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10/2/2008
Astrophysicists from the NAI’s Carnegie Institution of Washington team and their colleagues have shown for the first time that a supernova could have triggered the solar system’s formation under conditions of rapid heating and cooling. For several decades, scientists have thought that the solar system formed as a result of a shock wave from an exploding star—a supernova—that triggered the collapse of a dense, dusty gas cloud that contracted to form the sun and the planets. But detailed models of this formation process have only worked under the simplifying assumption that the temperatures during the violent events remained constant. The results, published in the October 20, 2008, issue of the Astrophysical Journal, have resolved this long-standing debate. |
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9/19/2008
Researchers from NAI’s University of Hawai’i team have a paper in the September 17 edition of Nature about the evolution of the animal gut. For more than 100 years zoologists have speculated about scenarios of how the bilaterally symmetrical animals (animals that have a left and a right side, like flies, fish, and humans) evolved from a simple circular (radially symmetric) ancestor that looked similar to jelly fish or corals. In the commonly presented scenarios this transition is connected to the evolution of a through-gut with an anterior mouth and posterior anus. It has been thought that both openings emerged simultaneously from a single embryological opening through which the inner tissues enter (called blastopore).
Recent molecular phylogenies however, place the marine acoel flatworms at the base of the bilaterally symmetric animals. Acoels are thus survivors from the Pre-Cambrian era that retain many ancestral characters (e.g. a nervous system composed of multiple nerve cords and only one opening to their digestive system). One can see Acoels as an evolutionary stepping stone that offers clues about the sequence of character evolution of bilateral animals.
To find out how the acoel digestive system, with its single opening (“mouth”), is related to the through gut present in some bilaterians like humans and flies, the researchers looked at the expression patterns of genes that play a role in the formation of both the mouth and the anus in bilaterian animals.
They were able to show that the sac-like gut of the bilaterian ancestor possessed a single opening that was inherited as the mouth in such diverse animals like flies and sea stars. Furthermore, the team accumulated evidence from gene expression patterns that the anal orifice evolved independently in different animal lineages, possibly in association with the gonoduct (the duct through which eggs and sperm are released). The independent evolution of the anus can be explained by the increase in body size and an elongation of the body. Increased energetic needs and a long blind gut would have made sorting food and waste through a single opening inefficient.
Their work, in conjunction with a better understanding of the evolutionary relationships of animals, clearly rejects previous ideas found in every zoology text book about the evolution of the last common ancestor of flies and humans from a radial symmetric animal (e.g. the Gastraea-Hypothesis of Ernst Haeckel). The team states that this ancestor that lived over 550 myr ago, before the radiation of the bilateral animals was far less complex morphologically than previously thought. At this time our ancestors were hermaphroditic worms, that had only a mouth and no anus. We literally had to spit out our undigested food. Our ancestor was likely a very small, soft-bodied animal that lived between the sand grains in the ocean, similar to the life-style of most acoel species. This also explains why no fossils have yet been found of these animals. The team is certain that their ongoing studies of the nervous system of these worms will yield to similar important insights into the evolutionary roots of the human brain and spinal cord. |
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9/19/2008
Members of NAI’s Penn State, Carnegie Institution, and MIT teams report in a recent issue of Earth and Planetary Science Letters, the distribution of biomarkers in 2.72–2.56 billion-year-old, Neoarchean rocks from the Hamersley Province on the Pilbara Craton in Western Australia. Their observations are consistent with a cyanobacterial source for 2-methylhopanes, in which cyanobacteria were likely the cornerstone of microbial communities in shallow-water ecosystems providing molecular oxygen, fixed carbon, and possibly fixed nitrogen.
