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Journal articles on the topic 'Aster de microtubules'

Author: Grafiati
Published: 25 May 2024

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1

Bringmann, Henrik. "Mechanical and genetic separation of aster- and midzone-positioned cytokinesis." Biochemical Society Transactions 36, no. 3 (2008): 381–83. http://dx.doi.org/10.1042/bst0360381.

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The mitotic spindle positions the cytokinesis furrow. The cytokinesis furrow then forms and ingresses at the site of the mitotic spindle, between the spindle poles. Two populations of spindle microtubules are implicated in cytokinesis furrow positioning: radial microtubule arrays called asters and bundled non-kinetochore microtubules called the spindle midzone. Here I will discuss our recent results that provided examples of how aster-positioned and midzone-positioned cytokinesis can be mechanically and genetically separated. These experiments illustrate how asters and midzone contribute to cy
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2

Sider, J. R., C. A. Mandato, K. L. Weber, et al. "Direct observation of microtubule-f-actin interaction in cell free lysates." Journal of Cell Science 112, no. 12 (1999): 1947–56. http://dx.doi.org/10.1242/jcs.112.12.1947.

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Coordinated interplay of the microtubule and actin cytoskeletons has long been known to be crucial for many cellular processes including cell migration and cytokinesis. However, interactions between these two systems have been difficult to document by conventional approaches, for a variety of technical reasons. Here the distribution of f-actin and microtubules were analyzed in the absence of fixation using Xenopus egg extracts as an in vitro source of microtubules and f-actin, demembranated Xenopus sperm to nucleate microtubule asters, fluorescent phalloidin as a probe for f-actin, and fluores
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3

Tse, Yu Chung, Alisa Piekny, and Michael Glotzer. "Anillin promotes astral microtubule-directed cortical myosin polarization." Molecular Biology of the Cell 22, no. 17 (2011): 3165–75. http://dx.doi.org/10.1091/mbc.e11-05-0399.

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Assembly of a cytokinetic contractile ring is a form of cell polarization in which the equatorial cell cortex becomes differentiated from the polar regions. Microtubules direct cytokinetic polarization via the central spindle and astral microtubules. The mechanism of central spindle–directed furrow formation is reasonably well understood, but the aster-directed pathway is not. In aster-directed furrowing, cytoskeletal factors accumulate to high levels at sites distal to the asters and at reduced levels at cortical sites near the asters. In this paper, we demonstrate that the cytoskeletal organ
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4

Schroeder, T. E., and D. E. Battaglia. ""Spiral asters" and cytoplasmic rotation in sea urchin eggs: induction in Strongylocentrotus purpuratus eggs by elevated temperature." Journal of Cell Biology 100, no. 4 (1985): 1056–62. http://dx.doi.org/10.1083/jcb.100.4.1056.

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"Spiral asters" composed of swirls of subcortical microtubules were recently described in fertilized eggs of the sea urchin Strongylocentrotus purpuratus. In our study, these structures did not occur at culture temperatures below 16 degrees C. When the culture temperature was elevated, however, "spiral asters" routinely appeared during a susceptible period before mitotic prophase when the sperm aster-diaster normally exists. A massive and protracted rotation of the cytoplasm (excluding an immobile cortex and perinuclear region) began within 1 min of exposure to elevated temperature. Fibrils of
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5

Kotani, Tomoya, та Masakane Yamashita. "Overexpression of truncated γ-tubulins disrupts mitotic aster formation in Xenopus oocyte extracts". Biochemical Journal 389, № 3 (2005): 611–17. http://dx.doi.org/10.1042/bj20050243.

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Mechanisms of spindle pole formation rely on minus-end-directed motor proteins. γ-Tubulin is present at the centre of poles, but its function during pole formation is completely unknown. To address the role of γ-tubulin in spindle pole formation, we overexpressed GFP (green fluorescent protein)-fused γ-tubulin (γ-Tu-GFP) in Xenopus oocytes and produced self-assembled mitotic asters in the oocyte extracts. γ-Tu-GFP associated with endogenous α-, β- and γ-tubulin, suggesting that it acts in the same manner as that of endogenous γ-tubulin. During the process of aster formation, γ-Tu-GFP aggregate
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6

Nguyen, P. A., C. M. Field, and T. J. Mitchison. "Prc1E and Kif4A control microtubule organization within and between large Xenopus egg asters." Molecular Biology of the Cell 29, no. 3 (2018): 304–16. http://dx.doi.org/10.1091/mbc.e17-09-0540.

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Prc1E and Kif4A prune out anti-parallel microtubules in the huge asters that position cleavage furrows in Xenopus eggs. Within asters, this promotes radial order in the face of the randomizing effect of nucleation away from centrosomes. At boundaries between asters, it blocks growth of a microtubule from one aster into its neighbor.
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7

Schroeder, M. M., and D. L. Gard. "Organization and regulation of cortical microtubules during the first cell cycle of Xenopus eggs." Development 114, no. 3 (1992): 699–709. http://dx.doi.org/10.1242/dev.114.3.699.

