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Metaphase

About: Metaphase is a research topic. Over the lifetime, 6925 publications have been published within this topic receiving 291590 citations. The topic is also known as: GO:0007091 & mitotic metaphase/anaphase transition.


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Journal ArticleDOI
TL;DR: The findings on the sea urchin confirm the classical theory of the paternal origin of centrosomes and contrast with observations tracing the mitotic poles of the mouse egg to maternal centrosomal material, which strengthens the conclusion that mouse centrosome derive from the oocyte.
Abstract: The forms and locations of centrosomes in mouse oocytes and in sea urchin eggs were followed through the whole course of fertilization and first cleavage by immunofluorescence microscopy. Centrosomes were identified with an autoimmune antiserum to centrosomal material. Staining of the same preparations with tubulin antibody and with the DNA dye Hoechst 33258 allowed the correlation of the forms of the centrosomes with the microtubule structures that they generate and with the stages of meiosis, syngamy, and mitosis. The results with sea urchin eggs conform to Boveri's view on the paternal origin of the functional centrosomes. Centrosomes are seen in spermatozoa and enter the egg at fertilization. Initially, the centrosomes are compact, but as the eggs enter the mitotic cycle the forms of the centrosomes go through a cycle in which they spread during interphase, apparently divide, and condense into two compact poles by metaphase. In anaphase, they spread to form flat poles. In telophase and during reconstitution of the daughter nuclei, the centrosomal material is disposed as hemispherical caps around the poleward surfaces of the nuclei. Mouse sperm lack centrosomal antigen. In the unfertilized mouse oocyte, the meiotic spindle poles are displayed as broad-beaded centrosomes. In addition, centrosomal material is detected in the cytoplasm as particles, about 16 in number, which are foci of small aster-like arrays of microtubules. The length and number of astral microtubules correlate with the size of the centrosomal foci. After sperm incorporation, as the pronuclei develop and more cytoplasmic microtubules assemble, a few of the foci associate with the peripheries of the nuclei. The number of foci multiplies during the first cell cycle. At the end of interphase, all of the centrosomal foci have concentrated on the nuclear peripheries and the cytoplasmic microtubules have disappeared. At prophase, the centrosomes are seen as two irregular clusters, marking the poles which, at metaphase and anaphase, appear as rough bands with foci, and the spindle is typically barrel-shaped. At telophase, the centrosomes are seen as arcs that lie on the nuclear peripheries after cleavage. The ordering of microtubules in all the stages reflects the shapes of the centrosomes. The findings on the sea urchin confirm the classical theory of the paternal origin of centrosomes and contrast with observations tracing the mitotic poles of the mouse egg to maternal centrosomal material. This evidence strengthens the conclusion that mouse centrosomes derive from the oocyte.

310 citations

Journal ArticleDOI
26 Aug 2005-Science
TL;DR: It is reported that chromosome-mediated interaction gradients between the small guanosine triphosphatase (GTPase) Ran and importin-β produce activity gradients that determine the spatial distribution of microtubule nucleation and stabilization around chromosomes and that are essential for the self-organization ofmicrotubules into a bipolar spindle.
Abstract: During cell division, chromosomes are distributed to daughter cells by the mitotic spindle. This system requires spatial cues to reproducibly self-organize. We report that such cues are provided by chromosome-mediated interaction gradients between the small guanosine triphosphatase (GTPase) Ran and importin-β. This produces activity gradients that determine the spatial distribution of microtubule nucleation and stabilization around chromosomes and that are essential for the self-organization of microtubules into a bipolar spindle.

