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
  • 1
    facet.materialart.
    Unknown
    Functional overlap of microtubule assembly factors in chromatin-promoted spindle assembly (2009)
    American Society for Cell Biology
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Society for Cell Biology, 2009. This article is posted here by permission of American Society for Cell Biology for personal use, not for redistribution. The definitive version was published in Molecular Biology of the Cell 20 (2009): 2766-2773, doi:10.1091/mbc.E09-01-0043.
    Description: Distinct pathways from centrosomes and chromatin are thought to contribute in parallel to microtubule nucleation and stabilization during animal cell mitotic spindle assembly, but their full mechanisms are not known. We investigated the function of three proposed nucleation/stabilization factors, TPX2, {gamma}-tubulin and XMAP215, in chromatin-promoted assembly of anastral spindles in Xenopus laevis egg extract. In addition to conventional depletion-add back experiments, we tested whether factors could substitute for each other, indicative of functional redundancy. All three factors were required for microtubule polymerization and bipolar spindle assembly around chromatin beads. Depletion of TPX2 was partially rescued by the addition of excess XMAP215 or EB1, or inhibiting MCAK (a Kinesin-13). Depletion of either {gamma}-tubulin or XMAP215 was partially rescued by adding back XMAP215, but not by adding any of the other factors. These data reveal functional redundancy between specific assembly factors in the chromatin pathway, suggesting individual proteins or pathways commonly viewed to be essential may not have entirely unique functions.
    Description: This work was supported by the American Cancer Society (grant PF0711401 to T. J. Maresca), the National Cancer Institute (grant CA078048-09 to T. J. Mitchison) and the National Institutes of Health (grant F32GM080049 to J. C. Gatlin and grant GM24364 to E. D. Salmon).
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: video/avi
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 2
    facet.materialart.
    Unknown
    Spindle assembly in the absence of a RanGTP gradient requires localized CPC activity (2009)
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Current Biology 19 (2009): 1210-1215, doi:10.1016/j.cub.2009.05.061.
    Description: During animal cell division, a gradient of GTP-bound Ran is generated around mitotic chromatin. It is generally accepted that this RanGTP gradient is essential for organizing the spindle since it locally activates critical spindle assembly factors. Here, we show in Xenopus egg extract, where the gradient is best characterized, that spindles can assemble in the absence of a RanGTP gradient. Gradient-free spindle assembly occurred around sperm nuclei but not around chromatin-coated beads and required the chromosomal passenger complex (CPC). Artificial enrichment of CPC activity within hybrid bead arrays containing both immobilized chromatin and the CPC supported local microtubule assembly even in the absence of a RanGTP gradient. We conclude that RanGTP and the CPC constitute the two major molecular signals that spatially promote microtubule polymerization around chromatin. Furthermore, we hypothesize that the two signals mainly originate from discreet physical sites on the chromosomes to localize microtubule assembly around chromatin: a RanGTP signal from any chromatin, and a CPC-dependent signal predominantly generated from centromeric chromatin.
    Description: This work was supported by the American Cancer Society (grant PF0711401 to T.J. Maresca), the National Cancer Institute (grant CA078048-09 to T.J. Mitchison) and the National Institutes of Health (grant F32GM080049 to J.C. Gatlin and grant GM24364 to E.D. Salmon).
    Repository Name: Woods Hole Open Access Server
    Type: Preprint
    Format: video/quicktime
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 3
    facet.materialart.
    Unknown
    Roles of polymerization dynamics, opposed motors, and a tensile element in governing the length of Xenopus extract meiotic spindles (2007)
    American Society for Cell Biology
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Society for Cell Biology, 2005. This article is posted here by permission of American Society for Cell Biology for personal use, not for redistribution. The definitive version was published in Molecular Biology of the Cell 16 (2005): 3064-3076, doi:10.1091/mbc.E05-02-0174.
    Description: Metaphase spindles assemble to a steady state in length by mechanisms that involve microtubule dynamics and motor proteins, but they are incompletely understood. We found that Xenopus extract spindles recapitulate the length of egg meiosis II spindles, by using mechanisms intrinsic to the spindle. To probe these mechanisms, we perturbed microtubule polymerization dynamics and opposed motor proteins and measured effects on spindle morphology and dynamics. Microtubules were stabilized by hexylene glycol and inhibition of the catastrophe factor mitotic centromere-associated kinesin (MCAK) (a kinesin 13, previously called XKCM) and destabilized by depolymerizing drugs. The opposed motors Eg5 and dynein were inhibited separately and together. Our results are consistent with important roles for polymerization dynamics in regulating spindle length, and for opposed motors in regulating the relative stability of bipolar versus monopolar organization. The response to microtubule destabilization suggests that an unidentified tensile element acts in parallel with these conventional factors, generating spindle shortening force.
