A window on ancient systems: Understanding the environmental distributions of hopanoids using compound-specific multi-isotope analysis and metagenomics

了解古代系统的窗口：使用化合物特异性多同位素分析和宏基因组学了解藿类化合物的环境分布

• 批准号: 1349126
• 负责人: Ann Pearson
• 金额: $ 34.86万
• 依托单位: Harvard University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-05-01 至 2017-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1349126&HistoricalAwards=false
• 关键词: window; ancient; systems; Understanding; environmental; window; ancient; systems; Understanding; environmental

Technical overview:A better understanding of the modern sources and distributions of hopanoids is essential for interpreting ancient sedimentary records. Here we will address questions of hopanoid provenance in marine settings using interdisciplinary analytical approaches, namely compound-specific multi-isotope (13C, D/H, and 14C) measurements combined with analysis of functional genes involved in hopanoid biosynthesis. The project will make a systematic survey of hopanoid isotope measurements and DNA metagenomes. The samples will cover locations ranging from arctic to tropical, and three sets of samples will span gradients of deltaic to pelagic depositional conditions, forming mini-transects. The samples will permit use of the established latitudinal patterns in 14C residence times and source water D/H to distinguish land-based from marine sources. Known patterns of 13C and D/H isotopic fractionation associated with different types of microbial metabolism will be used to determine the metabolic sources of individual compounds, because autotrophic or heterotrophic metabolism is reflected in isotopic variability. The diversity of hopanoid biosynthesis genes (sqhC, hpnP, hpnR, hpnG, hpnH) will be related to hopanoid compound distributions in an independent approach to test if local production is or is not related to local deposition of lipid assemblages. General importance:Organic molecules preserved in sedimentary rocks provide a record of Earth?s early biosphere. They help us understand ancient Earth environments and the expansion, diversification, and maintenance of microbial communities. Such compounds are called 'molecular fossils', and among the earliest and most abundant examples are compounds called hopanoids. Derived primarily from bacteria, hopanoids are detectable over timescales of billions of years and have been proposed to be among the most abundantly preserved molecules on Earth. However, to date we lack an overall picture of their environmental, physiological, and/or species origins. This project aims to answer basic questions about the hopanoids preserved in marine sedimentary environments. Are they primarily of marine origin, or do they come primarily from land? Are they likely to reflect particular sub-groups of microbial taxa, or are they broadly distributed among diverse species, habitats, and lifestyles? In this project we will use the natural distribution of the isotopes of carbon and hydrogen to help answer these questions.

技术概述：更好地理解霍托类动物的现代资源和分布对于解释古代沉积记录至关重要。 在这里，我们将使用跨学科的分析方法在海洋环境中解决霍托甘油素的问题，即复合特异性的多同位素（13C，d/h和14c）测量结果，结合了对霍烷生物合成涉及功能基因的分析。 该项目将对霍托甘油同位素测量和DNA宏基因组进行系统的调查。样品将覆盖从北极到热带的位置，三组样品将跨越三角洲至上层沉积条件的梯度，形成微型触发。 样品将允许在14C停留时间内使用已建立的纬度模式，并源水D/H来区分陆基和海洋来源。 与不同类型的微生物代谢相关的13C和D/H同位素分级的已知模式将用于确定单个化合物的代谢来源，因为在同位素变异性中反映了自身营养或异养代谢。在独立的方法中，Hopanoid Biosynsis基因（SQHC，HPNP，HPNR，HPNG，HPNH）的多样性将与Hopanoid化合物分布有关，以测试局部生产是否与脂质组合的局部生产无关。 一般重要性：保存在沉积岩中的有机分子提供了地球早期生物圈的记录。 它们帮助我们了解古代地球环境以及微生物群落的扩张，多样化和维护。 这样的化合物称为“分子化石”，最早和最丰富的例子是称为霍托甘酸盐的化合物。 在数十亿年的时间尺度上，霍甘酸是主要源自细菌的，并被认为是地球上保存最丰富的分子之一。 但是，迄今为止，我们缺乏对环境，生理和/或物种起源的整体情况。 该项目旨在回答有关在海洋沉积环境中保存的霍托甘油类似的基本问题。 它们主要是海洋来源，还是主要来自土地？ 它们是否可能反映了特定的微生物分类群，或者它们是在各种物种，栖息地和生活方式中广泛分布的？ 在这个项目中，我们将使用碳和氢的同位素的自然分布来帮助回答这些问题。