Microtubule dynamics in the chromosomal spindle fiber: Analysis by fluorescence and high-resolution polarization microscopy

1988 ◽  
Vol 10 (1-2) ◽  
pp. 185-196 ◽  
Author(s):  
L. Cassimeris ◽  
S. Inoué ◽  
E. D. Salmon
Keyword(s):  
High Resolution ◽  
Microtubule Dynamics ◽  
Polarization Microscopy ◽  
Spindle Fiber ◽  
Fiber Analysis

scholarly journals The impact of chromosomes and centrosomes on spindle assembly as observed in living cells.

1995 ◽  
Vol 129 (5) ◽  
pp. 1287-1300 ◽  
Author(s):  
D Zhang ◽  
R B Nicklas
Keyword(s):  
Spindle Assembly ◽  
Living Cells ◽  
Microtubule Dynamics ◽  
Specific Site ◽  
Polarization Microscopy ◽  
Spindle Microtubule ◽  
Single Chromosome ◽  
Bipolar Spindle ◽  
The Impact

We analyzed the role that chromosomes, kinetochores, and centrosomes play in spindle assembly in living grasshopper spermatocytes by reconstructing spindles lacking certain components. We used video-enhanced, polarization microscopy to distinguish the effect of each component on spindle microtubule dynamics and we discovered that both chromosomes and centrosomes make potent and very different contributions to the organization of the spindle. Remarkably, the position of a single chromosome can markedly affect the distribution of microtubules within a spindle or even alter the fate of spindle assembly. In an experimentally constructed spindle having only one chromosome, moving the chromosome to one of the two poles induces a dramatic assembly of microtubules at the nearer pole and a concomitant disassembly at the farther pole. So long as a spindle carries a single chromosome it will persist normally. A spindle will also persist even when all chromosomes are detached and then removed from the cell. If, however, a single chromosome remains in the cell but is detached from the spindle and kept in the cytoplasm, the spindle disassembles. One might expect the effect of chromosomes on spindle assembly to relate to a property of a specific site on each chromosome, perhaps the kinetochore. We have ruled out that possibility by showing that it is the size of chromosomes rather than the number of kinetochores that matters. Although chromosomes affect spindle assembly, they cannot organize a spindle in the absence of centrosomes. In contrast, centrosomes can organize a functional bipolar spindle in the absence of chromosomes. If both centrosomes and chromosomes are removed from the cell, the spindle quickly disappears.

scholarly journals Pressure-induced depolymerization of spindle microtubules. III. Differential stability in HeLa cells.

1976 ◽  
Vol 69 (2) ◽  
pp. 443-454 ◽  
Author(s):  
E D Salmon ◽  
D Goode ◽  
T K Maugel ◽  
D B Bonar
Keyword(s):  
Hydrostatic Pressure ◽  
Light Microscopy ◽  
Hela Cells ◽  
Atmospheric Pressure ◽  
Differential Effect ◽  
Polarization Microscopy ◽  
Spindle Fiber ◽  
Ultrastructural Studies ◽  
Differential Stability ◽  
Spindle Microtubules

Evidence from light microscopy (principally polarization microscopy) has demonstrated that hydrostatic pressure can reversibly inhibit mitosis by rapidly depolymerizing the spindle fiber microtubules. We have confirmed this finding in ultrastructural studies of mitotic HeLa cells incubated at 37 degrees C and pressurized at 680 atm (10,000 psi). Althouth there are many spindle microtubules in the cells at atmospheric pressure, electron micographs of cells pressurized for 10 min (and fixed while under pressure in a Landau-Thibodeau chamber) show few microtubules. Pressure has a differential effect on the various types of spindle microtubules. Astral and interpolar MTs appear to be completely depolymerized in pressurized cells, but occasional groups of kinetochore fiber microtubules are seen. Surprisingly, the length and density of microtubules of the stem bodies and midbody of telophase cells appear unchanged by pressurization. In cells fixed 10 min after pressure was released, microtubules were again abundant, the density often appearing to be higher than in control cells. Reorganization seems incomplete, however, since many of the microtubules are randomly oriented. Unexpectedly, kinetochores appeared diffuse and were difficult to identify in sections of pressurized cells. Even after 10 min of recovery at atmospheric pressure, their structure was less distinct than in unpressurized cells.

scholarly journals TACC3 is a microtubule plus end–tracking protein that promotes axon elongation and also regulates microtubule plus end dynamics in multiple embryonic cell types

