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海洋过去是什么样的。 当海洋生物死亡时，它们有时会沉到海底，尸体会堆积在泥土中。 即使是非常小的生物体也会发生这种情况，并且它们的一些蛋白质会被留下。 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。 你越深入沉积物，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该地点过去生活的生物类型以及它们在做什么的信息。 这些数据将使我们有可能重建过去海洋的生态。该研究将使用来自墨西哥太平洋沿岸的沉积物，那里的条件有利于保存蛋白质，并且过去生活的微生物群落预计将与今天截然不同。 该项目将支持一名墨西哥裔美国妇女博士后和一个高中实习项目。在该项目中，来自地球科学领域代表性不足的三名高中生将与本科生和格拉德生导师配对。过去的海洋环境往往使用与初级生产等重要海洋过程有关的特定有机替代物进行评估。提出了一种新的工具，用于重建过去的水柱生态（如估计群落结构和组成）。从一个良好的特征海洋沉积物中提取的肽，延伸到末次冰盛期将被用来重建过去的社区生态上覆水。提取的肽的成岩状态的同时评估提供了一个内置的措施有多少降解发生，允许反算的初级生产。开发新的基于肽的生物标志物将使过去的海洋条件能够在更大的生态细节中进行评估，从而能够更好地预测未来的变化。 将从沿下半岛的热带北太平洋东部沿着采集的特征良好的纹状沉积物岩心中提取肽。一种新的从头定向肽组的方法的基础上产生的串联质谱的计算分析将被用来确定从全新世和末次冰期的核心子样品中的肽。 这些被认为是从海洋沉积物中首次成功提取肽的方法之一。待评估的肽包括高度保守的肽，其仅与光合作用相关，但在界间是普遍的。因为这些肽是通用的，但对于自养生物是独特的，所以它们充当样品的总叶绿体（例如叶绿素，初级生产）的代表。还将寻求鉴定其他群落功能如固氮和反硝化的肽。总的肽组成记录了上覆水的时间切片。 岩心具有构造良好的年龄模型，并且已经分析了生物硅和颜料，从而提供了其他可比较的测量方法。 还将评估在ETNP核心位置及其附近收集的浮游生物和沉降颗粒的现代样本。 其目的是发展对古记录的定量理解，这些古记录可以从岩芯中的肽中提取，并将其与上覆水中将信号传递给沉积物的过程联系起来。该奖项反映了NSF的法定使命，并被认为值得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来支持。

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.