Their data, revealing relative abundances of 3-methylhopanes, but not 2-methylhopanes, strongly correlate to stable carbon isotopic composition of insoluble particulate organic matter (kerogen). The unanticipated nature of this relationship provides evidence for a shallow-water locus of carbon cycling through aerobic oxidation of methane and, coincidentally, a means to demonstrate biomarker syngenicity. |
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9/19/2008
Researchers from NAI’s University of Arizona team and their colleagues at the University of Leeds have a new paper in Angewandte Chemie International Edition dealing with prebiotic chemistry and the early Earth. Working both experimentally and with models of the early atmosphere, the team shows that the Hadean and early Archaean Earth was primed with an abundance of condensed phosphates, enabling the formation of the necessary precursors of RNA and DNA. This research removes one of the large stumbling blocks in prebiotic chemistry- that the early Earth lacked a low-temperature reservoir of activated phosphate compounds capable of eventually leading to the origin of life. |
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8/27/2008
Members of NAI’s University of Wisconsin, Madison team have a new paper in Earth and Planetary Science Letters presenting their analyses of 4.35 – 3.36 billion year old detrital zircons from the Jack Hills, Western Australia. Their data reveal relatively high lithium abundances compared to other zircons, as well as lithium isotope ratios that are similar to continental crust weathering products rather than ocean floor basalts. The results support the hypothesis that continental-type crust and oceans existed by 4.3 billion years ago, and suggest that weathering was extensive in the early Archean. |
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8/27/2008
Using data from the CRISM instrument on NASA’s Mars Reconnaissance Orbiter, astrobiologists from NAI’s SETI Institute and Marine Biological Laboratory teams present findings of silicate mineralogy indicating a wide range of past aqueous activity in the Mawrth Vallis on Mars. This work, published in the August 8 issue of Science, suggests that abundant water was once present on Mars and that hydrothermal activity may have occurred. The Mawrith Vallis could be a landing site for future rover missions to Mars. |
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8/27/2008
NAI’s University of Wisconsin team presents a review of iron isotope fingerprints created through biogeochemical cycling in the May, 2008 issue of The Annual Review of Earth and Planetary Sciences. This landmark paper brings together for the first time the co-evolution records of photosynthesis, bacterial sulfate reduction, and bacterial iron reduction in the early Earth. They review data on natural systems and experiments, looking at both abiological and biological processes, and conclude that the temporal carbon, sulfur, and iron isotope record reflects the interplay of changing microbial metabolisms over Earth’s history. |
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7/24/2008
Researchers from NAI’s Penn State, MBL, and UCLA Teams have completed a study of the subseafloor marine biosphere, which may be one of the largest reservoirs of microbial biomass on Earth, and which has recently been the subject of debate in terms of the composition of its microbial inhabitants. Their metagenomic analysis indicates that the subsurface environment is the most unique studied to date, distinct in its microbial make-up from the surface waters. The slowly-metabolizing populations may be akin to what could be found on other planets in our solar system, because such environments have much less energy available than on Earth. And, because they are so deeply buried, these microbes could have survived major Earth impacts, and ensuing extinction events. Their results are published in the July 23rd Early Edition of PNAS. |
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7/18/2008
Using new techniques, scientists from NAI’s Carnegie Institution of Washington Team have discovered for the first time that tiny beads of volcanic glasses collected from two Apollo missions to the Moon contain water. The researchers found that, contrary to previous thought, water was not entirely vaporized in the violent events that formed the Moon. The new study suggests that the water came from the Moon’s interior and was delivered to the surface via volcanic eruptions over 3 billion years ago. The finding calls into question some critical aspects of the “giant impact” theory of the Moon’s formation and may have implications for the origin of possible water reservoirs at the Moon’s poles. The research is published in the July 10, 2008, of Nature. |
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7/18/2008
Researchers from the NAI’s University of Arizona Team have published a new study in the current issue of Astrophysical Journal Letters of the potential habitability of the extrasolar planetary system OGLE-2006-BLG-109L. The first multiple-planet system ever to be discovered by gravitational microlensing, it has two large planets similar to Jupiter and Saturn. It’s possible that the system harbors other planets, including Earth-like planets, that are beyond the sensitivity of the microlensing observations.
