjacent constant region gene segments. Using a novel type of switch recombination substrate, constructed according to the intron-exon structure of the IgH locus, but with heterologous elements, we here have tested the structural requirements for targeting and the kinetics of switch recombination in activated primary murine B cells. When transfected at various times after activation, up to 10% of the transfected B cells perform recombination of the substrate within 12 h. Switch recombination in primary B cells is restricted to the first 72 h after onset of activation, then rapidly decreases to background levels, as obtained in plasmacytoma cells or with substrates carrying no S region sequences. In terms of structural requirements, switch recombination is targeted to any transcription unit that contains an intronic S region and depends on processing of the primary transcript by splicing.
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Affiliation(s)
- K Petry
- Institut für Genetik der Universität zu Köln, 50931 Köln, Germany Deutsches Rheumaforschungszentrum, Hannoversche Strasse 27, 10115 Berlin, Germany
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2
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Dolbeare F. Bromodeoxyuridine: a diagnostic tool in biology and medicine, Part III. Proliferation in normal, injured and diseased tissue, growth factors, differentiation, DNA replication sites and in situ hybridization. THE HISTOCHEMICAL JOURNAL 1996; 28:531-75. [PMID: 8894660 DOI: 10.1007/bf02331377] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
This paper is a continuation of parts I (history, methods and cell kinetics) and II (clinical applications and carcinogenesis) published previously (Dolbeare, 1995 Histochem. J. 27, 339, 923). Incorporation of bromodeoxyuridine (BrdUrd) into DNA is used to measure proliferation in normal, diseased and injured tissue and to follow the effect of growth factors. Immunochemical detection of BrdUrd can be used to determine proliferative characteristics of differentiating tissues and to obtain birth dates for actual differentiation events. Studies are also described in which BrdUrd is used to follow the order of DNA replication in specific chromosomes, DNA replication sites in the nucleus and to monitor DNA repair. BrdUrd incorporation has been used as a tool for in situ hybridization experiments.
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Affiliation(s)
- F Dolbeare
- Biology and Biotechnology Program, Lawrence Livermore National Laboratory, University of California 94551-9900, USA
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3
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Lundgren M, Ström L, Bergquist LO, Skog S, Heiden T, Stavnezer J, Severinson E. Cell cycle regulation of immunoglobulin class switch recombination and germ-line transcription: potential role of Ets family members. Eur J Immunol 1995; 25:2042-51. [PMID: 7621878 DOI: 10.1002/eji.1830250736] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Previous studies have indicated that transcription of germ-line (GL) CH genes is necessary to obtain immunoglobulin (Ig) class switching. We report here a correlation between proliferation, switching and GL transcripts. Smu-S gamma 1 switch recombination in lipopolysaccharide (LPS) + interleukin-4 (IL-4)-activated mouse B cells was assayed by a digestion-circularization polymerase chain reaction. Switching to gamma 1 is reduced upon inhibition of DNA synthesis with hydroxy-urea (HU) or aphidicholin (AC). Incubation of activated B cells with HU severely reduces steady-state levels of GL gamma 1 and epsilon RNA. By utilizing elutriation to synchronize B cell blasts in different phases of the cell cycle, it was found that GL gamma 1 transcripts are mainly expressed in G1 and S phases, but not in G0. Using the electrophoretic mobility shift assay, we characterized two major LPS-induced complexes, which bind to the GL gamma 1 promoter and are expressed at levels which correlate with the amount of LPS-induced DNA synthesis. Furthermore, the intensity of the complexes is reduced when cells are arrested with the DNA synthesis inhibitors HU or AC. Elutriation experiments revealed that the complexes are expressed in G1 and S, but not in G0. They bind to an Ets consensus element near the major initiation sites used in proliferating cells. The possible implications of these findings for Ig isotype switching are discussed.