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Anti-tubulin antibodies and confocal immunofluorescence microscopy were used to examine the organization and regulation of cytoplasmic and cortical microtubules during the first cell cycle of fertilized Xenopus eggs. Appearance of microtubules in the egg cortex temporally coincided with the outgrowth of the sperm aster. Microtubules of the sperm aster first reached the animal cortex at 0.25, (times normalized to first cleavage), forming a radially organized array of cortical microtubules. A disordered network of microtubules was apparent in the vegetal cortex as early as 0.35. Cortical microtu
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8

Dogterom, M., M. A. Félix, C. C. Guet, and S. Leibler. "Influence of M-phase chromatin on the anisotropy of microtubule asters." Journal of Cell Biology 133, no. 1 (1996): 125–40. http://dx.doi.org/10.1083/jcb.133.1.125.

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In many eukaryotic cells going through M-phase, a bipolar spindle is formed by microtubules nucleated from centrosomes. These microtubules, in addition to being "captured" by kinetochores, may be stabilized by chromatin in two different ways: short-range stabilization effects may affect microtubules in close contact with the chromatin, while long-range stabilization effects may "guide" microtubule growth towards the chromatin (e.g., by introducing a diffusive gradient of an enzymatic activity that affects microtubule assembly). Here, we use both meiotic and mitotic extracts from Xenopus laevis
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9

Steffen, W., H. Fuge, R. Dietz, M. Bastmeyer, and G. Müller. "Aster-free spindle poles in insect spermatocytes: evidence for chromosome-induced spindle formation?" Journal of Cell Biology 102, no. 5 (1986): 1679–87. http://dx.doi.org/10.1083/jcb.102.5.1679.

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Tipulid spermatocytes form normally functioning bipolar spindles after one of the centrosomes is experimentally dislocated from the nucleus in late diakinesis (Dietz, R., 1959, Z. Naturforsch., 14b:749-752; Dietz, R., 1963, Zool. Anz. Suppl., 23:131-138; Dietz, R., 1966, Heredity, 19:161-166). The possibility that dissociated pericentriolar material (PCM) is nevertheless responsible for the formation of the spindle in these cells cannot be ruled out based on live observation. In studying serial sections of complete cells and of lysed cells, it was found that centrosome-free spindle poles in th
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10

Verde, F., J. M. Berrez, C. Antony, and E. Karsenti. "Taxol-induced microtubule asters in mitotic extracts of Xenopus eggs: requirement for phosphorylated factors and cytoplasmic dynein." Journal of Cell Biology 112, no. 6 (1991): 1177–87. http://dx.doi.org/10.1083/jcb.112.6.1177.

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Taxol, a microtubule stabilizing drug, induces the formation of numerous microtubule asters in the cytoplasm of mitotic cells (De Brabander, M., G. Geuens, R. Nuydens, R. Willebrords, J. DeMey. 1981. Proc. Natl. Acad. Sci. USA. 78:5608-5612). The center of these asters share with spindle poles some characteristics such as the presence of centrosomal material and calmodulin. We have recently reproduced the assembly of taxol asters in a cell-free system (Buendia, B., C. Antony, F. Verde, M. Bornens, and E. Karsenti. 1990. J. Cell Sci. 97:259-271) using extracts of Xenopus eggs. In this paper, we
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11

Zhang, C., M. Hughes, and P. R. Clarke. "Ran-GTP stabilises microtubule asters and inhibits nuclear assembly in Xenopus egg extracts." Journal of Cell Science 112, no. 14 (1999): 2453–61. http://dx.doi.org/10.1242/jcs.112.14.2453.

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Ran is an abundant GTPase of the Ras superfamily that is highly conserved in eukaryotes. In interphase cells, Ran is mainly nuclear and thought to be predominantly GTP-bound, but it is also present in the cytoplasm, probably GDP-bound. This asymmetric distribution plays an important role in directing nucleocytoplasmic transport. Ran has also been implicated in cell cycle control, including the transition from mitosis to interphase when the compartmentalisation of the nucleus is established. Here, we have examined the role of Ran in this transition using a cell-free system of Xenopus egg extrac
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12

Félix, MA, C. Antony, M. Wright, and B. Maro. "Centrosome assembly in vitro: role of gamma-tubulin recruitment in Xenopus sperm aster formation." Journal of Cell Biology 124, no. 1 (1994): 19–31. http://dx.doi.org/10.1083/jcb.124.1.19.

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Centrioles organize microtubules in two ways: either microtubules elongate from the centriole cylinder itself, forming a flagellum or a cilium ("template elongation"), or pericentriolar material assembles and nucleates a microtubule aster ("astral nucleation"). During spermatogenesis in most species, a motile flagellum elongates from one of the sperm centrioles, whereas after fertilization a large aster of microtubules forms around the sperm centrioles in the egg cytoplasm. Using Xenopus egg extracts we have developed an in vitro system to study this change in microtubule-organizing activity.
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13

Luetjens, Craig Marc, and Adriaan W. C. Dorresteijn. "Dynamic changes of the microtubule system corresponding to the unequal and spiral cleavage modes in the embryo of the zebra mussel, Dreissena polymorpha (Mollusca, Bivalvia)." Zygote 6, no. 3 (1998): 239–48. http://dx.doi.org/10.1017/s0967199498000185.

