The distribution of the tail moments in single cell gel electrophoresis (comet assay) obeys a chi-square (χ2) not a gaussian distribution

Bauer, Eckhard; Recknagel, Rolf-Dieter; Fiedler, Ursula; Wollweber, Leo; Bock, Claudia; Greulich, Karl Otto

doi:10.1016/s0027-5107(97)00246-7

Cited by 100 publications

(50 citation statements)

References 24 publications

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“…A nonlinear regression analysis was performed on the OTM distribution frequencies by using a v 2 function with TableCurve 2D software (version 5.0; Jandel Scientific Software, San Rafael, CA). The calculated degrees of freedom (n) for this function were a quantitative measure of the DNA damage for a sample [Bauer et al, 1998;Jean et al, 2001]. The n was termed OTM v 2 and was used as the sole parameter for assessing levels Environmental and Molecular Mutagenesis.…”

Section: Statistical Analysesmentioning

confidence: 99%

Assessment of occupational exposure to welding fumes by inductively coupled plasma‐mass spectroscopy and by the alkaline Comet assay

Botta¹,

Iarmarcovai²,

Chaspoul³

et al. 2006

Environ and Mol Mutagen

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Welding fumes are classified as possibly carcinogenic to humans (Group 2B) by the International Agency for Research on Cancer. In the current study, blood and urine concentrations of aluminum (Al), cadmium (Cd), cobalt (Co), chromium (Cr), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn) were monitored by inductively coupled plasma-mass spectrometry (ICP-MS) in 30 welders and in 22 controls. In addition, DNA damage was examined in the lymphocytes of these subjects by the alkaline Comet assay. Two biological samples were taken from the welders at the beginning (BW) and at the end (EW) of a work week. In controls, collection of samples was limited to BW. Blood concentrations of Cd, Co, Cr, Ni, and Pb were higher in the welders than in the control group while higher concentrations of Al, Cd, Co, Cr, Ni, and Pb were detected in welder urines.There was no significant difference in the metal concentrations for the BW and EW welder samples. Increased levels of DNA damage were found in lymphocytes from welders as compared to the controls, and 20/30 welders had higher levels of DNA lesions in the EW than in the BW samples. Age had a significant effect on DNA damage in the control group. Spearman's rank correlation analysis indicated that there were positive correlations between blood concentrations of Al, Co, Ni, and Pb and the levels of DNA damage. A negative correlation was found between DNA damage and Mn in blood, while there was a positive correlation between urinary Mn concentration and DNA damage. These data indicate that occupational exposure to welding fumes increases DNA damage in lymphocytes. Environ. Mol. Mutagen. 47:284-295, 2006. V V C 2006 Wiley-Liss, Inc.

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Section: Statistical Analysesmentioning

confidence: 99%

Assessment of occupational exposure to welding fumes by inductively coupled plasma‐mass spectroscopy and by the alkaline Comet assay

Botta¹,

Iarmarcovai²,

Chaspoul³

et al. 2006

Environ and Mol Mutagen

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“…For g-irradiated cells, it has been reported previously that distributions of tail moments follow a chi-square distribution [Bauer et al, 1998]. Tail moment histograms are often asymmetrical, especially in samples displaying low levels of DNA damage.…”

Section: Data Analysis and Statistical Approachesmentioning

confidence: 99%

“…Thus, posttreatment with FPG should lead to increases in comet formation if oxidized DNA bases are formed by E2 or its metabolites. We also report on the application of a data analysis technique previously utilized for radiation-induced DNA damage assessment [Bauer et al, 1998], which deals with the non-Gaussian distribution of tail moment data.…”

Section: Introductionmentioning

confidence: 99%

Detection of DNA strand breaks and oxidized DNA bases at the single-cell level resulting from exposure to estradiol and hydroxylated metabolites

Rajapakse

Butterworth

Kortenkamp

2005

Environ. Mol. Mutagen.

