Amino Acid Molecular-Level Stable Isotopic and Enantiomeric Ratios: A New Approach for Understanding Source and Transformation of Organic Nitrogen in the Sea.

氨基酸分子水平稳定同位素和对映体比率：了解海洋有机氮来源和转化的新方法。

• 批准号: 0623622
• 负责人: Matthew McCarthy
• 金额: $ 42.91万
• 依托单位: University of California-Santa Cruz
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-09-15 至 2011-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0623622&HistoricalAwards=false
• 关键词: Amino; Acid; Molecular; Level; Stable

ABSTRACTProposal # OCE-0623622Particulate and dissolved organic nitrogenous material (PON & DON) represent the major active pools of reduced organic N in the ocean. Sinking PON and advected DON from the surface into the ocean's interior represent the main pathways for export of new production, nitrogen flux and remineralization, as well as long-term organic nitrogen storage as DON in the deep sea. The chemical identity of organic nitrogen is key to understanding its sources, roles in ocean food webs, and the biogeochemical mechanisms that regulate its cycles. However, the large majority of PON in the deep ocean, and DON at all depths, cannot be identified at the molecular level. Accumulating evidence now indicates that this material is composed of largely unaltered biomolecules (amide N functions), and is likely dominated in most reservoirs by amino acids (AA). While hydrolyzable AA composition has long been a powerful tool for investigating diagenetic transformations, traditional AA measurements have intrinsic limitations for differentiating specific sources and transformations of ON in the ocean's water column.In this research, two PIs from University of California Santa Cruz will develop a new set of molecular-level tools based on the recognition of *15N and *13C AA stable isotopic patterns that potentially record both a metabolic signature of their synthetic origin, as well as diagnostic signatures of subsequent heterotrophic transformations. They hypothesize that, together with enantiomeric (D/L) ratios, *15N and *13C AA signatures can be used to determine both ultimate source and heterotrophic processing of organic N at a level of specificity and detail that has not previously been possible. To test these hypotheses, they will conduct a set of lab experiments using multiple prokaryotic and eukaryotic algae in a linked series of feeding experiments with bacterial, protist, and macrozooplankton transformations. Upon completion of this proposal, ocean scientists will be in an excellent position to extend these methods from the laboratory to field studies with confidence. Among its broader impacts, this proposal will have far-reaching implications for our basic understanding of how organic nitrogen cycling works in the ocean. This in turn would have direct and indirect impacts on our understanding of carbon cycling, as well as how other researchers parameterize regional and global biogeochemical models. Undergraduate, graduate and post-doctoral education will be furthered through active participation in laboratory and data synthesis activities. Two graduate students will be provided a unique educational background in molecular level isotopic tools and biogeochemistry. Undergraduate research will also be involved throughout the project.

OCE-0623622号提案中的颗粒和溶解有机含氮物质（PON DON）是海洋中还原有机氮的主要活性库。从海洋表面下沉的PON和平流的DON代表了新产品输出的主要途径，氮通量和矿化，以及长期的有机氮储存在深海中的DON。有机氮的化学特性是理解其来源、在海洋食物网中的作用以及调节其循环的地球化学机制的关键。然而，深海中的绝大多数PON和所有深度的DON无法在分子水平上识别。越来越多的证据表明，这种物质主要由未改变的生物分子（酰胺N功能）组成，并且在大多数水库中可能由氨基酸（AA）主导。虽然可水解的AA组成长期以来一直是研究成岩转化的有力工具，但传统的AA测量在区分海洋水柱中ON的特定来源和转化方面具有固有的局限性。来自加州大学圣克鲁斯分校的两名研究人员将开发一套新的分子水平工具，这些工具基于对 * 15 N和 * 13 C AA稳定同位素模式，可能记录其合成来源的代谢特征，以及随后的异养转化的诊断特征。他们假设，与对映体（D/L）比，* 15 N和 * 13 C AA签名可以用来确定最终的来源和异养处理的有机N的特异性和细节的水平，以前是不可能的。 为了验证这些假设，他们将进行一系列实验室实验，使用多种原核和真核藻类进行一系列与细菌，原生生物和大型浮游动物转化相关的喂养实验。 这项建议完成后，海洋科学家将处于有利地位，有信心将这些方法从实验室推广到实地研究。在其更广泛的影响中，这一提议将对我们对海洋中有机氮循环如何运作的基本理解产生深远的影响。这反过来又会对我们对碳循环的理解产生直接和间接的影响，以及其他研究人员如何对区域和全球生物地球化学模型进行参数化。本科生、研究生和博士后教育将通过积极参与实验室和数据综合活动得到进一步发展。两名研究生将在分子水平同位素工具和地球化学方面获得独特的教育背景。本科生的研究也将参与整个项目。