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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: On the basis of staining reaction, late replicating heterochromatic regions fall into five categories, the relationships and functional significance of these categories is discussed.
Abstract: Cultured human peripheral blood lymphocytes were labelled with 3H-thymidine in the early or late S phase prior to mitosis. Quinacrine fluorescence patterns in metaphase chromosomes were then recorded photographically and the slides reprocessed for autoradiography so that the same metaphase cells were examined with the two techniques. The intensity and distribution of 3H-thymidine labelling was compared with the intensity and distribution of Q fluorescence with particular reference to chromosomes 1, 13, 14, 15, 17, 18, 19, 20, 21 and 22. It was found that chromosome regions showing bright fluorescence were also late replicating and that, in general, patterns of late replications reflected the patterns of fluorescence. Exceptions to this generalisation included the late labelling X chromosome in cells of female origin and areas near the centromeres on chromosomes 1, 9, 16 and 22. These centromeric regions show a dull fluorescence but, with exception of chromosome 9, are strongly Giemsa-positive in the ASG staining technique. On the basis of staining reaction, late replicating heterochromatic regions fall into five categories, the relationships and functional significance of these categories is discussed.

130 citations

Journal ArticleDOI
TL;DR: Using 3H-uridine, the course of RNA synthesis has been followed autoradiographically during all stages of male meiosis and spermiogenesis in the locusts Schistocerca gregaria and Cyrtacanthacris tartarica and the grasshopper Chorthippus brunneus.
Abstract: 1. Using 3H-uridine, the course of RNA synthesis has been followed autoradiographically during all stages of male meiosis and spermiogenesis in the locusts Schistocerca gregaria and Cyrtacanthacris tartarica and the grasshopper Chorthippus brunneus. Using 3H-thymidine, premeiotic DNA synthesis was followed in Cyrtacanthacris tartarica. 2. RNA synthesis is actively carried out by all autosomes throughout first meiotic prophase, up to and including diakinesis, and at second prophase. No RNA synthesis occurs at the contracted stages of first or second metaphase or first or second anaphase. 3. RNA is again synthesized by young spermatids, but such synthesis ceases by the time that differentiation begins. No label was detected in the nuclei of differentiating spermatids, even after 8 hours' incubation with 3H-uridine. 4. Morphological and functional comparisons suggest that orthopteran prophase chromosomes at male meiosis, and probably all prophase chromosomes, are lampbrush in nature, though to varying degrees. 5. The X univalent, allocyclic in its appearance and staining properties, is apparently completely inactive throughout the whole of meiosis. No RNA or DNA precursor could be successfully demonstrated to be incorporated by the X at any stage of male meiosis. 6. Nucleoli are present at interphase and early prophase but are usually absent during later prophase stages in this material. They do not label heavily in advance of, or at the same time as, the commencement of the labelling of the rest of the chromatin: they only accumulate greater densities of label after several hours' incubation with the labelled precursor. 7. No independent cytoplasmic synthesis of RNA could be detected after up to 2 hours' in vitro incubation in labelled saline at 30° C, though nuclei are heavily labelled after only 1/2 hour. It is some 2–4 hours before nuclear synthesized RNA appears to pass to the cytoplasm in detectable amounts.

130 citations

Journal ArticleDOI
TL;DR: The maintenance of the scaffold-DNA interaction in metaphase indicates that lamin proteins are not involved in the attachment site for at least a subset of Drosophila SARs, consistent with a fundamental role for these fragments in the organization of the genome into looped domains.

130 citations

Journal ArticleDOI
TL;DR: Comparative genomic hybridization was performed on 50 primary head and neck squamous cell carcinomas to discover molecular genetic alterations underlying the progression of these tumors.
Abstract: Background Comparative genomic hybridization (CGH) was performed on 50 primary head and neck squamous cell carcinomas (HNSCC) to discover molecular genetic alterations underlying the progression of these tumors. Methods In CGH, equal amounts of differently labeled tumor deoxyribonucleic acid (DNA) and normal reference DNA were hybridized simultaneously to normal metaphase chromosomes. They were visualized by different fluorochromes, and the signal intensities were quantitated separately as gray levels along the single chromosomes. The over- and underrepresented DNA segments were determined by computation of ratio images and average ratio profiles. Results Prevalent changes observed in more than 50% of the HNSCC included deletions of chromosomes 1p, 4, 5q, 6q, 8p, 9p, 11, 13q, 18q, and 21q and DNA overrepresentations of 11q13 as well as 3q, 8q, 16p, 17q, 19, 20q, and 22q. The calculation of ratio profiles of tumor subgroups revealed that well differentiated carcinomas (G1) were defined by the deletions of chromosomes 3p, 5q, and 9p together with the overrepresentation of 3q, suggesting the association with early tumor development. Accordingly, the undifferentiated tumors (G3) were characterized by additional deletions of chromosomes 4q, 8p, 11q, 13q, 18q, 21q, and overrepresentations of 1p, 11q13, 19, and 22q. Conclusion Our data indicate that the CGH patterns of chromosomal imbalances may help to define the malignant potential of head and neck squamous cell carcinomas. © 1998 John Wiley & Sons, Inc. Head Neck20: 145–151, 1998.

130 citations

Journal ArticleDOI
TL;DR: In this paper, the onset of the first mitosis after doses of 500 rads was delayed as expected from previous studies of the age dependence of "mitotic delay," and the interval between this mitosis and the next was indistinguishable from that for unirradiated control cells, while the subsequent two generations were again prolonged, on the average, though not so severely as was the irradiated generation.

130 citations


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