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Affiliation(s)
- M Lundgren
- Department of Cell and Molecular Biology, Karolinska Institute, Stockholm, Sweden
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4
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Poot M, Hoehn H, Kubbies M, Grossmann A, Chen Y, Rabinovitch PS. Cell-cycle analysis using continuous bromodeoxyuridine labeling and Hoechst 33358-ethidium bromide bivariate flow cytometry. Methods Cell Biol 1994; 41:327-40. [PMID: 7532264 DOI: 10.1016/s0091-679x(08)61726-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- M Poot
- Department of Human Genetics, University of Würzburg, Germany
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5
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Chen YY, Rosenberg N. Lymphoid cells transformed by Abelson virus require the v-abl protein-tyrosine kinase only during early G1. Proc Natl Acad Sci U S A 1992; 89:6683-7. [PMID: 1379715 PMCID: PMC49567 DOI: 10.1073/pnas.89.15.6683] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Cells infected with temperature-sensitive transformation mutants of the Abelson murine leukemia virus express low levels of kinase activity at the nonpermissive temperature, causing transformed pre-B cells to die under these conditions. Examination of cell cycle profiles of such populations prior to cell death reveals that the cells accumulate in the G1 phase of the cell cycle. Following G1 arrest, the cells die via apoptosis, an active process of cell elimination. Cell synchronization and temperature-shift experiments show that G1 arrest reflects the requirement for a functional v-abl protein during early G1 and that the molecule is not required at other phases of the cell cycle. These data indicate that the substrate(s) critical to v-abl-mediated transformation is involved in regulating G1 transit and that these interactions are dominant over all other changes required for the multistep process that results in the fully malignant phenotype associated with v-abl expression in lymphoid cells.
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Affiliation(s)
- Y Y Chen
- Immunology Graduate Program, Tufts University School of Medicine, Boston, MA 02111
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6
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Chen U. Application of BrdU/Hoechst-ethidium bromide two parameter flow cytometry in studying synchronous and non-synchronous mouse cells. Immunobiology 1992; 185:366-79. [PMID: 1280619 DOI: 10.1016/s0171-2985(11)80653-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
BrdU/Hoechst-EB bivariate flow cytometry has a wide application in the study of factors controlling cell cycle for asynchronous cells such as embryonic stem cells (ES), and for synchronous cells such as stimulated resting B cells (Bo). The technique allows one to calculate the average cell cycle duration time. ES cells are found to cycle every 8-10 h, and most B cells are 11-12 h, but there is a small subset of B cells with a cycle time of only 6-7 h. Using this technique, we also study the roles of different T lymphocytes on B cell activation when B cells are stimulated with anti-IgM antibodies (commonly used, anti-mu). Exposure to anti-mu recruits small B cells into the cell cycle, but arrests them in the G1 phase of the second cycle. Interleukin (IL) 4 is a costimulator of anti-mu. In addition, IL-4 is an S-phase progression factor. Contrary to that seen when B cells are stimulated by other mitogens, very few cells are in the G2 compartments after anti-mu plus IL-4 stimulation. This phenomenon is reminiscent of embryonic cells. Our findings provide strong evidence to propose that there are two restriction points for B cell activation: at the transition from G0 to G1 and at the transition from G1 to S phase.
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Affiliation(s)
- U Chen
- Basel Institute for Immunology, Switzerland
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7
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Ormerod MG, Kubbies M. Cell cycle analysis of asynchronous cell populations by flow cytometry using bromodeoxyuridine label and Hoechst-propidium iodide stain. CYTOMETRY 1992; 13:678-85. [PMID: 1280554 DOI: 10.1002/cyto.990130703] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Continuous labelling of cells with deoxybromouridine (BrdUrd) followed by staining with a bis-benzimidazole (Hoechst 33258) and a phenanthridinium (propidium iodide or ethidium bromide) allows the cells to be separated by flow cytometry according to the extent of their DNA replication. This BrdUrd-Hoechst/PI method has been used mainly to observe perturbations of the cell cycle in synchronously growing cells. In this paper we demonstrate that, when the method is applied to asynchronously dividing cells, more extensive information can be derived about the effects of cytotoxic and other treatments on the kinetics of the cell cycle. The interpretation of the data is explained, the effects of different types of cytotoxic agent are described, and the method is compared briefly to other methods for following cell cycle kinetics.
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Affiliation(s)
- M G Ormerod
- Institute of Cancer Research, Haddow Laboratories, Sutton, England
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8
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Waldschmidt TJ, Tygrett LT. The low affinity IgE Fc receptor (CD23) participates in B cell activation. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1992; 323:149-56. [PMID: 1485561 DOI: 10.1007/978-1-4615-3396-2_19] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- T J Waldschmidt
- Department of Pathology, University of Iowa, College of Medicine, Iowa City 52242
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9
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Chen U, Scheuermann RH, Wirth T, Gerster T, Roeder RG, Harshman K, Berger C. Anti-IgM antibodies down modulate mu-enhancer activity and OTF2 levels in LPS-stimulated mouse splenic B-cells. Nucleic Acids Res 1991; 19:5981-9. [PMID: 1658749 PMCID: PMC329056 DOI: 10.1093/nar/19.21.5981] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Stimulation of small, resting, splenic B cells with bacterial lipopolysaccharide (LPS) induces proliferation, differentiation to plasma cell formation, and the expression of immunoglobulin heavy chain (IgH). When this is combined with agents which crosslink surface Ig, differentiation and the induction of surface immunoglobulin are suppressed even though proliferation proceeds. We find that anti-mu antibodies suppresses Ig gene expression of transfected mu constructs, even if either the membrane or secretory segments have been deleted. We examined the effects of anti-mu treatment on the IgH enhancer (IgHE) attached to a heterologous test gene (CAT). Indeed the IgH enhancer alone was subject to anti-mu suppression, while the SV40 enhancer was insensitive. To determine what was responsible for suppression of enhancer function by anti-mu we examined nuclear extracts from stimulated splenic B cells for the presence of sequence-specific DNA binding activities to various sites within the enhancer. We found two specific differences--an induction in mu E5 binding activity, and a reduction in octamer transcription factor 2 (OTF2) binding activity, after anti-mu treatment. Analysis of these cells by in situ immunofluorescence with anti-OTF2 antibodies suggests that the nuclear localization of OTF2 in anti-mu treated cells may change, as well as its absolute level.
