246 Noble Research Center, Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK 74078, USA.
Mol Plant. 2012 Jan;5(1):187-204. doi: 10.1093/mp/ssr069. Epub 2011 Aug 25.
Acute ozone is a model abiotic elicitor of oxidative stress and a useful tool for understanding biochemical and molecular events during oxidative signaling. Two Medicago truncatula accessions with contrasting responses to ozone were used to examine translational regulation during ozone stress. In ozone-resistant JE154, significant reduction in ribosome loading was observed within one hour of ozone treatment, suggesting energy homeostasis as a vital factor for oxidative stress management. Polysomal RNA-based expression profiling with Affymetrix arrays revealed extensive changes in the translatomes of both accessions. Messenger RNAs with low GC content in their 5' and 3'-UTRs were preferentially associated with polysomes during oxidative stress. Genebins analysis revealed extensive changes in various gene ontologies in both accessions. Extensive changes in nicotinate and nicotinamide metabolism genes were corroborated with increased levels of NAD(+) and NADH in JE154. The significantly lower NAD(+):NADH redox status in JE154, in conjunction with higher ATP amounts, provided a cellular milieu conducive for overcoming oxidative stress. Low levels of ATP, NADH, and suppression of antioxidant defense responses, abet build-up of ozone-derived ROS and ultimately lead to oxidative cell death in Jemalong.
急性臭氧是一种模拟的非生物激发子，可用于氧化应激过程中的生化和分子事件的研究。本研究使用两个对臭氧具有不同响应的紫花苜蓿（Medicago truncatula）品系来研究臭氧胁迫下的翻译调控。在臭氧抗性品系 JE154 中，臭氧处理后一小时内观察到核糖体装载显著减少，表明能量稳态是氧化应激管理的重要因素。基于 Affymetrix 芯片的多核糖体 RNA 表达谱分析揭示了两个品系的翻译组都发生了广泛的变化。在氧化应激过程中，5'和 3'-UTR 中 GC 含量低的信使 RNA 优先与多核糖体结合。基因簇分析揭示了两个品系中各种基因本体论的广泛变化。烟碱酸和烟酰胺代谢基因的广泛变化与 JE154 中 NAD(+)和 NADH 水平的增加相吻合。JE154 中 NAD(+)：NADH 氧化还原状态显著降低，同时 ATP 含量较高，为克服氧化应激提供了有利的细胞环境。低水平的 ATP、NADH 和抗氧化防御反应的抑制，促进了臭氧衍生的 ROS 的积累，最终导致 Jemalong 发生氧化细胞死亡。