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Long-term exposure to steroidal estrogens is a key factor contributing to increases in the risk of developing breast cancer. Proposed mechanisms include receptor-activated increases in the rate of cell proliferation leading to the accumulation of genetic damage resulting from reading errors, and the production of DNA damage by species arising from metabolism of 17beta-estradiol (E2) resulting in mutations. In support of the second mechanism, catechol metabolites of E2 induce DNA damage in vitro. In the present study, utilizing the single-cell gel electrophoresis (Comet) assay, we observed increases in the number of single-strand breaks in estrogen receptor alpha-positive (MCF-7) and -negative (MDA-MB-231) breast cancer cells exposed to E2 (for 24 hr) or 4-hydroxy-17beta-estradiol (4-OH-E2; for 2 hr). The concentrations of 4-OH-E2 sufficient to induce these effects were approximately 100 nM, substantially lower than reported previously. The catechol 2-hydroxy-17beta-estradiol (2-OH-E2) also induced strand breaks. 2-OH-E2, often referred to as an improbable carcinogen in humans, is not a major metabolite of E2 in the breast; however, our findings show that it is as DNA-damaging as 4-OH-E2. Formamidopyrimidine glycosylase posttreatment of E2-, 4-OH-E2-, and 2-OH-E2-exposed MCF-7 cells led to an up to sixfold increase in mean tail moment, suggesting that oxidative DNA damage was formed. Comet formation could be partially attenuated by coincubation with dimethylsulfoxide, attributing a small DNA-damaging role to oxyradicals emanating from catechol redox cycling. Similar findings were obtained with MDA-MB-231 cells, indicating that estrogen receptor status is not relevant to these effects. Our observations show that exposure to E2 adds to the oxidative load of cells, and this may contribute to genomic instability.

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“…Comet assay was performed according to the alkaline version described by Singh and Tice (Bauer et al, 1998;Singh et al, 1988;Tice et al, 2000). In short, the incubation times were as follows: 1 hour lysis at 4°C, 1 hour unwinding at 4°C and 30 minutes electrophoresis at 1 V/cm also at 4°C.…”

Section: Comet Assaymentioning

confidence: 99%

After double-strand break induction by UV-A, homologous recombination and nonhomologous end joining cooperate at the same DSB if both systems are available

Rapp¹,

Greulich²

2004

Journal of Cell Science

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105

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After induction of DNA double-strand breaks (DSB) two repair systems, the error-prone `nonhomologous end joining' (NHEJ) and the more accurate `homologous recombination repair' (HRR) can compete for the same individual DSB site. In the human keratinocyte cell line, HaCaT, we have tested the spatial co-localisation and the temporal sequence of events. We used UV-A (365 nm) as a damaging agent, which can be applied in clearly defined doses and can lead to rare DSBs via propagation of clustered single-strand breaks (SSBs). DNA fragmentation and repair was measured by the Comet assay and persisting DSBs were quantified by the micronucleus assay. Direct DSB detection was performed by immunohistochemical labelling of γ-H2AX, a phosphorylated histone that is assumed to form one foci per DSB. Intra- and inter-pathway interactions were quantified by co-localisation, FRET imaging and by co-immunoprecipitation (Co-IP) of XRCC4, DNA-PK and Ku70 as representatives of NHEJ, Rad51 and Rad52 for HRR and γ-H2AX, Mre11 and Rad50 as representatives of both pathways. In G2 cells, where both systems are available, the temporal sequence after irradiation is: (1) γ-H2AX (2) Mre11 (3) DNA-PK Rad51 (4) XRCC4. That is, the first two proteins involved in both pathways `label' the damaged site and initiate repair, followed by the NHEJ, which is temporally overlapping with HRR activity. Taking all these observations together we suggest that a cell tries to repair DSBs with a combination of both HRR and NHEJ, if available.

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The distribution of the tail moments in single cell gel electrophoresis (comet assay) obeys a chi-square (χ2) not a gaussian distribution

Cited by 100 publications

References 24 publications

Assessment of occupational exposure to welding fumes by inductively coupled plasma‐mass spectroscopy and by the alkaline Comet assay

Assessment of occupational exposure to welding fumes by inductively coupled plasma‐mass spectroscopy and by the alkaline Comet assay

Detection of DNA strand breaks and oxidized DNA bases at the single-cell level resulting from exposure to estradiol and hydroxylated metabolites

After double-strand break induction by UV-A, homologous recombination and nonhomologous end joining cooperate at the same DSB if both systems are available

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