A micronucleus test is a test used in toxicological screening for potential genotoxic compounds. The assay is now recognized as one of the most successful and reliable assays for genotoxic carcinogens, i.e., carcinogens that act by causing genetic damage and is recommended by the OECD guideline for the testing of chemicals.[1] There are two major versions of this test, one in vivo and the other in vitro.
The in vivo test normally uses mouse bone marrow or mouse peripheral blood. When a bone marrow erythroblast develops into a polychromatic erythrocyte, the main nucleus is extruded; any micronucleus that has been formed may remain behind in the otherwise anucleated cytoplasm. Visualisation of micronuclei is facilitated in these cells because they lack a main nucleus. An increase in the frequency of micronucleated polychromatic erythrocytes in treated animals is an indication of induced chromosome damage.[2]
Micronuclei (B, C) and nuclear abnormalities (A, D) in peripheral blood erythrocytes of penguins Pygoscelis papua.
Micronuclei were first used to quantify chromosomal damage by H.J. Evans et al., in root tips of the Broad Bean, Vicia faba. Subsequently, the in vivo assay was developed independently by W. Schmid and by J.A. Heddle and their colleagues. The mouse peripheral blood assay was developed by J.T. MacGregor and has now been adapted for measurement by flow cytometry by A. Tometsko and colleagues. The first use of micronuclei in cultured cells was by J.A. Heddle and colleagues in human lymphocytes. The assay has been improved by M. Fenech and colleagues for use in lymphocytes and other cells in culture cells.
Simple Giemsa staining was originally used for MN scoring. Later, the cytokinesis-block micronucleus (CBMN) method was established, where Cyt-B, an inhibitor of the spindle assembly, was used to prevent cytokinesis occurring after nuclear division. The CBMN method is used for the assessment of chromosomal loss, breakage, and associated apoptosis and necrosis induced by different mutagens.[3]
A micronucleus is the erratic (third) nucleus that is formed during the anaphase of mitosis or meiosis.
Micronuclei (the name means 'small nucleus') are cytoplasmic bodies having a portion of acentric chromosome or whole chromosome which was not carried to the opposite poles during the anaphase. Their formation results in the daughter cell lacking a part or all of a chromosome. These chromosome fragments or whole chromosomes normally develop nuclear membranes and form as micronuclei as a third nucleus. After cytokinesis, one daughter cell ends up with one nucleus and the other ends up with one large and one small nucleus, i.e., micronuclei. There is a chance of more than one micronucleus forming when more genetic damage has happened.
The micronucleus test is used as a tool for genotoxicity assessment of various chemicals. It is easier to conduct than the chromosomal aberration test in terms of procedures and evaluation.
Using fluorescent in situ hybridization (FISH) with probes targeted to the centromere region, it can be determined if a whole chromosome, or only a fragment is lost.
^http://www.oecd.org/document/35/0,3746,en_2649_34377_45773411_1_1_1_1,00.html. Archived 2012-01-18 at the Wayback Machine
^http://www.oecd.org/dataoecd/18/34/1948442.pdf. Archived 2010-07-05 at the Wayback Machine
^Luzhna, Lidia; Kathiria, Palak; Kovalchuk, Olga (2013-01-01). "Micronuclei in genotoxicity assessment: from genetics to epigenetics and beyond". Frontiers in Genetics. 4: 131. doi:10.3389/fgene.2013.00131. PMC 3708156. PMID 23874352.
There is a chance of more than one micronucleus forming when more genetic damage has happened. The micronucleustest is used as a tool for genotoxicity...
catastrophic mutational event called chromothripsis. Many micronucleus assays have been developed to test for the presence of these structures and determine...
numerical aberrations of the genetic material. This is similar to the micronucleustest and chromosome aberration assay, which detect structural and numerical...
The micronucleustest is another type of assay that uses gut cells to observe clastogens, and there are a few different types. The micronucleustest on...
