2011 Annual Science Report

Astrobiology Roadmap Objective 5.2 Reports Reporting  |  SEP 2010 – AUG 2011

Project Reports

  • AIRFrame Technical Infrastructure and Visualization Software Evaluation

    We have analyzed over four thousand astrobiology articles from the scientific press, published over ten years to search for clues about their underlying connections. This information can be used to build tools and technologies that guide scientists quickly across vast, interdisciplinary libraries towards the diverse works of most relevance to them.

    ROADMAP OBJECTIVES: 1.1 1.2 2.1 2.2 3.1 3.2 3.3 3.4 4.1 4.2 4.3 5.1 5.2 5.3 6.1 6.2 7.1 7.2
  • Advancing Methods for the Analyses of Organics Molecules in Sediments

    Eigenbrode’s astrobiological research focuses on understanding the formation and preservation of organic and isotopic sedimentary records of ancient Earth, Mars, and icy bodies. To this end, and as part of GCA’s Theme IV effort, Eigenbrode seeks to overcome sampling and analytical challenges associated with organic analyses of astrobiology relevant samples with modification and development of contamination tracking, sampling, and analytical methods (primarily GCMS) that improve the recovery of meaningful observations and provide protocol guidance for future astrobiological missions. Advances have been made in five sub-studies and manuscript writing is in progress. Studies include: 1 & 2. Advancing protocols for organic molecular studies of iron-oxide rich sediments and sediments laden with perchlorate, 3. Carbon Isotopic Records of the Neoarchean, 4. Solid-phase sorbtive extraction of organic molecules in glacial ice, and 5. Amino acid composition of glacial ice.

    ROADMAP OBJECTIVES: 2.1 4.1 5.1 5.2 5.3 6.1
  • Ecology of Extreme Environments: Characterization of Energy Flow, Bioenergetics, and Biodiversity in Early Earth Analog Ecosystems

    The distribution of organisms and their metabolic functions on Earth is rooted, at least in part, to the numerous adaptive radiations that have resulted in the ability to occupy new ecological niches through evolutionary time. Such responses are recorded in extant organismal geographic distribution patterns (e.g., habitat range), as well as in the genetic record of organisms. The extreme variation in the geochemical composition of present day hydrothermal environments is likely to encompass many of those that were present on early Earth, when key metabolic processes are thought to have evolved. Environments such Yellowstone National Park (YNP), Wyoming harbor >12,000 geothermal features that vary widely in temperature and geochemical composition. Such environments provide a field laboratory for examining the tendency for guilds of organisms to inhabit particular ecological niches and to define the range of geochemical conditions tolerated by that functional guild (i.e., habitat range or zone of habitability). In this aim, we are examining the distribution and diversity of genes that encode for target metalloproteins in YNP environments that harbor geochemical properties that are thought to be similar to those that characterize early Earth. Using a number of newly developed computational approaches, we have been able to deduce the primary environmental parameters that constrain the distribution of a number of functional processes and which underpin their diversity. Such information is central to constraining the parameter space of environment types that are likely to have facilitated the emergence of these metal-based biocatalysts.

    ROADMAP OBJECTIVES: 3.2 3.3 3.4 4.1 4.2 5.1 5.2 5.3
  • Biosignatures in Relevant Microbial Ecosystems

    In this project, PSARC team members explore the isotope ratios, gene sequences, minerals, organic molecules, and other signatures of life in modern environments that have important similarities with early earth conditions, or with life that may be present elsewhere in the solar system and beyond. Many of these environments are “extreme” by human standards and/or have conditions that are at the limit for microbial life on Earth.

    ROADMAP OBJECTIVES: 4.1 4.3 5.1 5.2 5.3 6.1 7.1 7.2
  • Amino Acid Alphabet Evolution

    We study the question why did life on this planet “choose” a set of 20 standard building blocks (amino acids) for converting genetic instructions into living organisms? The evolutionary step has since been used to evolve organisms of such diversity and adaptability that modern biologists struggle to discover the limits to life-as-we-know-it. Yet the standard amino acid alphabet has remained more or less unchanged for 3 billion years.
    During the past year, we have found that the sub-set of amino acids used by biology exhibits some surprisingly simple, strikingly non-random properties. We are now building on this finding to solidify a new insight into the emergence of life here, and what it can reveal about the distribution and characteristics of life elsewhere in the universe.

