SEED IRRADIATION AND DEVELOPMENT OF HEAT RESISTANCE

种子辐照和耐热性的发展

• 批准号: 3287364
• 负责人: HOWARD S DUCOFF
• 金额: $ 6.81万
• 依托单位: UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN
• 依托单位国家: 美国
• 财政年份: 1985
• 资助国家: 美国
• 起止时间: 1985-07-01 至 1989-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3287364
• 关键词: DNA repair; Escherichia coli; Leguminoseae; cell growth regulation; chromatin; genetic mapping; ionizing radiation; radiation genetics; seeds; ultraviolet radiation

Yeast cells begin to develop heat resistance immediately after UV- or Alpha-irradiation, with maximal resistance reached 6-8 hours afterwards; bacteria begin synthesis of heat-stress proteins (hsp's) immediately after exposure to UV or to nalidixic acid. By contrast, insects develop significant resistance to heat (and to some other stresses) 2 weeks after -irradiation, and the resistance persists for many months; heat resistance develops promptly in heat-shocked insects, however, and declines within a few days. Slow development and long persistence of heat resistance in irradiated insects may stem from the fact that the critical sites of heat damage in intact insects are in differentiated postmitotic tissues; tight coiling of the chromatin in such tissues may alter the rate of recognition of, and the response to, DNA lesions. This phenomenon could greatly affect combined-modality treatment of cancer and, in particular, the response of differentiated normal tissues; fundamental aspects of cell regulation are also involved. Long-term objectives are comparisons between dormant vs. vegetative cells and between irradiation and heat shock in determining the magnitude and the kinetics of induction of heat resistance and of hsp synthesis. Chromatin is tighly coiled during the dry dormant stage of plant seeds, but "opens up" during preparation for germination after rehydration. Accordingly, irradiation or rapid or gradual heating will be applied to dry soybean (Gycine max) and barley (Hordeum vulgare) seeds, or at various times during or after rehydration. Subsequent heat stress will consist of a brief period at 52 degree or at 45 degree. In addition, the protection by a brief period of 45 degree against subsequent heating will be compared in normal and previously irradiated groups. End points scored will include fraction of seeds germinating, seedling growth, total protein synthesis, cell viability by dye exclusion, and hsp synthesis using electrophoresis.

酵母细胞在紫外线或 α-辐照，最大电阻达到6-8小时； 细菌立即开始合成热压力蛋白（HSP） 暴露于紫外线或纳利迪酸。 相比之下，昆虫发展 2周后2周 - 辐射，抵抗持续了多个月；耐热性 然而，迅速发展的昆虫，并在 几天。 缓慢的发育和耐热性的长期持久性 辐照昆虫可能源于热量的关键部位 完整昆虫的损害在分化的有丝分裂组织中；紧的 这种组织中染色质的盘绕可能会改变识别率 以及对DNA病变的反应。 这种现象可能会极大地影响 癌症的合并 - 模式治疗，尤其是 分化正常组织；细胞调节的基本方面是 也涉及。 长期目标是休眠与植物细胞之间的比较 在确定幅度和辐射和热冲击之间 耐热性和HSP合成的动力学。 染色质 在植物种子的干燥阶段时，被狡猾地盘绕，但“打开 在补液后准备发芽期间。相应地， 辐照或快速或逐渐加热将用于干豆豆 （Gycine Max）和大麦（Hordeum vulgare）种子，或在不同时间 或补液后。 随后的热应力将包括一个短暂的 以52度或45度的期间。 另外，通过 将比较45度与随后的加热的短期。 正常和以前的辐照组。 得分的终点将包括 种子发芽，幼苗生长，总蛋白质合成， 通过染料排除和使用电泳的HSP合成的细胞活力。