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Glossary of scientific and technical terms in bioengineering and biological engineering
Published in Megh R. Goyal, Scientific and Technical Terms in Bioengineering and Biological Engineering, 2018
Prophase (Gr. pro, before + phasis, appearance) is an early stage in nuclear division, characterized by the shortening and thickening of the chromosomes and their movement to the metaphase plate. It occurs between interphase and metaphase. During this phase, the centriole divides and the two daughter centrioles move apart. Each sister DNA strand from interphase replication becomes coiled, and the chromosome is longitudinally double except in the region of the centromere. Each partially separated chromosome is called a chromatid. The two chromatids of a chromosome are sister chromatids.
Genes and Genomics
Published in Firdos Alam Khan, Biotechnology Fundamentals, 2020
Mitosis is the process in which a eukaryotic cell separates the chromosomes in its cell nucleus into two identical sets in two daughter nuclei. It is generally followed immediately by cytokinesis, which divides the nuclei, cytoplasm, organelles, and cell membrane into two daughter cells containing roughly equal shares of these cellular components. Mitosis and cytokinesis together define the mitotic (M) phase of the cell cycle such as the division of the mother cell into two daughter cells, genetically identical to each other and to their parent cell. Mitosis divides the chromosomes in a cell nucleus. Mitosis occurs exclusively in eukaryotic cells but occurs in different ways in different species. For example, animals undergo an “open” mitosis in which the nuclear envelope breaks down before the chromosomes separate, whereas fungi such as Aspergillus nidulans and Saccharomyces cerevisiae (yeast) undergo a “closed” mitosis in which chromosomes divide within an intact cell nucleus. Prokaryotic cells, which lack a nucleus, divide using binary fission. The process of mitosis is complex and highly regulated. The sequence of events is divided into phases that correspond to the completion of one set of activities and the start of the next. These stages are the prophase, prometaphase, metaphase, anaphase, and telophase. During the process of mitosis, the pairs of chromosomes condense and attach to fibers that pull the sister chromatids to opposite sides of the cell. The cell then divides in cytokinesis to produce two identical daughter cells. Because cytokinesis usually occurs in conjunction with mitosis, “mitosis” is often used interchangeably with “mitotic phase.” However, there are many cells in which mitosis and cytokinesis occur separately, forming single cells with multiple nuclei. This mostly occurs among the fungi and slime molds but is also found in various other groups. Even in animals, cytokinesis and mitosis may occur independently such as during certain stages of fruit fly embryonic development. Errors in mitosis can either kill a cell through apoptosis or cause mutations that may lead to cancer (Figure 2.11).
An endophytic fungus, Penicillium simplicissimum conjugated with C60 fullerene for its potential antimitotic, anti-inflammatory, anticancer and photodegradation activities
Published in Environmental Technology, 2023
M. Govindappa, A. Vishaka, B.S. Akshatha, Dimple Popli, N. Sunayana, C. Srinivas, Arivalagan Pugazhendhi, Vinay B. Raghavendra
The Ps-FNPs exhibited the cellular, nucleolar and chromosomal abnormalities of cells of onion root tips on normal mitotic phases of the cell cycle, as shown in Figure 5(A–D). The Ps-FNPs-treated cells also showed a nucleolar shrinkage and cell arrest at prophase, binuclear and multinucleolar cells, a chromosomal bridge and diversion at anaphase was observed, whereas chromosomal fragment and abnormal distribution at metaphase stage, as shown in Figure 5(E–H). The percentage of the mitotic index of Ps-FNPs was found to be 17% when compared with the standard lapachol that showed 13%, whereas the untreated control showed 95%, as shown in Figure 6. The ability of Ps-FNPs to penetrate mitotic stages of the onion root tip showed aggregation at a lower extent in nucleolar shrinkage and cell arrest at the prophase stage when compared with C60 fullerene alone. Similar reports were also shown for stress generated by zinc oxide NPs in the vicinity of A. cepa roots [43].