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Unequal cleavage requires a highly organised cytoskeleton. We investigated the localisation of both tubulins and microtubular arrays in Dreissena eggs during and after fertilisation using confocal laser scanning microscopy. Freshly spawned eggs are arrested in metaphase I. A maternal pool of γ-tubulin is found mainly in the centre of the asters of the meiotic spindle. The paternal pool of γ-tubulin, present in the fertilising sperm, could not be traced within the egg, but a microtubule-organising centre forms near the male pronucleus at anaphase II. Male and female pronuclei grow as they migra
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14

Mountain, Vicki, Calvin Simerly, Louisa Howard, Asako Ando, Gerald Schatten, and Duane A. Compton. "The Kinesin-Related Protein, Hset, Opposes the Activity of Eg5 and Cross-Links Microtubules in the Mammalian Mitotic Spindle." Journal of Cell Biology 147, no. 2 (1999): 351–66. http://dx.doi.org/10.1083/jcb.147.2.351.

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We have prepared antibodies specific for HSET, the human homologue of the KAR3 family of minus end-directed motors. Immuno-EM with these antibodies indicates that HSET frequently localizes between microtubules within the mammalian metaphase spindle consistent with a microtubule cross-linking function. Microinjection experiments show that HSET activity is essential for meiotic spindle organization in murine oocytes and taxol-induced aster assembly in cultured cells. However, inhibition of HSET did not affect mitotic spindle architecture or function in cultured cells, indicating that centrosomes
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15

Gaglio, T., A. Saredi, and D. A. Compton. "NuMA is required for the organization of microtubules into aster-like mitotic arrays." Journal of Cell Biology 131, no. 3 (1995): 693–708. http://dx.doi.org/10.1083/jcb.131.3.693.

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NuMA (Nuclear protein that associates with the Mitotic Apparatus) is a 235-kD intranuclear protein that accumulates at the pericentrosomal region of the mitotic spindle in vertebrate cells. To determine if NuMA plays an active role in organizing the microtubules at the polar region of the mitotic spindle, we have developed a cell free system for the assembly of mitotic asters derived from synchronized cultured cells. Mitotic asters assembled in this extract are composed of microtubules arranged in a radial array that contain NuMA concentrated at the central core. The organization of microtubul
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16

Houliston, E., and R. P. Elinson. "Patterns of microtubule polymerization relating to cortical rotation in Xenopus laevis eggs." Development 112, no. 1 (1991): 107–17. http://dx.doi.org/10.1242/dev.112.1.107.

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Following fertilization, the Xenopus egg cortex rotates relative to the cytoplasm by 30 degrees about a horizontal axis. The direction of rotation, and as a result the orientation of the embryonic body axes, is normally specified by the position of sperm entry. The mechanism of rotation appears to involve an array of aligned microtubules in the vegetal cortex (Elinson and Rowning, 1988, Devl Biol. 128, 185–197). We performed anti-tubulin immunofluorescence on sections to follow the formation of this array. Microtubules disappear rapidly from the egg following fertilization, and reappear first
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17

Ault, J. G., A. J. DeMarco, E. D. Salmon, and C. L. Rieder. "Studies on the ejection properties of asters: astral microtubule turnover influences the oscillatory behavior and positioning of mono-oriented chromosomes." Journal of Cell Science 99, no. 4 (1991): 701–10. http://dx.doi.org/10.1242/jcs.99.4.701.

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The position of a mono-oriented chromosome changes as it oscillates to and from the pole to which it is attached. Such oscillatory behavior reveals that the net force on a mono-oriented chromosome is constantly changing. Fluctuations may occur in both the polewardly directed force acting at the kinetochore and the opposing outwardly directed force associated with the aster. We have examined the ejection properties of the aster—as well as the oscillatory behavior and positioning of mono-oriented chromosomes—in relation to astral microtubule turnover. We treated cells containing monopolar spindl
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18

Waterman-Storer, Clare, Devin Y. Duey, Kari L. Weber, et al. "Microtubules Remodel Actomyosin Networks in Xenopus Egg Extracts via Two Mechanisms of F-Actin Transport." Journal of Cell Biology 150, no. 2 (2000): 361–76. http://dx.doi.org/10.1083/jcb.150.2.361.

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Interactions between microtubules and filamentous actin (F-actin) are crucial for many cellular processes, including cell locomotion and cytokinesis, but are poorly understood. To define the basic principles governing microtubule/F-actin interactions, we used dual-wavelength digital fluorescence and fluorescent speckle microscopy to analyze microtubules and F-actin labeled with spectrally distinct fluorophores in interphase Xenopus egg extracts. In the absence of microtubules, networks of F-actin bundles zippered together or exhibited serpentine gliding along the coverslip. When microtubules w
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19

Maiato, Helder, Paula Sampaio, Catarina L. Lemos, et al. "MAST/Orbit has a role in microtubule–kinetochore attachment and is essential for chromosome alignment and maintenance of spindle bipolarity." Journal of Cell Biology 157, no. 5 (2002): 749–60. http://dx.doi.org/10.1083/jcb.200201101.

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Multiple asters (MAST)/Orbit is a member of a new family of nonmotor microtubule-associated proteins that has been previously shown to be required for the organization of the mitotic spindle. Here we provide evidence that MAST/Orbit is required for functional kinetochore attachment, chromosome congression, and the maintenance of spindle bipolarity. In vivo analysis of Drosophila mast mutant embryos undergoing early mitotic divisions revealed that chromosomes are unable to reach a stable metaphase alignment and that bipolar spindles collapse as centrosomes move progressively closer toward the c
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20

Euteneuer, U., and M. Schliwa. "Evidence for an involvement of actin in the positioning and motility of centrosomes." Journal of Cell Biology 101, no. 1 (1985): 96–103. http://dx.doi.org/10.1083/jcb.101.1.96.

