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Annual Review of Biophysics May 2018The assembly of the mitotic spindle and the subsequent segregation of sister chromatids are based on the self-organized action of microtubule filaments, motor proteins,... (Review)
Review
The assembly of the mitotic spindle and the subsequent segregation of sister chromatids are based on the self-organized action of microtubule filaments, motor proteins, and other microtubule-associated proteins, which constitute the fundamental force-generating elements in the system. Many of the components in the spindle have been identified, but until recently it remained unclear how their collective behaviors resulted in such a robust bipolar structure. Here, we review the current understanding of the physics of the metaphase spindle that is only now starting to emerge.
Topics: Humans; Metaphase; Spindle Apparatus
PubMed: 29792816
DOI: 10.1146/annurev-biophys-060414-034107 -
Seminars in Cell & Developmental Biology Sep 2021The mitotic spindle is a bipolar cellular structure, built from tubulin polymers, called microtubules, and interacting proteins. This macromolecular machine orchestrates... (Review)
Review
The mitotic spindle is a bipolar cellular structure, built from tubulin polymers, called microtubules, and interacting proteins. This macromolecular machine orchestrates chromosome segregation, thereby ensuring accurate distribution of genetic material into the two daughter cells during cell division. Powered by GTP hydrolysis upon tubulin polymerization, the microtubule ends exhibit a metastable behavior known as the dynamic instability, during which they stochastically switch between the growth and shrinkage phases. In the context of the mitotic spindle, dynamic instability is furthermore regulated by microtubule-associated proteins and motor proteins, which enables the spindle to undergo profound changes during mitosis. This highly dynamic behavior is essential for chromosome capture and congression in prometaphase, as well as for chromosome alignment to the spindle equator in metaphase and their segregation in anaphase. In this review we focus on the mechanisms underlying microtubule dynamics and sliding and their importance for the maintenance of shape, structure and dynamics of the metaphase spindle. We discuss how these spindle properties are related to the phenomenon of microtubule poleward flux, highlighting its highly cooperative molecular basis and role in keeping the metaphase spindle at a steady state.
Topics: Humans; Metaphase; Microtubules; Spindle Apparatus
PubMed: 34053864
DOI: 10.1016/j.semcdb.2021.05.016 -
Methods in Molecular Biology (Clifton,... 2017Chromosome banding is an essential technique used in chromosome karyotyping to identify normal and abnormal chromosomes for clinical and research purposes. Giemsa (G)-,...
Chromosome banding is an essential technique used in chromosome karyotyping to identify normal and abnormal chromosomes for clinical and research purposes. Giemsa (G)-, reverse (R)-, and centromere (C)-banding are the most commonly dye-based chromosome-banding techniques. G-banding involves the staining of trypsin-treated chromosomes and R-banding involves denaturing in hot acidic saline followed by Giemsa staining. C-banding is specifically used for identifying heterochromatin by denaturing chromosomes in a saturated alkaline solution followed by Giemsa staining. Different banding techniques may be selected for the identification of chromosomes.
Topics: Chromosome Banding; Humans; Karyotyping; Metaphase
PubMed: 27910014
DOI: 10.1007/978-1-4939-6703-2_6 -
Medical & Biological Engineering &... Aug 2016The karyotype is analyzed to detect the genetic abnormalities. It is generated by arranging the chromosomes after extracting them from the metaphase chromosome images.... (Review)
Review
The karyotype is analyzed to detect the genetic abnormalities. It is generated by arranging the chromosomes after extracting them from the metaphase chromosome images. The chromosomes are non-rigid bodies that contain the genetic information of an individual. The metaphase chromosome image spread contains the chromosomes, but these chromosomes are not distinct bodies; they can either be individual chromosomes or be touching one another; they may be bent or even may be overlapping and thus forming a cluster of chromosomes. The extraction of chromosomes from these touching and overlapping chromosomes is a very tedious process. The segmentation of a random metaphase chromosome image may not give us correct and accurate results. Therefore, before taking up a metaphase chromosome image for analysis, it must be analyzed for the orientation of the chromosomes it contains. The various reported methods for metaphase chromosome image selection for automatic karyotype generation are compared in this paper. After analysis, it has been concluded that each metaphase chromosome image selection method has its advantages and disadvantages.
Topics: Humans; Image Processing, Computer-Assisted; Karyotyping; Metaphase
PubMed: 26676686
DOI: 10.1007/s11517-015-1419-z -
Methods in Molecular Biology (Clifton,... 2023After DNAs are damaged, DNA repair proteins accumulate and are activated at the DNA damaged site. These accumulated proteins are visualized as foci by fluorescent...
After DNAs are damaged, DNA repair proteins accumulate and are activated at the DNA damaged site. These accumulated proteins are visualized as foci by fluorescent immunocytochemistry technique. This allows the DNA damage responses in interphase nuclei to be detected; it was earlier times difficult to analyze DNA damage in situ. In order to analyze DNA damage in interphase cells, either DNA is extracted to assay breaks biochemically, or premature chromosome condensation is conducted to observe as chromatin breaks. Although DNA damage-induced foci are typically analyzed in interphase cells, these foci can be also visualized on mitotic chromosomes. The foci where the repair proteins accumulate at the damage site is observed as mitotic chromosome break site. Since mitotic cells attach loosely or not attached to cell culture vessels, it is difficult to analyze foci on chromosomes in culture vessels under a microscope, so metaphase chromosome spread must be prepared for accurate analysis. The cytocentrifuge system is an ideal method to adhere mitotic cells to microscope slides for the fluorescent immunocytochemistry. This chapter introduces cytocentrifuge method to prepare metaphase spread for DNA damage foci analysis.