    Description: This work was funded by National Institutes of Health Grants GM-39565 (to T.J.M.), GM-24364 and GM-606780 (to E.D.S.), and GM-65933 (to T.M.K.), and by Marine Biological Laboratory fellowships from Universal Imaging and Nikon.
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
    Format: text/html
    Format: video/quicktime
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 4
    facet.materialart.
    Unknown
    Microtubule plus-end dynamics in Xenopus egg extract spindles (2007)
    American Society for Cell Biology
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Society for Cell Biology, 2004. This article is posted here by permission of American Society for Cell Biology for personal use, not for redistribution. The definitive version was published in Molecular Biology of the Cell 15 (2004): 1776-1784, doi:10.1091/mbc.E03-11-0824.
    Description: Microtubule dynamics underlie spindle assembly, yet we do not know how the spindle environment affects these dynamics. We developed methods for measuring two key parameters of microtubule plus-end dynamic instability in Xenopus egg extract spindles. To measure plus-end polymerization rates and localize growing plus ends, we used fluorescence confocal imaging of EB1. This revealed plus-end polymerization throughout the spindle at ~11 µm/min, similar to astral microtubules, suggesting polymerization velocity is not regionally regulated by the spindle. The ratio of EB1 to microtubule fluorescence revealed an enrichment of polymerizing ends near the spindle middle, indicating enhanced nucleation or rescue there. We measured depolymerization rates by creating a front of synchronized depolymerization in spindles severed with microneedles. This front could be tracked by polarization and fluorescence microscopy as it advanced from each cut edge toward the associated pole. Both imaging modalities revealed rapid depolymerization (~30 µm/min) superimposed on a subset of microtubules stable to depolymerization. Larger spindle fragments contained a higher percentage of stable microtubules, which we believe were oriented with their minus ends facing the cut. Depolymerization was blocked by the potent microtubule stabilizing agent hexylene glycol, but was unaffected by {alpha}-MCAK antibody and AMPPNP, which block catastrophe and kinesin motility, respectively. These measurements move us closer to understanding the complete life history of a spindle microtubule.
    Description: This work was supported by a Universal Imaging Corporation Fellowship to the Cell Division Group at the Marine Biological Laboratories, Woods Hole, MA; and by National Institutes of Health Grants DK02578 and DK58766 (to J.S.T.), GM- 24364 and GM-60678 (to E.D.S.), and GM-39565 (to T.J.M.).
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
    Format: video/quicktime
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 5
    facet.materialart.
    Unknown
    Directly probing the mechanical properties of the spindle and its matrix (2010)
    Rockefeller University Press
    Details
    Publication Date: 2022-05-25
    Description: © The Authors, 2010. This article is distributed under the terms of the Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported License. The definitive version was published in Journal of Cell Biology 188 (2010): 481-489, doi:10.1083/jcb.200907110.
    Description: Several recent models for spindle length regulation propose an elastic pole to pole spindle matrix that is sufficiently strong to bear or antagonize forces generated by microtubules and microtubule motors. We tested this hypothesis using microneedles to skewer metaphase spindles in Xenopus laevis egg extracts. Microneedle tips inserted into a spindle just outside the metaphase plate resulted in spindle movement along the interpolar axis at a velocity slightly slower than microtubule poleward flux, bringing the nearest pole toward the needle. Spindle velocity decreased near the pole, which often split apart slowly, eventually letting the spindle move completely off the needle. When two needles were inserted on either side of the metaphase plate and rapidly moved apart, there was minimal spindle deformation until they reached the poles. In contrast, needle separation in the equatorial direction rapidly increased spindle width as constant length spindle fibers pulled the poles together. These observations indicate that an isotropic spindle matrix does not make a significant mechanical contribution to metaphase spindle length determination.
    Description: This work was supported by National Institute of General Medicine grants to J.C. Gatlin (F32GM080049) and E.D. Salmon (GM24364). T.J. Mitchison was funded by a grant from the National Cancer Institute (CA078048-09).
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: video/quicktime
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 6
    facet.materialart.
    Unknown
    Bipolarization and poleward flux correlate during xenopus extract spindle assembly (2007)
    American Society for Cell Biology
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Society for Cell Biology, 2004. This article is posted here by permission of American Society for Cell Biology for personal use, not for redistribution. The definitive version was published in Molecular Biology of the Cell 15 (2004): 5603-5615, doi:10.1091/mbc.E04-05-0440.
