RECONSTRUCTING PAST ECOLOGIES USING PEPTIDOMICS

该项目将试图通过观察在海底发现的泥浆中的蛋白质来了解过去的海洋是什么样子。当海洋生物死亡时，它们有时会沉到海底，它们的尸体会堆积在泥里。即使是非常小的生物体也会发生这种情况，它们的一些蛋白质被留下了。就像树干的年轮一样，海底的沉积物慢慢积累，并作为过去的记录。沉积物越深，蛋白质就越古老。这项研究将从大约15万年前的沉积物中提取蛋白质。这些蛋白质将根据它们在生物体中所具有的功能以及它们来自的生物体进行分类。这项研究将发现数百种古老的蛋白质。这些蛋白质将提供有关过去生活在该地点的生物类型以及它们在做什么的信息。这些数据将使重建过去海洋的生态成为可能。这项研究将使用来自墨西哥太平洋沿岸的沉积物，那里的条件很好，可以保存蛋白质，而且那里过去生活的微生物群落预计与现在有很大的不同。该项目将支持一名墨西哥裔美国女性博士后和一个高中实习项目。在这个项目中，来自地球科学领域代表性不足群体的三名高中生将与本科生和研究生导师配对。过去的海洋环境通常使用与重要的海洋过程（如初级生产）相关的特定有机代用品来评估。提出了一种重建水柱过去生态的新工具（如估算群落结构和组成）。从延伸至末次盛冰期的海洋沉积物中提取的肽将用于重建上覆水域过去的群落生态。同时评估提取肽的成岩状态提供了一个内置的测量多少降解已经发生，允许反计算初级生产。新的基于肽的生物标记物的开发将允许对过去的海洋条件进行更详细的生态评估，从而能够更好地预测未来的变化。多肽将从沿巴哈半岛东部热带北太平洋收集的特征良好的变异沉积物芯中提取。一种基于串联质谱计算分析的全新定向肽组学方法将用于识别全新世和LGM岩心亚样品中的肽。这些被认为是从海洋沉积物中首次成功提取肽。要评估的肽包括高度保守的肽，这些肽只与光合作用有关，但在各个王国都是普遍存在的。由于这些多肽是普遍存在的，但对自养生物来说是独特的，它们可以作为一个样品的总叶绿体（如叶绿素，初级生产）的代理。鉴定其他群落功能如固氮和反硝化的肽也将被寻找。整体的肽组成记录了上覆水的时间切片。岩心有一个构造良好的年龄模型，并且已经分析了生物成因二氧化硅和色素，从而提供了其他比较措施。在ETNP核心位置及其附近收集的浮游生物和下沉颗粒的现代样本也将进行评估。其目的是发展对古记录的定量理解，这些记录可以从岩心中的肽中提取出来，并将其与上覆水中向沉积物传递信号的过程联系起来。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The project will try to understand what the ocean was like in the past by looking at proteins in mud found at the bottom of the ocean. When marine organisms die they sometimes sink to the bottom of the ocean and their carcasses accumulate in the mud. This happens even for very small organisms, and some of their proteins are left behind. Like the rings of a tree trunk, sediment at the bottom of the ocean slowly accumulates and acts as a recording of the past. The deeper you go into the sediment the older the proteins are. The study will extract protein from sediment that goes back about 150,000 years. The proteins will be sorted by the functions the proteins had when they were in the living organism, and by the organisms that they came from. The study should discover hundreds of ancient proteins. Those proteins will provide information about the types of organisms living in the past at that spot and what they were doing. Those data will make it possible to reconstruct the ecology of the past ocean. The study will use sediments from the Pacific coast of Mexico where conditions are good to preserve proteins, and where the community of microscopic organisms living in the past is expected to be dramatically different from today. The project will support a Mexican-American woman postdoc and a high school internship program. In that program three high school students from groups underrepresented in the earth sciences will be paired with undergraduate and grad student mentors. Past ocean environments are often evaluated using specific organic proxies that are linked to important oceanic processes such as primary production. A new tool for reconstructing the past ecology of the water column (e.g. estimating community structure and composition) is proposed. Peptides extracted from a well-characterized marine sediment that extends back into the Last Glacial Maximum will be used to reconstruct the past community ecology of the overlying water. Simultaneous assessment of the diagenetic status of extracted peptides provides a built-in measure of how much degradation has occurred, allowing for back-calculation of primary production. The development of new peptide-based biomarkers will allow for past oceanic conditions to be assessed in much greater ecological detail, thus enabling better prediction of future change. Peptides will be extracted from a well-characterized varved sediment core collected in the Eastern Tropical North Pacific along the Baja peninsula. A novel de novo-directed peptidomic approach based on computational analyses of resultant tandem mass spectra will be used to identify peptides in subsamples of the core from the Holocene and the LGM. These are believed to be among the first successful peptide extractions from marine sediments. The peptides to be evaluated include highly conserved peptides that are found only associated with photosynthesis but are universal across kingdoms. Because these peptides are universal but unique to autotrophs, they serve as a proxy for the total chloroplast (e.g. chlorophyll, primary production) of a sample. Peptides that identify other community functions such as nitrogen fixation and denitrification will also be sought. The overall peptide composition records a slice in time of the overlying water. The core has a well-constructed age model and has already been analyzed for biogenic silica and pigments, thus providing other measures to compare against. Modern samples of plankton and sinking particles collected at and near the ETNP core location will also be assessed. The intent is to develop a quantitative understanding of the paleo record that can be extracted from the peptides in the core and relate it back to the processes in the overlying water that deliver the signal to the sediment.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.