- 著者
- TAKEO OHNISHI KEN OHNISHI AKIHISA TAKAHASHI YOSHITAKA TANIGUCHI MASARU SATO TAMOTSU NAKANO SHUNJI NAGAOKA
- 出版者
- Journal of Radiation Research Editorial Committee
- 雑誌
- Journal of Radiation Research (ISSN:04493060)
- 巻号頁・発行日
- vol.43, no.S, pp.S133-S136, 2002 (Released:2003-05-02)
- 参考文献数
- 7
- 被引用文献数
- 20
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 β-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.
- 著者
- Ken Ohnishi Akihisa Takahashi Hiroaki Tanaka Takeo Ohnishi
- 出版者
- 日本宇宙生物科学会
- 雑誌
- Biological Sciences in Space (ISSN:09149201)
- 巻号頁・発行日
- vol.10, no.4, pp.247-251, 1996 (Released:2006-02-01)
- 参考文献数
- 4
- 被引用文献数
- 5 5
The catfish Synodontis nigriventris shows a unique habit taking a stable upsidedown posture in free water regardless of an above, one-sided illumination. This upsidedown posture can be observed when the catfish is apart from objects because the catfish usually orients its ventral side towards the water bottom or objects due to a so-called ventral substrate response. Thus, it is not easy to study the mechanism of the upside-down posture. To resolve this problem, the frequency of the upside-down posture was measured by using various sizes of vessel in which the catfish was kept. Video analysis showed that the frequency of the upside-down posture depended on the space size around the catfish. The smaller the size became, the higher the frequency of the upside-down posture became. Furthermore, the frequency of the upside-down posture depended on the shape of the vessel bottom. Curved-bottom vessels induced the upside-down posture more frequently than flat bottom. These findings suggest that a small, curved-bottom vessel is ideal for researching the upside-down postural control mechanism.