308 citations

Journal ArticleDOI
TL;DR: It is demonstrated that the chromosomes move along stationary kinetochore microtubules and that depolymerization of these microtubule during anaphase takes place at the kinetchore.
Abstract: During the movement of chromosomes in anaphase, microtubules that extend between the kinetochores and the poles shorten. We sought to determine where subunits are lost from these microtubules during their shortening. Prophase or prometaphase cells on coverslips were injected with fluoresceinated tubulin and allowed to progress through mitosis. Immediately after the onset of anaphase, a bar-shaped beam of laser light was used to mark a domain on the kinetochore fibers by photobleaching a band, approximately 1.0 micron wide, across the spindle. In different cells, spindles were photobleached at varying distances from the chromosomes. Cells were allowed to continue in anaphase until the chromosomes had further separated. They were then lysed, fixed, and prepared for double-label immunofluorescence with an antibody to fluorescein that does not bind appreciably to bleached fluorescein, and with an antibody to tubulin. Photobleached domains of microtubules appeared as bands of reduced fluorescence in the anti-fluorescein image. However, the anti-tubulin labeling revealed that microtubules were present and continuous through the photobleached domains. In all cases, the chromosomes approached and invaded the bleached domain while the bleached domain itself remained stationary with respect to the near pole. These results demonstrate that the chromosomes move along stationary kinetochore microtubules and that depolymerization of these microtubules during anaphase takes place at the kinetochore. In contrast to the generally accepted older view that chromosomes are passive objects pulled by "traction fibers," we suggest that the kinetochore is an active participant in generating the motive force that propels the chromosome to the pole.

308 citations

Journal ArticleDOI
TL;DR: It is shown here that mutations in the Drosophila gene fizzy (fzy) block the mitotic degradation of these cyclins, indicating that fzy plays a crucial role in the metaphase/anaphase transition.
Abstract: While entry into mitosis is triggered by activation of cdc2 kinase, exit from mitosis requires inactivation of this kinase. Inactivation results from proteolytic degradation of the regulatory cyclin subunits during mitosis. At least three different cyclin types, cyclins A, B and B3, associate with cdc2 kinase in higher eukaryotes and are sequentially degraded in mitosis. We show here that mutations in the Drosophila gene fizzy (fzy) block the mitotic degradation of these cyclins. Moreover, expression of mutant cyclins (delta cyclins) lacking the destruction box motif required for mitotic degradation affects mitotic progression at distinct stages. Deltacyclin A results in a delay in metaphase, deltacyclin B in an early anaphase arrest and deltacyclin B3 in a late anaphase arrest, suggesting that mitotic progression beyond metaphase is ordered by the sequential degradation of these different cyclins. Coexpression of deltacyclins A, B and B3 allows a delayed separation of sister chromosomes, but interferes wit chromosome segregation to the poles. Mutations in fzy block both sister chromosome separation and segregation, indicating that fzy plays a crucial role in the metaphase/anaphase transition.

308 citations

Journal ArticleDOI
TL;DR: In cows, protein synthesis is required for germinal vesicle breakdown (GVBD) and the nuclear changes in the bovine oocyte during 24 h of culture are examined more closely.
Abstract: In cows, protein synthesis is required for germinal vesicle breakdown (GVBD). This study examines more closely the need for protein synthesis and the nuclear changes in the bovine oocyte during 24 h of culture. Bovine oocytes with compact and complete cumulus were washed and incubated in groups of 10 for up to 24 h in SO-pd drops of TCM-199 supplemented with follicle-stimulating hormone (NIAMADD, 0.5 �.Lg/ml), luteinizing hormone (LH) NJAMADD, 5 �.tg/ml), estradiol-17fi (1 �.tg/ml), pyruvate (20 pM), and 10% heattreated fetal calf serum. Medium was overlaid with paraffin oil. Oocytes (n = 891) were fixed at the end of each 3-h interval from 0 to 24 h of culture, or at 24 h after addition of cycloheximide (10 pg/ml at 10 different times during maturation (0, 1, 2, 3, 6, 9, 12, 15, 18, 21 h; n = 175). At each time point, the chromosomal status of oocytes was evaluated, frequencies were computed, and the time spent on each step was determined. The germinal vesicle (GV) was present from 0 to 6.6 h, GVBD at 6.6 to 8.0 h, chromatin condensation at 8.0 to 10.3 h, metaphase I at 10.3 to 15.4 h, anaphase I at 15.4 to 16.6, telophase I at 16.6 to 18.0 h, and metaphase II at 18.0 to 24 h. Cycloheximide blocked oocyte maturation at GVBD, if added from 0 to 3 h; at chromatin condensation, 4fpresent from 6 to 24 h; and at metaphase 1, when present from 9 to 12 h. When cycloheximide was present from 12 to 24 h an increasing number of oocytes reached metaphase II (19% for 12 h, 36% for 15 h, 51% for 18 h, 90% for 21 h, 94% for 24 h), but many abnormalities were noted:

306 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202373
2022116
202182
202087
2019113
201888