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2010 Annual Science Report

Pennsylvania State University Reporting  |  SEP 2009 – AUG 2010

Executive Summary

The Penn State Astrobiology Research Center (PSARC) is pursuing a comprehensive and interdisciplinary investigation of biosignatures at all scales, from individual cells to the composition of planetary atmospheres. Our projects are aimed at developing novel approaches to detecting and characterizing life, investigating biosignatures in mission-relevant microbial ecosystems and ancient rocks, and evaluating the potential for biosignatures in extraterrestrial settings. This past year saw exciting progress on many of our research directions, as well as the creation of new collaborations. For example, we established a formal collaborative program between PSARC and the Centro de Astrobiologia in Spain. The goal of the research collaboration is to increase our understanding of the origins, evolution, and distribution of life on Earth and other planets of the Solar system. Our education and public outreach efforts included the continuation of undergraduate and graduate programs for students in Astrobiology, education workshops for science teachers, a large public “Exploration Day” event, and the hosting of the “Beyond the Edge of the Sea” museum exhibit.

Of principle importance, this past year, our four teams made fundamental progress in our understanding of Astrobiology through the research encompassed by our major biosignature themes.

Developing New Biosignatures

The development and experimental testing of potential indicators of life is essential for providing a critical scientific basis for the exploration of life in the cosmos. In microbial cultures, potential new biosignatures can be found among isotopic ratios, elemental compositions, and chemical changes to the growth media. Additionally, life can be detected and investigated in natural systems by directing cutting-edge instrumentation towards the investigation of microbial cells, microbial fossils, and microbial geochemical products. Our efforts are focused on creating innovative approaches for the analyses of cells and other organic material, finding ways in which metal abundances and isotope systems reflect life, and developing creative approaches for using environmental DNA to study present and past life.

During this last year, the Schopf laboratory made great progress in applying Raman imaging to a diversity of different fossils in a variety of matrices. During this reporting period, Raman imaging was applied to the investigation of microbial fossils preserved in gypsum, possible fungi in Cambrian paleosols, apatite-biomineralized protists, and organic microfossils permineralized in chert.

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We also made significant progress in our investigations of chemical, elemental, and isotopic signatures of life. This work includes investigations of bedrock weathering in the laboratory and in the field. The work suggests that Fe, Al, P, Cu, Y, and the rare earth elements can be thought of as candidate organomarkers that document the effects of organic molecules in weathered rocks. The Freeman laboratory has been investigating isotopic patterns in lipids from vascular plants (13C/12C) and in pigments, including scytonomin, in cyanobacteria (15N/14N and 13C/12C). In contrast to previous reports in the literature (Chikarishi et al., 2004; Monson and Hayes, 1980; DeNiro and Epstein, 1977), and especially in literature for microbial life (reviewed by Hayes, 2002), they consistently find that both MEP and MVA-derived terpenoid compounds in the leaves of higher plants (C3, trees) exhibit minimal fractionation relative to biomass (~ ±1 permil). Also, PSARC research has resulted in the first observation of scytonemin (a marker for cyanobacteria) in ancient sediments.

Our diverse research relating to the development of new biosignatures resulted in twenty-nine published papers during the reporting period.

Biosignatures in relevant microbial ecosystems

PSARC is investigating microbial life in some of Earth’s most mission-relevant ecosystems. These environments include the Dead Sea, the Chesapeake Bay impact structure, Eel River Basin methane seeps, Greenland glacier ice, and sulfidic cave systems. PSARC is targeting environments that, when studied, provide fundamental information that can serve as the basis for future solar system exploration. Combining our expertise in molecular biology, geochemistry, microbiology, and metagenomics, we are deciphering the microbiology, fossilization processes, and recoverable biosignatures from these mission-relevant environments.

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Much of the PSARC research that is proceeding on these relevant ecosystems, is targeting low biomass environments. Working with such samples is quite challenging. Presently, graduate student Kristine Korzow-Richter has established new DNA extraction, purification, and contamination control protocols targeting the low biomass and high concentration of interfering chemicals present in the Chesapeake Bay impact structure core. She is now poised to generate metagenomic data that will shed light on the persistence of biosignatures for transient hydrothermal ecosystems in impact basins. The Brenchley laboratory and colleagues continue to develop new cultivation strategies that allow laboratory studies of microorganisms preserved deep within the Greenland ice sheet. Their research shows that microbial cells are abundant not only in the mineral-rich ice at the base of the ice sheet, but also in “dusty” layers deposited throughout the ice sheet.

