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Assessment of DNA damage in multiple organs of mice after whole body X-irradiation using the comet assay |
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| Authors: | Shunji Ueno Takashige Kashimoto Nobuyuki Susa Hoshiko Natsume Maiko Toya Nobuhiko Ito Shino Takeda-Homma Yoshikazu Nishimura Yu F Sasaki Masayasu Sugiyama |
| Institution: | 1. USP, Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av. do Café, s/n, 14040-903 Ribeirão Preto, SP, Brazil;2. Programa de Pós-Graduação em Toxicologia e Análises Toxicológicas, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, Av. Lineu Prestes, 580, Bl. 13, 05508-900 São Paulo, SP, Brazil;3. UNESP, Instituto de Química, Universidade Estadual Paulista “Júlio de Mesquita Filho”, R. Francisco Degni, s/n, 14800-900 Araraquara, SP, Brazil;4. SABESP, Companhia de Saneamento Básico de São Paulo, R. Conselheiro Saraiva, 519, 02037-900 São Paulo, SP, Brazil;5. CETESB, Divisão de Toxicologia, Genotoxicidade e Microbiologia Ambiental da Companhia de Tecnologia de Saneamento Ambiental, Av. Prof. Frederico Hermann Jr., 345, 05459-900 São Paulo, SP, Brazil |
| Abstract: | The comet assay was performed to elucidate the linearity of calibration curves and detection limits for DNA damage in multiple organs of whole body X-irradiated mice, and rates of reduction in DNA damage by DNA repair during the irradiation period were estimated in the respective organs by comparing the rates of increase in DNA damage at different absorbed dose rates of X-rays. Of the assay parameters, tail length and the percentage DNA in the tail showed a higher sensitivity to DNA damage in most organs than Olive tail moment. Data at the higher absorbed dose rates (2.22 or 1.44 Gy/min) showed good correlations between absorbed doses and these two parameters, with correlation coefficients of more than 0.7 in many organs. However, this assay had difficulty detecting DNA damage at the lower absorption dose rate (0.72 Gy/min). The estimated rates of increase in DNA damage and those of DNA repair during the irradiation period in the respective organs suggested differences in the radiosensitivity of nuclear DNA and DNA repair capacity among organs. Our results indicated that absorbed dose rates of 1.0–1.3 Gy/min or greater were needed to induce detectable DNA damages by the comet assay in many organs. |
| Keywords: | Comet assay Ionizing radiation DNA damage DNA repair Whole body X-irradiation Mice |
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