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  • mitosis  (3)
  • Centrosomes  (1)
  • Stereomicroscopy  (1)
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  • 1
    Digitale Medien
    Digitale Medien
    Chromosome fiber dynamics and congression oscillations in metaphase PtK2 Cells at 23°C (1991)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 18 (1991), S. 131-142 
    Details
    ISSN: 0886-1544
    Schlagwort(e): mitosis ; microtubules ; tubulin incorporation ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: A bioriented chromosome is tethered to opposite spindle poles during congression by bundles of kinetochore microtubules (kMts). At room temperature, kinetochore fibers are a dominant component of mitotic spindles of PtK2 cells. PtK2 cells at room temperature were injected with purified tubulin covalently bound to DTAF and congression movements of individual chromosomes were recorded in time lapse. Congression movements of bioriented chromosomes between the poles occur over distances of 4.5 μm or greater. DTAF-tubulin injection had no effect on either the velocity or extent of these movements. Other cells were lysed, fixed, and the location of DTAF-tubulin incorporation was detected from digitally processed images of indirect immunofluorescence of an antibody to DTAF. Microtubules were labeled with an anti-beta tubulin antibody. At 2-5 minutes after injection, concentrated DTAF-tubulin staining was seen in the kinetochore fibers proximal to the kinetochores; a low concentration of DTAF-tubulin staining occurred at various sites through the remaining length of the fibers toward the pole. Kinetochore fibers in the same cell displayed different lengths (0.2 to 4 μm) of concentrated DTAF-tubulin incorporation proximal to the kinetochore, as did sister kinetochore fibers. Ten minutes after injection, the lengths of DTAF-containing chromosomal fibers were greater than expected if incorporation resulted solely from the lengthening of kinetochore microtubules due to congression movements of the chromosomes. Besides incorporation as a result of chromosome movement, two other mechanisms might explain the length of the DTAF-containing segments: (1) a poleward flux of tubulin subunits (Mitchison, 1989) or (2) capture of DTAF-containing nonkinetochore microtubules.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cm.970180208
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Keratin filaments restrict organelle migration into the forming spindle of newt pneumocytes (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 15 (1990), S. 111-120 
    Details
    ISSN: 0886-1544
    Schlagwort(e): prometaphase ; mitosis ; intermediate filaments ; video microscopy ; high-voltage electron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: When viewed by light microscopy the mitotic spindle of newt pneumocytes appears to assemble in an optically clear area of cytoplasm, virtually devoid of mitochondria and other organelles, which is often much larger than the spindle. This clear area is also frequently larger than the region previously occupied by the nucleus. It forms even in prometaphase cells depleted of microtubules prior to nuclear envelope breakdown by colchicine treatment. Time-lapse video microscopy reveals that as prometaphase proceeds this clear area slowly and progressively collapses around the forming spindle so that it is greatly diminished or nonexistent by the onset of anaphase. The sharply defined nature of the boundary between the clear area and the remaining cytoplasm and the fact that organelles accumulate at its periphery suggest that a structural barrier is present at the boundary that limits organelle migration into the forming spindle. Immunofluo- rescence and electron microscopy, of cells previously followed in the living state, reveal that the periphery of the clear area contains prominent bundles of keratin filaments but lacks microtubules and actin. From our observations we conclude that keratin filaments form a loosely organized cage that surrounds the forming newt pneumocyte spindle. We propose that this cage functions, in part, to restrict the dispersion of chromosomes during nuclear envelope breakdown and to impede the bulk migration of organelles into the forming spindle.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cm.970150207
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Primary cilia cycle in PtK1 cells: Effects of colcemid and taxol on cilia formation and resorption (1987)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 7 (1987), S. 187-197 
    Details
    ISSN: 0886-1544
