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Sanders J, Thienpont A, Anthonissen R, Vanhaecke T, Mertens B. Impact of experimental design factors on the potency of genotoxicants in in vitro tests. Mutagenesis 2022; 37:248-258. [PMID: 36448879 DOI: 10.1093/mutage/geac025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 11/14/2022] [Indexed: 12/02/2022] Open
Abstract
Previous studies have shown that differences in experimental design factors may alter the potency of genotoxic compounds in in vitro genotoxicity tests. Most of these studies used traditional statistical methods based on the lowest observed genotoxic effect levels, whereas more appropriate methods, such as the benchmark dose (BMD) approach, are now available to compare genotoxic potencies under different test conditions. We therefore investigated the influence of two parameters, i.e. cell type and exposure duration, on the potencies of two known genotoxicants [aflatoxin B1 and ethyl methanesulfonate (EMS)] in the in vitro micronucleus (MN) assay and comet assay (CA). Both compounds were tested in the two assays using two cell types (i.e. CHO-K1 and TK6 cells). To evaluate the effect of exposure duration, the genotoxicity of EMS was assessed after 3 and 24 h of exposure. Results were analyzed using the BMD covariate approach, also referred to as BMD potency ranking, and the outcome was compared with that of more traditional statistical methods based on lowest observed genotoxic effect levels. When comparing the in vitro MN results obtained in both cell lines with the BMD covariate approach, a difference in potency was detected only when EMS exposures were conducted for 24 h, with TK6 cells being more sensitive. No difference was observed in the potency of both EMS and aflatoxin B1 in the in vitro CA using both cell lines. In contrast, EMS was more potent after 24 h exposure compared with a 3 h exposure under all tested conditions, i.e. in the in vitro MN assay and CA in both cell lines. Importantly, for several of the investigated factors, the BMD covariate method could not be used to confirm the differences in potencies detected with the traditional statistical methods, thus highlighting the need to evaluate the impact of experimental design factors with adequate approaches.
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Affiliation(s)
- Julie Sanders
- Department of Chemical and Physical Health Risks, Sciensano, Brussels, Belgium.,Department of In Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel, Brussels, Belgium
| | - Anouck Thienpont
- Department of Chemical and Physical Health Risks, Sciensano, Brussels, Belgium.,Department of In Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel, Brussels, Belgium
| | - Roel Anthonissen
- Department of Chemical and Physical Health Risks, Sciensano, Brussels, Belgium
| | - Tamara Vanhaecke
- Department of In Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel, Brussels, Belgium
| | - Birgit Mertens
- Department of Chemical and Physical Health Risks, Sciensano, Brussels, Belgium
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Al-Naqeb G, Sidarovich V, Scrinzi D, Mazzeo I, Robbiati S, Pancher M, Fiori L, Adami V. Hydrochar and hydrochar co-compost from OFMSW digestate for soil application: 3. Toxicological evaluation. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2022; 320:115910. [PMID: 35947910 DOI: 10.1016/j.jenvman.2022.115910] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 07/26/2022] [Accepted: 07/28/2022] [Indexed: 06/15/2023]
Abstract
Modern societies produce ever-increasing amounts of waste, e.g. organic fraction of municipal solid waste (OFMSW). According to the best available techniques, OFMSW should be treated through anaerobic digestion to recover biogas and subsequently composted. An innovative scheme is under investigation, where anaerobic digestion is combined with hydrothermal carbonization (HTC) and composting. The final product, referred to as hydrochar co-compost (HCO), is under study to be used as an unconventional soil improver/fertilizer. Recent studies showed that HCO is not phytotoxic. However, nothing is known about the toxicity of HCO on cells as part and organisms as a whole. This study aims to investigate in vitro genotoxicity and cytotoxicity of the HCO and its precursors in the production process. In particular, we tested water and methanolic extracts of HCO (WEHCO and MEHCO) from one side and methanolic extracts of hydrochar (MEH) and OFMSW digestate (MED) as well as liquor produced downstream HTC (HTCL) from the other side. Genotoxicity was investigated using cytokinesis-block micronucleus assay in Chinese Hamster Ovarian K1 (CHO-K1) cells. Cytotoxicity was tested in vitro against a panel of human cells line. Zebrafish embryo toxicity upon MEH treatment was also investigated. Results show that incubation of CHO-K1 cells with all the tested samples at different concentrations did not cause any induction of micronucleus formation compared to the vehicle-treated control. Treatment of cells with MEH, MED, HTCL and MEHCO, but not WEHCO, induced some degree of cytotoxicity and MEH showed to be more cytotoxic against tested cells compared to the MEHCO. Toxicity effect at the highest tested concentrations of MEH on zebrafish embryos resulted in coagulation, induction of pericardial edema and death. In conclusion, the hydrochar co-compost cytotoxicity is similar to standard compost cytotoxicity. Hence composting the hydrochar from OFMSW digestate is a good step to eliminate the cytotoxicity of hydrochar.