    ROADMAP OBJECTIVES: 3.1 3.2 4.1 4.2 4.3 5.2 5.3 6.2 7.1
  • Biomechanics of the Rangeomorph Fauna

    The oldest communities of fossil eukaryotes are found in the sedimentary rocks of Mistaken Point Newfoundland. These sediments were deposited in deep, slow-moving waters, at depths where light could not penetrate. Communities of fossil fronds preserved here reached up off the bottom, much like plants, but are thought to have lived by absorbing reduced compounds through their large surface area. In our work we show that growth off the seafloor provides an opportunity to reach higher flow velocity in this low flow environment. This exposure to flow breaks down diffusional limits, permitting more rapid uptake and growth. This opportunity is only available to larger-sized organisms, and this size advantage is exclusive to multicellular eucaryotes – not to competing bacteria with their smaller cell-size, and minimal multicellularity. Thus these communities and this advantage to multicellular form represents an important step in the evolution of complex multicellular life.

    ROADMAP OBJECTIVES: 4.2 5.2 6.1
  • Biosignatures in Ancient Rocks

    The Earth’s Archean and Proterozoic eons offer the best opportunity for investigating a microbial world, such as might be found elsewhere in the cosmos. The ancient record on Earth provides an opportunity to see what geochemical signatures are produced by microbial life and how these signatures are preserved over geologic time. As part of our integrated plan, we will study geochemical, isotopic, and sedimentary signatures of life in order to understand the context in which these biosignatures formed.

    ROADMAP OBJECTIVES: 1.1 3.2 4.1 4.2 4.3 5.1 5.2 5.3 6.1 6.2 7.1 7.2
  • Metabolic Networks From Single Cells to Ecosystems

    Members of the Segre’ group use systems biology approaches to study the complex network of metabolic reactions that allow microbial cells to survive and reproduce under varying environmental conditions. The resource allocation problem that underlies these fundamental processes changes dramatically when multiple cells can compete or cooperate with each other, for example through metabolic cross-feeding. Through mathematical models of microbial ecosystems and computer simulations of spatially structured cell populations, the Segre’ team aims at understanding the environmental conditions and evolutionary processes that favor the emergence of multicellular organization in living systems.

    ROADMAP OBJECTIVES: 4.1 4.2 5.1 5.2 6.1
  • Planetary Surface and Interior Models and SuperEarths

    We use computer models to simulate the evolution of the interior and the surface of real and hypothetical planets around other stars. Our goal is to work out what sorts of initial characteristics are most likely to contribute to making a planet habitable in the long run. Observations in our own Solar System show us that water and other essential materials are continuously consumed via weathering (and other processes) and must be replenished from the planet’s interior via volcanic activity to maintain a biosphere. The surface models we are developing will be used to predict how gases and other materials will be trapped through weathering over time. Our interior models are designed to predict how much and what sort of materials will come to a planet’s surface through volcanic activity throughout its history.

    ROADMAP OBJECTIVES: 1.1 1.2 4.1 5.2 6.1
  • Deep (Sediment-Buried Basement) Biosphere

    The ocean crust comprises the largest aquifer on earth. Deep sediment cover provides an environ-ment for a unique biosphere hosting microorganisms surviving under extreme conditions. Frac-tured rock provides abundant surfaces that can be colonized by diverse microbes and water-rock reactions promote chemical conditions that influence key geochemical cycles within the Earth’s crust and oceans. Team members participated in a 14-day research cruise to study the sediment-buried basement (basaltic crust) biosphere, to provide unprecedented and unique insight into the mobility and origin of microorganisms within this remote biosphere.