    Schlagwort(e): mitosis ; centrosome ; centriole ; cytoplasmic microtubules ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The effects of colcemid (0.16-1.0 μM) and taxol (10 μM) on the primary cilia cycle in PtK1 cells were studied by antitubulin immunofluorescence microscopy and by high-voltage electron microscopy of serial 0.25-μm sections. Although these dings induce a fully characteristic rearrangement (taxol) or disassembly (colcemid) of cytoplasmic microtubulcs, neither affects the structure of primary cilia formed prior to the treatment or the resorption of primary cilia during the initial stages of mitosis. Cells arrested in mitosis by taxol or colcemid remain in mitosis for 5-7 h at 37°C and then form 4N “micronucleated” restitution nuclei. Formation of primary cilia in these micronucleated cells is blocked by colcemid in a concentration-dependent fashion: normal cilia with expanded (ie, bulbed) distal ends form at the lower (0.16-0.25 μM) concentrations, while both cilia formation and centriole replication are inhibited at the higher (≥ 1.0 μM) concentrations. However, even in the presence of 1.0 μM colcemid, existing centrioles acquire the appendages characteristically associated with ciliating centrioles and attach to the dorsal cell surface. Continuous treatment with colcemid thus produces a population of cells enriched for the early stages of primary cilia formation. Micronucleated cells formed from a continuous taxol treatment contain two normal centriole pairs, and one or both parenting centrioles possess a primary cilium. Taxol, which has been reported to stabilize microtubules in vitro, does not inhibit the cell-cycle-dependent assembly and disassembly of axonemal microtubules in vivo.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cm.970070302
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Electron microscopy of semithick sections: Advantages for biomedical research (1985)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 2 (1985), S. 11-28 
    Details
    ISSN: 0741-0581
    Schlagwort(e): Ultrastructure ; Semithick sections ; Three-dimensional ; Serial sections ; Stereomicroscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Allgemeine Naturwissenschaft
    Notizen: Many transmission electron microscopes are available which can be used to examine biological material in 0.25-0.50-μm-thick sections. When compared to the traditional thin section, these “semithick” sections possess a number of inherent advantages: They can be screened for content with the phase contrast light microscope, they facilitate many types of studies requiring an analysis of serial sections, and they are frequently the optimum thickness for stereomicroscopy. Structures such as microtubule-associated components, as well as structural relationships between cellular constituents, may also be clearly visible in semithick sections which are not visible, or go unnoticed, in thin sections. Together these advantages enable an investigator to obtain a more complete three-dimensional picture of a cell or cell component in a significantly (i.e., up to 90%) shorter period of time than would be required if thin sections were used. Semithick sections may, therefore, make a study feasible which is not approachable, or which is approachable only with great difficulty, by conventional thin sectioning techniques.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jemt.1060020103
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
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    Unbekannt
    Extra centrosomes and/or chromosomes prolong mitosis in human cells (2008)
    Details
    Publikationsdatum: 2022-05-26
    Beschreibung: Author Posting. © The Author(s), 2008. This is the author's version of the work. It is posted here by permission of Nature Publishing Group for personal use, not for redistribution. The definitive version was published in Nature Cell Biology 10 (2008): 748-751, doi:10.1038/ncb1738.
    Beschreibung: Using laser microsurgery and cell fusion we have explored how additional centrosomes and/or chromosomes influence the duration of mitosis in human cells. We find that doubling the chromosome number adds ~10 minutes to a 20 minute division while doubling the number of centrosomes adds ~30 minutes more, and extra centrosomes and/or chromosomes prolong mitosis by delaying satisfaction of the spindle assembly checkpoint. Thus mitosis can be prolonged by non genetic means and extra chromosomes and centrosomes likely contribute to the elevated mitotic index seen in many tumors.
    Beschreibung: This work was supported by National Institutes of General Medical Sciences grants 40198 (to C.L.R.) and 59363 (to A.K.).
    Schlagwort(e): Mitosis ; Centrosomes ; Chromosomes ; Cancer ; Spindle assembly checkpoint
    Repository-Name: Woods Hole Open Access Server
    Materialart: Preprint
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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