DNA Content of Micronuclei in Human Lymphocytes

Pincu, Madeleine; Callisen, Hannes; Norman, Amos

doi:10.3109/rab.47.4.423

Cited by 25 publications

(9 citation statements)

References 3 publications

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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: 97%

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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Section: Discussionmentioning

confidence: 97%

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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“…To discriminate between the aneugenic and the clastogenic effects of chemicals and to further study the mechanisms underlying the origin of aneuploidy, the in vitro micronucleus test in combination with molecular techniques, such as centromere probing or kinetochore protein detection, has provided a sensitive, relatively easy, and fast assay [Vig and Swearngin, 1986;Degrassi and Tanzarella, 1988;Eastmond and Tucker, 1989;Miller and Adler, 1990;Miller et al, 1991;Russo et al, 1992 and Obe, 1985;Vanderkerken et al, 1989;Van Hummelen and Kirsch-Volders, 19921, DNA content, and area or diameter of the MN [Pincu et al, 1985;Vanderkerken et al, 1989;Vanparys et al, 1990;Van Hummelen and KirschVolders, 19921 have also been proposed for discriminating between aneugens and clastogens. However, they might be less accurate for such goals as detection of an aneuploidy threshold.…”

Section: Discussionmentioning

confidence: 99%

Indications for a threshold of chemically‐induced aneuploidy in vitro in human lymphocytes

Elhajouji

Kirsch‐Volders

1995

Environ and Mol Mutagen

162

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The possible existence of a threshold for compounds inducing chromosomal loss was investigated for four known aneugens (colchicine, COL; carbendazim, MBC; mebendazole, MEB; nocodazole, NOC) and two clastogens (methyl methanesulfonate, MMS; mitomycin C, MMC) using the micronucleus (MN) test in human lymphocytes. The presence of a whole chromosome in the MN was studied by fluorescent in situ hybridization (FISH) using a synthetic pancentromeric oligonucleotide probe. FISH was applied on two different MN preparations: cytokinesis-blocked MN (MNCB) assay, and MN sorted by flow cytometry. At subtoxic concentrations analyzed by MNCB and FISH, COL, MEB, MBC, and NOC induced a concentration-dependent increase in centromere-positive MN (MNCen+). MMC seemed to induce an increase in both types of MN (MNCen- and MNCen+), while MMS induced only MNCen-. On the sorted micronuclei (in a wide range of low to subtoxic concentrations), the concentration-effect profile for MNCen+, with the four aneugens tested, showed a statistically nonsignificant increase over a range of concentrations, followed by a second range of high concentrations with a statistically significant increase. To analyze the existence of a threshold, a piecewise linear regression was applied to the data. The first concentration that showed a statistically significant increase in MNCen+ was chosen as a breakpoint (0.037 microM for COL, 2.62 microM for MBC, 0.27 microM for MEB, and 0.066 microM for NOC). The statistical correlation between observed and predicted values showed a high correlation (r = 0.99), indicating a clear threshold for aneuploidy induction. However, for MMS the concentration-effect profile for MNCen+ showed a continuous concentration-dependent decrease with no threshold. With the two cytotoxicity assays used (Bio-Rad and MTT), no significant reduction was detected either in the protein content or in mitochondrial succinate dehydrogenase activity with all chemicals tested for MN induction. Therefore, our data suggest that the observed thresholds were not due to indirect toxic effects but to real aneugenic effects.

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“…Reports in the literature on replication and mitotic condensation of micronuclei have mainly been concerned with micronuclei derived from acentric fragments: in cultured mammalian cells an asynchronous pattern of DNA synthesis has been shown, (Kato and Sandberg 1968;Ikeuchi 1973;Griffiths and Carpenter 1979) which has been linked to PCC. In human lymphocytes both asynchronous (Obe and Beck 1975) and synchronous (Pincu et al 1985) DNA synthesis pattern have been found. In V.faba DNA replication of micronuclei has been shown to occur either synchronously with main nuclei or not at all (Das 1962;Scott and Evans 1964).…”

Section: Discussionmentioning

confidence: 98%

Indirect mitotic nondisjunction in Vicia faba and Chinese hamster cells

et al. 1989

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Abstract. The hypothesis of indirect mitotic nondisjunction was tested in plant and mammalian cells. This hypothesis states that micronuclei derived from lagging chromosomes or chromatids are able to perform DNA synthesis and undergo mitotic condensation synchronously with main nuclei. Hence, as chromosomes, they can be moved to spindle poles together with the chromosomes of the main nuclei during mitosis. In that way chromosomes "lost" as micronuclei can be reincorporated in the main nuclei. In order to test this, both Vicia faba meristematic cells and cells of a Chinese hamster line (CI-I) were treated with low doses of colchicine. Mitotic anomalies, micronuclei and cells with a polyploid or aneuploid karyotype were scored at different fixation times. A detailed analysis was performed on single chromosome misdistributions, as well as on micronuclei and cells with aneuploid karyotypes derived from single chromosome misdistributions. Indirect mitotic nondisjunction was shown to play a primary role in the origin of aneuploid karyotypes in Viciafaba, but not in CI-1 cells.

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DNA Content of Micronuclei in Human Lymphocytes

Cited by 25 publications

References 3 publications

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

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

Indications for a threshold of chemically‐induced aneuploidy in vitro in human lymphocytes

Indirect mitotic nondisjunction in Vicia faba and Chinese hamster cells

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