Molecular Distributions and D/H Ratios of Marine Archaea Lipids: Evaluating their Potential as Paleosalinity Proxies

古生物群是远洋海洋微生物区系中的重要组成部分，在世界海洋中分布广泛。这些生物的膜由乙醚连接的类异戊二烯类脂组成，这些脂类相对顽强，因此在沉积记录中保存完好。最近对这些化合物的研究表明，重要的环境信息由它们的结构和相对丰度记录下来，包括地表水温度。脂膜构成了细胞生命和其物理环境之间的界面，其他环境特性，特别是盐度，很可能与膜结构特性的变化有关。在这个项目中，宾夕法尼亚州立大学的研究人员将评估水和脂类之间的氢同位素分馏以及脂结构及其分布，以确定这些性质与生长环境中水的性质之间的关系。他们将调查从多个深度和时间从海洋和沿海水域收集的悬浮颗粒物中提取的脂质。他们将从钦科蒂格湾采集样本，钦科蒂格湾是一个相对原始的河口，水域的空间和季节性从新鲜到海洋不等，还将使用在前往黑海、地中海和百慕大附近水域的预定邮轮上收集的样本。他们之前曾从西西里岛海岸一个制盐基地的高盐度盆地收集样本并存档。研究的样本范围从新鲜到高盐条件。实地研究将通过使用选定的古生代分类群进行对照实验来补充，这些类群生长在一定的温度和盐度范围内，并使用同位素限制的基质。这种双重性质方法的实用性将通过分析与中新世晚期梅西尼期盐度危机有关的ODP样中的脂类来评估。将开发一个支持性的MS论文项目，利用过去8000年的沉积物记录来调查与黑海海洋入侵事件有关的类脂记录

ABSTRACTOCE-0327347The Archaea constitute a significant portion of pelagic marine microbiota, with members of the Euryarchaeota and Crenarchaeota abundant and widespread in the world's oceans. The membranes of these organisms are composed of ether-linked isoprenoid lipids, which are relatively recalcitrant and therefore well preserved in sedimentary records. Recent investigations of these compounds reveal important environmental information is recorded by their structures and their relative abundances, including surface-water temperatures. Lipid membranes comprise the interface between cellular life and its physical environment, and it is likely that other environmental properties, especially salinity, are associated with changes in the properties of membrane structures. Further, these structures are potentially useful recorders of the hydrogen isotopic composition of water in their growth environment, providing an independent measure of salinity.On this project, researchers at the Pennsylvania State University will evaluate H isotopic fractionation between waters and lipids, as well as lipid structures and their distributions in order to determine relationships between these properties and those of waters in the growth environment. They will survey lipids extracted from suspended particulate matter collected at multiple depths and times from oceanic and coastal waters. They will collect samples from the Chincoteague Bay, a relatively pristine estuary, with waters that range spatially and seasonally from fresh to marine and will also employ samples collected during scheduled cruises to the Black Sea, the Mediterranean and to waters near Bermuda. They have previously collected and archived samples from hypersaline basins in a salt-manufacturing site on the coast of Sicily. The samples studied will range from fresh to hypersaline conditions. Field studies will be complemented by controlled experiments using selected Archaea taxa, grown under a range of temperatures and salinities and using isotopically constrained substrates. The utility of this dual-property approach will be evaluated by analysis of lipids in ODP samples associated with the late-Miocene Messinian Salinity Crisis. A supporting MS thesis project will be developed to investigate the lipid record associated with the marine incursion event in the Black Sea using sediment records from the past 8,000 years