Our research investigating life in the Dead Sea resulted in a published paper on a remarkable relationship between predicted amino acid content of proteins (acidic to basic amino acids) and salinity at an environmental scale. Presently, the DNA-based research is being combined with lipid biogeochemistry to understand the roles of archaeal membrane adaptations and shifts in community composition in biomarker records of hypersaline environments.

Team members at Caltech working on marine methane seeps provided evidence this year that AOM-induced carbonates form close to the seabed and record the sediment associated microbial diversity, rather than specific methane-oxidizing lineages exclusively. They also demonstrated the frequent occurrence of a silica-rich mineral phase associated with the exterior of methanotrophic aggregates, and investigated the origins of fossil-like, abiotic structures in Quaternary methane seep carbonates. These results are important because the ability to differentiate between cellular remains and acellular mineral matter is critical for life detection efforts on other planets, as well as for tracking the evolution of biogeochemical cycles on Earth.

Biosignatures in ancient rocks

This team of geologists, geochemists, paleontologists and biologists seeks signs of early life in ancient rocks from Earth. Working mostly on that part of Earth history before the advent of skeletons and other preservable hard parts in organisms, our group focuses on geochemical traces of life and their activities. We also investigate how life has influenced, and has been influenced by changes in the surface environment, including the establishment of an oxygen-rich environment and the initiation of extreme climate states including global glaciations. For this we use a combination of observations from modern analogous environments, studies of ancient rocks, and numerical modeling.

Our work for the reporting period includes new progress on understanding the report of sulfur mass-independent fractionation (MIF). This work requires photochemical modeling, model simulation, and high-resolution measurement of SO2 isotopologue cross sections. Also, our hydrothermal experiments showing anomalous sulfur isotopic fractionation has proceeded with Watanabe et al., (2009) publishing fractionations during thermochemical sulfate reduction.

The Hedges group continued its research on the refinement of the timescale of life, with emphasis on relating the origin of different groups of organisms to chemical and geological biomarkers.

During the reporting period, there was also significant progress in research directly on ancient rocks. This included collecting samples in China from the Mesoproterozoic deep ocean, further research on the trace element geochemistry of Archean submarine basalts, investigations of the marine ecosystem during the deposition of the Pibara sediments, work on ancient black shales, and characterization of 3.4 Ga lateritic paeosols from the North Pole Dome.

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Biosignatures in extraterrestrial settings

This team investigates the abundance of sulfur gases and elucidates how these gases can be expected to evolve with time on young terrestrial planets. They are continuing studies of planet formation in the presence of migration and model radial transport of volatiles in young planetary systems, and are involved with searches for M star planetary companions and planets around K-giant stars.

During the reporting period, Kasting’s group has shown in a new published paper that SO2 is not sufficient for warm early Mars. Jim Lyons has continued work on CO photolysis and how it related to oxygen isotope anomalies in the early solar system. Finally, Sigurdsson and colleagues have moved the Pathfinder near infrared spectrograph through calibration and into its first science operations with an integrated laser comb.

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Publications

  • MOCZYDŁOWSKA, M., Schopf, J. W., & Willman, S. (2009). Micro- and nano-scale ultrastructure of cell walls in Cryogenian microfossils: revealing their biological affinity. Lethaia, 43(2), 129–136. doi:10.1111/j.1502-3931.2009.00175.x

  • Bailey, J. V., Orphan, V. J., Joye, S. B., & Corsetti, F. A. (2009). Chemotrophic Microbial Mats and Their Potential for Preservation in the Rock Record. Astrobiology, 9(9), 843–859. doi:10.1089/ast.2008.0314

  • Bailey, J. V., Raub, T. D., Meckler, A. N., Harrison, B. K., Raub, T. M. D., Green, A. M., & Orphan, V. J. (2010). Pseudofossils in relict methane seep carbonates resemble endemic microbial consortia. Palaeogeography, Palaeoclimatology, Palaeoecology, 285(1-2), 131–142. doi:10.1016/j.palaeo.2009.11.002

