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.
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TL;DR: In a blind study, chromosome aberrations in tumor cells were analyzed by conventional cytogenetic techniques (G banding) and nonradioactive in situ hybridization with chromosome-specific probes and gave reliable results and allowed detection of cell subpopulations that were not detected by analyzing metaphase chromosomes.
127 citations
TL;DR: Based on the marked reduction in Holliday junction (HJ) resolution activity in Rad51c-null mouse embryonic fibroblasts, it is proposed that this late function may be associated with HJ resolution.
Abstract: RAD51C is a member of the RecA/RAD51 protein family, which is known to play an important role in DNA repair by homologous recombination. In mice, it is essential for viability. Therefore, we have generated a hypomorphic allele of Rad51c in addition to a null allele. A subset of mice expressing the hypomorphic allele is infertile. This infertility is caused by sexually dimorphic defects in meiotic recombination, revealing its two distinct functions. Spermatocytes undergo a developmental arrest during the early stages of meiotic prophase I, providing evidence for the role of RAD51C in early stages of RAD51-mediated recombination. In contrast, oocytes can progress normally to metaphase I after superovulation but display precocious separation of sister chromatids, aneuploidy, and broken chromosomes at metaphase II. These defects suggest a possible late role of RAD51C in meiotic recombination. Based on the marked reduction in Holliday junction (HJ) resolution activity in Rad51c-null mouse embryonic fibroblasts, we propose that this late function may be associated with HJ resolution.
127 citations
TL;DR: A single kinetochore moves twice the normal mass of chromatin (two chromatids) at the same velocity with which it moves a single chromatid, showing that the velocity withWhich a kinetchore moves is independent, within limits, of the mass associated with it.
Abstract: The role of the kinetochore in chromosome movement was studied by 532-nm wavelength laser microirradiation of mitotic PtK2 cells. When the kinetochore of a single chromatid is irradiated at mitotic prometaphase or metaphase, the whole chromosome moves towards the pole to which the unirradiated kinetochore is oriented, while the remaining chromosomes congregate on the metaphase plate. The chromatids of the irradiated chromosome remain attached to one another until anaphase, at which time they separate by a distance of 1 or 2 micrometers and remain parallel to each other, not undergoing any poleward separation. Electron microscopy shows that irradiated chromatids exhibit either no recognizable kinetochore structure or a typical inactive kinetochore in which the tri-layer structure is present but has no microtubules associated with it. Graphical analysis of the movement of the irradiated chromosome shows that the chromosome moves to the pole rapidly with a velocity of approximately 3 micrometers/min. If the chromosome is close to one pole at irradiation, and the kinetochore oriented towards that pole is irradiated, the chromosome moves across the spindle to the opposite pole. The chromosome is slowed down as it traverses the equatorial region, but the velocity in both half-spindles is approximately the same as the anaphase velocity of a single chromatid. Thus a single kinetochore moves twice the normal mass of chromatin (two chromatids) at the same velocity with which it moves a single chromatid, showing that the velocity with which a kinetochore moves is independent, within limits, of the mass associated with it.
127 citations
TL;DR: It was found that the cells originally in the G2 phase were about three to four times more radiosensitive than those in the S phase, which suggests that the subunits of each chromatid separate at the time the cell commences DNA synthesis.
127 citations
TL;DR: It is demonstrated that this process is required for the phosphorylation of MKlp1 at S911, an Aurora B consensus site overlapping a bipartite nuclear localization sequence (NLS).
127 citations