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Project Reports

• Biomimetic Cluster Synthesis: Bridging the Structure and Reactivity of Biotic and Abiotic Iron-Sulfur Motifs

  Synthetic approaches are being utilized to bridge the gap between Fe-S minerals and highly evolved biological Fe-S metalloenzymes. These studies are focusing on organic template (protein) mediated cluster assembly (biomineralization), probing properties of synthetic clusters, both as homogeneous and heterogeneous catalysts, investigating the impact of size scale on the properties of synthetic Fe-S clusters, and computational modeling of the structure and catalytic properties of synthetic Fe-S nanoparticles in the 5-50 nm range.

  ROADMAP OBJECTIVES: 3.1 3.2 3.3 3.4 7.1 7.2

• Amino Acid Preservation in Saline-Lake Sediments and Mars-Simulant Regolith

  Potentially habitable environments on the Martian surface have been identified by orbital spectroscopy and by landed instruments on the Mars Exploration Rovers (MERs). Identification of evaporite mineral assemblages on Mars provides strong evidence for the widespread role of evaporitic water bodies of water in the past. Evaporite minerals may provide enhanced preservation of biomolecules by sequestration of organic constituents into mineral matrices during crystallization. The utilization of amino acids, the building blocks of proteins, as a distinct biosignature that could be extracted from evaporite phases would provide a strong biosignature for life having existed in the past or persisting to the present on Mars.

  ROADMAP OBJECTIVES: 2.1 3.2 5.1 5.3 7.1

• Module 1: The Building Blocks of Life

  Molecular material that may lead to life on planet surfaces has its origin in interstellar space. Using a combination of laboratory spectroscopic measurements and radio astronomical observations, this module has been tracing the life cycle of carbon and phosphorus containing compounds from their formation in outflows around old stars to their arrival on planet surfaces via exogenous delivery. We have been investigating what carbon and phosphorus compounds are found in matter lost from stars, and how the chemical composition changes as this material flows into the interstellar medium and forms dense clouds
  in space. We are following what happens to these compounds as these clouds evolve into solar systems, and how comets, meteorites, and dust particles may have brought interstellar pre-biotic material to Earth and other planets.

  ROADMAP OBJECTIVES: 3.1 3.2 4.2 7.1

• Computational Chemical Modeling the Link Between Structure and Reactivity of Iron-Sulfur Motifs

  The Fe-S mineral catalysis, Fe-S enzyme catalysis, and a biomimetic thrust areas of ABRC have their own unique ways to probe the relationships between structure and reactivity at the active sites of iron-sulfur enzymes and the structure and reactivity of iron-sulfur minerals. We have developed a cohesive link among these thrust areas through bridging the enzymatic/mineral catalysis and molecular structure/chemical reactivity by computational chemistry.

  ROADMAP OBJECTIVES: 3.1 3.2 3.3 7.1 7.2

• Advancing Techniques for in Situ Analysis of Complex Organics

  Our research in laser mass spectrometry is part of the overall program of the Goddard Center for Astrobiology to investigate the origin and evolution of organics in planetary systems. Laser mass spectrometry is a technique that is used to determine the chemical composition of sample materials such as rocks, dust, ice, meteorites in the lab. It also may be miniaturized so it could fit on a robotic spacecraft to an asteroid, a comet, or even Mars. On such a mission it could be used to discover any organic compounds preserved there, which in turn would give us insight into how Earth got its starting inventory of organic compounds that were necessary for life. The technique uses a high-intensity laser to “zap” atoms and molecules directly off the surface of the sample. The mass spectrometer instantly captures these particles and provides data that allow us to determine their molecular weights, and therefore their chemical composition. We are developing this technique to understand the mass spectra that would be obtained from a meteorite or an unknown rock sample encountered on a remote planetary mission.

  ROADMAP OBJECTIVES: 2.1 2.2 3.1 3.2 7.1

• Early Metabolic Pathways

  The project is aimed at characterizing the emergence of functional proteins and their early evolution leading to the formation of primitive metabolism in ancestors of contemporary cells. Through a combination of molecular biology and computer modeling we investigate the origins of both water-soluble enzymes and membrane proteins that mediate transport of small molecules and ions across cell walls.