  • Barnett, R., Shapiro, B., Barnes, I., Ho, S. Y. W., Burger, J., Yamaguchi, N., … Cooper, A. (2009). Phylogeography of lions ( Panthera leo ssp.) reveals three distinct taxa and a late Pleistocene reduction in genetic diversity. Molecular Ecology, 18(8), 1668–1677. doi:10.1111/j.1365-294×.2009.04134.x

  • Bunce, M., Worthy, T. H., Phillips, M. J., Holdaway, R. N., Willerslev, E., Haile, J., … Cooper, A. (2009). The evolutionary history of the extinct ratite moa and New Zealand Neogene paleogeography. Proceedings of the National Academy of Sciences, 106(49), 20646–20651. doi:10.1073/pnas.0906660106

  • Campos, P. F., Willerslev, E., Sher, A., Orlando, L., Axelsson, E., Tikhonov, A., … Gilbert, M. T. P. (2010). Ancient DNA analyses exclude humans as the driving force behind late Pleistocene musk ox (Ovibos moschatus) population dynamics. Proceedings of the National Academy of Sciences, 107(12), 5675–5680. doi:10.1073/pnas.0907189107

  • Collins, M. J., Penkman, K. E. H., Rohland, N., Shapiro, B., Dobberstein, R. C., Ritz-Timme, S., & Hofreiter, M. (2009). Is amino acid racemization a useful tool for screening for ancient DNA in bone?. Proceedings of the Royal Society B: Biological Sciences, 276(1669), 2971–2977. doi:10.1098/rspb.2009.0563

  • Czaja, A. D., Johnson, C. M., Beard, B. L., Eigenbrode, J. L., Freeman, K. H., & Yamaguchi, K. E. (2010). Iron and carbon isotope evidence for ecosystem and environmental diversity in the ∼2.7 to 2.5Ga Hamersley Province, Western Australia. Earth and Planetary Science Letters, 292(1-2), 170–180. doi:10.1016/j.epsl.2010.01.032

  • Dekas, A. E., & Orphan, V. J. (2011). Identification of Diazotrophic Microorganisms in Marine Sediment via Fluorescence In Situ Hybridization Coupled to Nanoscale Secondary Ion Mass Spectrometry (FISH-NanoSIMS). Methods in Enzymology, None, 281–305. doi:10.1016/b978-0-12-381294-0.00012-2

  • Diefendorf, A. F., Mueller, K. E., Wing, S. L., Koch, P. L., & Freeman, K. H. (2010). Global patterns in leaf 13C discrimination and implications for studies of past and future climate. Proceedings of the National Academy of Sciences, 107(13), 5738–5743. doi:10.1073/pnas.0910513107

  • Ferry, J. G. (2010). CO in methanogenesis. Annals of Microbiology, 60(1), 1–12. doi:10.1007/s13213-009-0008-5

  • Ferry, J. G. (2010). How to Make a Living by Exhaling Methane. Annu. Rev. Microbiol., 64(1), 453–473. doi:10.1146/annurev.micro.112408.134051

  • Ferry, J. G. (2010). The chemical biology of methanogenesis. Planetary and Space Science, 58(14-15), 1775–1783. doi:10.1016/j.pss.2010.08.014

  • Firth, C., Kitchen, A., Shapiro, B., Suchard, M. A., Holmes, E. C., & Rambaut, A. (2010). Using Time-Structured Data to Estimate Evolutionary Rates of Double-Stranded DNA Viruses. Molecular Biology and Evolution, 27(9), 2038–2051. doi:10.1093/molbev/msq088

  • Hausrath, E. M., Neaman, A., & Brantley, S. L. (2009). Elemental release rates from dissolving basalt and granite with and without organic ligands. American Journal of Science, 309(8), 633–660. doi:10.2475/08.2009.01

  • Ho, S. Y. W., Lanfear, R., Phillips, M. J., Barnes, I., Thomas, J. A., Kolokotronis, S-O., & Shapiro, B. (2011). Bayesian Estimation of Substitution Rates from Ancient DNA Sequences with Low Information Content. Systematic Biology, 60(3), 366–375. doi:10.1093/sysbio/syq099

  • Jiang, S., Bralower, T. J., Patzkowsky, M. E., Kump, L. R., & Schueth, J. D. (2010). Geographic controls on nannoplankton extinction across the Cretaceous/Palaeogene boundary. Nature Geosci, 3(4), 280–285. doi:10.1038/ngeo775