    ROADMAP OBJECTIVES: 4.1 4.2 5.2 5.3 6.1 6.2 7.1 7.2
  • Molecular and Isotopic Investigations Across the Neoproterozoic

    We gathered new data on molecular and isotopic stratigraphic trends from Cryogenian and Ediacaran sequences from Canada, Oman and Mongolia. These continue to show that the biogeochemical carbon cycle was anomalous, and unlike any other period in Earth history, prior to the advent of complex animal life. While difficult to interpret in a robust way these data are reproducible, reflect real trends and are not the result of 'diagenetic alteration’ as some have proposed.

    ROADMAP OBJECTIVES: 4.2 5.2 6.1
  • Neoproterozoic Carbon Cycle

    The rock record late Neoproterozoic (540-800 Ma) appears to exhibit strong
    perturbations to Earth’s carbon cycle. This project seeks an understanding
    of the mechanisms that drive such events and their biogeochemical significance.

    ROADMAP OBJECTIVES: 3.2 4.2 5.1 5.2 6.1
  • Project 3A: Stable Isotope and Mineralogical Studies of Banded Iron Formations – O and Si Isotopes by SIMS

    We have studied the mineralogy and microscopic textures of four banded iron formations (BIFs): Isua, Greenland (3.8 Ga); Hamersley, Western Australia (2.5 Ga); Transvaal, South Africa (2.5 Ga), and Biwabik, Minnesota, USA (1.9 Ga). These rocks have been interpreted to preserve records of conditions and chemistry of Precambrian oceans. This hypothesis is evaluated with in situ SIMS analysis of oxygen (δ18O) and silicon isotope ratios (δ30Si) in chert domains within the BIFs. The paragenesis of magnetite and hematite is important to understanding the fluid and thermal history of unmetamorphosed or low-temperature (sub-greenschist facies) oxide-facies BIFs. We identified silician (up to 3 wt% SiO2) magnetite overgrowths in samples of the Dales Gorge BIF from Wittenoom. We hypothesize that silician magnetite is stabilized by organic matter and thus is a biosignature. We investigated the distribution of δ18O values in quartz, magnetite, silician magnetite, and hematite by SIMS and found that while quartz is homogeneous (average δ18O = 22.0 ±1.3‰ 2SD, VSMOW), values of δ18O for magnetite and hematite vary by 13‰ (-5 to +7‰) and are correlated with different generations of magnetite and hematite.

    ROADMAP OBJECTIVES: 4.1 5.2 7.1
  • Stromatolites in the Desert: Analogs to Other Worlds

    In this task biologists go to field sites in Mexico to better understand the environmental effects on growth rates for freshwater stromatolites. Stromatolites are microbial mat communities that have the ability to calcify under certain conditions. They are believed to be an ancient form of life, that may have dominated the planet’s biosphere more than 2 billion years ago. Our work focuses on understanding these communities as a means of characterizing their metabolisms and gas outputs, for use in planetary models of ancient environments.

    ROADMAP OBJECTIVES: 4.1 4.2 5.2 5.3 6.1 6.2
  • The Subglacial Biosphere – Insights Into Life-Sustaining Strategies in an Extraterrestrial Analog Environment

    Sub-ice environments are prevalant on Earth today and are likely to have been more prevalent the Earth’s past during episodes of significant glacial advances (e.g., snow-ball Earth). Numerous metabolic strategies have been hypothesized to sustain life in sub-ice environments. Common among these hypotheses is that they are all independent of photosynthesis, and instead rely on chemical energy. Recently, we demonstrated the presence of an active assemblage of methanogens in the subglacial environment of an Alpine glacier (Boyd et al., 2010). The distribution of methanogens is narrowly constrained, due in part to the energetics of the reactions which support this functional class of organism (namely carbon dioxide reduction with hydrogen and acetate fermentation). Methanogens utilize a number of metalloenzymes that have active site clusters comprised of a unique array of metals. During the course of this study, we identified other features that were suggestive of other active and potentially relevant metabolic strategies in the subglacial environment, such as nitrogen cycling. The goals of this project are 1) identifying a suite of biomarkers indicative of biological CH4 production 2). quantifying the flux of CH4 from sub-ice systems and 3). developing an understanding how life thrives at the thermodynamic limits of life. This project represents a unique extension of the ABRC and bridges the research goals of several nodes, namely the JPL-Icy Worlds team and the ASU-Follow the Elements team.

