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.

Rapid isolation of metaphase chromosomes containing high molecular weight DNA.

Abstract: Metaphase chromosomes with high molecular weight DNA were isolated from Chinese hamster ovary (CHO) cells in a neutral buffer containing polyamines and chelators. The individual, unfixed chromosomes retained their centromeric and secondary constrictions, distinct sister chromatids, and complex banding patterns. The DNA from these chromosomes was 100-fold larger (2 x 10(8) daltons) than DNA from chromosomes isolated by other procedures. These characteristics indicate preservation during isolation of considerable native structure. In contrast to chromosomes produced by other methods, these chromosomes were stable in storage and did not aggregate, thus providing useful material for studies of the structure and biochemistry of individual chromosomes.

Specific metaphase and interphase detection of the breakpoint region in 8q24 of Burkitt lymphoma cells by triple-color fluorescence in situ hybridization

Abstract: Triple fluorescence in situ hybridization with a plasmid DNA library from sorted human chromosomes 8 in combination with bacteriophage clones flanking the breakpoint in 8q24 of the Burkitt lymphoma cell line Jl was used for the specific delineation of this breakpoint in individual tumor cells. With this approach, tumor-specific breakpoints in translocation chromosomes can be detected at all stages of the cell cycle with high specificity.

Anaphase onset and dephosphorylation of mitotic phosphoproteins occur concomitantly

Abstract: The cyclical phosphorylation and dephosphorylation of the centrosome during mitosis was analyzed by immunofluorescence methods using the MPM-2 antibody, which reacts with a subset of mitotic phosphoproteins. Quantification of MPM-reactivity indicated that centrosomal phosphorylation attained a maximal level just prior to anaphase onset. This level was maintained in metaphase cells blocked from further mitotic progression with the microtubule depolymerizing agent nocodazole. However, when nocodazole was added to cells that had just initiated anaphase, the level of centrosomal phosphorylation decreased rapidly as in untreated anaphase cells. We conclude that the onset of dephosphorylation of the centrosome coincided with the onset of anaphase and continued in the absence of chromosome movement. Dephosphorylation of MPM-2 reactive phosphoproteins may be taken as a biochemical indicator of anaphase onset.

A New Method for Improving Metaphase Chromosome Spreading

Abstract: Background The success of complex molecular cytogenetic studies depends on having properly spread chromosomes. However, inconsistency of optimum chromosome spreading remains a major problem in cytogenetic studies. Methods The metaphase spreading process was carefully timed to identify the most critical phase of chromosome spreading. The effects of dropping height of cell suspension, slide condition, drying time, fixative ratio, and relative humidity on the quality of metaphase spreads were studied by quantitative examination of metaphase chromosome spreads. Normal and immortalized human epithelial ovarian cells, neuroblastoma cells, and normal lymphocytes were tested. Results Humidity over the slide was the most important variable affecting the quality of chromosome spreads. Consistent improvement in chromosome spreading (larger metaphase area, less chromosome overlaps, or lower frequencies of broken metaphases) was obtained for all cell types if dynamic cell rehydration, occurring as fixative absorbs moisture from air, was made to coincide with the prompt fixation of spread chromosomes to the slide. This was achieved by dropping cells on dry glass slides placed in a shallow metal tray and then quickly lowering the tray into a covered 50°C water bath for slide drying. Conclusions A new and simple method for improving metaphase chromosome spreading was developed based on our study on the characteristics of chromosome spreading. Cytometry Part A 51A:46–51, 2003. © 2002 Wiley-Liss, Inc.

Association of p34cdc2/cyclin B complex with microtubules in starfish oocytes.

Abstract: The microtubular cytoskeleton exhibits a dramatic reorganization, progressing from interphase radial arrays to a mitotic spindle at the G2/M transition. Although this reorganization has been suspected to be caused by maturation promoting factor (MPF: p34cdc2/cyclin B complex), little is known about how p34cdc2 kinase controls microtubule networks. We provide evidence of the direct association of the p34cdc2/cyclin B complex with microtubules in starfish oocytes. Anti-cyclin B staining of detergent-treated oocytes, isolated asters and meiotic spindles revealed fluorescence associated with microtubule fibers, chromosomes and centrosomes. Microtubules prepared from starfish oocytes were associated with cyclin B and p34cdc2 proteins. Microtubule-bound p34cdc2 and cyclin B were released from microtubules by a high-salt solution and possessed a complex form as shown by the adsorption to suc1-beads and by immunoprecipitation with the anti-cyclin B antibody. The p34cdc2/cyclin B complex associated to microtubules had high histone H1 kinase activity at meiotic metaphase. However, it was not necessary for the p34cdc2/cyclin B complex to be active for microtubule binding, as an inactive form in immature oocytes was also observed to bind to microtubules. The coprecipitation of suc1-column purified p34cdc2/cyclin B with purified porcine brain microtubules in the presence of starfish oocyte microtubule-associated proteins (MAPs) indicates that the association of p34cdc2/cyclin B with microtubules in vitro is mediated by MAPs.