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Affiliation(s)
- U Chen
- Basel Institute for Immunology, Switzerland
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10
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Seyschab H, Hoehn H, Rabinovitch PS, Chen U. Differential activity of recombinant lymphokines on mouse B cell proliferation and cell cycle progression are revealed by 5-bromo-2'-deoxyuridine/Hoechst 33258 dye flow cytometry. Eur J Immunol 1991; 21:2153-60. [PMID: 1909644 DOI: 10.1002/eji.1830210925] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Activation of resting mouse B cells with anti-mu chain antibodies (anti-mu) leads to cell proliferation. We have investigated the effect of recombinant T cell interleukins (IL 2 to IL 6) on such anti-mu-induced proliferation. No proliferative response was detected when IL 2, IL 3 and IL 6, either alone or in combination with anti-mu, were studied. Furthermore, neither IL 4 nor IL 5 could induce proliferation when added alone to B cell cultures. However, when combined with anti-mu, IL 4 as well as IL 5 stimulated cell growth. Analysis by 5-bromo-2'-deoxyuridine/Hoechst 33258 flow cytometry revealed distinct effects of IL 4 and IL 5 on B cell growth. In the presence of anti-mu, both IL 4 and IL 5 co-stimulated unfractionated splenic B cells. However, when B cells were separated into subpopulations by density, IL 4 proved to be a cell cycle progression factor, stimulating the majority of resting B cells to enter the cell cycle. In contrast, IL 5 had little effect on the resting fraction of B cells. Rather, IL 5 acted as a co-competence factor, stimulating predominantly low-density B cells. Following exposure of anti-mu alone, most B cells accumulated in the G1 of the second cycle. Upon addition of IL 4, the cells acquired the ability to progress into the next S phase compartment. Contrary to what is seen when B cells are stimulated by other mitogens, very few cells are in the G2 compartments after anti-mu plus IL 4 stimulation. This phenomenon was not due to a differential cell cycle progression rate. Our findings provide an analytical basis for fractionating cell-cycle-compartment-specific B cells for their molecular study.
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Affiliation(s)
- H Seyschab
- Department of Human Genetics, University of Würzburg
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11
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Hodgkin PD, Go NF, Cupp JE, Howard M. Interleukin-4 enhances anti-IgM stimulation of B cells by improving cell viability and by increasing the sensitivity of B cells to the anti-IgM signal. Cell Immunol 1991; 134:14-30. [PMID: 2013100 DOI: 10.1016/0008-8749(91)90327-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The lymphokine IL-4 is a potent enhancer of anti-IgM-induced B cell proliferation. Although the mechanism of this enhancement is not known, a commonly held view suggests that IL-4 acts together with anti-IgM as a costimulating factor for the activation of a subpopulation of B cells. To evaluate this hypothesis we examined the effect of IL-4 on the proportion of B cells stimulated to divide by different doses of anti-IgM using flow cytometry in combination with measurements of tritiated-thymidine incorporation. The results suggest a novel and surprisingly simple model for the mode of action of IL-4. Our analysis revealed that at high saturating anti-IgM concentrations, the proportion of live B cells which enter into S phase of the cell cycle is the same (approximately 65%) for cells cultured with or without IL-4. Cultures containing IL-4, however, exhibit a twofold increase in thymidine uptake over cultures without IL-4. This increase can be explained completely by the ability of IL-4 to enhance the viability of small dense B cells over the first 24 hr from approximately 50 to 90% of the starting cell number. Normalizing the maximum response levels obtained with and without IL-4 reveals that B cells incubated with IL-4 exhibit a 10-fold decrease in the concentration of anti-IgM required to stimulate the half-maximum proliferation level. Furthermore, evaluation of the number of cells in S phase by flow cytometry and analysis of the kinetics of cell proliferation revealed that the increased response effected by IL-4 at lower anti-IgM concentrations was due to a greater number of proliferating B cells rather than the same number of cells undergoing a faster division rate. We also found a highly nonlinear relationship between B cell number and proliferative response, implying a requirement for an additional, cell cooperation-mediated, activating signal for maximum B cell proliferation. IL-4 enhanced proliferation by the same proportion at all cell concentrations indicating that it does not replace or alter this requirement for cell cooperation. Taken together these results suggest that anti-IgM in combination with a second unidentified cell-cooperation-dependent signal leads to proliferation of up to 65% of small resting B cells. IL-4 does not provide an essential activation signal but serves to raise the sensitivity of B cells to the anti-IgM-generated signal.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- P D Hodgkin
