title: Detection of DNA damage induced by space radiation in Mir and space shuttle.
abstract: Although physical monitoring of space radiation has been accomplished, we aim to measure exact DNA damage as caused by space radiation. If DNA damage is caused by space radiation, we can detect DNA damage dependent on the length of the space flight periods by using post-labeling methods. To detect DNA damage caused by space radiation, we placed fixed human cervical carcinoma (HeLa) cells in the Russian Mir space station for 40 days and in an American space shuttle for 9 days. After landing, we labeled space-radiation-induced DNA strand breaks by enzymatic incorporation of [3H]-dATP with terminal deoxyribo-nucleotidyl transferase (TdT). We detected DNA damage as many grains on fixed silver emulsion resulting from beta-rays emitted from 3H-atoms in the nuclei of the cells placed in the Mir-station (J/Mir mission, STS-89), but detected hardly any in the ground control sample. In the space shuttle samples (S/MM-8), the number of cells having many grains was lower than that in the J/Mir mission samples. These results suggest that DNA damage is caused by space radiation and that it is dependent on the length of the space flight.
authors.affiliation: Department of Biology, Nara Medical University, 840 Shijo-cho, Kashihara, Nara, 634-8521, Japan. tohnishi@naramed-u.ac.jp
authors.forename: Takeo
authors.initials: T
authors.lastname: Ohnishi
authors.forename: Ken
authors.initials: K
authors.lastname: Ohnishi
authors.forename: Akihisa
authors.initials: A
authors.lastname: Takahashi
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Taniguchi
authors.forename: Masaru
authors.initials: M
authors.lastname: Sato
authors.forename: Tamotsu
authors.initials: T
authors.lastname: Nakano
authors.forename: Shunji
authors.initials: S
authors.lastname: Nagaoka
mesh_terms: D003359:Cosmic Radiation / Q000009:adverse effects*; D004247:DNA / Q000528:radiation effects*; D004249:DNA Damage; D006367:HeLa Cells; D006801:Humans; D012426:Russia; D013026:Space Flight; D013997:Time Factors; D014481:United States
chemical_list: D004247:DNA