Detection of space radiation-induced double strand breaks as a track in cell nucleus.
To identify DNA damage induced by space radiations such as the high linear energy transfer (LET) particles, phospho-H2AX (gammaH2AX) foci formation was analyzed in human cells frozen in an International Space Station freezer for 133days. After recovering the frozen sample to the earth, the cells were cultured for 30 min, and then fixed. Here we show a track of gammaH2AX positive foci in them by immuno-cytochemical methods. It is suggested that space radiations, especially high LET particles, induced DSBs as a track. From the formation of the tracks in nuclei, exposure dose rate was calculated to be 0.7 mSv per day as relatively high-energy space radiations of Fe-ions (500 MeV/u, 200 keV/microm). From the physical dosimetry with CR-39 plastic nuclear track detectors and thermo-luminescent dosimeters, dose rate was 0.5 mSv per day. These values the exposed dose rate were similar between biological and physical dosimetries.
Department of Biology, School of Medicine, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8521, Japan. tohnishi@naramed-u.ac.jp
Takeo
T
Ohnishi
Akihisa
A
Takahashi
Aiko
A
Nagamatsu
Katsunori
K
Omori
Hiromi
H
Suzuki
Toru
T
Shimazu
Noriaki
N
Ishioka
D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism / Q000528:radiation effects*; D053903:DNA Breaks, Double-Stranded; D004735:Energy Transfer; D005118:Extraterrestrial Environment; D006657:Histones / Q000032:analysis / Q000378:metabolism*; D006801:Humans; D010766:Phosphorylation; D011839:Radiation, Ionizing
C468783:H2AX protein, human; D006657:Histones