- DNAX Research Institute of Molecular and Cellular Biology, Palo Alto, California 94304
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12
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Chen U. Analysis of cell proliferation and mu-RNA processing during activation of mouse B-cells by anti-mu and T lymphokines. Mol Immunol 1990; 27:1249-57. [PMID: 2125697 DOI: 10.1016/0161-5890(90)90029-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Anti-immunoglobulin (anti-Ig, anti-mu is commonly used) activates resting mouse B-cells to proliferate but not to differentiate and secrete Ig. Differentiation requires additional help from T-cells including soluble factors such as lymphokines. The capability of lymphokines, alone and in combination, to promote the differentiation of anti-mu activated B-cells has been investigated. Some lymphokines, like interleukin (IL) 2 and 3, as well as human-interferon beta-2 (IL-6), have no significant effect on differentiation. IL-4 and 5 maintain cell growth but do not lead to differentiation, which requires multiple factors present in ConA supernatant or partially purified TRF. Anti-mu and interferon-gamma (IFN-gamma) exert both positive and negative effects on B-cell maturation. Anti-mu induces cell proliferation. IFN-gamma enhances Ig transcription, but it has no apparent proliferation or differentiation activity. Anti-mu and IFN-gamma inhibit Ig secretion by causing the accumulation of nuclear mu-RNA precursors. Although phorbol ester plus ionomycin induce cell proliferation, the negative effect of anti-mu in RNA processing could not be mimicked by these reagents. I show that anti-mu and IFN-gamma interfere with the splicing of nuclear hnRNA. This phenomenon is independent of known 2'-5'(A)n synthetase activity. The data suggest that post-transcriptional regulation of mu-RNA processing might be a critical event in controlling the generation of the plasma cells (which secrete IgM), memory precursor cells or abortive cells (both of which do not secrete IgM).
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Affiliation(s)
- U Chen
- Basel Institute for Immunology, Switzerland
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13
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Burger C, Radbruch A. Protective methylation of immunoglobulin and T cell receptor (TcR) gene loci prior to induction of class switch and TcR recombination. Eur J Immunol 1990; 20:2285-91. [PMID: 2122953 DOI: 10.1002/eji.1830201018] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Methylation of the S gamma 1 switch region and C gamma 1 constant region gene from the immunoglobulin heavy chain locus and of the J beta 2 and C beta regions from the T cell receptor beta chain (TcR beta) locus is compared here in murine germ-line cells, nonlymphoid cells and lymphocytes. In germ-line cells and in lymphocytes prior to recombination all four regions show strong methylation, i.e. most Msp I sites are methylated. After activation of lymphocytes, demethylation is observed for those regions which are activated for recombination, at specific sites 5' of S gamma 1 in B cells activated with bacterial lipopolysaccharide and interleukin 4, and for J beta 2 in thymocytes. In nonlymphoid cells, where these regions cannot be used for recombination, considerable demethylation is observed for all four regions analyzed as compared to lymphocytes. The result implies an important role for methylation of recombinatorial regions. Methylation may be involved in protecting them from uninduced recombination, thus allowing regulated expression of distinct genes in lymphocyte ontogeny.
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Affiliation(s)
- C Burger
- Institute for Genetics, University of Cologne, Köln, FRG
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14
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Poot M, Hoehn H, Kubbies M, Grossmann A, Chen YC, Rabinovitch PS. Cell cycle analysis using continuous bromodeoxyuridine labeling and Hoechst 33258-ethidium bromide bivariate flow cytometry. Methods Cell Biol 1990; 33:185-98. [PMID: 1707482 DOI: 10.1016/s0091-679x(08)60524-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- M Poot
- Department of Human Genetics, University of Würzburg Biocenter, Federal Republic of Germany
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