ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • cytoplasmic extracts  (1)
  • kinetochore  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Microtubule dynamics in the chromosomal spindle fiber: Analysis by fluorescence and high-resolution polarization microscopy (1988)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 10 (1988), S. 185-196 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970100123
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Buffer conditions and non-tubulin factors critically affect the microtubule dynamic instability of sea urchin egg tubulin (1992)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 21 (1992), S. 1-14 
    Details
    ISSN: 0886-1544
    Keywords: Pipes ; Hepes ; calcium ; VE-DIC microscopy ; cytoplasmic extracts ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The dynamic instability of individual microtubules (Mts) in cytoplasmic extracts or assembled from highly purified sea urchin egg tubulin was examined using video-enhanced, differential-interference contrast (VE-DIC) light microscopy. Extract Mts (endogenous tubulin = 12.1 μM) displayed only plus-ended growth. The elongation velocity was 7.8 μm/min for an average duration of 1.3 min before switching (catastrophe) to rapid shortening, which occurred at 13.0 μm/ min for an average duration of 0.5 min before switching (rescue) back to the elongation phase. These parameters are typical of interphase Mt dynamic instability. Surprisingly, Mts assembled from purified urchin egg tubulin in standard buffers were less dynamic that those reported for purified brain tubulin or Mts in the extract. Buffer parameters were changed in an attempt to mimic the extract Mt results. The pH buffer itself, Hepes or Pipes, drastically altered Mt dynamics but could not achieve high elongation velocity with high catastrophe frequencies. Calcium at 1 μM had negligible effects, while increasing pH from 6.9 to 7.2 stimulated elongation velocity. Finally, Mt dynamics of purified egg tubulin (11.9 μM) were assayed in ultrafiltiates (MW cut-off 〈30 kD) of the cytoplasmic extracts. Mts elongated slowly at 1.2 μm/min for 26 min before a catastrophe and rapid shortening at 11.8 μm/min. Rescue was less frequent than unfiltered extracts, minus-ended growth was observed, and self-assembly occurred at slightly higher tubulin concentrations. Therefore, the egg extracts and cytoplasm must contain non-buffer factors which stimulate elongation velocity by 6.5-fold without self-assembly, increase catastrophe frequency by 20-fold, and block minus-ended growth.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970210102
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...