Disease Prediction and Drug Development
Arvind Kumar Bansal, Javed Iqbal Khan, S. Kaisar Alam in Introduction to Computational Health Informatics, 2019
Mitosis is a multiphase process. The main stages are: 1) prophase; 2) prometaphase; 3) metaphase; 4) anaphase and 5) telophase. In the prophase, the chromosome-strands called chromatids separate. However, the chromatids remain connected at the constricted region joining the chromatids. After that, chromatids undergo a condensation process on a bipolar fibrous material within a cell. This fibrous material is called mitotic spindle. During prometaphase, the nuclear envelope within a cell is divided into multiple fluid-filled fragments called a vesicle. These vesicles are divided eventually in daughter-cells. In the anaphase, the sister-chromatids separate abruptly. The spindle-poles separate using motor proteins. Mitosis ends with telophase when the separated chromosomes reach the poles of the spindle, and the chromosomes begin to decondense from the spindle. Telophase is followed by cytokinesis – the division of the cytoplasm into identical cells: cells having identical genetic composition.
Basic Cell Biology
Kedar N. Prasad in Handbook of RADIOBIOLOGY, 2020
In mitosis, each chromosome duplicates itself. The duplicated strands separate as the nucleus divides, so that the daughter nuclei have the same set of chromosomes as their parent cell. Figure 2.2 shows a diagrammatic representation of the process of mitosis in a cell. During mitosis, a cell passes through four stages: prophase, metaphase, anaphase, and telophase. During prophase, each chromosome doubles itself, and the nuclear membrane and nucleus disappear. During metaphase, spindles form and chromosomes lie on the equatorial plate. During anaphase, chromosomes separate, and each half moves toward a pole. During telophase, the nucleus appears, and the cell divides into two daughter cells — each having an identical set of diploid chromosomes. The process of mitosis is so precise that any change in the chromosomes or DNA would definitely reflect in daughter cells after completion of cell division.
Micronucleus assay and oral hygiene index in smokers
Ade Gafar Abdullah, Isma Widiaty, Cep Ubad Abdullah in Medical Technology and Environmental Health, 2020
Smoking and breathing the smoke of cigarettes can damage the DNA due to genotoxic substances such as benzopyrene and nicotine. In addition, tobacco also has carcinogenic ingredients and the heat generated from smoking can add to the aggressive action of the carcinogenic material on the oral mucosa. Titrated nicotine is a dangerous nitrosamine compound, according to the International Agency for Research on Cancer (IARC), in producing DNA adducts either through methylation or hydroxylation pathways. DNA adducts can then induce the formation of a micronucleus, a mass with a structure like a nucleus that has a small size and that is located close to the real nucleus, in the cytoplasm. It is formed due to chromosomal abnormalities in the cell division phase – namely anaphase. Chromosome damage caused by genotoxic substances in basal cells can be seen in the form of micronuclei that migrate to the upper epithelial layer until they are exfoliated. Micronucleus frequency is a measure of chromosomal damage at the beginning of cell division and the number of micronuclei related to carcinogenic stimuli, before the development of clinical symptoms – namely premalignant and malignant events.