  • Jones, D. S., Tobler, D. J., Schaperdoth, I., Mainiero, M., & MacAlady, J. L. (2010). Community Structure of Subsurface Biofilms in the Thermal Sulfidic Caves of Acquasanta Terme, Italy. Applied and Environmental Microbiology, 76(17), 5902–5910. doi:10.1128/aem.00647-10

  • Kasting, J. F. (2010). Early Earth: Faint young Sun redux. Nature, 464(7289), 687–689. doi:10.1038/464687a

  • Kuhn, T. S., McFarlane, K. A., Groves, P., Mooers, A. Ø., & Shapiro, B. (2010). Modern and ancient DNA reveal recent partial replacement of caribou in the southwest Yukon. Molecular Ecology, 19(7), 1312–1323. doi:10.1111/j.1365-294×.2010.04565.x

  • Kump, L., Bralower, T., & Ridgwell, A. (2009). Ocean Acidification in Deep Time. Oceanography, 22(4), 94–107. doi:10.5670/oceanog.2009.100

  • Lal, D., Schopf, J. W., Abbott, P. L., Vacher, L., Jull, A. J. T., & McHargue, L. (2010). Nuclear, chemical and biological characterization of formation histories of ironstones from several sites in Southern California: Dominant role of bacterial activity. Earth and Planetary Science Letters, 296(3-4), 227–234. doi:10.1016/j.epsl.2010.05.002

  • Loveland-Curtze, J., Miteva, V. I., & Brenchley, J. E. (2011). Evaluation of a new fluorimetric DNA–DNA hybridization method. Canadian Journal of Microbiology, 57(3), 250–255. doi:10.1139/w10-121

  • Loveland-Curtze, J., Miteva, V., & Brenchley, J. (2009). Novel ultramicrobacterial isolates from a deep Greenland ice core represent a proposed new species, Chryseobacterium greenlandense sp. nov.. Extremophiles, 14(1), 61–69. doi:10.1007/s00792-009-0287-6

  • Luo, G., Kump, L. R., Wang, Y., Tong, J., Arthur, M. A., Yang, H., … Xie, S. (2010). Isotopic evidence for an anomalously low oceanic sulfate concentration following end-Permian mass extinction. Earth and Planetary Science Letters, 300(1-2), 101–111. doi:10.1016/j.epsl.2010.09.041

  • Margesin, R., & Miteva, V. (2011). Diversity and ecology of psychrophilic microorganisms. Research in Microbiology, 162(3), 346–361. doi:10.1016/j.resmic.2010.12.004

  • McInerney, F. A., Helliker, B. R., & Freeman, K. H. (2011). Hydrogen isotope ratios of leaf wax n-alkanes in grasses are insensitive to transpiration. Geochimica et Cosmochimica Acta, 75(2), 541–554. doi:10.1016/j.gca.2010.10.022

  • Mueller, K. E., Diefendorf, A. F., Freeman, K. H., & Eissenstat, D. M. (2010). Appraising the roles of nutrient availability, global change, and functional traits during the angiosperm rise to dominance. Ecology Letters, 13(5), E1–E6. doi:10.1111/j.1461-0248.2010.01455.x

  • Otake, T., Wesolowski, D. J., Anovitz, L. M., Allard, L. F., & Ohmoto, H. (2010). Mechanisms of iron oxide transformations in hydrothermal systems. Geochimica et Cosmochimica Acta, 74(21), 6141–6156. doi:10.1016/j.gca.2010.07.024

  • Polissar, P. J., & Freeman, K. H. (2010). Effects of aridity and vegetation on plant-wax δD in modern lake sediments. Geochimica et Cosmochimica Acta, 74(20), 5785–5797. doi:10.1016/j.gca.2010.06.018

  • Polissar, P. J., Freeman, K. H., Rowley, D. B., McInerney, F. A., & Currie, B. S. (2009). Paleoaltimetry of the Tibetan Plateau from D/H ratios of lipid biomarkers. Earth and Planetary Science Letters, 287(1-2), 64–76. doi:10.1016/j.epsl.2009.07.037