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Affiliation(s)
- Ghanya Al-Naqeb
- Center Agriculture Food Environment (C3A), University of Trento, Trento, Italy; Department of Food Sciences and Nutrition, Faculty of Agriculture Food and Environment, University of Sana'a, Sana'a, Yemen.
| | - Viktoryia Sidarovich
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Donato Scrinzi
- Department of Civil, Environmental and Mechanical Engineering, University of Trento, Trento, Italy
| | - Ilaria Mazzeo
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Sergio Robbiati
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Michael Pancher
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Luca Fiori
- Center Agriculture Food Environment (C3A), University of Trento, Trento, Italy; Department of Civil, Environmental and Mechanical Engineering, University of Trento, Trento, Italy
| | - Valentina Adami
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
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Rodrigues MA, Probst CE, Zayats A, Davidson B, Riedel M, Li Y, Venkatachalam V. The in vitro micronucleus assay using imaging flow cytometry and deep learning. NPJ Syst Biol Appl 2021; 7:20. [PMID: 34006858 PMCID: PMC8131758 DOI: 10.1038/s41540-021-00179-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 02/16/2021] [Indexed: 02/07/2023] Open
Abstract
The in vitro micronucleus (MN) assay is a well-established assay for quantification of DNA damage, and is required by regulatory bodies worldwide to screen chemicals for genetic toxicity. The MN assay is performed in two variations: scoring MN in cytokinesis-blocked binucleated cells or directly in unblocked mononucleated cells. Several methods have been developed to score the MN assay, including manual and automated microscopy, and conventional flow cytometry, each with advantages and limitations. Previously, we applied imaging flow cytometry (IFC) using the ImageStream® to develop a rapid and automated MN assay based on high throughput image capture and feature-based image analysis in the IDEAS® software. However, the analysis strategy required rigorous optimization across chemicals and cell lines. To overcome the complexity and rigidity of feature-based image analysis, in this study we used the Amnis® AI software to develop a deep-learning method based on convolutional neural networks to score IFC data in both the cytokinesis-blocked and unblocked versions of the MN assay. We show that the use of the Amnis AI software to score imagery acquired using the ImageStream® compares well to manual microscopy and outperforms IDEAS® feature-based analysis, facilitating full automation of the MN assay.
