関: germline micronuclei、germline micronucleus、micronucleate、micronuclei

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/04/09 06:38:04」(JST)

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The micronucleus is the smaller nucleus in ciliate protozoans, such as the Paramecium. In fission it divides by mitosis, and in conjugation it furnishes the pairing of gamete nuclei, by whose reciprocal fusion a zygote nucleus is formed, which gives rise to the macronuclei and micronuclei of the individuals of the next cycle of fission.

Other meaning

Micronucleus is also the name given to the small nucleus that forms whenever a chromosome or a fragment of a chromosome is not incorporated into one of the daughter nuclei during cell division. In newly formed red blood cells in humans, these are known as Howell-Jolly bodies. In normal people and many other mammals, which do not have nuclei in their red blood cells, the micronuclei are removed rapidly by the spleen. Hence high frequencies of micronuclei in human peripheral blood indicate a ruptured or absent spleen. In mice, these are not removed, which is the basis for the in vivo micronucleus test.

In a micronucleus test, the genotoxicity of a chemical compound is tested.

English Journal

Co-assessment of cell cycle and micronucleus frequencies demonstrates the influence of serum on the in vitro genotoxic response to amorphous monodisperse silica nanoparticles of varying sizes.

Gonzalez L, Lukamowicz-Rajska M, Thomassen LC, Kirschhock CE, Leyns L, Lison D, Martens JA, Elhajouji A, Kirsch-Volders M.Author information Laboratory for Cell Genetics, Vrije Universiteit Brussel , Brussels , Belgium.AbstractAbstract Serum proteins have been shown to modulate the cytotoxic and genotoxic responses to nanomaterials. The aim was to investigate the influence of serum on the induction of micronuclei (MN) by nanoparticles (NPs) of different sizes. Therefore, A549 human lung carcinoma cells and amorphous monodisperse silica nanoparticles (SNPs) were used as models. Assessment of the cell viability, cell cycle changes and induction of MN by SNPs ranging from 12 to 174 nm was performed in presence or absence of serum, applying the in vitro flow cytometry-based MN assay. Here, it has been demonstrated that serum has an influence on these end points, with a lower cell viability in absence of serum compared with the presence of serum. Further, cell cycle changes, specifically, G1 and S-phase arrest, were observed in absence of serum for four out of six SNPs tested. A size-dependent MN induction was observed: larger SNPs being more active in absence of serum. In addition, the serum influence was characterised by a size-dependency for cytotoxic and genotoxic effects, with a higher influence of serum for smaller particles. The data indicate that the in vitro micronucleus assay in presence and absence of serum could be advised for hazard assessment because it demonstrates a higher sensitivity in serum-free conditions than in conditions with serum. However, this recommendation applies only if the cell line used is able to proliferate under serum-free conditions because cell division is a prerequisite for MN expression.
Nanotoxicology.Nanotoxicology.2014 Dec;8:876-84. doi: 10.3109/17435390.2013.842266.
Abstract Serum proteins have been shown to modulate the cytotoxic and genotoxic responses to nanomaterials. The aim was to investigate the influence of serum on the induction of micronuclei (MN) by nanoparticles (NPs) of different sizes. Therefore, A549 human lung carcinoma cells and amorphous monod
PMID 24040841

Gold-nanobeacons for gene therapy: evaluation of genotoxicity, cell toxicity and proteome profiling analysis.

