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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
01 May 1999-Genetics
TL;DR: In this first report of single-copy FISH to SC spreads, the probe sequences were unambiguously mapped on the long arm of tomato SC 11, and the order of two of the FISH markers is reversed in relation to their order on the molecular linkage map.
Abstract: Fluorescence in situ hybridization (FISH) is a powerful means by which single- and low-copy DNA sequences can be localized on chromosomes. Compared to the mitotic metaphase chromosomes that are normally used in FISH, synaptonemal complex (SC) spreads (hypotonically spread pachytene chromosomes) have several advantages. SC spreads (1) are comparatively free of debris that can interfere with probe penetration, (2) have relatively decondensed chromatin that is highly accessible to probes, and (3) are about ten times longer than their metaphase counterparts, which permits FISH mapping at higher resolution. To investigate the use of plant SC spreads as substrates for single-copy FISH, we probed spreads of tomato SCs with two single-copy sequences and one low-copy sequence (ca. 14 kb each) that are associated with restriction fragment length polymorphism (RFLP) markers on SC 11. Individual SCs were identified on the basis of relative length, arm ratio, and differential staining patterns after combined propidium iodide (PI) and 4', 6-diamidino-2-phenylindole (DAPI) staining. In this first report of single-copy FISH to SC spreads, the probe sequences were unambiguously mapped on the long arm of tomato SC 11. Coupled with data from earlier studies, we determined the distance in micrometers, the number of base pairs, and the rates of crossing over between these three FISH markers. We also observed that the order of two of the FISH markers is reversed in relation to their order on the molecular linkage map. SC-FISH mapping permits superimposition of markers from molecular linkage maps directly on pachytene chromosomes and thereby contributes to our understanding of the relationship between chromosome structure, gene activity, and recombination.

104 citations

Journal ArticleDOI
TL;DR: Quinacrine-bright polymorphic regions are especially resistant to fluorescence quenching by counterstains with G.C binding specificity, strengthening the evidence that these latter regions are highly enriched for A.T base pair clusters.
Abstract: Intermolecular energy transfer between appropriately chosen pairs of dyes can be used to induce or enhance banding patterns in human metaphase chromosomes. Energy transfer, calibrated by fluorometric studies on soluble dye·DNA complexes, can also be detected by photometric measurements on cytological preparations of metaphase chromosomes stained with pairs of fluorochromes. If a fluorescent dye with one type of binding or quantum yield specificity (e.g., quinacrine, 33258 Hoechst, or chromomycin A3) is employed together with a counterstain (e.g., actinomycin D, 7-aminoactinomycin D, or methyl green) exhibiting a complementary base pair binding specificity and satisfying spectral overlap criteria for energy transfer, contrast in fluorescence from the first dye is enhanced in specific subsets of standard chromosome bands. Extensive energy transfer presumably suppress donor fluorescence except in chromosomal region containing clusters of at least 20 base pairs predominantly of one type, within which the donor but not the acceptor can bind and fluoresce. Quinacrine-bright polymorphic regions are especially resistant to fluorescence quenching by counterstains with G·C binding specificity, strengthening the evidence that these latter regions are highly enriched for A·T base pair clusters. The ability to highlight selectively many such polymorphic regions may prove of further, practical, utility in a number of cytogenetic problems.

103 citations

Journal ArticleDOI
TL;DR: It is proposed that PAP's multiple cdk sites, and their differential sensitivity to MPF, provide a mechanism to link repression specifically to late M‐phase, and the possibility that this reflects a general means to control the timing of cdk‐dependent regulatory events during the cell cycle.
Abstract: We showed previously that p34(cdc2)/cyclin B (MPF) hyperphosphorylates poly(A) polymerase (PAP) during M-phase of the cell cycle, causing repression of its enzymatic activity. Mutation of three cyclin-dependent kinase (cdk) consensus sites in the PAP C-terminal regulatory domain prevented complete phosphorylation and MPF-mediated repression. Here we show that PAP also contains four nearby non-consensus cdk sites that are phosphorylated by MPF. Remarkably, full phosphorylation of all these cdk sites was required for repression of PAP activity, and partial phosphorylation had no detectable effect. The consensus sites were phosphorylated in vitro at a 10-fold lower concentration of MPF than the non-consensus sites. Consistent with this, during meiotic maturation of Xenopus oocytes, consensus sites were phosphorylated prior to the non-consensus sites at metaphase of meiosis I, and remained so throughout maturation, while the non-consensus sites did not become fully phosphorylated until after 12 h of metaphase II arrest. We propose that PAP's multiple cdk sites, and their differential sensitivity to MPF, provide a mechanism to link repression specifically to late M-phase. We discuss the possibility that this reflects a general means to control the timing of cdk-dependent regulatory events during the cell cycle.

103 citations

Journal ArticleDOI
R. Brown1
TL;DR: In this article, a technique for determining the durations of the different phases of division is described, and the effects of different temperatures have been determined, and it is shown that all stages are accelerated by an increase in temperature from 15o to 25° C.
Abstract: A new technique for determining the durations of the different phases of division is described. It is shown that at 15o C. the mean durations of the several phases in the root tip of the pea are as follows : interphase 23 hours ; prophase 2 hours ; metaphase 25 minutes; anaphase 5 minutes; telophase 22 minutes. The effects of different temperatures have been determined, and it is shown that all stages are accelerated by an increase in temperature from 15o to 25° C., the ratios of the durations at the two temperatures being about 2-0 or slightly less. It is suggested that since interphase is the longest stage of the division cycle, in terms of growth effects on this stage are the most significant.

103 citations

Journal ArticleDOI
TL;DR: This work reports the isolation and analysis of a murine homologue of BUB3, a gene whose deletion abolishes mitotic checkpoint function in Saccharomyces cerevisiae, and shows that mBub3, like yeast Bub3p, binds to Bub1 to form a complex with protein kinase activity.
Abstract: Accurate chromosome segregation at mitosis is ensured both by the intrinsic fidelity of the mitotic machinery and by the operation of checkpoints that monitor chromosome-microtubule attachment. When unattached kinetochores are present, anaphase is delayed and the time available for chromosome-microtubule capture increases. Genes required for this delay first were identified in budding yeast (the MAD and BUB genes), but it is not yet known how the checkpoint senses unattached chromosomes or how it signals cell-cycle arrest. We report the isolation and analysis of a murine homologue of BUB3, a gene whose deletion abolishes mitotic checkpoint function in Saccharomyces cerevisiae. mBub3 belongs to a small gene family that has been highly conserved through evolution. By expressing recombinant proteins in insect cells, we show that mBub3, like yeast Bub3p, binds to Bub1 to form a complex with protein kinase activity. During prophase and prometaphase, preceding kinetochore-microtubule attachment, Bub3 localizes to kinetochores. High levels of mBub3 remain associated with lagging chromosomes but not with correctly aligned chromosomes during metaphase, consistent with a role for Bub3 in sensing microtubule attachment. Intriguingly, the number of lagging chromosomes with high Bub3 staining increases dramatically in cells treated with low (and pharmacologically relevant) concentrations of the chemotherapeutic taxol and the microtubule poison nocodazole.

103 citations


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