    ROADMAP OBJECTIVES: 2.1 2.2 5.1 5.2 5.3 6.1 6.2 7.1 7.2
  • Protists of the Neoproterozoic

    T. Bosak (MIT), S. Pruss (Smith College), F. Macdonald (Harvard U.) and D. Lahr (U. Sao Paolo) discovered fossils of microscopic eukaryotes in limestone and dolostone strata deposited between the two Neoproterozoic low-latitude glaciations (between ~ 716 and 635 million years ago). These fossils include amoeba-like organisms that incorporated mineral-rich particles from the environment into their shells, mineral-rich shells of the oldest putative foraminiferans, and thick flask-shaped organic envelopes of the first putative ciliates, representatives of a major group of modern eukaryotes. These fossils demonstrate a previously unrecognized record of body fossils during the ~ 70 million years between the two “Snowball Earth” episodes and document the increasing diversity of morphologically and compositionally modern eukaryotes before the rise of complex animals.

    ROADMAP OBJECTIVES: 4.1 4.2 5.2 6.1
  • Viral Ecology and Evolution

    This project is aimed at probing the occurrence and evolution of archaeal viruses in the extreme environments in the thermal areas in Yellowstone National Park. Viruses are the most abundant life-like entities on the planet and are likely a major reservoir of genetic diversity for all life on the planet and these studies are aimed at providing insights into the role of viruses in the evolution of early life on Earth.

    ROADMAP OBJECTIVES: 5.1 5.2 5.3 6.1 6.2
  • Stoichiometry of Life – Task 1 – Laboratory Studies in Biological Stoichiometry

    This project component involves a diverse set of studies of various microorganisms with which we are trying to better understand how living things use chemical elements (nitrogen, phosphorus, iron, etc) and how they cope, in a physiological sense, with shortages of such elements. For example, how does the “elemental recipe of life” change when an organism is starved for phosphorus? Is this change similar for diverse species of microorganisms? Are the changes the same if the organism is limited by a different key nutrient? Furthermore, how does an organism shift its patterns of gene expression when it is starved by various nutrients? This will help in interpreting studies of gene expression in natural environments. At an even more profound level: can an organism substitute an element that is similar to the one that is limiting, as in the case of arsenic for phosphorus?

    ROADMAP OBJECTIVES: 5.2 5.3 6.1 6.2
  • Proxies for Ocean Anoxia

    Episodes of widespread anoxia in past oceans are known as “Ocean Anoxic Events”. The ecosystem consequences of these events are actively debated. In this project, we are examining the chemical and isotopic signatures of the photosynthetic pigment, chlorophyll, to understand changes in ecosystems and the nutrients that fueled them. The seasonal oxygen minimum zone (OMZ) offshore Chile is being used as a modern analog.

    ROADMAP OBJECTIVES: 4.1 4.2 5.2 5.3 6.1
  • Stoichiometry of Life, Task 2a: Field Studies – Yellowstone National Park

    Field work and subsequent laboratory analysis is an integral part of following the elements. One of our field areas is the hot spring ecosystems of Yellowstone, which are dominated by microbes, and where reactions between water and rock generate diverse chemical compositions. These natural laboratories provide numerous opportunities to test our ideas about how microbes respond to different geochemical supplies of elements. Summer field work and lab work the rest of the year includes characterizing the natural systems, and controlled experiments on the effects of changing nutrient and metal concentrations (done so as to not impact the natural features!).

