EAGER: Intra-Clay Trapping of Organic Molecules – A Key Step in the Chemical Evolution of Life?

大约40亿年前，地球是一个不适合生命形成和演化的环境。那时没有像我们今天这样的臭氧层保护我们免受猛烈、有害的紫外线辐射。考虑到过度的火山活动，温度可能非常高。在这种条件下，导致生命形成的化学反应就不可能发生。那么，是什么让生命在我们的星球上成为可能呢？一些科学家同意诺贝尔奖得主生物化学家罗杰·科恩伯格的说法：“生命就是化学。”然而，将生命的形成简单地理解为复杂的分子相互作用的过程并不能充分解释地球早期的恶劣条件。它也不能解释是什么变化突然使得生命有可能在如此恶劣的条件下形成。今天，我们知道，生命的组成部分RNA和DNA受到细胞膜的保护，使它们免受潜在有害环境的影响，但这些细胞膜在40亿年前并不存在于地球上。一个基于地质学而非化学的科学假设认为，通常在沉积物和岩石中发现的粘土矿物，其功能类似细胞膜，保护最终形成生命所必需的RNA和DNA的分子。研究人员建议研究粘土矿物的功能，像细胞膜一样容纳那些早期的有机分子。简而言之，他们想研究地质在生命出现中的作用。更好地了解生命形成的地质维度可以改变人们对地球上生命起源的看法，并可能改变人们寻找和定义地球以外生命的方式。这一科学目标是美国国家科学基金会推动科学进步使命的核心。该提案的更广泛影响部分是探索一个新的场所，以增加多样性和参与地球科学研究生课程中代表性不足的群体。研究人员建议与塔斯卡卢萨（AL）的HBCU机构Stillman学院合作，将化学和生物学的本科生作为实验室研究助理，进行地球生物学和低温地球化学的研究。这将使这些学生接触到不同类型的地质学，而不是“只是看岩石”的普遍看法，并获得类似于研究生课程的学术研究经验。最终目标是在UA和Stillman学院之间建立长期合作关系，并促进非裔美国学生进入地质学和其他STEM学科的研究生课程。生命的化学进化研究是自然科学领域的一个基础性交叉研究课题。这项研究的一个基本方面是了解原始生物分子如何在地球早期的恶劣环境条件下“生存”下来。矿物，特别是粘土，长期以来被认为是促进生物分子积累和聚合的有效吸附表面，支持生命的进化。最近的一种假说甚至认为，粘土可能起到了类似于细胞膜的约束结构的作用，保护这些原始生物分子，同时促进最终导致RNA和DNA发育的生化反应。这意味着生物分子必须被封闭在粘土的层间空间中；然而，没有直接观察到这种捕获机制。该建议的智力优势在于，该团队首次提出使用最先进的原子探针断层扫描（APT）技术在三维空间中可视化有机分子是否可以存在于粘土矿物的层间区域。如果这些有机物“穿透”了粘土结构，它们将证明在冥古宙晚期或太古宙早期的生命起源中，粘土充当“细胞膜”的假设是可能的。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。

About 4 billion years ago, Earth was an inhospitable environment for the formation and evolution of life. There was no ozone layer like we have today protecting us from violent, harmful UV radiation. Temperatures likely were extremely high given the presence of excessive volcanic activity. Under these conditions, the chemical reactions that lead to the formation of life could not have occurred. So, what happened to make life possible on our planet? Some scientists agree with Nobel Prize winning biochemist Roger Kornberg in stating, “life is only chemistry.” However, to understand the formation of life as simply the process of complex molecular interactions does not adequately account for the early Earth's harsh conditions. Nor does it explain what changed to suddenly make it possible for life to form under those severe conditions. Today, it is known that RNA and DNA, the building blocks of life, are protected by a cell membrane that shields them from potentially harmful environments, but those cell membranes were not present on Earth 4 billion years ago. One scientific hypothesis, based on geology rather than chemistry, suggests that clay minerals, typically found in sediments and rocks, functioned like cell membranes, protecting the molecules that would eventually form the RNA and DNA that are essential to life. Investigators propose to examine the capacity of clay minerals to function like cell membranes that housed those early organic molecules. In short, they want to study the role of geology in the emergence of life. Understanding better the geological dimensions of life formation can change how one thinks about the beginnings of life on this planet and possibly alter the ways one looks for and define life beyond Earth. This scientific goal is at the core of NSF's mission to promote the progress of science. The Broader Impact component of this proposal is to explore a new venue to increase diversity and the participation of underrepresented groups in Geosciences graduate programs. Investigators propose to partner with Stillman College, a HBCU institution in Tuscaloosa (AL), to incorporate undergraduate students from Chemistry and Biology, as laboratory research assistants, to do research in geobiology and low-temperature geochemistry. This will expose these students to a different type of geology than the common perception of “just looking at rocks”, and to an academic research experience similar to that found in a graduate program. The ultimate goal is to establish a long-term collaboration between UA and Stillman College and to facilitate the access of African American students to graduate programs in Geology, and other STEM disciplines.The study of the chemical evolution of life is a fundamental interdisciplinary research topic in Natural Sciences. A fundamental aspect of this research is the understanding of how primitive biomolecules “survived” the harsh environmental conditions present on early Earth. Minerals, especially clays, have been long suggested as effective adsorption surface to promote the accumulation and polymerization of biomolecules to support the evolution of life. A more recent hypothesis even suggests that clays could have acted as confinement structures, similar to cell membranes, protecting these primitive biomolecules while promoting biochemical reactions ultimately leading to the development of RNA and DNA. This would imply that biomolecules had to be occluded within clays inter-layer spaces; however, there are no direct observations of this trapping mechanism. The Intellectual Merit of this proposal is that for the first time, the team proposes to visualize in three-dimensions whether organic molecules can be present within the interlayer regions of clays minerals using the state-of-the-art atom probe tomography (APT) technique. If these organics “penetrate” the clay structure, they would have demonstrated that the hypothesis of clays acting as "cell membranes" was a possibility during the life origin in the late Hadean or early Archean.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.