2014 ◽  
Vol 25 (21) ◽  
pp. 3350-3362 ◽  
Author(s):  
Belinda U. Nwagbara ◽  
Anna E. Faris ◽  
Elizabeth A. Bearce ◽  
Burcu Erdogan ◽  
Patrick T. Ebbert ◽  
...  
Keyword(s):  
High Resolution ◽  
Coiled Coil ◽  
Cell Types ◽  
Embryonic Cell ◽  
Microtubule Dynamics ◽  
Imaging Data ◽  
Domain Family ◽  
Axon Elongation ◽  
Microtubule Polymerization

Microtubule plus end dynamics are regulated by a conserved family of proteins called plus end–tracking proteins (+TIPs). It is unclear how various +TIPs interact with each other and with plus ends to control microtubule behavior. The centrosome-associated protein TACC3, a member of the transforming acidic coiled-coil (TACC) domain family, has been implicated in regulating several aspects of microtubule dynamics. However, TACC3 has not been shown to function as a +TIP in vertebrates. Here we show that TACC3 promotes axon outgrowth and regulates microtubule dynamics by increasing microtubule plus end velocities in vivo. We also demonstrate that TACC3 acts as a +TIP in multiple embryonic cell types and that this requires the conserved C-terminal TACC domain. Using high-resolution live-imaging data on tagged +TIPs, we show that TACC3 localizes to the extreme microtubule plus end, where it lies distal to the microtubule polymerization marker EB1 and directly overlaps with the microtubule polymerase XMAP215. TACC3 also plays a role in regulating XMAP215 stability and localizing XMAP215 to microtubule plus ends. Taken together, our results implicate TACC3 as a +TIP that functions with XMAP215 to regulate microtubule plus end dynamics.

scholarly journals Okadaic acid induces interphase to mitotic-like microtubule dynamic instability by inactivating rescue.

1992 ◽  
Vol 119 (5) ◽  
pp. 1271-1276 ◽  
Author(s):  
N R Gliksman ◽  
S F Parsons ◽  
E D Salmon
Keyword(s):  
High Resolution ◽  
Sea Urchin ◽  
Okadaic Acid ◽  
Dynamic Instability ◽  
Major Change ◽  
Microtubule Dynamics ◽  
Regulatory Pathway ◽  
Microtubule Dynamic ◽  
Interphase Cells ◽  
Frequent Switching

We used high-resolution video microscopy to visualize microtubule dynamic instability in extracts of interphase sea urchin eggs and to analyze the changes that occur upon addition of 0.8-2.5 microM okadaic acid, an inhibitor of phosphatase 1 and 2A (PP1, PP2a) (Bialojan, D., and A. Takai. 1988. Biochem. J. 256:283-290). Microtubule plus-ends in these extracts oscillated between the elongation and shortening phases of dynamic instability at frequencies typical for interphase cells. Switching from elongation to shortening (catastrophe) was frequent, but microtubules persisted and grew long because of frequent switching back to elongation (rescue). Addition of okadaic acid to the extract induced rapid (< 5 min) conversion to short, dynamic microtubules typical of mitosis. The frequency of catastrophe doubled and the velocities of elongation and shortening increased slightly; however, the major change was an elimination of rescue. Thus, modulation of the rescue frequency by phosphorylation-dependent mechanisms may be a major regulatory pathway for selectively controlling microtubule dynamics without dramatically changing velocities of microtubule elongation and shortening.

scholarly journals Yeast Kinetochore Microtubule Dynamics Analyzed by High-Resolution Three-Dimensional Microscopy

2005 ◽  
Vol 89 (4) ◽  
pp. 2835-2854 ◽  
Author(s):  
J.F. Dorn ◽  
K. Jaqaman ◽  
D.R. Rines ◽  
G.S. Jelson ◽  
P.K. Sorger ◽  
...  
Keyword(s):  
High Resolution ◽  
Three Dimensional ◽  
Microtubule Dynamics

Observations of the spatial structure of interstellar hydrogen

1967 ◽  
Vol 31 ◽  
pp. 45-46
Author(s):  
Carl Heiles
Keyword(s):  
High Resolution ◽  
Spatial Structure ◽  
Velocity Dispersion ◽  
Temperature Variations

High-resolution 21-cm line observations in a region aroundlII= 120°,b11= +15°, have revealed four types of structure in the interstellar hydrogen: a smooth background, large sheets of density 2 atoms cm-3, clouds occurring mostly in groups, and ‘Cloudlets’ of a few solar masses and a few parsecs in size; the velocity dispersion in the Cloudlets is only 1 km/sec. Strong temperature variations in the gas are in evidence.

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