| Budget Amount *help |
¥5,070,000 (Direct Cost: ¥3,900,000、Indirect Cost: ¥1,170,000)
Fiscal Year 2015: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2014: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
Fiscal Year 2013: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
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| Outline of Final Research Achievements |
To investigate how normal stem cells respond to low-dose heavy ion particles which are included in space radiations, the ICR mice were irradiated with carbon-ion beams at 0.01-5Gy. After irradiation, the apoptosis in small intestine and testis cells were observed dose-dependently even in the small dose range of 0.01 - 0.05 Gy. The hyper-radio-sensitivity at low-dose in the bone marrow stem and progenitor cells was observed 1 days after irradiation with the carbon-ion beams at less than 0.5Gy. The surviving curve at greater than 0.5Gy indicated the feature of linear quadratic model with a big shoulder. However, the reduction of surviving fractions was completely recovered in the bone marrow cells 14 days after irradiation at less than 1Gy.
These findings suggest that homologous recombination repair may be preferentially functioned to heavy ion-induced DNA damage less than 1Gy. These results might contribute to protect space-radiation effects including heavy ion particles.
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