放射線 照射가 당근 CALLUS의 核酸 및 核蛋白質에 미치는 影響에 關한 硏究 = Studies on Radiation Effects of Nucleic Acid and Nucleoprotein of Carrot Callus

다국어 초록 (Multilingual Abstract)

These investigations were conducted in order to observe effects of ionizing radiation on cultured carrot calli. Carrot discs were cultured on media composed of sucrose, yeast extract and N-AA in White's basic medium in the dark at 2i±2℃ for 60 days. Cultured carrot calli were irradiated with 400 rad,(designed as Low-Level Gamma Callus in text) and 10,000 rad,(designed High-Level Gamma Callus in text) of ^(60)CO at room temperature. Irradiated calli were incubated under the same conditions for 40 days.
Some of the results obtained me these studios are summerized as follows:
1. The growth value of low dose group was increased approximateiy 25% as compared with the unirradiated group, and the growth value of high dose group were decreased about 40%.
2. Growth of fresh carrot calli was not affected by the media which had been irradiated with 400 and 10,000 rad of gamma ray.
3. In the ratio of fresh weight to dryed weight of callus, high dose group was higher than low does group and unirradiated group, and low dose group was similar to control.
4. DNA and RNA contents of low does group were inclined to inclease as compared with the contents of unirradiated group, those of high dose group were decreased gradually depending upon incubation time. The ratio of RNA content to DNA content of the all experimental group was constantly about 3.0.
5. RNA was generally distributed much in microsome-soluble fraction of sub-cellular in all experimental groups. But RNA of high does group was distributed relatively much than another groups.
6. Protein content of low dose group was increased approximately 15% than that of unirradiated group, and that of high dose group was decreased gradually depending upon cultivation period. Protein content of all groups was distributed mostly in microsome-soluble fraction. Among others, protein of high dose group was found more abundantly in microsome-soluble franction.
7. In the snthesis of DNA and RNA of cultured carrot callus, incorporations of thymine-2^-(14)C and uracil-2-^(14)C into DNA and RNA of low dose group were more vigorous at the initial stage as compared with the control. The incorporations of high dose group were less than the control.
8. As for the RNA metabolisms, there were changes in all experimental groups. At 3 hours after irradiation 40S^(*), as RNA precursor or ribosome like substances, was absorbed relatively higher gradually depending upon incubation time in all experimental groups.
9. DNA degradation of low dose group, by means of ionizing radiation, increased 21% more than the control, and the degradation of high dose group also increased more 43% more than the control, while the degradation of low dose group was recovered almost depending upon cultivation period. By alkaine sucrose gradient centrifugation, sedimentation profiles of DNA of irradiated groups were found somes the differences to the control.
10. Compositon of chromatin of cultured carrot callus was ahout 34.5% of total histone protein, 32.0% of DNA, 17.5% of non-histone protein and 15.5% of RNA in all experimental groups.
11. Histone phosphorylation was increased particularly in low dose group as compared with the high dose group and control.