DNA synthesis in radiation-induced micronuclei studied by bromodeoxyuridine (BrdUrd) labelling and anti-BrdUrd antibodies

Kramer, Johannes; Schaich-Walch, G.; Nüsse, Michael

doi:10.1093/mutage/5.5.491

Cited by 31 publications

(9 citation statements)

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“…Therefore, micronuclei may be formed from chromosomal material fragmented during mitosis and not incorporated in daughter nuclei at completion of telophase. Micronuclei are then coated with a nucleus envelope, and their DNA is often transcriptionally active and undergoes replication (Nusse, 1981;Kramer et al, 1990). The frequency of the presence of micronuclei serves as a measure of in vitro or in vivo exposure to mutagens and carcinogens.…”

Section: Discussionmentioning

confidence: 99%

Genotoxicity, cytotoxicity and toxicological evaluation of whole plant extracts of the medicinal plant Phyllanthus niruri (Phyllanthaceae)

Asare¹,

Bugyei²,

Sittie³

et al. 2012

Genet. Mol. Res.

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ABSTRACT. Phyllanthus niruri is a medicinal plant (commonly known as stone breaker) found in the tropics and other parts of the world. It is known for its capacity to block the formation of calcium oxalate crystals and kidney stone formation in urolithiasis. This plant has been used to treat hyperglycemia, hypertension, pain, and mild cases of malaria. We examined the geno-, cyto-and overall toxicity of P. niruri whole plant ethanolic extract. The extract was administered as a single dose of 30 or 300 mg/kg to laboratory rats by gavage, accompanied by negative (0.9% saline) and positive (10 mg/mL N-ethyl-N-nitrosourea) controls that were injected intramuscularly 48 h after extract administration. The ratio of polychromatic (PCE)/normochromatic erythrocytes (NCE) from femur bone marrow was scored for genotoxicity. Cytotoxicity was determined using descending concentrations (0.2-0.0125 g/mL) of the extract incubated with peripheral blood mononuclear cells. Phyllanthus niruri geno-and cytotoxicity Lactate dehydrogenase release from damaged cells was determined and the CC 50 calculated. Subchronic administration of the extract at 30 or 300 mg/kg was done for 90 days to determine general toxicity. PCE:NCE (%) for the extract and negative control was 63, compared to 168 (positive control). The CC 50 was 26.3 mg/mL and hepato-renal toxicity after subchronic extract administration was nil. We conclude that ethanol extract of P. niruri is not cytotoxic or genotoxic, and is generally non-toxic on subchronic administration.

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Section: Discussionmentioning

confidence: 99%

Genotoxicity, cytotoxicity and toxicological evaluation of whole plant extracts of the medicinal plant Phyllanthus niruri (Phyllanthaceae)

Asare¹,

Bugyei²,

Sittie³

et al. 2012

Genet. Mol. Res.

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“…They suggested that fragments or breaks whose termini were not repaired might be subject to nuclease degradation resulting in gene loss. In the case of persistent fragments it has been shown that those incorporated into micronuclei often retain the capacity to synthesise DNA (Pincu et al 1985, Kramer et al 1990). However, in an unirradiated Burkitt's lymphoma line, Kato and Sandberg (1968) observed spontaneously-occurring micronuclei that were unable to synthesize RNA.…”

Section: Discussionmentioning

confidence: 99%

Prediction of the Initial Slope of the Acute Clonogenic Survival Curve by the Post-irradiation Behaviour of Cytochalasin-induced Polykaryons

Davies

Court

Burn

1995

International Journal of Radiation Biology

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We have investigated the behaviour of 11 lines of cultured cells in a survival assay whose endpoint is the ability of cells to become polyploid when incubated in the presence of cytochalasin B (CB). Single cells were induced by CB to form polykaryons after irradiation, and, by analogy with the colony-forming assay, the survival of polykaryon-forming units (PFUs) was defined as the fraction of cells able to achieve a given DNA content (at least 16C in most experiments). There was a radiation dose-dependent reduction in PFU survival, which, following the appearance of cells containing at least 16C DNA, was not markedly dependent upon the sampling time. In all cases, PFUs appeared to be more radioresistant than clonogens, especially at high dose. In 9/11 lines the PFU dose-response curves were exponential, while in two there was a pronounced curvature (quadratic parameter). There was a highly significant positive correlation between PFU response and the corresponding clonogenic initial slope. We suggest that in polykaryons the opportunity for the mechanical loss of DNA fragments may be reduced because the cells do not divide, and therefore that DNA damage resulting from chromosome aberrations may be less important in PFUs than in clonogens. Consequently, PFUs may express lesions not directly associated with mechanical gene loss. This assay may yield an alternative estimate for the clonogenic initial slope, and could be of use where colony-forming assays fail due to incomplete cell monodispersion.

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“…Thus, micronuclei formation has paved a pathway for stabilization of genetic structure. It has been reported that micronuclei are able to synthesize DNA (Kramer et al 1990) and there is ultra-structural similarity between micronuclei and cell nuclei (Schiffmann and De Boni 1991).…”

Section: Discussionmentioning

confidence: 99%

Nuclear Blebs Assay for Genome Instability in <i>Phaseolus vulgaris</i> L.

Kumar

Chaudhary

2015

CYTOLOGIA

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Summary Micronuclei are extra nuclear structures, formed by the exclusion of chromosomes during cell division. The genotoxicity of a compound and its impact on the genome can be assessed via micronuclei formation. The present study has been undertaken to evaluate the mutagenic effect of the alkylating agent EMS on the meiotic behavior of pollen mother cells of Phaseolus vulgaris L. The cytological analysis revealed the induction of micronuclei at all the three administered concentrations of EMS, viz. 0.1, 0.3 and 0.5%. Besides micronuclei formation, other meiotic abnormalities associated with chromosomal segregation, such as stickiness, laggard, bridge, multivalent, etc., were also reported at metaphase I/II and anaphase I/II. The micronuclei formed would have two fates either it remains until the tetrad stage or is expelled out in the form of microcytes which will give rise to sterile pollen grains affecting the pollen fertility. The present study also documents the first instance of nuclear budding in Phaseolus vulgaris L. It is contemplated that these nuclear buds will later on convert into micronuclei. The micronuclei formation results in partial elimination of the genome, which could be efficiently utilized in breeding programmes for the production of addition and substitution lines. Similarly, haploid lines could also be produced by the complete loss of genome. It is therefore essential to understand the biological aspects of micronuclei formation, its consequences on the cell carrying it and other factors related to it so that in the future, it could be used as a marker of genetic damage and also be utilized in breeding programmes.

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DNA synthesis in radiation-induced micronuclei studied by bromodeoxyuridine (BrdUrd) labelling and anti-BrdUrd antibodies

Cited by 31 publications

References 0 publications

Genotoxicity, cytotoxicity and toxicological evaluation of whole plant extracts of the medicinal plant Phyllanthus niruri (Phyllanthaceae)

Genotoxicity, cytotoxicity and toxicological evaluation of whole plant extracts of the medicinal plant Phyllanthus niruri (Phyllanthaceae)

Prediction of the Initial Slope of the Acute Clonogenic Survival Curve by the Post-irradiation Behaviour of Cytochalasin-induced Polykaryons

Nuclear Blebs Assay for Genome Instability in <i>Phaseolus vulgaris</i> L.

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