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Cultured human polymorphonuclear leukocytes exposed to the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) spread on the substratum and undergo centrosome splitting. The two centrioles may separate by a distance of several micrometers, each being surrounded by an aster of microtubules. Here we show that the centriole/aster complexes are in constant, rapid motion through the cytoplasm, carrying with them some of the cytoplasmic granules while pushing aside others, or deforming and displacing the nucleus. An analysis of this unique motility phenomenon was undertaken. We show that intac
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21

Sallé, Jérémy, Jing Xie, Dmitry Ershov, Milan Lacassin, Serge Dmitrieff, and Nicolas Minc. "Asymmetric division through a reduction of microtubule centering forces." Journal of Cell Biology 218, no. 3 (2018): 771–82. http://dx.doi.org/10.1083/jcb.201807102.

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Asymmetric divisions are essential for the generation of cell fate and size diversity. They implicate cortical domains where minus end–directed motors, such as dynein, are activated to pull on microtubules to decenter asters attached to centrosomes, nuclei, or spindles. In asymmetrically dividing cells, aster decentration typically follows a centering phase, suggesting a time-dependent regulation in the competition between microtubule centering and decentering forces. Using symmetrically dividing sea urchin zygotes, we generated cortical domains of magnetic particles that spontaneously cluster
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22

Meaders, Johnathan L., and David R. Burgess. "Microtubule-Based Mechanisms of Pronuclear Positioning." Cells 9, no. 2 (2020): 505. http://dx.doi.org/10.3390/cells9020505.

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The zygote is defined as a diploid cell resulting from the fusion of two haploid gametes. Union of haploid male and female pronuclei in many animals occurs through rearrangements of the microtubule cytoskeleton into a radial array of microtubules known as the sperm aster. The sperm aster nucleates from paternally-derived centrioles attached to the male pronucleus after fertilization. Nematode, echinoderm, and amphibian eggs have proven as invaluable models to investigate the biophysical principles for how the sperm aster unites male and female pronuclei with precise spatial and temporal regula
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23

Cao, Tracy T., Wakam Chang, Sarah E. Masters, and Mark S. Mooseker. "Myosin-Va Binds to and Mechanochemically Couples Microtubules to Actin Filaments." Molecular Biology of the Cell 15, no. 1 (2004): 151–61. http://dx.doi.org/10.1091/mbc.e03-07-0504.

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Myosin-Va was identified as a microtubule binding protein by cosedimentation analysis in the presence of microtubules. Native myosin-Va purified from chick brain, as well as the expressed globular tail domain of this myosin, but not head domain bound to microtubule-associated protein-free microtubules. Binding of myosin-Va to microtubules was saturable and of moderately high affinity (∼1:24 Myosin-Va:tubulin; Kd = 70 nM). Myosin-Va may bind to microtubules via its tail domain because microtubule-bound myosin-Va retained the ability to bind actin filaments resulting in the formation of cross-li
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24

Harris, P. J., and B. P. Rubin. "Transition from mitosis to interphase in sea urchin first division: immunofluorescence studies of tubulin distribution in methacrylate sections." Journal of Histochemistry & Cytochemistry 35, no. 3 (1987): 343–49. http://dx.doi.org/10.1177/35.3.3546483.

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Previous immunofluorescence studies of microtubule distribution in fertilized sea urchin eggs have suffered from poor resolution caused by cell thickness, unavoidable artifacts resulting from excessive flattening, or extraction by detergents of membranes and other lipid-containing structures that may be of interest in relation to the microtubules. To avoid these difficulties, we have developed a fixation and embedding protocol based on buffered paraformaldehyde fixation and butyl-methyl methacrylate embedment, which allows immunofluorescence staining of 0.5-1 micron sections. Polymerization ar
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25

Mangal, Sriyash, Jennifer Sacher, Taekyung Kim, et al. "TPXL-1 activates Aurora A to clear contractile ring components from the polar cortex during cytokinesis." Journal of Cell Biology 217, no. 3 (2018): 837–48. http://dx.doi.org/10.1083/jcb.201706021.

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During cytokinesis, a signal from the central spindle that forms between the separating anaphase chromosomes promotes the accumulation of contractile ring components at the cell equator, while a signal from the centrosomal microtubule asters inhibits accumulation of contractile ring components at the cell poles. However, the molecular identity of the inhibitory signal has remained unknown. To identify molecular components of the aster-based inhibitory signal, we developed a means to monitor the removal of contractile ring proteins from the polar cortex after anaphase onset. Using this assay, w
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26

Palazzo, R. E., E. A. Vaisberg, D. G. Weiss, S. A. Kuznetsov, and W. Steffen. "Dynein is required for spindle assembly in cytoplasmic extracts of Spisula solidissima oocytes." Journal of Cell Science 112, no. 9 (1999): 1291–302. http://dx.doi.org/10.1242/jcs.112.9.1291.

