STUDY OF THE OXYGEN EFFECT IN RADIATION BIOLOGY

辐射生物学中氧效应的研究

• 批准号: 3172090
• 负责人: MELVIN L MORSE
• 金额: $ 5.41万
• 依托单位: UNIVERSITY OF COLORADO DENVER
• 依托单位国家: 美国
• 财政年份: 1984
• 资助国家: 美国
• 起止时间: 1984-12-01 至 1987-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3172090
• 关键词: glutathione; hypoxia; ionizing radiation; radiation genetics; radiation recovery; respiratory oxygen; thin layer chromatography

There is evidence that the oxygen effect (oxygen sensitizes cells to ionizing radiation) is genetically determined and, therefore, there must be mutants defective in the effect. It is proposed to isolate and study such mutants in order to understand at the molecular level the mechanism(s) of the oxygen effect. Evidence has been found that indicates the effect is a post-irradiation repair process, at least for direct radiation effects. It has been demonstrated that gamma-radiation in the absence of oxygen, but not in its presence, forms an adduct between DNA, glutathione (GSH), and other cellular substances, and it is proposed that excision of these adducts post-irradiation is the mechanism of higher cell survival in the absence of oxygen. It is proposed: (1) to study the in vivo labeling of DNA with GSH and other substances in toluenized or EDTA-Tris treated E. coli and urea-treated phage T4 particles (II particle) whose DNA is labile to DNAse; (2) to use T1 DNA which has adducts produced by irradiation to isolate E. coli mutants defective in post-irradiation repair. Nonmutants will commit suicide by repairing the T1 DNA and defective mutants will be enriched among the survivors and recognized by their inability to be protected from radiation by oxygen deprivation. Ultimately, two dimensional electrophoretic gels of the cellular proteins of the mutants will be compared with the proteins of nonmutants to identify the protein(s) involved which subsequently can be studied in vitro for its action on DNA adducts. The oxygen effect is important medically because most tumor cells are at reduced oxygen tension and therefore radiation resistant. Understanding the effect at the molecular level can lead to the development of methods to lessen radiation resistance. This study involves the methodologies of genetics, biochemistry, biophysics, and molecular biology.

有证据表明，氧气效应(氧气使细胞对 电离辐射)是由基因决定的，因此 在效果上有缺陷的突变体。建议对其进行分离和研究 突变体，以在分子水平上了解其发病机制(S) 氧气效应。已经发现的证据表明，这种影响是一种 辐射后修复过程，至少对于直接辐射影响。它 已经证明了无氧条件下的伽马辐射，但是 不在其存在时，在DNA、谷胱甘肽(GSH)和 其他细胞物质，并建议将这些物质 照射后加合物是提高细胞存活率的机制 缺氧。建议：(1)进行体内标记的研究 在甲苯化或EDTA-Tris处理的E. 大肠杆菌和尿素处理的噬菌体T4颗粒(II颗粒)，其DNA不稳定 到DNase；(2)使用具有辐射产生的加合物的T1 DNA来 分离在辐射后修复中有缺陷的大肠杆菌突变体。非突变型 会通过修复T1 DNA而自杀，而有缺陷的突变体将 在幸存者中变得富有，并因他们无法成为 通过缺氧保护免受辐射。最终，有两个 突变体细胞蛋白的双向凝胶电泳法 将其与非突变体的蛋白质进行比较，以鉴定该蛋白质(S) 随后可在体外研究其对DNA的作用 加合物。 氧气效应在医学上很重要，因为大多数肿瘤细胞都在 降低氧分压，因此耐辐射。理解 分子水平上的影响可以导致方法的发展 降低辐射抵抗力。 这项研究涉及遗传学、生物化学、 生物物理学和分子生物学。