    Description: We investigated the mechanism by which meiotic spindles become bipolar and the correlation between bipolarity and poleward flux, using Xenopus egg extracts. By speckle microscopy and computational alignment, we find that monopolar sperm asters do not show evidence for flux, partially contradicting previous work. We account for the discrepancy by describing spontaneous bipolarization of sperm asters that was missed previously. During spontaneous bipolarization, onset of flux correlated with onset of bipolarity, implying that antiparallel microtubule organization may be required for flux. Using a probe for TPX2 in addition to tubulin, we describe two pathways that lead to spontaneous bipolarization, new pole assembly near chromatin, and pole splitting. By inhibiting the Ran pathway with excess importin-alpha, we establish a role for chromatin-derived, antiparallel overlap bundles in generating the sliding force for flux, and we examine these bundles by electron microscopy. Our results highlight the importance of two processes, chromatin-initiated microtubule nucleation, and sliding forces generated between antiparallel microtubules, in self-organization of spindle bipolarity and poleward flux.
    Description: This work was funded by National Institutes of Health grants GM39565 (T.J.M.), GM24364 and GM606780 (E.D.S.), and by MBL fellowships from UIC Inc. and Nikon Inc.
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
    Format: video/quicktime
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 7
    facet.materialart.
    Unknown
    Intrakinetochore stretch is associated with changes in kinetochore phosphorylation and spindle assembly checkpoint activity (2009)
    Rockefeller University Press
    Details
    Publication Date: 2022-05-25
    Description: © 2009 Maresca and Salmon. This is an open-access article distributed under the terms of the Creative Commons Attribution 3.0 License. The definitive version was published in Journal of Cell Biology 184 (2009): 373-381, doi:10.1083/jcb.200808130.
    Description: Cells have evolved a signaling pathway called the spindle assembly checkpoint (SAC) to increase the fidelity of chromosome segregation by generating a "wait anaphase" signal until all chromosomes are properly aligned within the mitotic spindle. It has been proposed that tension generated by the stretch of the centromeric chromatin of bioriented chromosomes stabilizes kinetochore microtubule attachments and turns off SAC activity. Although biorientation clearly causes stretching of the centromeric chromatin, it is unclear whether the kinetochore is also stretched. To test whether intrakinetochore stretch occurs and is involved in SAC regulation, we developed a Drosophila melanogaster S2 cell line expressing centromere identifier–mCherry and Ndc80–green fluorescent protein to mark the inner and outer kinetochore domains, respectively. We observed stretching within kinetochores of bioriented chromosomes by monitoring both inter- and intrakinetochore distances in live cell assays. This intrakinetochore stretch is largely independent of a 30-fold variation in centromere stretch. Furthermore, loss of intrakinetochore stretch is associated with enhancement of 3F3/2 phosphorylation and SAC activation.
    Description: This work was supported by the American Cancer Society (grant PF0711401 to T.J. Maresca) and the National Institutes of Health (grant GM24364 to E.D. Salmon).
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: video/quicktime
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 8
    facet.materialart.
    Unknown
    Chromosomes can congress to the metaphase plate before biorientation (2006)
    Details
    Publication Date: 2022-05-26
    Description: Author Posting. © The Authors, 2005. This is the author's version of the work. It is posted here by permission of American Association for the Advancement of Science for personal use, not for redistribution. The definitive version was published in Science 311 (2006): 388-391, doi:10.1126/science.1122142.
    Description: The stable propagation of genetic material during cell division depends on the congression of chromosomes to the spindle equator before the cell initiates anaphase. It is generally assumed that congression requires that chromosomes are connected to the opposite poles of the bipolar spindle (i.e., “bi-oriented”). We found that chromosomes can congress before becoming bioriented. By combining the use of reversible chemical inhibitors, live-cell light microscopy and correlative electron microscopy, we found that mono-oriented chromosomes could glide towards the spindle equator alongside kinetochore fibers attached to other already bi-oriented chromosomes. This congression mechanism depended on the kinetochore-associated plus enddirected microtubule motor CENP-E (kinesin-7).
    Description: Supported by grants from the NIH (GM59363 to A.K., GM65933 to T.M.K., GM24364 to E.D.S, and GM06627 to B.F.M)
    Repository Name: Woods Hole Open Access Server
    Type: Preprint
    Format: 299446 bytes
    Format: 9756354 bytes
    Format: 9759362 bytes
    Format: 8833124 bytes
    Format: 4945863 bytes
    Format: video/quicktime
    Format: video/quicktime
    Format: video/quicktime
    Format: application/pdf
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 9
    Electronic Resource
    Electronic Resource
    The Drosophila claret segregation protein is a minus-end directed motor molecule (1990)
    [s.l.] : Nature Publishing Group
    Nature 347 (1990), S. 780-782 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Mutants in the claret (ca) locus in Drosophila show frequent chromosome nondisjunction and loss. Molecular analysis of the locus demonstrates that claret eye colour is caused by mutations in a gene that is closely linked, but separate from the segregation gene4. Mutations that cause both claret eye ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/347780a0
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Meeting report (1980)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 1 (1980), S. 159-162 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970010112
    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...