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  • Cell & Developmental Biology  (3)
  • Semithick sections
  • Wiley-Blackwell  (3)
  • 1990-1994  (3)
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  • Wiley-Blackwell  (3)
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  • 1
    Electronic Resource
    Electronic Resource
    Diffuse kinetochores and holokinetic anaphase chromatin movement during mitosis in the hemipteran Agallia constricta (leafhopper) cell line AC-20 (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 15 (1990), S. 245-259 
    Details
    ISSN: 0886-1544
    Keywords: polycentric chromosome ; light microscopy ; electron microscopy ; high-pressure freezing ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Mitosis in the hemipteran Agallia constricta (leafhopper) cell line AC-20 was examined by light microscopy of living and fixed cells. During early prometaphase the numerous small (0.30-3.0-μm) chromosomes appear as discrete units that lack a primary constriction. However, by late prometaphase the chromosomes are tightly packed at the spindle equator and are no longer clearly resolvable as individuals. When viewed from the side the metaphase chromatin appears as a 2-3-μm wide band that spans the width of the spindle; when viewed from the pole it appears as a fenestrated disk. The metaphase chromatin splits at anaphase into two sister chromatin plates, each of which exhibits holokinetic poleward movement, i.e., all parts of each plate move as a single unit with the same velocity. In many early-to-mid anaphase cells the separating sister plates are connected by chromatin-containing bridges that break as anaphase progresses. Ultrastructural analyses of serial thick and thin sections from cells fixed by conventional, OsO4/KFeCN, or high pressure rapid freezing methods, reveal that by metaphase all of the chromosomes are interconnected to form a large, irregularly shaped fenestrated disk of chromatin. Similar analyses reveal that adjacent chromatids remain interconnected throughout anaphase. Each disk of metaphase and anaphase chromatin contains numerous kinetochores recessed within its polefacing surface. Kinetochores consist of a fine, faintly staining fibrillar material arranged along the chromatin surface as thin (0.1-0.3 μm dia.) rods varying considerably (0.15-2.3 μm) in length. From these observations we conclude that the polycentric metaphase chromatin of A. constricta, and its holokinetic behavior during anaphase, arises from the aggregation or cohesion of smaller prometaphase chromosomes, each of which contains a single, diffuse kinetochore.
    Additional Material: 22 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970150407
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Estrogen-stimulation of postconfluent cell accumulation and foci formation of human MCF-7 breast cancer cells (1991)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 45 (1991), S. 177-187 
    Details
    ISSN: 0730-2312
    Keywords: estrogen dependent ; tumor cell heterogeneity ; postconfluent growth ; antiestrogen ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Foci, nodules of cellular overgrowth, that appear after confluence are an in vitro characteristic of malignant transformation. A well-studied in vitro model of estrogen-dependent tumors is the MCF-7 cell line, derived from a pleural metastasis of a human breast adenocarcinoma. We report that cultivation of MCF-7 cells, using routine methods, results in extensive estrogen-stimulated postconfluent cell accumulation characterized by discrete three-dimensional arrays. Side view Nomarski optical sections revealed these to be principally multicellular foci with occasional domes and pseudoacinar vacuoles. This effect on MCF-7 cell growth occurs in media containing fetal bovine serum but not with calf serum or charcoal-dextran-treated fetal bovine serum unless supplemented with estrogens. Foci formation starts 5-6 days after confluence, and the number of foci generated is a function of the concentration of added estrogens. Foci formation is suppressed by the antiestrogens Tamoxifen and LY 156758. Addition of progesterone, testosterone, or dexamethasone had little or no effect, while various estrogens (ethinyl estradiol, diethylstilbestrol, and moxestrol) induced foci development. Clones derived from single cells of the initial MCF-7 population revealed a wide variance in estrogen-induced foci formation, demonstrating heterogeneity of this tumor cell line. The postconfluent cell growth of the estrogen receptor-deficient cell line, MDA-MB-231, contrasted with MCF-7 by developing an extensive multilayer morphology devoid of discrete structures. The tumorigenic potential of the MCF-7 cells used in our experiments was confirmed by their estrogen-dependent growth in immunosuppressed male BDF1 mice.These data suggest an estrogen receptor-based mechanism for the development of multicellular foci during postconfluent growth of MCF-7 cells. After confluence, foci, in contrast to the quiescent surrounding monolayer, retain proliferating cells. Focus formation, therefore, reflects the heterogeneous responsiveness of these cells to estrogens and should provide a model permitting in vitro comparisons between the progenitor cells of multicellular foci and the monolayer population.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240450209
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  • 3
    Electronic Resource
    Electronic Resource
    Morphological and proliferative responses of endothelial cells to hydrostatic pressure: Role of fibroblast growth factor (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 157 (1993), S. 603-614 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Subconfluent bovine pulmonary artery endothelial cells on rigid substrates were exposed to 1.5-15 cm H2O sustained hydrostatic pressure for up to 7 days and exhibited elongation, cytoskeletal rearrangement, increased cell proliferation, and bilayering. The role of basic fibroblast growth factor (bFGF) in the mechanism(s) of these endothelial cell responses to sustained hydrostatic pressure was investigated. Evidence that bFGF was released from endothelial cells exposed to sustained hydrostatic pressure or compression was provided by the following experimental results: (1) Cells exposed to control (3 mm H2O) pressure displayed intense nuclear and cytoplasmic bFGF staining by immunocytochemical techniques; this staining was absent in cells exposed to 10 cm H2O for 7 days. (2) Conditioned medium from endothelial cells exposed to 10 cm H2O for 7 days contained at ansferable, growth-promoting activity exhibiting heparin-Sepharose affinity, lability to both heat and freeze/thawing, and neutralization by anti-bovine bFGF. (3) Suramin (0.1 mM), a growth-factor receptor inhibitor, abrogated the proliferative and morphological responses of endothelial cells exposed to sustained hydrostatic pressure. Endothelial cells exposed to elevated hydrostatic pressure demonstrated no detectable decrement in cell viability as assessed by Trypan blue exclusion. The results of the present study indicate that hydrostatic pressure or compression can induce bFGF release from endothelial cells independent of cell injury or death; bFGF is subsequently responsible for the morphological, proliferative, and bilayering responses of endothelial cells to hydrostatic pressure. © 1993 Wiley-Liss, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041570321
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