OECD Guidelines for the Testing of Chemicals (OECD TG) are a set of internationally accepted specifications for the testing of chemicals decided on by...
chemical. In micronucleusTest, cells are examined for micronuclei, which are fragments or chromosomes left behind at anaphase, and is therefore a test for clastogenic...
genotoxicity such as the comet assay, cytokinesis-block micronucleustest and chromosome aberrations test. In humans, this damage can happen in primary parotid...
making it easy for a micronucleustest of its root tips to recognize genotoxic compounds. A lectin from V. graminea is used to test for the medically significant...
or long-term exposure to radiation. The micronucleustest and the premature chromosome condensation (PCC) test are available to measure acute exposure...
Assessment of Chios Mastic Oil by the In Vitro MicronucleusTest on Human Lymphocytes and the In Vivo Wing Somatic Test on Drosophila". PLOS ONE. 10 (6): e0130498...
Dunkelberg H. In vitro genotoxicity of polycyclic musk fragrances in the micronucleustest. Mutation Research, 395(2-3), 145-150. Kevekordes S. , Mersch-Sundermann...
found to be mutagenic in in vitro in the Ames test, CHL test, and in vitro in the mice micronucleustest. Azvudine is toxic to the reproductive system...
743–747. doi:10.1093/mutage/ges041. PMID 22869611. "Genotoxicity: The MicronucleusTest". Crios. Archived from the original on 28 August 2012. Retrieved 19...
In fact the genetic damage observed in studies performed with the micronucleustest applied on wild rodents from the Piana del Garigliano resulted among...
strength, body fat, body length and plasma immunoglobulins, abnormal open field test and modified SHIRPA behaviour, and severe hearing impairment at 13 weeks...
The latter is generated from the micronucleus by amplification of the genome and heavy editing. The micronucleus passes its genetic material to offspring...
maintains two distinct nuclear genomes, the micronucleus and the macronucleus. The macronucleus and micronucleus are located in the same cytoplasm, however...
that it was not mutagenic (assessed by the micronucleustest), nor was it genotoxic as assessed by the Ames test and Comet assay. When administered orally...
overweight Italian children as evaluated by the gamma-H2AX focus assay and micronucleustest". FASEB J. 25 (2): 685–93. doi:10.1096/fj.10-168427. PMID 21068397...
Forward- and Reverse-mutation Assays and in the Mouse Bone-marrow MicronucleusTest. University of Kentucky. Corcoran, John W. (6 December 2012). Biosynthesis...
3'-Dinitrobisphenol A is found to be genotoxic in male ICR mice on a micronucleustest. Its estrogenic potential is not known however it has shown some binding...
aberration assay on human lymphocytes in vitro and the mouse bone marrow micronucleustest in vivo". Environmental and Molecular Mutagenesis. 28 (2): 133–144...
mutant mice of both sex displayed various abnormalities in a modified SHIRPA test, including abnormal gait, tail dragging and an absence of pinna reflex, a...
Astyanax) Exposed to the Waters of Engano River (Brazil) as Determined by MicronucleusTests in Erythrocytes". Archives of Environmental Contamination and Toxicology...
They have a bigger, non-germline macronucleus and a small, germline micronucleus in each cell at the same time and these two carry out different functions...
macronucleus and a micronucleus, and both are usually visible. The macronucleus is large and sausage-shaped while the micronucleus is less prominent....
Brightfield whole slide imaging, IHC quantitative scoring, Cytokinesis-blocked micronucleus, region of interest annotating and measuring, tissue matching and FISH...
genotoxic effect of magnetic resonance negligible? Low persistence of micronucleus frequency in lymphocytes of individuals after cardiac scan". Mutat. Res...
; Hamada, S.; et al., Repeated-dose liver and gastrointestinal tract micronucleus assays with CI Solvent Yellow 14 (Sudan I) using young adult rats. Mutation...
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