Cancer Biology and Genetics for Non-Biologists
Trevor F. Cox in Medical Statistics for Cancer Studies, 2022
When a cell divides into two daughter cells, it passes through two gap phases (G1 and G2), a synthesis phase (S) and a mitosis phase (M). A brief description of the phases is: G1 phase: the cell enlarges, organelles are copied, preparation for cell divisionS phase: DNA replicatesG2 phase: the cell further enlarges, proteins and organelles are madeM phase: the splitting of the cell, first mitosis consisting of the phases: prophase, metaphase, anaphase and telophase, followed by cytokinesis where the cytoplasm of the cell is split in two, resulting in the two new cells
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.
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.
Toxicogenetic profile of the monoterpene alpha-terpineol on normal and tumor eukaryotic cells
Published in Drug and Chemical Toxicology, 2023
Helber Alves Negreiros, Sabryna Brena Cunha Fontele, Felipe Alves Batista, Marlene Gomes de Farias, Felipe Cavalcanti Carneiro da Silva, Maria Luisa Lima Barreto do Nascimento, Kariely Gonçalves de Moura, Layde de Sousa Correa, Ana Rafaela Silva Pereira, Luana de Oliveira Lopes, Paulo Michel Pinheiro Ferreira, Anderson Nogueira Mendes, Juan Carlos Ramos Gonçalves, Ana Amélia de Carvalho Melo-Cavalcante, João Marcelo de Castro e Sousa
The cytotoxic and mutagenic activity of alpha-terpineol was also analyzed by a phytoassay using meristematic cells from Allium cepa roots according to Guerra and Souza (2022). Initially, the similar bulbs were roots cleaned in distilled water for 48 h at room temperature. After growth, roots measuring approximately 1 cm were placed in different treatment solutions (negative control (NC), T1: 10 µg/mL, T2: 50 µg/mL, T3: 100 µg/mL and PC) and incubated for 24, 48, and 72 h. The NC and PC used for Allium cepa test were distilled water and copper sulfate 0.6 μg/mL, respectively. After each exposure time, the roots were measured with a digital pachymeter. Roots very short (≤0.5 cm) or very lengthy (≥1.2 cm) were rejected. Root size (RS) was used as toxicity parameter. After measurement, the roots were collected and fixed in ethanol:acetic acid (3:1) for 24 h. Once fixed, the roots were washed in distilled water, hydrolyzed in 1 M HCl at 60 °C for 10 min and stained with 2% acetic orcein. Mutagenicity was evaluated through analysis of chromosomal and micronuclei alterations in A. cepa meristematic cells (1000 cells/bulb). Cytotoxicity was determined by the mitotic index (MI). Mitotic index was calculated as follows: prophase + metaphase + anaphase + telophase/total number of cells × 100. A total of 5000 cells per concentration (1000 cells/slide) were counted. Analyses were performed by light microscope (Olympus, Tokyo, Japan).
Occam’s broom and the dirty DSB: cytogenetic perspectives on cellular response to changes in track structure and ionization density
Published in International Journal of Radiation Biology, 2021
Cell killing is the damage endpoint that immediately comes to mind when discussing RBE/LET relationships, and the causal relationship it shares with chromosome aberrations is well established. The asymmetrical exchanges, which constitute the remaining half of rejoining products, always produce acentric fragments. Since the fragments lack a spindle mechanism to ensure proper segregation during telophase, they are eventually lost from cell progeny during subsequent mitoses. Under controlled experimental conditions, there is a near-perfect 1:1 correlation between IR-induced asymmetrical exchange events and lethality as measured by clonogenic survival after exposure of human diploid cells in G1/G0 (Cornforth and Bedford 1987). Moreover, for diploid cells similarly exposed, there is a direct correspondence between individual cells containing microscopically visible acentric fragments and failure of those same exact cells to survive (Revell 1983).
Genotoxic and mutagenic studies of teratogens in developing rat and mouse
Published in Drug and Chemical Toxicology, 2019
Eyyüp Rencüzoğulları, Muhsin Aydın
Micronucleus is a small nucleus that forms whenever a chromosome or a fragment of a chromosome is not incorporated into one of the daughter nuclei during the cell division. It is found outside the main nucleus and formed in telophase due to the acentric chromosomal or chromatid fractures. Also, it could be formed during the telophase from one or a few chromosomes or chromatids that lag behind the anaphase (anaphase bridge) (Surrallés et al. 1995). In addition, multipolar anaphase and telophase could cause MN formation (Topaktas and Rencuzogullari 2010). Chromosome loss or nondisjunction of chromosomes that may lead to MN formation is one of the important events that is observed in cancer and aging. This is probably the result of disruption in spindle apparatus and centromere or condensation of the chromosome prior to metaphase (Dellarco et al. 1985). Thus, both the clastogenic and the aneugenic effects can be determined by the MN test (Kirsch-Volders et al. 1997, Norppa and Falck 2003). In previous studies, the increase in MN frequency in peripheral blood lymphocytes from cancer patients was found to be as much as the MN frequency in the targeted cancer tissue (Cheng et al. 1996, Duffaud et al. 1997, Bonassi et al. 2007). In addition, in the study of Fenech et al. (1999), which have been conducted with an international collaboration, has clearly shown the relationship between MN and cancer in humans.
Related Knowledge Centers
- Chromatid
- Eukaryote
- Nuclear Envelope
- Prometaphase
- Meiosis
- Nucleolus
- Mitosis
- Cell
- Prophase
- Chromosome