Topics: Chromosomes; DNA; DNA Damage; Interphase; Metaphase
PubMed: 36066713
DOI: 10.1007/978-1-0716-2433-3_10 -
Current Protocols Feb 2022Interphase or metaphase nuclei can be accessed in molecular cytogenetic analyses. Metaphase spreads are routinely studied by fluorescence in situ hybridization (FISH) to...
Interphase or metaphase nuclei can be accessed in molecular cytogenetic analyses. Metaphase spreads are routinely studied by fluorescence in situ hybridization (FISH) to answer clinical genetic questions. Even though metaphase quality is essential for FISH studies, there is limited ability in clinical cases to improve the quality of cytogenetic preparations. However, the quality of preps is important for the exact localization of FISH signals, which is necessary to identify individual chromosomes and chromosomal sub-regions using inverted DAPI banding. Here we present an efficient and easy-to-perform variant of standard slide pretreatment before a normal FISH procedure. This method reproducibly leads to solid, "steel," nonfuzzy, and well-DAPI-banded metaphases. This protocol works in blood lymphocyte and amniotic fluid-derived fibroblasts. © 2022 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol: Slide pretreatment for high-quality metaphases for molecular cytogenetics.
Topics: Cytogenetic Analysis; Cytogenetics; In Situ Hybridization, Fluorescence; Interphase; Metaphase
PubMed: 35213072
DOI: 10.1002/cpz1.392 -
Molecular Reproduction and Development Apr 2002
Review
Topics: Amphibians; Animals; Female; Genes, mos; MAP Kinase Signaling System; Maturation-Promoting Factor; Metaphase; Oocytes
PubMed: 11891929
DOI: 10.1002/mrd.10112 -
Experimental Cell Research Dec 1996
Review
Topics: Cell Nucleus; Chromosomes, Human; DNA Replication; Humans; Interphase; Metaphase; Transcription, Genetic
PubMed: 8986597
DOI: 10.1006/excr.1996.0359 -
Molecular Reproduction and Development 2011Mammalian eggs await fertilisation while arrested at the second metaphase stage of meiotic division. A network of signalling pathways enables the establishment and... (Review)
Review
Mammalian eggs await fertilisation while arrested at the second metaphase stage of meiotic division. A network of signalling pathways enables the establishment and maintenance of this metaphase-II arrest. In the absence of fertilisation, mammalian eggs can spontaneously exit metaphase II when parthenogenetically stimulated, or sometimes without any obvious stimulation. Ovulated rat eggs abortively release from metaphase-II arrest once removed from egg donors. Spontaneously activated rat eggs extrude the second polar body and proceed to the so-called metaphase III-'like' stage, with clumps of condensed chromatin scattered in the egg cytoplasm. It is still unclear what makes rat eggs susceptible to spontaneous activation; however, a vague picture of the signalling pathways involved in the process of spontaneous activation is beginning to emerge. Such cell cycle instability is one of the major reasons why it is more difficult to establish nuclear transfer in the rat. This review examines the known predisposing factors and biochemical mechanisms involved in spontaneous activation. The strategies used to prevent spontaneous metaphase-II release in rat eggs will also be discussed.
Topics: Animals; Cell Cycle Checkpoints; Female; Meiosis; Metaphase; Models, Biological; Oogenesis; Ovum; Parthenogenesis; Rats; Time Factors
PubMed: 21910153
DOI: 10.1002/mrd.21385 -
Medical & Biological Engineering &... Jan 2022Chromosomes are bodies that contain human genetic information. Chromosomal disorders can cause structural and functional disorders in individuals. Detecting the...
Chromosomes are bodies that contain human genetic information. Chromosomal disorders can cause structural and functional disorders in individuals. Detecting the metaphase stages of the cells accurately is a crucial step to detect possible defects in chromosomes. Thus, it is vital at this stage to identify the identical chromosome of each chromosome, to perform the pairing process, and to identify problems arising from this process. In this study, it was investigated whether the analyzable metaphase images can be analyzed by using the transfer learning and fine tuning approaches of deep learning models. The weights of VGG16 and InceptionV3 models trained with ImageNet data set were transferred to this problem and the classification process was carried out. True positive ratio values are 99%(± 0.9) and 99%(± 0.9) for VGG and Inception networks, respectively. The classification performances obtained depending on the changing training set ratios are presented comparatively in figures. F-measure, precision, and recall values obtained for the VGG and Inception networks were observed as 99%(± 1.0) and 99%(± 1.0), respectively. F-measure, precision, and recall values of VGG and Inceptionv3 networks are also presented with respect to the ratio of training size. The obtained results have compared with the state-of-the-art methods in the literature and supported with the tables and graphics. The training phase was also accelerated by using transfer learning and fine tuning methods. Transfer learning and fine tuning processes have almost similar performance as the models used in the literature and trained from scratch in metaphase Graphical Abstract The Flowchart of the proposed system for classifying metaphase candidates detection.
Topics: Deep Learning; Humans; Metaphase; Neural Networks, Computer
PubMed: 34822119
DOI: 10.1007/s11517-021-02474-z