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Affiliation(s)
| | | | - Artiom Zayats
- Amnis Flow Cytometry, Luminex Corporation, Seattle, WA, USA
| | - Bryan Davidson
- Amnis Flow Cytometry, Luminex Corporation, Seattle, WA, USA
| | - Michael Riedel
- Amnis Flow Cytometry, Luminex Corporation, Seattle, WA, USA
| | - Yang Li
- Amnis Flow Cytometry, Luminex Corporation, Seattle, WA, USA
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Zhang W, Guo C, Wang XL, Lv ZL, Fan L, Yang YY, Li X, Qi J, Zhao SL, Wang XL. Double-endpoint Genotoxicity Quantification and PAHs Characterization of Drinking Water Source alongside Polluted Yinghe River with High Tumor Mortality. Curr Med Sci 2021; 41:189-198. [PMID: 33877535 DOI: 10.1007/s11596-021-2336-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 02/10/2021] [Indexed: 11/26/2022]
Abstract
The etiology for the high tumor mortality in heavy polluted Yinghe river basin is still unclear and polycyclic aromatic hydrocarbons (PAHs) belong to the priority pollutants in water based on the former surveillance data. In order to explore the potential genotoxicants contributing to the double-endpoint genotoxicity of polluted drinking water source, 12 groundwater and 3 surface water samples were collected from 3 villages and the nearby rivers alongside Yinghe river basin, respectively and their comprehensive genotoxicity was estimated with a bioassay group of SOS/umu test and micronucleus (MN) test (MNT). Some groundwater samples showed positive genotoxicity and all surface water samples were highly genotoxic. Eight groundwater samples showed DNA genotoxic effect with the average 4-NQO equivalent concentration (TEQ(4-NQO)) of 0.067 µg/L and 0.089 µg/L in wet and dry season, respectively. The average MN ratios of groundwater samples were 14.19‰ and 17.52‰ in wet and dry season, respectively. Groundwater samples showed different genotoxic effect among 3 villages. The total PAHs concentrations in all water samples ranged from 8.98 to 25.17 ng/L with an average of 14.97±4.85 ng/L. BaA, CHR, BkF, BaP and DBA were the main carcinogenic PAHs contributing to the genotoxicity of water samples. In conclusion, carcinogenic PAHs are possibly related to the high tumor mortality in the target area. Characterization of carcinogenic PAHs to genotoxicity of drinking water source may shed light on the etiology study for high tumor mortality in Yinghe river basin.
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Affiliation(s)
- Wei Zhang
- National Institute of Environmental Health, Chinese Center for Disease Control and Prevention, China CDC Key Laboratory of Environment and Population Health, Beijing, 100021, China
| | - Chen Guo
- China State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China
| | - Xiao-Li Wang
- College of Life Science and Bioengineering, Beijing University of Technology, Beijing, 100124, China
| | - Zhan-Lu Lv
- China State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China
| | - Lin Fan
- National Institute of Environmental Health, Chinese Center for Disease Control and Prevention, China CDC Key Laboratory of Environment and Population Health, Beijing, 100021, China
| | - Yu-Yan Yang
- National Institute of Environmental Health, Chinese Center for Disease Control and Prevention, China CDC Key Laboratory of Environment and Population Health, Beijing, 100021, China
| | - Xu Li
- National Institute of Environmental Health, Chinese Center for Disease Control and Prevention, China CDC Key Laboratory of Environment and Population Health, Beijing, 100021, China
| | - Jing Qi
- National Institute of Environmental Health, Chinese Center for Disease Control and Prevention, China CDC Key Laboratory of Environment and Population Health, Beijing, 100021, China
| | - Shu-Li Zhao
- China National Environmental Monitoring Center, Beijing, 100012, China
| | - Xian-Liang Wang
- National Institute of Environmental Health, Chinese Center for Disease Control and Prevention, China CDC Key Laboratory of Environment and Population Health, Beijing, 100021, China.
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Stubbs BJ, Nikiforov AI, Rihner MO, Weston S, Higley N, Roy S, Dakoulas E, Verdin E, Newman JC. Genetic Toxicity Studies of the Ketogenic Ester Bis Hexanoyl (R)-1,3-Butanediol. Int J Toxicol 2021; 40:242-249. [PMID: 33611970 DOI: 10.1177/1091581821991772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
A series of studies was conducted to assess the genetic toxicity of a novel ketone ester, bis hexanoyl (R)-1,3-butanediol (herein referred to as BH-BD), according to Organization for Economic Co-operation and Development testing guidelines under the standards of Good Laboratory Practices. In bacterial reverse mutation tests, there was no evidence of mutagenic activity in any of the Salmonella typhimurium strains tested or in Escherichia coli strain WP2uvrA, at dose levels up to 5,000 μg/plate in the presence or absence of Aroclor 1254-induced rat liver (S9 mix) for metabolic activation. In the in vitro micronucleus test using human TK6 cells, BH-BD did not show a statistically significant increase in the number of cells containing micronuclei when compared with concurrent control cultures at all time points and at any of the concentrations analyzed (up to 100 μg/mL, final concentration in culture medium), with and without S9 mix activation. In the in vivo micronucleus test using Sprague Dawley rats, BH-BD did not show a statistically significant increase in the incidence of micronucleated polychromatic erythrocytes relative to the vehicle control group. Therefore, BH-BD was concluded to be negative in all 3 tests. These results support the safety assessment of BH-BD for potential use in food.