  • Polissar, P. J., Fulton, J. M., Junium, C. K., Turich, C. C., & Freeman, K. H. (2009). Measurement of 13 C and 15 N Isotopic Composition on Nanomolar Quantities of C and N. Anal. Chem., 81(2), 755–763. doi:10.1021/ac801370c

  • Rambaut, A., Ho, S. Y. W., Drummond, A. J., & Shapiro, B. (2008). Accommodating the Effect of Ancient DNA Damage on Inferences of Demographic Histories. Molecular Biology and Evolution, 26(2), 245–248. doi:10.1093/molbev/msn256

  • Rhodes, M. E., Fitz-Gibbon, S. T., Oren, A., & House, C. H. (2010). Amino acid signatures of salinity on an environmental scale with a focus on the Dead Sea. Environmental Microbiology, 12(9), 2613–2623. doi:10.1111/j.1462-2920.2010.02232.x

  • Rijsdijk, K. F., Hume, J. P., Bunnik, F., Florens, F. B. V., Baider, C., Shapiro, B., … Gittenberger, E. (2009). Mid-Holocene vertebrate bone Concentration-Lagerstätte on oceanic island Mauritius provides a window into the ecosystem of the dodo (Raphus cucullatus). Quaternary Science Reviews, 28(1-2), 14–24. doi:10.1016/j.quascirev.2008.09.018

  • Saltzman, M. R., Young, S. A., Kump, L. R., Gill, B. C., Lyons, T. W., & Runnegar, B. (2011). Pulse of atmospheric oxygen during the late Cambrian. Proceedings of the National Academy of Sciences, 108(10), 3876–3881. doi:10.1073/pnas.1011836108

  • Schopf, J. W., & Kudryavtsev, A. B. (2010). A renaissance in studies of ancient life. Geology Today, 26(4), 140–145. doi:10.1111/j.1365-2451.2010.00760.x

  • Schopf, J. W., Kudryavtsev, A. B., & Sergeev, V. N. (2010). Confocal Laser Scanning Microscopy and Raman Imagery of the Late Neoproterozoic Chichkan Microbiota of South Kazakhstan. Journal of Paleontology, 84(3), 402–416. doi:10.1666/09-134.1

  • Schopf, J. W., Kudryavtsev, A. B., Sugitani, K., & Walter, M. R. (2010). Precambrian microbe-like pseudofossils: A promising solution to the problem. Precambrian Research, 179(1-4), 191–205. doi:10.1016/j.precamres.2010.03.003

  • Schouten, S., Hopmans, E. C., Van Der Meer, J., Mets, A., Bard, E., Bianchi, T. S., … Sinninghe Damsté, J. S. (2009). An interlaboratory study of TEX 86 and BIT analysis using high-performance liquid chromatography-mass spectrometry. Geochem. Geophys. Geosyst., 10(3), n/a–n/a. doi:10.1029/2008gc002221

  • Segura, A., Walkowicz, L. M., Meadows, V., Kasting, J., & Hawley, S. (2010). The Effect of a Strong Stellar Flare on the Atmospheric Chemistry of an Earth-like Planet Orbiting an M Dwarf. Astrobiology, 10(7), 751–771. doi:10.1089/ast.2009.0376

  • Sergeev, V. N., & William Schopf, J. (2010). Taxonomy, Paleoecology and Biostratigraphy of the Late Neoproterozoic Chichkan Microbiota of South Kazakhstan: The Marine Biosphere on the Eve of Metazoan Radiation. Journal of Paleontology, 84(3), 363–401. doi:10.1666/09-133.1

  • Taylor, P. D., Vinn, O., Kudryavtsev, A., & William Schopf, J. (2010). Raman spectroscopic study of the mineral composition of cirratulid tubes (Annelida, Polychaeta). Journal of Structural Biology, 171(3), 402–405. doi:10.1016/j.jsb.2010.05.010

  • Thomas, B., Freeman, K. H., & Arthur, M. A. (2009). Intramolecular carbon isotopic analysis of acetic acid by direct injection of aqueous solution. Organic Geochemistry, 40(2), 195–200. doi:10.1016/j.orggeochem.2008.10.011

  • Tian, F., Claire, M. W., Haqq-Misra, J. D., Smith, M., Crisp, D. C., Catling, D., … Kasting, J. F. (2010). Photochemical and climate consequences of sulfur outgassing on early Mars. Earth and Planetary Science Letters, 295(3-4), 412–418. doi:10.1016/j.epsl.2010.04.016

