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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: For most hamster chromosomes, there is a strong correlation between relative fluorescence and stain base preference suggesting that staining differences may be determined primarily by differences in average base composition.
Abstract: The cytochemical properties of metaphase chromosomes from Chinese hamster and human cells were studied by flow cytometry. This technique allows precise quantitation of the fluorescence properties of individual stained chromosome types. Chromosomes were stained with the following fluorescent DNA stains: Hoechst 33258, DAPI, chromomycin A3, ethidium bromide, and propidium iodide. The relative fluorescence of individual chromosome types varied depending on the stain used, demonstrating that individual chromosome types differ in chemical properties. Flow measurements were performed as a function of stain and chromosome concentration to characterize the number and distribution of stain binding sites. Flow analysis of double stained chromosomes show that bound stains interact by energy transfer with little or no binding competition. For most hamster chromosomes, there is a strong correlation between relative fluorescence and stain base preference suggesting that staining differences may be determined primarily by differences in average base composition. A few hamster chromosome types exhibit anomalous staining which suggests that some other property, such as repetitive DNA sequences, also may be an important determinant of chromosomal staining.

81 citations

Journal ArticleDOI
TL;DR: An improved method is described for making chromosome spreads of the plasmodium of the myxomycete, Physarum polycephalum, which consists of isolating metaphase nuclei, spreading the chromosomes with hot lactic acid, and staining with acetic-orcein.

81 citations

Journal ArticleDOI
TL;DR: Electron microscopic analysis of the plasmodium showed that the accumulation of tubulin RNA begins long before the polymerization of mitotic spindle microtubules, and the decay oftubulin RNA after metaphase coincides with the depolymerization of the spindlemicrotubules.
Abstract: The temporal relationship between tubulin expression and the assembly of the mitotic spindle microtubules has been investigated during the naturally synchronous cell cycle of the Physarum plasmodium. The cell cycle behavior of the tubulin isoforms was examined by two-dimensional gel electrophoresis of proteins labeled in vivo and by translation of RNA in vitro. alpha 1-, alpha 2-, beta 1-, and beta 2-tubulin synthesis increases coordinately until metaphase, and then falls, with beta 2 falling more rapidly than beta 1. Nucleic acid hybridization demonstrated that alpha- and beta-tubulin RNAs accumulate coordinately during G2, peaking at metaphase. Quantitative analysis demonstrated that alpha-tubulin RNA increases with apparent exponential kinetics, peaking with an increase over the basal level of greater than 40-fold. After metaphase, tubulin RNA levels fall exponentially, with a short half-life (19 min). Electron microscopic analysis of the plasmodium showed that the accumulation of tubulin RNA begins long before the polymerization of mitotic spindle microtubules. By contrast, the decay of tubulin RNA after metaphase coincides with the depolymerization of the spindle microtubules.

81 citations

Journal ArticleDOI
04 Aug 1972-Nature
TL;DR: In amphibia, the cell cycle is completed in less than an hour at 180° C, and during early cleavage in Xenopus there is reportedly1 no G1 phase, and the G2 is either absent or very short.
Abstract: DURING maternal embryogenesis, the vertebrate egg is blocked in meiotic prophase. At ovulation it proceeds to the metaphase of the second meiotic division, which is complete after fertilization or an artificial stimulus. The first mitotic division occurs about three hours later, and is followed by a series of rapid mitoses without cell growth. In amphibia, the cell cycle is completed in less than an hour at 180° C. During early cleavage in Xenopus there is reportedly1 no G1 phase, and the G2 is either absent or very short.

81 citations

Journal ArticleDOI
TL;DR: The biochemical properties of in vitro lamina disassembly suggest that the activity that depolymerizes the lamina during mitosis is soluble in metaphase cells, and support the notion that this activity is a lamin protein kinase.
Abstract: We describe a cell-free system in which a postribosomal supernatant (s140) from metaphase Chinese hamster ovary (CHO) cells induces prophase-like changes in isolated CHO cell nuclei, including chromatin condensation, and nuclear envelope and lamina disassembly. These events are strongly promoted by gamma-S-ATP and an ATP-regenerating system, and do not take place with an s140 derived from G2-phase cells. The metaphase cell s140 also induces disassembly of an isolated nuclear lamina fraction that is depleted of membranes, chromatin, and nuclear pore complexes. Disassembly of the isolated lamina is accompanied by phosphorylation of the major lamina proteins (lamins A, B, and C) to levels characteristic of metaphase cells. Kinetic analysis of lamina depolymerization indicates that cooperativity may be involved in this process. The biochemical properties of in vitro lamina disassembly suggest that the activity that depolymerizes the lamina during mitosis is soluble in metaphase cells, and support the notion that this activity is a lamin protein kinase.

81 citations


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