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Affiliation(s)
| | | | | | | | | | | | | | - Eric Verdin
- 6129Buck Institute for Research on Aging, CA, USA
| | - John C Newman
- 6129Buck Institute for Research on Aging, CA, USA.,Division of Geriatrics, UCSF, CA, USA
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The application of an in vitro micronucleus test in mouse fibroblast L929 cells. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2019; 841:36-42. [DOI: 10.1016/j.mrgentox.2019.05.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 04/16/2019] [Accepted: 05/10/2019] [Indexed: 12/19/2022]
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Rodrigues MA. Automation of the in vitro micronucleus assay using the Imagestream ® imaging flow cytometer. Cytometry A 2018; 93:706-726. [PMID: 30118149 PMCID: PMC6174940 DOI: 10.1002/cyto.a.23493] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 04/16/2018] [Accepted: 04/25/2018] [Indexed: 12/02/2022]
Abstract
The in vitro micronucleus (MN) assay is a well‐established test for evaluating genotoxicity and cytotoxicity. The use of manual microscopy to perform the assay can be laborious and often suffers from user subjectivity and interscorer variability. Automated methods including slide‐scanning microscopy and conventional flow cytometry have been developed to eliminate scorer bias and improve throughput. However, these methods possess several limitations such as lack of cytoplasmic visualization using slide‐scanning microscopy and the inability to visually confirm the legitimacy of MN or storage of image data for re‐evaluation using flow cytometry. The ImageStreamX® MK II (ISX) imaging flow cytometer has been demonstrated to overcome all of these limitations. The ISX combines the speed, statistical robustness, and rare event capture capability of conventional flow cytometry with high resolution fluorescent imagery of microscopy and possesses the ability to store all collected image data. This paper details the methodology developed to perform the in vitro MN assay in human lymphoblastoid TK6 cells on the ISX. High resolution images of micronucleated mono‐ and bi‐nucleated cells as well as polynucleated cells can be acquired at a high rate of capture. All images can then be automatically identified, categorized and enumerated in the data analysis software that accompanies the ImageStream, allowing for the scoring of both genotoxicity and cytotoxicity. The results demonstrate that statistically significant increases in MN frequency when compared with solvent controls can be detected at varying levels of cytotoxicity following exposure to well‐known aneugens and clastogens. This work demonstrates a fully automated method for performing the in vitro micronucleus assay on the ISX imaging flow cytometry platform. © 2018 The Author. Cytometry Part A published by Wiley Periodicals, Inc. on behalf of ISAC.
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Revollo J, Petibone DM, McKinzie P, Knox B, Morris SM, Ning B, Dobrovolsky VN. Whole genome and normalized mRNA sequencing reveal genetic status of TK6, WTK1, and NH32 human B-lymphoblastoid cell lines. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2015; 795:60-9. [PMID: 26774668 DOI: 10.1016/j.mrgentox.2015.11.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 11/12/2015] [Accepted: 11/14/2015] [Indexed: 01/05/2023]
Abstract
Closely related TK6, WTK1, and NH32 human B-lymphoblastoid cell lines differ in their p53 functional status. These lines are used frequently in genotoxicity studies and in studies aimed at understanding the role of p53 in DNA repair. Despite their routine use, little is known about the genetic status of these cells. To provide insight into their genetic composition, we sequenced and analyzed the entire genome of TK6 cells, as well as the normalized transcriptomes of TK6, WTK1, and NH32 cells. Whole genome sequencing (WGS) identified 21,561 genes and 5.17×10(6) small variants. Within the small variants, 50.54% were naturally occurring single nucleotide polymorphisms (SNPs) and 49.46% were mutations. The mutations were comprised of 92.97% single base-pair substitutions and 7.03% insertions or deletions (indels). The number of predicted genes, SNPs, and small mutations are similar to frequencies observed in the human population in general. Normalized mRNA-seq analysis identified the expression of transcripts bearing SNPs or mutations for TK6, WTK1, and NH32 as 2.88%, 2.04%, and 1.71%, respectively, and several of the variant transcripts identified appear to have important implications in genetic toxicology. These include a single base deletion mutation in the ferritin heavy chain gene (FTH1) resulting in a frame shift and protein truncation in TK6 that impairs iron metabolism. SNPs in the thiopurine S-methyltransferase (TPMT) gene (TPMT*3A SNP), and in the xenobiotic metabolizing enzyme, NADPH quinine oxidoreductase 1 (NQO1) gene (NQO1*2 SNP), are both associated with decreased enzyme activity. The clinically relevant TPMT*3A and NQO1*2 SNPs can make these cell lines useful in pharmacogenetic studies aimed at improving or tailoring drug treatment regimens that minimize toxicity and enhance efficacy.
