International Research Fellowship Program: Impacts of Solar Ultraviolet Radiation and Nutrient Limitation on Marine Microorganisms

0502339 Meador国际研究奖学金计划使美国科学家和工程师能够在国外进行三到二十四个月的研究。该计划的奖项提供了联合研究的机会，以及使用国外独特或互补的设施，专业知识和实验条件。该奖项将支持Jarah A. Meador与法国格勒诺布尔原子能中心的Theirry Douki和Jean Cadet博士以及法国Banyuls sur-Mer的巴黎第六大学的Fabien Joux博士合作。这项研究的重点是确定温度和营养限制是否是影响紫外线诱导海洋细菌DNA损伤和修复的因素。全球环境正在发生变化，温度、降雨量、云量、紫外线辐射和营养物负荷预计都将因人类活动而发生重大变化。虽然正在研究单一环境变量变化的实际和潜在影响，但多个压力源的交互影响很少受到关注。这些因素可能以协同的方式相互作用。浮游植物和浮游细菌构成海洋食物网的基础，紫外线辐射对这些生物群落的分子效应可能对海洋生态系统产生深远的影响。虽然浮游植物对紫外线辐射的反应已被广泛研究，但浮游细菌对紫外线辐射的反应相对较少。阐明这些反应强烈的紫外线辐射是重要的了解紫外线辐射对细菌多样性和光适应过程的影响，并最终对紫外线辐射可能对其他生态过程的影响。由于DNA很容易吸收UV-B区域内的太阳紫外线，阳光的大部分生物活性取决于这种分子的光化学。紫外线屏蔽和修复机制可能存在，以防止或减弱UV-B介导的DNA损伤。紫外线辐射的净生物效应取决于损伤诱导率和损伤修复率之间的平衡。重要的是要评估紫外线辐射敏感性与物种特异性差异诱导的DNA损伤，DNA修复能力，生存和人口增长。使用高效液相色谱-串联质谱法（HPLC-MS/MS），通过DNA水解后的特定色谱分析获得UVR诱导的光产物在细胞DNA中的完整分布。

0502339MeadorThe International Research Fellowship Program enables U.S. scientists and engineers to conduct three to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support a three-month research fellowship by Dr. Jarah A. Meador to work with Drs. Theirry Douki and Jean Cadet at Centre d'Energie Atomique de Grenobe, Laboratoire des Lesions de Acides Nucleiques (UMR CNRS) in Grenoble, France, and Dr. Fabien Joux at the Universite Paris VI in Banyuls sur-Mer, France.The focus of this research will be to determine if temperature and nutrient limitations are factors that influence UV induced DNA damage and repair in marine bacteria. The global environment is changing and substantial shifts in temperature, rainfall, cloud cover, ultraviolet radiation (UVR) and nutrient loading are all predicted as a result of anthropogenic activity. Although the actual and potential effects of changes in single environmental variables are being studied, the interactive effects of multiple stressors have received little attention. It is possible that these factors interact with each other in a synergistic manner. Phytoplankton and bacterioplankton comprise the base of oceanic foodwebs, and the molecular effects of UVR on these communities may have far reaching impacts on marine ecosystems. Although UVR responses of phytoplankton have been extensively studied, the responses of bacterioplankton to UVR are comparatively less well understood. Elucidating these responses to intense UVR is important for understanding the influence of UVR on bacterial diversity and photoadaptation processes and ultimately on the impact that UVR may have on other ecological processes. Because DNA readily absorbs solar UVR within the UV-B region, much of the biological activity of sunlight is dependent on the photochemistry of this molecule. UV-screening and repair mechanisms may exist to prevent or attenuate UV-B mediated damage to DNA. The net biological effect of UVR is dependent upon the balance between the rate of damage induction and the rate at which that damage is repaired. It is important to evaluate UVR sensitivity in relation to species-specific differences in induction of DNA damage, DNA repair capacity, survival, and population growth. A complete distribution of the UVR induced photoproducts within cellular DNA will be obtained from specific chromatographic analyses following DNA hydrolysis, using a high performance liquid chromatographic-tandem mass spectrometry method (HPLC-MS/MS).