    ROADMAP OBJECTIVES: 5.1 5.2 5.3 6.1 6.2 7.2
  • Understanding Past Earth Environments

    For much of the history Earth, life on the planet existed in an environment dramatically different than that of modern-day Earth. Thus, the ancient Earth represents a planet with a biosphere that is both dramatically different than the one in which we live and is accessible to detailed study. As such, is serves as a model for what types of biospheres we may find on other planets. A particular focus of our work was on the “Early Earth” (formation through to about 500 million years ago), a timeframe poorly represented in the geological and fossil records but comprises the majority of Earth’s history. We have studied the composition of the ancient atmosphere, modeled the effects of clouds on such a planet, studied the sulfur, oxygen and nitrogen cycles, and the atmospheric formation of molecules that were likely important to the origins of life on Earth.

    ROADMAP OBJECTIVES: 1.1 1.2 4.1 4.2 5.1 5.2 6.1
  • Stoichiometry of Life, Task 2b: Field Studies – Cuatro Cienegas

    Cuatro Cienegas is a unique biological preserve in México (state of Coahuila) in which there is striking microbial diversity, potentially related to extreme scarcity of phosphorus. We aim to understand this relationship via field sampling of biological and chemical characteristics and a series of enclosure and whole-pond fertilization experiments.

    ROADMAP OBJECTIVES: 5.1 5.2 5.3 6.1 6.2
  • Stoichiometry of Life – Task 2d – Field Studies – Marine Hydrothermal Systems: Deep Hot Biosphere – Lead

    The deep hot biosphere beneath the seafloor remains one of the most extremely poorly understood ecosystems on Earth. Collaborator Hartnett participated in Leg 331 Deep Hot Biosphere of the Integrated Ocean Drilling Program and collected sediments drilled from hydrothermal mounds in the Okinawa Trough region. The organic geochemistry of the sediments will be assessed and related to the presence and activity of microorganisms beneath the seafloor. The scientific party included NAI scientists from three teams (ASU, Penn State, Hawaii) as well as astrobiologists from Japan; the main research objective was to document the existence of an active, metabolically diverse subvent biosphere associated with hydrothermal activity.

    ROADMAP OBJECTIVES: 5.2 5.3
  • Stoichiometry of Life, Task 3b: Ancient Records – Genomic

    The goal of Task 3b is to advance understanding of elemental cycling in ancient ecosystems. Team members are developing experimental and computational approaches aimed at genomic analysis of modern ecosystems, and extending these approaches in novel ways to infer the function and composition of ancient communities.

    ROADMAP OBJECTIVES: 5.1 5.2 5.3
  • Stoichiometry of Life, Task 4: Biogeochemical Impacts on Planetary Atmospheres

    Oxygenation of Earth’s early atmosphere must have involved an efficient mode of carbon burial. In the modern ocean, carbon export of primary production is dominated by fecal pellets and aggregates produced by the animal grazer community. But during most of Earth history the oceans were dominated by unicellular, bacteria-like organisms (prokaryotes) causing a substantially altered biogeochemistry. In this task we experiment with the marine cyanobacterium Synechococcus sp. as a model organism and test its aggregation and sinking speed as a function of nutrient (nitrogen, phosphorus, iron) limitation. We have found so far that aggregation and sinking of these minute cyanobacteria is influenced by the concentration of nutrients in the growth medium.

    ROADMAP OBJECTIVES: 4.1 4.2 5.2 6.1 7.2
  • Project 7C: Improving Accuracy of in Situ Stable Isotope Analysis by SIMS

    Isotopic analysis of biologically important elements in petrographic context is a fundamental tool for astrobiology. Secondary ion mass spectrometry (SIMS) is a powerful tool used to understand biogeochemical processes at the spatial scale of the individual microorganisms that drive them. The benefits of the extremely high spatial resolution offered by SIMS do not come without costs, however. Unconstrained physical and chemical variables in the sample of interest can introduce biases leading to inaccurate measurements. Understanding and constraining these barriers to accuracy as we move towards ever finer spatial resolution and analytical precision is a primary focus at WiscSIMS.

    ROADMAP OBJECTIVES: 4.1 5.1 5.2 5.3 7.1