ANTIOXIDANT METABOLISM IN CHLAMYDOMONAS

活性氧（ROS）是不可避免地产生在细胞中的所有 好氧生物，从细菌植物和动物。应对 ROS产生的潜在破坏性后果是一个问题， 广泛的生物学意义。 参与的兴奋和高度 有氧光合作用中的反应中间体带来了独特的问题 藻类和植物产生活性氧。 的 拟议的研究计划集中在光合作用如何 生物体防止或最小化由ROS引起的光氧化损伤。 到 解剖叶绿体中的抗氧化防御， 单细胞绿色衣藻Chlamydiumreinhardtii。 几种突变体影响叶黄素色素的代谢， 在所有藻类和植物的光保护中起着关键作用。 一个npq 1 lor 1双突变体，其缺乏叶黄素和玉米黄质， 在强光下发生光氧化漂白，可能是由于 增加活性氧的产生和/或减少活性氧的猝灭，特别是 单线态氧 这项研究将检查照片的类型- 氧化损伤和各种抗氧化系统的反应， npq 1 lor 1细胞。 分离叶黄素中受影响的基因 突变体将能够确定突变体的分子基础 表型，并将为进一步遗传提供坚实的基础 分析，包括分离npq 1 lor 1的抑制子。 的 其他ROS的产生和/或清除在另一组中受到干扰 突变体，这将是其特征在于使用分子的组合， 遗传学、生物化学和生理学方法。了解 藻类中叶黄素和其他抗氧化剂的代谢和功能 而植物将提供这些重要作用的见解， 分子在预防老年性疾病，如黄斑 并将使抗氧化剂的工程 植物的新陈代谢有益于人类的营养和健康。

Reactive oxygen species (ROS) are generated inevitably in cells of all aerobic organisms, from bacteria plants and animals. Coping with the potentially damaging consequences of ROS generation is a problem of broad biological significance. The involvement of excited and highly reactive intermediates in oxygenic photosynthesis poses unique problems for algae and plants with respect to the generation of ROS. The proposed research plan is focused on the question of how photosynthetic organisms prevent or minimize photo-oxidative damage caused by ROS. To dissect antioxidant defenses in the chloroplast, mutants of the unicellular green alga Chlamydomonas reinhardtii, have been isolated. Several mutants affect the metabolism of xanthophyll pigments, which have critical roles in photoprotection in all algae and plants. An npq1 lor1 double mutant, which is deficient in lutein and zeaxanthin, undergoes photo-oxidative bleaching in high light, presumably due to increased production and/or decreased quenching of ROS, especially singlet oxygen. The proposed research will examine the types of photo- oxidative damage and the responses of various antioxidant systems in npq1 lor1 cells. Isolation of the genes affected in the xanthophyll mutants will enable determination of the molecular basis for the mutant phenotypes and will provide a strong foundation for further genetic analysis, including isolation of suppressors of npq1 lor1. The generation and/or scavenging of other ROS is perturbed in another group of mutants, which will be characterized using a combination of molecular genetic, biochemical, and physiological approaches. Understanding the metabolism and function of xanthophylls and other antioxidants in algae and plants will provide insights into the important roles of these molecules in preventing age-related diseases such as macular degeneration in humans and will enable engineering of antioxidant metabolism in plants to benefit human nutrition and health.