Electrochemical generation of microbubbles by carbon nanotube interdigital electrodes to increase the permeability and material uptakes of cancer cells
Published in Drug Delivery, 2019
Mohammad Ali Khayamian, Shahriar Shalileh, Shohreh Vanaei, Mohammad Salemizadeh Parizi, Saeid Ansaryan, Mohammad Saghafi, Fereshteh Abbasvandi, Amirali Ebadi, Pouya Soltan Khamsi, Mohammad Abdolahad
In addition to AV/PI viability assay, cell cycle flow cytometry assay was conducted to evaluate the impact of the different treatments on the cell cycle phases of the cancer cells. When a cell is entered into the mitosis phase of its life cycle, the transition from metaphase to anaphase occurs by depolymerization of the microtubules originated from the centrosomes to the chromosomes (Mitchison, 1971). Nevertheless, since the paclitaxel prevents depolymerization of microtubules, therefore the cell is not able to enter to the anaphase and is remained at metaphase stage (Schiff & Horwitz, 1980; Weaver, 2014). Hence, cells are arrested in mitotic phase and consequently could be tracked in the cell cycle flow cytometry. Figure S1-B demonstrates the different cell cycle phase of MDA-MB-231 cells in the 5 groups of treatment. As expected, the groups of control and US + MBs indicate no mitotic arrest in their typical graph of cell cycle, which pertains to lack of PTX uptake by the cells. The ratio of G2/M to G0/G1 peaks are displayed in the Figure 5-B. Fall in the peak of G0/G1 and rise of G2/M peak as the sign of mitosis arrest could be observed in the latter 3 groups of treatment which reaches a high in the US + Drug + MBs and corroborates the effect of generated microbubbles on better uptake of PTX by cells.
Morphological and chromosomal abnormalities in gamma radiation-induced mutagenized faba bean genotypes
Published in International Journal of Radiation Biology, 2018
Nurmansyah, Salem S. Alghamdi, Hussein M. Migdadi, Muhammad Farooq
Stickiness is one of the most common chromosome aberrations in mitotic and meiotic cells. Stickiness occurs when chromosomes clump together because of nucleic acid depolymerization or partial nucleoprotein dissociation (Choudhary et al. 2012). Koernicke (1905) first identified chromosome stickiness as an effect of ionizing radiation, and Beadle (1932) later reported that a mutation in a recessive allele called sticky (st) caused the condition. Another common chromosome aberration in this study is laggard, which was present in both mitotic and meiotic cells. Laggard occurs when a chromosome is improperly positioned, in relation to other chromosomes. Upon exposure to radiations, the spindle fibers may fail to carry the respective chromosome to the polar regions and resultantly the lagging chromosomes appeared at anaphase I (Tarar and Dnyansagar 1980; Das and Roy 1989; Saad-Allah et al. 2014). Laggards may also be formed due to late chiasma terminalisation (Pagliarini 1990) and improper spindle functioning (Kumar and Rai 2007). However, disturbed polarity at anaphase and telophase can be caused by disturbances in spindle fiber formation (Aslam et al. 2016).
Assessment of the in vitro genotoxicity of TiO2 nanoparticles in a regulatory context
Published in Nanotoxicology, 2018
Sandrine Charles, Stéphane Jomini, Valérie Fessard, Emilie Bigorgne-Vizade, Christophe Rousselle, Cécile Michel
DNA damage can also arise through indirect mechanisms where the NPs do not physically interact with the DNA molecule, but with other cellular proteins such as those involved in cell division, DNA replication, transcription, and repair. Indeed, many of the proteins involved in the repair machinery possess metallic linked functions that may be disturbed by the NPs due to competition for biological sites or due to redox potential modification (Carriere et al. 2017). This hypothesis was highlighted in a microarray test using plasmid containing fluorescent nucleotides showing decreased nucleotide excision repair (NER) and base excision repair (BER) activities in A549 cells exposed to TiO2-NPs (Jugan et al. 2012) and confirmed in a direct in vitro test on the same cell line (Armand et al. 2016). TiO2-NPs have a very high affinity for phosphate groups, possibly engendering a high reactivity and trapping against DNA itself (DNA contains high levels of phosphate residues) and phosphorylation–dephosphorylation reactions, such as those implicated in DNA repair machinery (Carriere et al. 2017). Finally, another mode of action proposed for TiO2-NPs is an alteration of the mitotic spindle apparatus. Some publications reported disturbance of mitosis, and abnormal multipolar spindle formation, chromosomal alignment, and segregation during anaphase and telophase, as well as disturbance of the cell cycle checkpoint function (Magdolenova et al. 2014).
Related Knowledge Centers
- Chromatid
- Protease
- Ubiquitin
- Mitosis
- Metaphase
- Chromosome
- Anaphase-Promoting Complex
- Chaperone
- Securin
- Separase