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Meiosis I spindle assembly is induced in lysate-extract mixtures prepared from clam (Spisula solidissima) oocytes. Unactivated lysate prepared from unactivated oocytes contain nuclei (germinal vesicles, GVs) which house condensed chromosomes. Treatment of unactivated lysate with clarified activated extract prepared from oocytes induced to complete meiosis by treatment with KCl induces GV breakdown (GVBD) and assembly of monopolar, bipolar, and multipolar aster-chromosome complexes. The process of in vitro meiosis I spindle assembly involves the assembly of microtubule asters and the associatio
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27

Horne, Melinda M., and Thomas M. Guadagno. "A requirement for MAP kinase in the assembly and maintenance of the mitotic spindle." Journal of Cell Biology 161, no. 6 (2003): 1021–28. http://dx.doi.org/10.1083/jcb.200304144.

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Circumstantial evidence has suggested the possibility of microtubule-associated protein (MAP) kinase's involvement in spindle regulation. To test this directly, we asked whether MAP kinase was required for spindle assembly in Xenopus egg extracts. Either the inhibition or the depletion of endogenous p42 MAP kinase resulted in defective spindle structures resembling asters or half-spindles. Likewise, an increase in the length and polymerization of microtubules was measured in aster assays suggesting a role for MAP kinase in regulating microtubule dynamics. Consistent with this, treatment of ext
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28

Chakravarty, Arijit, Louisa Howard, and Duane A. Compton. "A Mechanistic Model for the Organization of Microtubule Asters by Motor and Non-Motor Proteins in a Mammalian Mitotic Extract." Molecular Biology of the Cell 15, no. 5 (2004): 2116–32. http://dx.doi.org/10.1091/mbc.e03-08-0579.

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We used computer simulation to understand the functional relationships between motor (dynein, HSET, and Eg5) and non-motor (NuMA) proteins involved in microtubule aster organization. The simulation accurately predicted microtubule organization under all combinations of motor and non-motor proteins, provided that microtubule cross-links at minus-ends were dynamic, and dynein and HSET were restricted to cross-linking microtubules in parallel orientation only. A mechanistic model was derived from these data in which a combination of two aggregate properties, Net Minus-end–directed Force and micro
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Nédélec, François. "Computer simulations reveal motor properties generating stable antiparallel microtubule interactions." Journal of Cell Biology 158, no. 6 (2002): 1005–15. http://dx.doi.org/10.1083/jcb.200202051.

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An aster of microtubules is a set of flexible polar filaments with dynamic plus ends that irradiate from a common location at which the minus ends of the filaments are found. Processive soluble oligomeric motor complexes can bind simultaneously to two microtubules, and thus exert forces between two asters. Using computer simulations, I have explored systematically the possible steady-state regimes reached by two asters under the action of various kinds of oligomeric motors. As expected, motor complexes can induce the asters to fuse, for example when the complexes consist only of minus end–dire
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30

Riparbelli, Maria Giovanna, Giuliano Callaini, David M. Glover, and Maria do Carmo Avides. "A requirement for the Abnormal Spindle protein to organise microtubules of the central spindle for cytokinesis inDrosophila." Journal of Cell Science 115, no. 5 (2002): 913–22. http://dx.doi.org/10.1242/jcs.115.5.913.

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Drosophila abnormal spindle (asp) mutants exhibit a mitotic metaphase checkpoint arrest with abnormal spindle poles, which reflects a requirement for Asp for the integrity of microtubule organising centres (MTOCs). In male meiosis, the absence of a strong spindle integrity checkpoint enables asp mutant cells to proceed through anaphase and telophase. However, the central spindle region is not correctly organised and cells frequently fail to complete cytokinesis. This contrasts with meiosis in wild-type males where at late anaphase a dense array of microtubules forms in the central spindle regi
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31

Gaglio, Tirso, Mary A. Dionne, and Duane A. Compton. "Mitotic Spindle Poles are Organized by Structural and Motor Proteins in Addition to Centrosomes." Journal of Cell Biology 138, no. 5 (1997): 1055–66. http://dx.doi.org/10.1083/jcb.138.5.1055.

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The focusing of microtubules into mitotic spindle poles in vertebrate somatic cells has been assumed to be the consequence of their nucleation from centrosomes. Contrary to this simple view, in this article we show that an antibody recognizing the light intermediate chain of cytoplasmic dynein (70.1) disrupts both the focused organization of microtubule minus ends and the localization of the nuclear mitotic apparatus protein at spindle poles when injected into cultured cells during metaphase, despite the presence of centrosomes. Examination of the effects of this dynein-specific antibody both
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32

Gundersen, G. G., S. Khawaja, and J. C. Bulinski. "Postpolymerization detyrosination of alpha-tubulin: a mechanism for subcellular differentiation of microtubules." Journal of Cell Biology 105, no. 1 (1987): 251–64. http://dx.doi.org/10.1083/jcb.105.1.251.

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Tyrosinated (Tyr) and detyrosinated (Glu) alpha-tubulin, species interconverted by posttranslational modification, are largely segregated in separate populations of microtubules in interphase cultured cells. We sought to understand how distinct Tyr and Glu microtubules are generated in vivo, by examining time-dependent alterations in Tyr and Glu tubulin levels (by immunoblots probed with antibodies specific for each species) and distributions (by immunofluorescence) after microtubule regrowth and stabilization. When microtubules were allowed to regrow after complete depolymerization by microtu
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33

Gaglio, T., A. Saredi, J. B. Bingham, et al. "Opposing motor activities are required for the organization of the mammalian mitotic spindle pole." Journal of Cell Biology 135, no. 2 (1996): 399–414. http://dx.doi.org/10.1083/jcb.135.2.399.