Antimitotic and toxicogenetic action of Stevia urticifolia aerial parts on proliferating vegetal and mammalian cells: in vitro and in vivo traditional and replacement methods
Published in Journal of Toxicology and Environmental Health, Part A, 2022
Paulo Michel Pinheiro Ferreira, Ian Jhemes Oliveira Sousa, Kamilla Nunes Machado, Leonel Antônio da Silva Neto, Milena Monteiro de Freitas, Ingredy Lopes dos Santos, Débora Caroline do Nascimento Rodrigues, Rayran Walter Ramos de Sousa, Antonielly Campinho dos Reis, Maria Luisa Lima Barreto do Nascimento, Ag-Anne Pereira Melo de Menezes, Andréa Mendes do Nascimento, José Roberto de Oliveira Ferreira, Ana Paula Peron, João Marcelo de Castro e Sousa
Root growth was significantly inhibited by EtAcSur (33.2 ± 8.1, 30.2 ± 8.1 and 64.3 ± 5.4%) at concentrations of 25, 50 or 100 µg/ml (1.53 ± 0.1, 1.54 ± 0.1 and 1.07 ± 0.1 cm, respectively) compared to negative control (1.99 ± 0.1 cm). Copper sulfate-treated bulbs exhibited roots with 0.36 ± 0.02 cm and growth inhibition of 86.2 ± 1.3% (Figure 3). This inhibition of root growth was corroborated by MI regression at 25, 50 and 100 µg/ml (33 ± 4.4, 28.3 ± 3.4 and 21.1 ± 1.6%, respectively) in comparison with negative control (68.7 ± 3.4%), and modifications in cycle phases, including increased number of cells in interphase and reduced amount of mitosis (prophase, metaphase, anaphase and telophase) in a similar way found for positive control (Table 1). Mitotic index is an important indicator of cell proliferation (Fernandes, Mazzeo, and Marin-Morales 2007; Leme and Marin-Morales 2009). The observed decrease was linked to inhibition of DNA synthesis or blockade of cell cycle, which delays mitosis progression or alternatively induces cell to G0 as noted with EtAcSur, preventing returning to the cell division.
Phytochemical screening, phenolic and flavonoid contents, antioxidant and cytogenotoxicity activities of Combretum leprosum Mart. (Combretaceae)
Published in Journal of Toxicology and Environmental Health, Part A, 2021
Herbert Gonzaga Sousa, Valdiléia Teixeira Uchôa, Suzana Maria Galvão Cavalcanti, Pedro Marcos de Almeida, Mariana Helena Chaves, José De Sousa Lima Neto, Paulo Humberto Moreira Nunes, Joaquim Soares da Costa Júnior, Mahendra Rai, Iolanda Souza Do Carmo, Elcilene Alves de Sousa
Cytotoxicity and genotoxicity tests performed with A. cepa were based on the method described by Leme and Marin-Morales (2009) with some modifications. The seeds of A. cepa (Vale-Ouro IPA-11) were germinated in Petri dishes containing distilled water at 28°C until the radicles reached 2 cm in length. These radicles were separated and exposed to different concentrations of the EEB and EEL (100, 250, 500, 1000, or 2000 µg/ml) for a period of 24 hr at room temperature. The positive control was made with methylmethosulfonate (MMS, Sigma-Aldrich, CAS N° 66–27-3), with a concentration of 10 ppm and negative control (NC) with distilled water. The radicles were collected and fixed with a 3:1 solution of ethyl alcohol and frozen acetic acid and underwent hydrolysis in 1 M HCl at 60°C for 10 min. To prepare the slides, the radicles were submitted to the Schiff’s reactive for 2 hr in the dark. The meristematic and F1 regions of the radicles were separated, covered with coverslips and carefully squashed in drop of 2% acetic carmine (Vetec), for subsequent examination under a light microscope (Olympus CX 21) at a total magnification of 40x. Ten slides for each treatment were prepared to evaluate the chromosomal aberrations (CA), micronuclei (MN) and mitotic indices (MI) in all mitosis stages (Interphase, Prophase, Metaphase, Anaphase, and Telophase). In each slide, about 500 cells were analyzed, totaling approximately 5000 cells per treatment.