  ROADMAP OBJECTIVES: 3.2 3.4

• Molecular Beam Studies of Nitrogen Reactions on Iron-Sulfur Surfaces

  It is generally accepted that surface-mediated reactions occur on defect sites. The role of defects in the formation of ammonia is being evaluated using molecular beam-surface scattering experiments in which a deuterium atom plasma source is used to hydrogenate a pyrite surface with D atoms. The hydrogenated surface is subsequently bombarded with a molecular beam of energetic N2 molecules and the conversion of N2 to products such as ammonia is probed through mass spectrometry.

  ROADMAP OBJECTIVES: 3.1 3.2 3.3 7.1 7.2

• 4. Prebiotic Molecular Selection and Organization

  ROADMAP OBJECTIVES: 3.1 3.2 3.4 4.1 7.1

• Origin of Life and Catalysis – Philosophical Considerations

  Our goal is to provide a solid philosophical foundation for the ABRC research program. To achieve this goal, we have several sub-goals like helping the students to develop their position as a group regarding a viable account for the metabolism-first theory, examining some methodological assumptions of the current astrobiological community, and finally propagating the information learned in our group to a larger community by offering courses on the origin of life.

  ROADMAP OBJECTIVES: 3.1 3.2 3.3 3.4 4.2

• Pearson Project

  ROADMAP OBJECTIVES: 3.2 4.2 6.1 7.1

• Probing the Structure and Nitrogen Reduction Activity of Iron-Sulfur Minerals

  Fe-S compounds are common in both biological and geological systems. The adaptation of Fe-S clusters from the abiotic world to the biological world may have been an early event in the development of life on Earth and possibly a common feature of life elsewhere in the universe. The Iron-sulfur mineral thrust of the ABRC is focused on examining the structure and reactivity of FeS minerals using nitrogen fixation as a model reaction.

  ROADMAP OBJECTIVES: 3.1 3.2 3.3 3.4 7.1 7.2

• Structure, Function, and Biosynthesis of the Complex Iron-Sulfur Clusters at the Active Sites of Nitrogenases and Hydrogenases

  Iron-sulfur clusters are thought to be among the most ancient cofactors in living systems. The Fe-S enzyme thrust is focused on examining the structure, mechanism, and biosynthesis of the complex Fe-S enzymes nitrogenase and hydrogenase.

  ROADMAP OBJECTIVES: 3.1 3.2 3.3 7.1 7.2

• Requirements for the Development and Maintenance of Complex Life

  ROADMAP OBJECTIVES: 3.2 4.2

• Planetary-Scale Transition From Abiotic to Biotic Nitrogen Cycle

  Nitrogen is an essential element for life. Understanding the planetary nitrogen cycle is critical to understanding the origin and evolution of life. The earth’s atmosphere is full of nitrogen gas (N2). However, this large pool of nitrogen is unavailable to most of the life on earth except a few microbes capable of “fixing” nitrogen into a form that can be used by other organisms (e.g., NH3, NH4+, NOx, organic-N). Without fixed nitrogen life would not have originated on earth and would most likely not occur on any other planet. The Atacama Desert in Chile is an enigma in that it contains vast nitrate (a type of fixed nitrogen) deposits. Elsewhere on earth, nitrate is either denitrified (transformed into N2 and released back into the atmosphere) through the activity of microorganisms, or is dissolved and leached from the system. Although the Atacama is the driest desert in the world we have shown that lack of water alone cannot account for the lack of nitrogen cycling in this desert. Preliminary data suggest that it may be due to the high oxidation level of the soil in combination with a lack of organic material in the soil.

  ROADMAP OBJECTIVES: 1.1 2.1 3.2 4.1 5.1 5.2 5.3 6.1

• Functional Genomics of Thioredoxins in Halobacterium Sp. NRC-1

  This project addresses the functions of an ancient protein family in Archaea that occupy extreme environments. Some of these proteins may play roles similar to those of comparable proteins in other living organisms, and thus may tell us about functions that evolved in the last universal common ancestor of life. Others may have evolved as the Archaea began to occupy specialized and often extreme environments. This project also addresses the emergence of proto-metabolic networks that supplied the precursors for the RNA World.

