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  • video microscopy  (2)
  • cytoskeleton  (1)
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 24 (1993), S. 167-178 
    ISSN: 0886-1544
    Keywords: cytoplasmic dynein ; kinesin ; bundling ; crosslinking ; video microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have developed a method for producing sea urchin egg cytoplasmic extracts which support substantial microtubule-associated motility, particularly minus end-directed motility characteristic of cytoplasmic dynein. Particles translocated along microtubules and axonemes predominantly in the minus end direction; microtubules and axonemes glided across the coverslip surface only in the plus end direction (as expected for a minus-end directed motor bound to the coverslip surface); and microtubules crosslinked into bundles in an antiparallel orientation. Velocities of particle and microtubule translocation were in the range of 0.5-1.8 μm/sec. Vanadate at 10 μM inhibited all gliding of the microtubules and axonemes, yet bidirectional particle transport persisted. Vanadate at concentrations of 25 μM and higher inhibited nearly all microtubule-based motility in the preparation and produced parallel bundling of the microtubules. Motility was slowed but not stopped in the presence of 5 mM AMP-PNP.Usually when a particle bound to a microtubule wall, it moved to the microtubule minus end. These particles often remained attached to the minus end. When a microtubule plus end in the shortening phase of dynamic instability reached a stationary particle on the microtubule, sometimes normal minus enddirected motility was activated, or at other times the particle remained attached to the shortening plus end. © 1993 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 10 (1988), S. 380-390 
    ISSN: 0886-1544
    Keywords: stress fiber ; cytoskeleton ; microvilli ; tubulin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We present the first study of the changes in the assembly and organization of actin filaments and microtubules that occur in epithelial cells subjected to the hydrostatic pressures of the deep sea. Interphase BSC-1 epithelial cells were pressurized at physiological temperature and fixed while under pressure. Changes in cell morphology and cytoskeletal organization were followed over a range of pressures from 1 to 610 atm. At atmospheric pressure, cells were flat and well attached. Exposure of cells to pressures of 290 atm or greater caused cell rounding and retraction from the substrate. This response became more pronounced with increased pressure, but the degree of response varied within the cell population in the pressure range of 290-400 atm, Microtubule assembly was not noticeably affected by pressures up to 290 atm, but by 320 atm, few microtubules remained. Most actin stress fibers completely disappeared by 290 atm. High pressure did not simply induce the overall depolymerization of actin filaments for, concurrent with cell rounding, the number of visible microvilli present on the cell surface increased dramatically. These effects of high pressure were reversible. Cells re-established their typical morphology, microtubule arrays appeared normal, and stress fibers reformed after approximately 1 hour at atmospheric pressure. High pressure may disrupt the normal assembly of microtubules and actin filaments by affecting the cellular regulatory mechanisms that control cytological changes during the transition from interphase into mitosis.
    Additional Material: 7 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 10 (1988), S. 185-196 
    ISSN: 0886-1544
    Keywords: mitosis ; kinetochore ; video microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We describe preliminary results from two studies exploring the dynamics of microtubule assembly and organization within chromosomal spindle fibers. In the first study, we microinjected fluorescently labeled tubulin into mitotic PtK1 cells and measured fluorescence redistribution after photobleaching (FRAP) to determine the assembly dynamics of the microtubules within the chromosomal fibers in metaphase cells depleted of nonkinetochore microtubules by cooling to 23-24°C. FRAP measurements showed that the tubulin throughout at least 72% of the microtubules within the chromosomal fibers exchanges with the cellular tubulin pool with a half-time of 77 sec. There was no observable poleward flux of subunits. If the assembly of the kinetochore microtubules is governed by dynamic instability, our results indicate that the half-life of microtubule attachment to the kinetochore is less than several min at 23-24°C.In the second study, we used high-resolution polarization microscopy to observe microtubule dynamics during mitosis in newt lung epithelial cells. We obtained evidence from 150-nm-thick optical sections that microtubules throughout the spindle laterally associate for several sec into “rods” composed of a few microtubules. These transient lateral associations between microtubules appeared to produce the clustering of nonkinetochore and kinetochore microtubules into the chromosomal fibers. Our results indicate that the chromosomal fiber is a dynamic structure, because microtubule assembly is transient, lateral interactions between microtubules are transient, and the attachment of the kinetochores to microtubules may also be transient.
    Additional Material: 5 Ill.
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