  • Weinstock, J., Shapiro, B., Prieto, A., Marín, J. C., González, B. A., Gilbert, M. T. P., & Willerslev, E. (2009). The Late Pleistocene distribution of vicuñas (Vicugna vicugna) and the “extinction” of the gracile llama (“Lama gracilis”): New molecular data. Quaternary Science Reviews, 28(15-16), 1369–1373. doi:10.1016/j.quascirev.2009.03.008

  • William Schopf, J. (2010). The paleobiological record of photosynthesis. Photosynthesis Research, 107(1), 87–101. doi:10.1007/s11120-010-9577-1

  • Young, S. A., Saltzman, M. R., Foland, K. A., Linder, J. S., & Kump, L. R. (2009). A major drop in seawater 87Sr/86Sr during the Middle Ordovician (Darriwilian): Links to volcanism and climate?. Geology, 37(10), 951–954. doi:10.1130/g30152a.1

  • Zazula, G. D., MacKay, G., Andrews, T. D., Shapiro, B., Letts, B., & Brock, F. (2009). A late Pleistocene steppe bison (Bison priscus) partial carcass from Tsiigehtchic, Northwest Territories, Canada. Quaternary Science Reviews, 28(25-26), 2734–2742. doi:10.1016/j.quascirev.2009.06.012

  • Zerkle, A. L., Kamyshny, A., Kump, L. R., Farquhar, J., Oduro, H., & Arthur, M. A. (2010). Sulfur cycling in a stratified euxinic lake with moderately high sulfate: Constraints from quadruple S isotopes. Geochimica et Cosmochimica Acta, 74(17), 4953–4970. doi:10.1016/j.gca.2010.06.015

  • Zugger, M. E., Kasting, J. F., Williams, D. M., Kane, T. J., & Philbrick, C. R. (2010). LIGHT SCATTERING FROM EXOPLANET OCEANS AND ATMOSPHERES. The Astrophysical Journal, 723(2), 1168–1179. doi:10.1088/0004-637x/723/2/1168