  ROADMAP OBJECTIVES: 3.1 3.2 5.1 5.3

• 7. Astrobiotechnology

  ROADMAP OBJECTIVES: 2.1 2.2 3.1 3.2 5.3 6.2 7.1

• Microbial Diversity of a Hypersaline Microbial Mat

  The goal of this project is to survey the microbial life that comprises a hypersaline microbial mat at Guerrero Negro, Mexico using culture independent technology (ribosomal and other gene sequences). The results have expanded significantly our knowledge of microbial diversity, bacterial, archaeal and eucaryotic.

  ROADMAP OBJECTIVES: 3.2 3.3 5.1 5.2 5.3 7.2

• Mars Forward Contamination Studies Utilizing a Mars Environmental Simulation Chamber

  A variety of microorganisms have been selected for experimental culturing in a Mars environmental simulation chamber. The test organisms are adapted on Earth to desiccation resistance and cold tolerance so they are suitable for exposure to simulated surface conditions on Mars. The test chamber is capable of reproducing temperatures, solar radiation, and atmospheric conditions inferred for Mars. Results from these tests will provide critical information for the design and engineering of sampling and caching equipment on a future mission to sample rocks and sediments on Mars and return those samples to Earth for laboratory study.

  ROADMAP OBJECTIVES: 2.1 3.2 3.3 5.1 5.2 5.3 6.1 6.2 7.1

• Philosophical Problems in Astrobiology; Issues on the Origin of Life,

  My project is exploring philosophical issues in astrobiology. My central focus this year was on the origin of life: what is the proper level of analysis for a successful theory of the origin of life? Among other things, I compared and contrasted contemporary scientific theories of the origin of life in light of what philosophers of science have learned about the structure and justification of scientific theories.

  ROADMAP OBJECTIVES: 3.1 3.2 3.3 3.4 4.1 4.2

• Origin and Evolution of Organics in Planetary Systems

  Professor Fegley’s group at Washington University in St Louis modeled chemistry of outgassed volatiles during accretion of the Earth. Accretion of the Earth, and especially the Moon-forming impact, heats the Earth to temperatures high enough to melt and vaporize its silicate crust and mantle. The Earth has a silicate atmosphere during this phase of its history. As the Earth cools down, the silicate atmosphere collapses and a steam atmosphere forms. This atmosphere is not pure steam, but contains H₂O, H₂, CO, CO₂, CH₄ in varying proportions depending on temperature and pressure. Further cooling leads to a collapse of the steam atmosphere and a gaseous atmosphere forms. This is an early reducing atmosphere with CH₄, H₂, NH₃, and water vapor.

  ROADMAP OBJECTIVES: 1.1 3.1 3.2

• The Diversity of the Original Prebiotic Soup: Re-Analyzing the Original Miller-Urey Spark Discharge Experiments

  Recently obtained samples from some of the original Stanley Miller spark discharge experiments have been reanalyzed using High Pressure Liquid Chromatography-Flame Detection and Liquid Chromatography-Flame Detection/Time of Flight-Mass Spectrometry in order to identify lesser constituents that would have been undetectable by analytical techniques 50 years ago. Results show the presence of several isoforms of aminobutyric acid, as well as several serine species, isomers of threonine, isovaline, valine, phenylalanine, ornithine, adipic acid, ethanolamine and other methylated and hydroxylated amino acids. Diversity and yield increased in experiments utilizing an aspirating device to increase the gas flow rates; this could be applied as a simulation of prebiotic chemistry during a volcanic eruption. The variety of products formed in these experiments is significantly greater than previously published and mimic the assortment of compounds detected in Murchison and CM meteorites.

  ROADMAP OBJECTIVES: 2.1 3.1 3.2 3.4 4.1 4.2 5.1 6.2 7.1 7.2