Their study examines the prospects for an Earth-like habitable planet in this system. They found that two smaller putative Earth-mass planets, perhaps yet undetected, could produce a planetary architecture of a potentially habitable system. With two “terrestrial” planets and two Jovian planets, it could bear very close resemblance to our own solar system. |
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6/26/2008
A recent study in Earth and Planetary Science Letters from NAI’s Teams at NASA Goddard Space Flight Center, Carnegie Institution of Washington, and University of Wisconsin, shows that nucleic acids of extraterrestrial origin are present in the Murchison meteorite. Carbon-rich meteorites such as the Murchison are thought to be responsible for delivering biologically-relevant organic material to the young Earth. These results demonstrate that the nucleic acids discovered in the meteorite, which are components of the genetic code in modern biochemistry, were already present in the early solar system and may have played a key role in life’s origin. Read more at ScienceNOW. |
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6/4/2008
Researchers from NAI's Penn State Team announced at the American Society of Microbiology General Meeting in Boston their discovery of a novel species of ultra-small bacteria that has survived for more than 120,000 years within the ice of a Greenland glacier at a depth of nearly two miles. The species is related genetically to certain bacteria found in fish, marine mud, and the roots of some plants, yet it has persisted in a low-temperature, high-pressure, reduced-oxygen, and nutrient-poor habitat. The study's authors speculate that it's unusual size helped enable it's survival in the ice for so long. |
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5/28/2008
Researchers from NAI's University of California, Berkeley Team have a new study in Science focused on Box Canyon in Idaho. Incised into a basaltic plain with no drainage network upstream, and approximately 10 cubic meters per second of seepage emanating from its vertical headwall, the canyon is a veritable poster child of groundwater seepage erosion. But this new study posits evidence that the canyon?s formation was caused rather by catastrophic megaflood 45,000 years ago. Their results imply that flooding of this kind may have caused similar features on Mars. |
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5/28/2008
Researchers from NAI's Marine Biological Laboratory Team continue their study of the deep biosphere, reporting the latest results in Nature. This new study reveals that bacterial communities dwelling on ocean-bottom rocks are more abundant and diverse than previously thought, especially relative to the overlying water column. The microbes appear to ?feed? on the oceanic crust through seawater-rock alteration reactions involving the oxidation and hydration of glassy basalt.
Astrobiologists hypothesize that shallow water, not deep water, may have cradled the planet's first life; that the dark, carbon-poor depths offered little energy to emerging life. But the newfound abundance of seafloor microbes makes it theoretically possible that early life thrived - and maybe even began - on the seafloor. "Some might even favor the deep ocean for the emergence of life since it was a bastion of stability compared with the surface, which was constantly being blasted by comets and other objects," suggests study author and NAI member Katrina Edwards in the University of Southern California press release. For images and resources, see NSF's press page.
