BIOLOGICALLY SIGNIFICANT DAMAGE IN DNA

我们已经提出了DNA双链断裂的机制， (DSB)产生所述声称的生物学上显著的损伤（1）， 细胞内的电离辐射（2）。 机制预测 其他局部多重受损站点（LMDS）产生于 其不存在链断裂损伤。 据预测， 以比实际DSB更大的产率形成。 个人 可以产生LMDS的组成损伤部位， DNA的相对链之间的距离相对较大， 在分子水平上，多达10+个碱基对。 如此好的分离 受损部位可以像单个受损部位一样进行修复 这样，土地就不会对细胞造成危害，尽管它们会 在常规测定中作为LMDS测定。 在所提出的工作中，我们的目标是测量各种 在最初使用SV 40 DNA的模型系统中， 溶液被保护到与细胞中相同的OH'清除状态 然后是哺乳动物细胞内的染色质中的SV 40。 的 然后将SV 40 DNA的反应与细胞的反应进行比较。 使用非洲绿色的α串联重复序列的DNA 猴子作为一个模型。 然后我们将确定 分离LMDS对侧的构成损害 DNA链，最初同样使用SV 40模型系统，然后 扩展到如上所述的蜂窝系统。 最后经过 为了充分开发α DNA的检测方法，我们将探索 细胞修复各种类型的LMDS（非链 断裂对链断裂，短分离对长分离）。 因此，我们希望 为了明确定义各种重要的DNA损伤， 在维修时要注意。 这将有助于制定一个具体的 显著损伤的测定和分配酶 可以修复的过程。

We have suggested mechanisms whereby the DNA double strand break (DSB) the purported biologically significant lesion (1) is produced intracellularly by ionizing radiation (2). The mechanisms predict that other locally multiply damaged sites (LMDS) are produced in which none strand break damage is present. These are predicted to be formed in greater yield than actual DSBs. The individual constituent damage sites of an LMDS can be produced, separated on the opposite strands of the DNA by relatively large distances on the molecular level, up to 10+ base pairs. Such well separated damage sites could be repaired as if they were singly damaged sites land would then not be hazardous to the cell even though they would assay as LMDS in the usual assays. In the proposed work, we aim to measure the yields of the various types of LMDS in model systems initially using SV 40 DNA in solution protected to the same OH' scavenging state as in the cell and then SV 40 in chromatin then within the mammalian cell. The response of the SV 40 DNA will then be compared to that of cellular DNA using the alpha tandem repeat sequence of the African green monkey as a model. We will then determine the distribution of separation of the constituent damages of LMDS on the opposite Strands of DNA, again initially with the SV 40 model system, then extending to the cellular system as described above. Finally after developing the assay of alpha DNA fully, we will explore the ability of cells to repair the various types of LMDS (non-strand break vs strand break, short separation vs long). Thus, we hope to define clearly the variety of significant DNA damage which must be considered during repair. This will aid in devising a specific assay for significant damage and in assigning the enzymatic processes by which they can be repaired.