| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 1998: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1997: ¥2,500,000 (Direct Cost: ¥2,500,000)
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| Research Abstract |
DNA damage in five strains of rice by irradiation of UV-B and its ability of repair were searched by alkaline agarose gel electrophoresis and its image analysis system. Compare of CPD(cyclobutyl pyrimidine dimmer) in DNA formed by UV-B irradiation was very similar in the five strains, which were sensitive(Oryza sativa L.var. Sasashigure and Norin1) and resistant (Oryza sativa L.var. Hatsunishiki, Koshihikari, and Sasanishiki) against UV.However, their abilities of photoreactivation were different. UV-resistant strain showed high abilities of photoreactivation, although UV-sensitive one was comparatively weak ability of repair system. While the photoreactivation quickly responded to formation of the CPD, the excision repair system was very slow response. Those results showed that UV-resistance of rice was originated high ability of repair systems and the ability of repair in rice is useful as one of the estimation of productivity.
DNA damage, abilities of photoreactivation and excision repair at the 1-2 leaves, 3-4 leaves, and 5-6 leaves stage of rice were searches with measurement of their CPD.Their results showed that stages of 1-2 and 3-4 leaves stage of the rice were very similar ability, although DNA damage and their abilities of repair in rice of 5-6 leaves stage was diminish of about 20%. The reason was thought that UV-B reaching to nucleus in the cell was reduced, as rice at this stage contained many chloroplasts and became to be thick and rigid. It is necessary to search the ability against UV-B in rices cultivated in Japan.
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