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We use both in vitro and in vivo approaches to examine the roles of Eg5 (kinesin-related protein), cytoplasmic dynein, and dynactin in the organization of the microtubules and the localization of NuMA (Nu-clear protein that associates with the Mitotic Apparatus) at the polar ends of the mammalian mitotic spindle. Perturbation of the function of Eg5 through either immunodepletion from a cell free system for assembly of mitotic asters or antibody microinjection into cultured cells leads to organized astral microtubule arrays with expanded polar regions in which the minus ends of the microtubules
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34

Ribbeck, Katharina, Aaron C. Groen, Rachel Santarella, et al. "NuSAP, a Mitotic RanGTP Target That Stabilizes and Cross-links Microtubules." Molecular Biology of the Cell 17, no. 6 (2006): 2646–60. http://dx.doi.org/10.1091/mbc.e05-12-1178.

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Nucleolar and spindle-associated protein (NuSAP) was recently identified as a microtubule- and chromatin-binding protein in vertebrates that is nuclear during interphase. Small interfering RNA-mediated depletion of NuSAP resulted in aberrant spindle formation, missegregation of chromosomes, and ultimately blocked cell proliferation. We show here that NuSAP is enriched on chromatin-proximal microtubules at meiotic spindles in Xenopus oocytes. When added at higher than physiological levels to Xenopus egg extract, NuSAP induces extensive bundling of spindle microtubules and causes bundled microtu
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35

Inoue, S., O. C. Yoder, B. G. Turgeon, and J. R. Aist. "A cytoplasmic dynein required for mitotic aster formation in vivo." Journal of Cell Science 111, no. 17 (1998): 2607–14. http://dx.doi.org/10.1242/jcs.111.17.2607.

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An astral pulling force helps to elongate the mitotic spindle in the filamentous ascomycete, Nectria haematococca. Evidence is mounting that dynein is required for the formation of mitotic spindles and asters. Obviously, this would be an important mitotic function of dynein, since it would be a prerequisite for astral force to be applied to a spindle pole. Missing from the evidence for such a role of dynein in aster formation, however, has been a dynein mutant lacking mitotic asters. To determine whether or not cytoplasmic dynein is involved in mitotic aster formation in N. haematococca, a dyn
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Dikovskaya, Dina, Ian P. Newton, and Inke S. Näthke. "The Adenomatous Polyposis Coli Protein Is Required for the Formation of Robust Spindles Formed in CSF Xenopus Extracts." Molecular Biology of the Cell 15, no. 6 (2004): 2978–91. http://dx.doi.org/10.1091/mbc.e03-08-0613.

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Mutations in the adenomatous polyposis coli (APC) protein occur early in colon cancer and correlate with chromosomal instability. Here, we show that depletion of APC from cystostatic factor (CSF) Xenopus extracts leads to a decrease in microtubule density and changes in tubulin distribution in spindles and asters formed in such extracts. Addition of full-length APC protein or a large, N-terminally truncated APC fragment to APC-depleted extracts restored normal spindle morphology and the intact microtubule-binding site of APC was necessary for this rescue. These data indicate that the APC prote
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37

Zimmerman, Wendy C., James Sillibourne, Jack Rosa та Stephen J. Doxsey. "Mitosis-specific Anchoring of γ Tubulin Complexes by Pericentrin Controls Spindle Organization and Mitotic Entry". Molecular Biology of the Cell 15, № 8 (2004): 3642–57. http://dx.doi.org/10.1091/mbc.e03-11-0796.

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Microtubule nucleation is the best known function of centrosomes. Centrosomal microtubule nucleation is mediated primarily by γ tubulin ring complexes (γ TuRCs). However, little is known about the molecules that anchor these complexes to centrosomes. In this study, we show that the centrosomal coiled-coil protein pericentrin anchors γ TuRCs at spindle poles through an interaction with γ tubulin complex proteins 2 and 3 (GCP2/3). Pericentrin silencing by small interfering RNAs in somatic cells disrupted γ tubulin localization and spindle organization in mitosis but had no effect on γ tubulin lo
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38

Hamaguchi, Y., M. Toriyama, H. Sakai, and Y. Hiramoto. "Distribution of fluorescently labeled tubulin injected into sand dollar eggs from fertilization through cleavage." Journal of Cell Biology 100, no. 4 (1985): 1262–72. http://dx.doi.org/10.1083/jcb.100.4.1262.

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Porcine brain tubulin labeled with fluorescein isothiocyanate (FITC) was able to polymerize by itself and co-polymerize with tubulin purified from starfish sperm flagella. When we injected the FITC-labeled tubulin into unfertilized eggs of the sand dollar, Clypeaster japonicus, and the eggs were then fertilized, the labeled tubulin was incorporated into the sperm aster. When injected into fertilized eggs at streak stage, the tubulin was quickly incorporated into each central region of growing asters. It was clearly visualized that the labeled tubulin, upon reaching metaphase, accumulated in th
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Kim, Bong-Ki, Youn-Jeong Lee, Xiang-Shun Cui, and Nam-Hyung Kim. "Chromatin and microtubule organisation in maturing and pre-activated porcine oocytes following intracytoplasmic sperm injection." Zygote 10, no. 2 (2002): 123–29. http://dx.doi.org/10.1017/s0967199402002174.

