Genetic Analysis of Radiation Response in Plants

山 MCB 978125植物经常暴露于来自太阳的UV-B光和作为新陈代谢产物的氧气，两者都可以并且确实会损害DNA。因此，植物可能利用有效的机制来修复这些类型的DNA损伤。已经分离出对紫外光异常敏感的拟南芥突变体，并发现其包含在不同位置映射的几个互补组。目前正在研究两个基因，这两个基因已被初步确定为参与核苷酸切除修复紫外线损伤途径的编码产物。 目前正在尝试定位克隆UVH 1和UVH 3。初步证据表明，UVH 1基因座可能是人类XP-B基因的同源物，该基因是参与人类遗传疾病着色性干皮病的几个互补组之一，以及酵母Rad 25基因。将完成这些基因的克隆，进行互补试验，并对突变基因进行测序。放射免疫分析和适当的酵母突变体的互补将进一步探索基因的功能。 将研究对不断变化的环境条件的反应，例如通过修改转录调控来改变紫外线强度和氧气产生。其他拟南芥切除修复基因将被确定，表征和映射。 可以预期植物需要高效的机制来去除和修复DNA损伤，因为它们不断暴露于阳光和分子氧，这两种因素都已知会导致DNA损伤。由于植物的生殖器官是从未分化的体细胞组织发育而来的，因此这项任务在植物中变得更加重要。从这项正在进行的研究中获得的信息将使人们更深入地了解修复过程。

Mount MCB 978125 Plants are constantly exposed to UV-B light from the sun and oxygen as a product of metabolism and both can and do damage DNA. Hence, plants are likely to utilize efficient mechanisms for repairing these types of DNA damage. Mutants of Arabidopsis that are abnormally sensitive to UV light have been isolated and found to comprise several complementation groups that map in different locations. Two genes, which have been tentatively identified as encoding products which are involved in the pathway for nucleotide excision repair of UV damage are under study. An attempt to positionally clone UVH1 and UVH3 is underway. Preliminary evidence suggests that the UVH1 locus may be a homolog of the human XP-B gene, a gene which is one of the several complementation groups involved in the human genetic disease xeroderma pigmentosum, as well as the yeast Rad 25 gene. The cloning of these genes will be completed, complementation tests performed and mutant genes sequenced. A radioimmune assay and complementation of the appropriate yeast mutants will further explore the function of the genes. The response to changing environmental conditions such as variation in UV light intensity and oxygen-production by the modification of transcriptional regulation will be investigated. Additional Arabidopsis excision repair genes will be identified, characterized and mapped. Plants can be expected to require highly efficient mechanisms for removal and repair of DNA damage since they are constantly exposed to sunlight and molecular oxygen, both factors known to cause DNA damage. Since the reproductive organs of plants are developmentally derived from undifferentiated somatic tissues, that task becomes even more critical in plants. Information derived from this on-going study will give greater insight into that repair process.