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Affiliation(s)
- Javier Revollo
- Division of Genetic and Molecular Toxicology, FDA/NCTR, Jefferson, AR 72079, United States
| | - Dayton M Petibone
- Division of Genetic and Molecular Toxicology, FDA/NCTR, Jefferson, AR 72079, United States.
| | - Page McKinzie
- Division of Genetic and Molecular Toxicology, FDA/NCTR, Jefferson, AR 72079, United States
| | - Bridgett Knox
- Division of Systems Biology, FDA/NCTR, Jefferson, AR 72079, United States
| | - Suzanne M Morris
- Division of Genetic and Molecular Toxicology, FDA/NCTR, Jefferson, AR 72079, United States
| | - Baitang Ning
- Division of Systems Biology, FDA/NCTR, Jefferson, AR 72079, United States
| | - Vasily N Dobrovolsky
- Division of Genetic and Molecular Toxicology, FDA/NCTR, Jefferson, AR 72079, United States
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Sobol Z, Spellman RA, Thiffeault C, Dobo KL, Schuler M. Impact of cell cycle delay on micronucleus frequency in TK6 cells. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2014; 55:64-69. [PMID: 23982927 DOI: 10.1002/em.21810] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 07/16/2013] [Accepted: 07/17/2013] [Indexed: 06/02/2023]
Abstract
Previous studies with TK6 cells have shown that extending the recovery period after pulse treatment allows for greater micronucleus expression for some compounds. This study explores the role of cell cycle delay in micronucleus expression after pulse treatment with three model genotoxins [mitomycin C, etoposide (ETOP), vinblastine]. Cells were treated for 4 hr and allowed to recover for 36 hr with samples removed at various time points during the recovery period and analyzed for cell cycle distribution, apoptosis and micronucleus frequency. Our results show that mitomycin C causes cell cycle delay for 20 hr after pulse treatment and cell cycle perturbation is no longer evident after 36 hr of recovery. The micronucleus frequency of cells sampled at 36 hr is doubled when compared with cells sampled at 20 hr after mitomycin C removal. When cells were treated with indirect acting genotoxins (ETOP, vinblastine), cell cycle perturbation was not observed at the 20 hr time point. Micronucleus frequency after treatment with either ETOP or vinblastine did not differ between the 20 hr and the 36 hr time point. All three compounds induced similar levels of apoptosis ranging from 4.5 to 5.6% with maximum induction occurring at the 36-hr time point. We conclude that TK6 cells exhibit extended cell cycle arrest after exposure to MMC and can go on to express micronuclei, after overcoming cell cycle arrest.
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Affiliation(s)
- Zhanna Sobol
- Pfizer Worldwide Research and Development, Genetic Toxicology Center of Expertise, Eastern Point Road, Groton, Connecticut
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Development and validation of an in vitro micronucleus assay platform in TK6 cells. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2012; 746:29-34. [DOI: 10.1016/j.mrgentox.2012.02.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Revised: 02/13/2012] [Accepted: 02/14/2012] [Indexed: 11/24/2022]
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