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

University Of Alabama Tuscaloosa, Tuscaloosa AL

Investigators

Abstract

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.