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Chromatin and microtubule organisation was determined in maturing and activated porcine oocytes following intracytoplasmic sperm injection in order to obtain insights into the nature of sperm chromatin decondensation and microtubule nucleation activity. Sperm chromatin was slightly decondensed at 8 h following injection into germinal vesicle stage oocytes. Sperm-derived microtubules were not seen in these oocytes. Following injection into metaphase I (MI)-stage oocytes, sperm chromatin went to metaphase in most cases. A meiotic-like spindle was seen in the sperm metaphase chromatin. In a few M
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Ookata, K., S. Hisanaga, J. C. Bulinski, et al. "Cyclin B interaction with microtubule-associated protein 4 (MAP4) targets p34cdc2 kinase to microtubules and is a potential regulator of M-phase microtubule dynamics." Journal of Cell Biology 128, no. 5 (1995): 849–62. http://dx.doi.org/10.1083/jcb.128.5.849.

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We previously demonstrated (Ookata et al., 1992, 1993) that the p34cdc2/cyclin B complex associates with microtubules in the mitotic spindle and premeiotic aster in starfish oocytes, and that microtubule-associated proteins (MAPs) might be responsible for this interaction. In this study, we have investigated the mechanism by which p34cdc2 kinase associates with the microtubule cytoskeleton in primate tissue culture cells whose major MAP is known to be MAP4. Double staining of primate cells with anti-cyclin B and anti-MAP4 antibodies demonstrated these two antigens were colocalized on microtubu
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41

Tsai, Miao-Chih, and Julie Ahringer. "Microtubules are involved in anterior-posterior axis formation in C. elegans embryos." Journal of Cell Biology 179, no. 3 (2007): 397–402. http://dx.doi.org/10.1083/jcb.200708101.

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Microtubules deliver positional signals and are required for establishing polarity in many different organisms and cell types. In Caenorhabditis elegans embryos, posterior polarity is induced by an unknown centrosome-dependent signal. Whether microtubules are involved in this signaling process has been the subject of controversy. Although early studies supported such an involvement (O'Connell, K.F., K.N. Maxwell, and J.G. White. 2000. Dev. Biol. 222:55–70; Wallenfang, M.R., and G. Seydoux. 2000. Nature. 408:89–92; Hamill, D.R., A.F. Severson, J.C. Carter, and B. Bowerman. 2002. Dev. Cell. 3:67
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Bonaccorsi, Silvia, Maria Grazia Giansanti, and Maurizio Gatti. "Spindle Self-organization and Cytokinesis During Male Meiosis in asterless Mutants of Drosophila melanogaster." Journal of Cell Biology 142, no. 3 (1998): 751–61. http://dx.doi.org/10.1083/jcb.142.3.751.

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While Drosophila female meiosis is anastral, both meiotic divisions in Drosophila males exhibit prominent asters. We have identified a gene we call asterless (asl) that is required for aster formation during male meiosis. Ultrastructural analysis showed that asl mutants have morphologically normal centrioles. However, immunostaining with antibodies directed either to γ tubulin or centrosomin revealed that these proteins do not accumulate in the centrosomes, as occurs in wild-type. Thus, asl appears to specify a function required for the assembly of centrosomal material around the centrioles. D
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Stefanovic, Sandra, Miriam Windsor, Koh-ici Nagata, Masaki Inagaki, and Thomas Wileman. "Vimentin Rearrangement during African Swine Fever Virus Infection Involves Retrograde Transport along Microtubules and Phosphorylation of Vimentin by Calcium Calmodulin Kinase II." Journal of Virology 79, no. 18 (2005): 11766–75. http://dx.doi.org/10.1128/jvi.79.18.11766-11775.2005.

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ABSTRACT African swine fever virus (ASFV) infection leads to rearrangement of vimentin into a cage surrounding virus factories. Vimentin rearrangement in cells generally involves phosphorylation of N-terminal domains of vimentin by cellular kinases to facilitate disassembly and transport of vimentin filaments on microtubules. Here, we demonstrate that the first stage in vimentin rearrangement during ASFV infection involves a microtubule-dependent concentration of vimentin into an “aster” within virus assembly sites located close to the microtubule organizing center. The aster may play a struct
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Zhu, Jie, Anton Burakov, Vladimir Rodionov, and Alex Mogilner. "Finding the Cell Center by a Balance of Dynein and Myosin Pulling and Microtubule Pushing: A Computational Study." Molecular Biology of the Cell 21, no. 24 (2010): 4418–27. http://dx.doi.org/10.1091/mbc.e10-07-0627.

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The centrosome position in many types of interphase cells is actively maintained in the cell center. Our previous work indicated that the centrosome is kept at the center by pulling force generated by dynein and actin flow produced by myosin contraction and that an unidentified factor that depends on microtubule dynamics destabilizes position of the centrosome. Here, we use modeling to simulate the centrosome positioning based on the idea that the balance of three forces—dyneins pulling along microtubule length, myosin-powered centripetal drag, and microtubules pushing on organelles—is respons
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Fujinami, N., Y. Hosoi, H. Kato, et al. "313 EFFECTS OF ETHANOL TREATMENT AFTER INTRACYTOPLASMIC SPERM INJECTION (ICSI) ON SPERM AFTER FORMATION AND THE MICROTUBULE ORGANIZATION OF BOVINE OOCYTES." Reproduction, Fertility and Development 17, no. 2 (2005): 307. http://dx.doi.org/10.1071/rdv17n2ab313.