Conde J, Larguinho M, Cordeiro A, Raposo LR, Costa PM, Santos S, Diniz MS, Fernandes AR, Baptista PV.Author information CIGMH, DCV, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa , Caparica , Portugal.AbstractAbstract Antisense therapy is a powerful tool for post-transcriptional gene silencing suitable for down-regulating target genes associated to disease. Gold nanoparticles have been described as effective intracellular delivery vehicles for antisense oligonucleotides providing increased protection against nucleases and targeting capability via simple surface modification. We constructed an antisense gold-nanobeacon consisting of a stem-looped oligonucleotide double-labelled with 3'-Cy3 and 5'-Thiol-C6 and tested for the effective blocking of gene expression in colorectal cancer cells. Due to the beacon conformation, gene silencing was directly detected as fluorescence increases with hybridisation to target, which can be used to assess the level of silencing. Moreover, this system was extensively evaluated for the genotoxic, cytotoxic and proteomic effects of gold-nanobeacon exposure to cancer cells. The exposure was evaluated by two-dimensional protein electrophoresis followed by mass spectrometry to perform a proteomic profile and 3-(4,5-Dimethylthiazol-2-Yl)-2,5-Diphenyltetrazolium Bromide (MTT) assay, glutathione-S-transferase assay, micronucleus test and comet assay to assess the genotoxicity. This integrated toxicology evaluation showed that the proposed nanotheranostics strategy does not exhibit significant toxicity, which is extremely relevant when translating into in vivo systems.
Nanotoxicology.Nanotoxicology.2014 Aug;8:521-32. doi: 10.3109/17435390.2013.802821. Epub 2013 May 28.
Abstract Antisense therapy is a powerful tool for post-transcriptional gene silencing suitable for down-regulating target genes associated to disease. Gold nanoparticles have been described as effective intracellular delivery vehicles for antisense oligonucleotides providing increased protection aga
PMID 23642008

Mechanisms of genotoxicity. A review of in vitro and in vivo studies with engineered nanoparticles.

Magdolenova Z, Collins A, Kumar A, Dhawan A, Stone V, Dusinska M.Author information NILU-Norwegian Institute for Air Research, MILK, Health Effects Laboratory , Kjeller , Norway.AbstractAbstract Engineered nanoparticles (NPs) are widely used in different technologies but their unique properties might also cause adverse health effects. In reviewing recent in vitro and in vivo genotoxicity studies we discuss potential mechanisms of genotoxicity induced by NPs. Various factors that may influence genotoxic response, including physico-chemical properties and experimental conditions, are highlighted. From 4346 articles on NP toxicity, 112 describe genotoxicity studies (94 in vitro, 22 in vivo). The most used assays are the comet assay (58 in vitro, 9 in vivo), the micronucleus assay (31 in vitro, 14 in vivo), the chromosome aberrations test (10 in vitro, 1 in vivo) and the bacterial reverse mutation assay (13 studies). We describe advantages and potential problems with different methods and suggest the need for appropriate methodologies to be used for investigation of genotoxic effects of NPs, in vitro and in vivo.
Nanotoxicology.Nanotoxicology.2014 May;8:233-78. doi: 10.3109/17435390.2013.773464. Epub 2013 Mar 20.
Abstract Engineered nanoparticles (NPs) are widely used in different technologies but their unique properties might also cause adverse health effects. In reviewing recent in vitro and in vivo genotoxicity studies we discuss potential mechanisms of genotoxicity induced by NPs. Various factors that ma
PMID 23379603

Japanese Journal

Effective use of the Pig-a gene mutation assay for mutagenicity screening : measuring CD59-deficient red blood cells in rats treated with genotoxic chemicals

Kimoto Takafumi,Chikura Satsuki,Suzuki-Okada Kumiko [他]
The Journal of toxicological sciences 37(5), 943-955, 2012-10
NAID 40019458167

Estimation of a Safe Level for Occupational Exposure to Vinyl Chloride Using a Benchmark Dose Method in Central China

JIAO Jie,FENG Nan-nan,LI Yong,SUN Yuan,YAO Wu,WANG Wei,ZHANG Guang-hui,SUN Shi-yi,TAN Hong-shan,WANG Qi,ZHU Yiliang,LI Yongliang,BRANDT-RAUF Paul W.,XIA Zhao-lin
Journal of occupational health 54(4), 263-270, 2012-07-01
NAID 10030495913