  • Boney, E., Lyons, J.R. & Marcus, R.A.  (2010).  Self-shielding of the E(1)-X(0) band of CO in a hot solar nebula.  LPSC.  The Woodlands, TX.
  • Gill, B., Lyons, T., Young, S., Kump, L., Knoll, A. & Saltzman, M.R.  (2010, In Press).  Did deep ocean anoxia stifle early 1 animal evolution during the later Cambrian?  Nature.
  • Güdel, M. & Kasting, J.F.  (In Press).  The young Sun and its influence on planetary atmospheres.  In: Gargaud, M., Lopez-Garcia, P. & Martin, H. (Eds.).  Origin of Life: an Astrobiology Perspective.  Cambridge Univ. Press.
  • Haqq-Misra, J.  (2010).  A Meteorological Condition for Atmospheric Stability on Synchronously Rotating Planets. Revisiting the Habitable Zone.  Talaris Conference Center.  Seattle, WA.
  • Haqq-Misra, J.  (2010).  Astrobiology, Sustainability, and Outreach.  Astrobiology Science Conference 2010.  South Shore Harbour Resort and Conference Center, League City, TX.
  • Haqq-Misra, J., Lee, S. & Frierson, D.  (2009).  Eddy-driven Responses of the Hadley Cell and Tropopause.  American Geophysical Union Fall Meeting.  Moscone Convention Center, San Francisco, CA.
  • Hoashi, M., Watanabe, Y. & Ohmoto, H.  (2009).  Primary hematite formation in an oxygenated deep sea 3.46 billion years ago. 19th Goldschmidt conference, Davos, Switzerland.  Geochim. Cosmochim. Acta, 73(13S): A536.
  • Johnson, C.M., Yamaguchi, K.E., Poulson, S.R., Ohmoto, H. & Beard, B.L.  (2009).  Fe, S, and C isotopes record great microbial diversity in the Neoarchean. 19th Goldschmidt conference, Davos, Switzerland.  Geochim. Cosmochim. Acta, 73(13S): A600.
  • Johnson, I., Watanabe, Y., Stewart, B. & And Ohmoto, H.  (2010).  Evidence for terrestrial life and an O2-rich atmosphere in the oldest (~3.4 Ga) paleosol in the east Pilbara craton, Western Australia.  6th Astrobiology Sci. Conference.  League City, TX.
  • Johnson, I., Watanabe, Y., Stewart, B. & Ohmoto, H.  (2009).  Earth’s oldest (~3.4 Ga) lateritic paleosol in the Pilbara craton, Western Australia. 19th Goldschmidt conference, Davos, Switzerland.  Geochim. Cosmochim. Acta, 73(13S): A601.
  • Jones, D.S.  (2010).  Metagenomic, phylogenetic, and culture-based analysis of subsurface extremophile microbial communities.  ISME J, in review.
  • Kasting, J. & Haqq-Misra, J.  (2009).  Gaia Through Time: The Coevolution of Life and Climate.  American Geophysical Union Fall Meeting.  Moscone Convention Center, San Francisco, CA.
  • Kasting, J.F.  (2010).  Early Mars was warm.  Astrobiology Science Conf.  Houston.
  • Kasting, J.F.  (2010).  How to Find a Habitable Planet.  In: Press, P.U. (Eds.).
  • Kasting, J.F.  (2010).  Stellar radiative effects on habitable zones.  Workshop on Redefining the Habitable Zone.  Seattle, WA.
  • Kasting, J.F.  (In Press).  How to find a habitable planet.  In: Ribas, I. (Eds.).  Pathways Towards Habitable Planets.
  • Kasting, J.F.  (In Press).  The global O2 cycle, in Fundamentals of Geobiology, K. Konhauser, A. Knoll, and D. Canfield.  In: Blackwell (Eds.).
  • Lyons, J.R.  (2010).  CO self-shielding yields oxygen with a δ17O/δ18O ratio of unity.  Meteoritical Society meeting.  New York City, NY.
  • Lyons, J.R.  (2010).  N2 self-shielding in the solar nebula: An update.  Meteoritical Society meeting.  New York City, NY.
  • Lyons, J.R., Stark, G. & Heays, A.N.  (2010).  Assessment of CO photodissociation experiments by model simulations and spectroscopic measurements.  LPSC.  The Woodlands, TX.
  • Mahadevan, S., Ramsey, L., Wright, J., Endl, M., Redman, S., Bender, C., Roy, A., Zonak, S., Troupe, N., Engel, L., Sigurdsson, S., Wolszczan, A. & Zhao, B.  (2010).  The habitable zone planet finder: a proposed high-resolution NIR spectrograph for the Hobby Eberly Telescope to discover low-mass exoplanets.  SPIE.
  • Meyer, K.M., Kump, L.R., MacAlady, J., Schaperdoth, I. & Freeman, K.  (In Review).  Benthic production of a putative planktonic biomarker.  Geobiology.
  • Narbonne, G.M., Schopf, J.W. & Walter, M.R.  (2010).  Hans J. Hofmann (1936-2010).  Geolog, 39(2): 13-14.
  • Nasdala, L., Beyssac, O., Schopf, J.W. & Bleisteiner, B.  (2010, In Press).  Application of Raman-based images in the Earth sciences.  In: Zoubir, A. (Eds.).  Raman Imaging.  Amsterdam: Springer.
  • Ohmoto, H.  (2009).  Redox evolution of volcanic gas through geologic time. 19th Goldschmidt Conference, Davos, Switzerland.  Geochim. Cosmochim. Acta, 73(13S): A965.
  • Ohmoto, H.  (2010, In Press).  Dioxygen.  In: Henderson, J.C. & et al. (Eds.).  Encyclopedia of Astrobiology.
  • Ohmoto, H., Bevacqua, D.C. & Watanabe, Y.  (2010).  Hydrothermal alteration chemistry of Archean submarine volcanic rocks: evidence for a fully oxygenated atmosphere-ocean system since ~3.5 Ga.  6th Astrobiology Sci. Conference.  League City, TX.
  • Ohmoto, H., Bevacqua, D.C., Johnson, I. & Watanabe, Y.  (2010).  Geochemical cycles of Fe, Mo, U, Cu, Cr, REEs, and S during the period 3.5-3.2 Ga ago.  Geochim. Cosmochim. Acta, 74(12S): A774.
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