Topic
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.
Papers published on a yearly basis
Papers
More filters
••
TL;DR: This methodology sets a new standard for imaging membrane dynamics in single cells and multicellular assemblies with high resolution and high precision.
Abstract: Membrane remodeling is an essential part of transferring components to and from the cell surface and membrane-bound organelles and for changes in cell shape, which are particularly critical during cell division. Earlier analyses, based on classical optical live-cell imaging and mostly restricted by technical necessity to the attached bottom surface, showed persistent formation of endocytic clathrin pits and vesicles during mitosis. Taking advantage of the resolution, speed, and noninvasive illumination of the newly developed lattice light-sheet fluorescence microscope, we reexamined their assembly dynamics over the entire cell surface and found that clathrin pits form at a lower rate during late mitosis. Full-cell imaging measurements of cell surface area and volume throughout the cell cycle of single cells in culture and in zebrafish embryos showed that the total surface increased rapidly during the transition from telophase to cytokinesis, whereas cell volume increased slightly in metaphase and was relatively constant during cytokinesis. These applications demonstrate the advantage of lattice light-sheet microscopy and enable a new standard for imaging membrane dynamics in single cells and multicellular assemblies.
99 citations
••
TL;DR: It is found that both anaphase and cytokinesis occur independently of chromosomes: stage-specific changes occur at an appropriate time and in the correct way, despite the absence of chromosomes.
Abstract: ANAPHASE and cytokinesis are key processes in the segregation of replicated chromosomes to the daughter cells: in anaphase, chromosomes move apart; in cytokinesis, a cleavage furrow forms midway between the separated chromosomes. Some evidence suggests that chromosomes may be involved both in controlling the timing of anaphase onset1–3 and in dictating the position of the cleavage furrow3. Other evidence indicates that the controlling mechanisms are intrinsic to the spindle and the cell4–7. Here we test these possibilities in grasshopper spermatocytes by observing spindles and cells after removal of chromosomes. We found that both anaphase and cytokinesis occur independently of chromosomes: stage-specific changes occur at an appropriate time and in the correct way, despite the absence of chromosomes. This finding is particularly noteworthy because chromosomes have an important impact on spindle microtubule assembly8,9 and the timing of anaphase onset10 in these cells.
99 citations
••
TL;DR: The localization of Ca2+/calmodulin-dependent protein kinase II in the cell nucleus and the mitotic apparatus suggests that the enzyme may play a role in thecell cycle progression of mammalian cells.
Abstract: Indirect immunofluorescence was used to determine the distribution of Ca2+/calmodulin-dependent protein kinase II (CaM kinase II) in rat embryo fibroblast 3Y1 cells, rat C6 glioma cells, and human epidermoid carcinoma KB cells. During interphase at growing phase, CaM kinase II was localized diffusely in the cytoplasm and in the nucleus. In the nucleus, the enzyme was localized within the whole nuclear matrix in which the enzyme was specially concentrated in nucleoli. During mitosis, CaM kinase II was found to be a dynamic component of the mitotic apparatus, particularly present at microtubule-organizing centers. In metaphase and anaphase, CaM kinase II was observed at centrosomes and between the spindle poles. During telophase, CaM kinase II was condensed as a bright fluorescent dot at the midzone of the intercellular bridge between two daughter cells, while tubulin was found at each side of the midbody. Colchicine, a microtubule inhibitor, disorganized the tubulin- and CaM kinase II specific fluorescent structure of mitotic 3Y1 cells. In cold-treated cells, CaM kinase II was localized predominantly at centrosomes. The localization of CaM kinase II in the cell nucleus and the mitotic apparatus suggests that the enzyme may play a role in the cell cycle progression of mammalian cells.
99 citations
••
TL;DR: It is shown that immunodepletion of Bub1 from egg extracts blocks the ability of Mos to establish CSF arrest, and arrest can be restored by the addition of wild-type, but not kinase-dead, Bub1.
99 citations
••
TL;DR: Results of experiments in which spindle microtubules were depolymerized by hydrostatic pressure are presented, to examine the Inoué dynamic equilibrium concept of spindle assembly and the possible role of microtubule depolymization-polymerization in the movement of chromosomes.
Abstract: In this paper I have presented results of experiments in which spindle microtubules were depolymerized by hydrostatic pressure, in order to examine the Inoue dynamic equilibrium concept of spindle assembly and the possible role of microtubule depolymerization-polymerization in the movement of chromosomes. Using a newly developed optical hydrostatic pressure chamber, I investigated with polarization microscopy the quantitative effects of pressure on the polymerization of spindle microtubules and, with phase contrast microscopy, the relationship of pressure-induced spindle microtubule depolymerization to chromosome movement in living cells. From results of earlier experiments, principally those of Inoue et al. with low temperature and colchicine as microtubule-depolymerizing agents, and from results of my own research, I have concluded that: (1) spindle fiber microtubules are sensitive to depolymerization by pressure (3000-7000 psi), spindle microtubules do exist in a labile equilibrium with a pool of subunits, and the Inoue simple equilibrium model does predict changes in spindle microtubule assembly at metaphase induced by pressure; (2) the stability of microtubules depends on the number of "attached ends;" (3) the longest interpolar microtubules and the longest chromosomal fiber microtubules regulate the spindle interpolar length and the chromosome-to-pole positions; (4) chromosome velocity is independent of the number of spindle microtubules, as well as of the drag force of the chromosomes; (5) the chromosomal fiber microtubules transmit the forces between the poles and between the chromosomes and the poles; and (6) polymerization of microtubules does produce pushing forces and, if controlled microtubule depolymerization does not actually produce pulling forces, at least it governs the velocity of chromosome-to-pole movement.
99 citations