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The cleavage rate of bovine embryos is very low without activation of oocytes after intracytoplasmic sperm injection (ICSI), although both male and female pronuclei are formed. We previously reported that the stimulus due to the injected sperm alone was sufficient to lower the MPF activity of bovine oocytes after ICSI, and the activation treatment of oocytes with ethanol at 4 h after ICSI served to maintain the low levels of MPF activity until the next cell cycle started (Fujinami et al. 2004 J. Reprod. Dev. 50, 171–178). These results suggested that activation treatment is necessary to improv
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46

Giet, Régis, Doris McLean, Simon Descamps, et al. "Drosophila Aurora A kinase is required to localize D-TACC to centrosomes and to regulate astral microtubules." Journal of Cell Biology 156, no. 3 (2002): 437–51. http://dx.doi.org/10.1083/jcb.200108135.

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Disruption of the function of the A-type Aurora kinase of Drosophila by mutation or RNAi leads to a reduction in the length of astral microtubules in syncytial embryos, larval neuroblasts, and cultured S2 cells. In neuroblasts, it can also lead to loss of an organized centrosome and its associated aster from one of the spindle poles, whereas the centrosome at the other pole has multiple centrioles. When centrosomes are present at the poles of aurA mutants or aurA RNAi spindles, they retain many antigens but are missing the Drosophila counterpart of mammalian transforming acidic coiled coil (TA
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47

Endow, S. A., and D. J. Komma. "Assembly and dynamics of an anastral:astral spindle: the meiosis II spindle of Drosophila oocytes." Journal of Cell Science 111, no. 17 (1998): 2487–95. http://dx.doi.org/10.1242/jcs.111.17.2487.

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The meiosis II spindle of Drosophila oocytes is distinctive in structure, consisting of two tandem spindles with anastral distal poles and an aster-associated spindle pole body between the central poles. Assembly of the anastral:astral meiosis II spindle occurs by reorganization of the meiosis I spindle, without breakdown of the meiosis I spindle. The unusual disk- or ring-shaped central spindle pole body forms de novo in the center of the elongated meiosis I spindle, followed by formation of the central spindle poles. gamma-Tubulin transiently localizes to the central spindle pole body, imply
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48

Wittmann, Torsten, Haralabia Boleti, Claude Antony, Eric Karsenti, and Isabelle Vernos. "Localization of the Kinesin-like Protein Xklp2 to Spindle Poles Requires a Leucine Zipper, a Microtubule-associated Protein, and Dynein." Journal of Cell Biology 143, no. 3 (1998): 673–85. http://dx.doi.org/10.1083/jcb.143.3.673.

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Xklp2 is a plus end–directed Xenopus kinesin-like protein localized at spindle poles and required for centrosome separation during spindle assembly in Xenopus egg extracts. A glutathione-S-transferase fusion protein containing the COOH-terminal domain of Xklp2 (GST-Xklp2-Tail) was previously found to localize to spindle poles (Boleti, H., E. Karsenti, and I. Vernos. 1996. Cell. 84:49–59). Now, we have examined the mechanism of localization of GST-Xklp2-Tail. Immunofluorescence and electron microscopy showed that Xklp2 and GST-Xklp2-Tail localize specifically to the minus ends of spindle pole a
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49

Kamada, Takashi, and Shigeru Tanabe. "The role of the cytoskeleton in the movement and positioning of nuclei in Coprinus cinereus." Canadian Journal of Botany 73, S1 (1995): 364–68. http://dx.doi.org/10.1139/b95-269.

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Coprinus cinereus exhibits conspicuous nuclear movement and precise nuclear positioning during its life cycle. Examples include transhyphal migration of nuclei in compatible mating giving rise to a dikaryon, nuclear positioning relative to the hyphal apex in the dikaryon, the close spacing in interphase and conjugate division of the two nuclei in the dikaryon, and the migration of nuclei from the basidium into developing spores. We have investigated the roles of the cytoskeleton in these processes using cytoskeleton mutants as well as fluorescence microscopy. Some of the α1- and β1-tubulin mut
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50

Dufresne, L., I. Neant, J. St-Pierre, F. Dube, and P. Guerrier. "Effects of 6-dimethylaminopurine on microtubules and putative intermediate filaments in sea urchin embryos." Journal of Cell Science 99, no. 4 (1991): 721–30. http://dx.doi.org/10.1242/jcs.99.4.721.

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The effects of 6-dimethylaminopurine (6-DMAP) (a putative phosphorylation inhibitor) on the state of assembly of microtubules and intermediate filaments have been studied during the first cell cycle of the sea urchin Strongylocentrotus droebachiensis. Changes in the spatial organization of cytoskeletal structures were studied by indirect immunofluorescence with anti-tubulin and anti-IFa antibodies. The rates and patterns of protein phosphorylation in control and treated eggs were also investigated. The transfer of fertilized eggs to 600 microM 6-DMAP within 4 min following insemination inhibit
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