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5/27/2008
A new study from NAI's Montana State University Team appears in the current issue of the Journal of the American Chemical Society. The study probes the hydrogenase enzyme, a large, complex enzyme which plays a major role in anaerobic metabolism by creating molecular hydrogen. The research team produced a crystal structure of the enzyme to unprecedented resolution, revealing a new level of detail in the enzyme's active site, and providing clues about it's evolution. These results further our understanding of the transition from the abiotic (non-living) world to the biological world which may have been an early event in the development of life on Earth, and possibly a common feature of life elsewhere in the universe. |
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5/22/2008
A new study in the May 15th issue of Nature from NAI’s Carnegie Institution of Washington Team reveals that Europa’s poles may not have always been located in the same place. Using images from three NASA spacecraft, Voyager, Galileo, and New Horizons, the study mapped surface features on Europa and matched them with a pattern predicted if Europa had experienced an episode of ~80 degree true polar wander. This movement of the pole and subsequent change in rotation axis is only possible if Europa’s outer shell is decoupled from the core by a liquid layer, so the study also reinforces evidence for the presence of an ocean on Europa. |
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5/9/2008
Shawn D. Domagal-Goldman (NAI PSU team), J.F. Kasting (NAI PSU team), D. T. Johnson (NAI CIW team), and J. Farquhar (NAI CIW and UCLA teams) have just published an article Organic haze, glaciations and multiple sulfur isotopes in the Mid-Archean era in Earth and Planetary Science Letters. The team used sulfur isotope signatures within ancient sediments and a photochemical model of sulfur dioxide photolysis to interpret the evolution of the atmosphere over the first half of Earth’s history. |
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3/27/2008
Former NAI Postdoctoral Fellow Giovanna Tinetti is co-author on a groundbreaking paper in Nature detailing the observation of methane and water vapor in the atmosphere of the extrasolar planet HD 189733b. The team used the NASA Hubble Space Telescope to observe the transiting exoplanet, using the NICMOS camera to obtain a spectrophotometric time series. This result is a milestone in the search for life elsewhere in the Universe, most importantly because it demonstrates that we have the technology to identify these molecules in exoplanet atmospheres. |
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3/25/2008
Scientists from NAI’s Carnegie Institution of Washington Team have a new paper in Meteoritics and Planetary Science detailing their discovery of amino acids in two meteorites at concentrations ten times higher than levels previously measured in other similar meteorites. The result suggests that the early solar system was far richer in the organic building blocks of life than scientists had thought, and that fallout from space may have spiked Earth’s primordial broth. |
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3/6/2008
Researchers from NAI's University of Hawai'i Team used ground-based telescopes to observe the magnetic field of the planet hosting star tau Bootis, and found that its overall polarity has reversed direction since their observation one year prior. They report their findings in the Monthly Notices of the Royal Astronomical Society. This is the first time that a global magnetic polarity switch is observed in a star other than the Sun. |
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2/14/2008
Matt Pasek from NAI's University of Arizona Team recently published a paper in PNAS positing that the geochemistry of phosphorus on the early Earth was controlled by reduced oxidation state phosphorus compounds such as phosphite, rather than orthophosphate. This alternate view of early Earth phosphorus geochemistry provides an unexplored route to the formation of pertinent prebiotic phosphorus compounds, suggests a facile reaction pathway to condensed phosphates, and is consistent with the biochemical usage of reduced oxidation state phosphorus compounds in life today. |
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2/14/2008
New work from NAI's University of Hawai'i Team in Icarus indicates that astronomers will eventually be able to discriminate between extrasolar Earth-like planets with surface oceans and those without using the shape of phase light curves in the visible and near-IR spectrum. Their results suggest several new ways of directly identifying water on distant planets. |
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1/7/2008
A decade of planetary exploration, focusing on a “follow the water” approach, has yielded a tantalizing array of astrobiologically compelling targets. But the growing list of water-bearing planets and moons has also underscored the need to develop additional metrics for habitability. Research from within the NASA Astrobiology Institute is developing a “follow the energy” approach to complement “follow the water." The new issue of Astrobiology compiles several papers on this approach, guest-edited by Tori Hoehler from NAI's Ames Team. |
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1/7/2008
Researchers from NAI's Carnegie Institution of Washington Team have found the first indications of highly complex organic molecules in the disk of red dust surrounding a distant star. The eight-million-year-old star, known as HR 4796A, is inferred to be in the late stages of planet formation, suggesting that the basic building blocks of life may be common in planetary systems. The paper appears in the Astrophysical Journal Letters; a copy of the paper can be found here. |
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11/28/2007
Researchers from NAI's University of Hawai'i Team have a new paper in The Astronomical Journal describing a major survey of visual binaries toward the Orion Nebula Cluster. The team used images obtained with the Advanced Camera for Surveys on the Hubble Space Telescope through an Hα filter. Among 781 stars that fulfill the criteria for membership in the Orion Nebula Cluster, the group found 78 multiple systems (75 binaries and 3 triples), of which 55 are new discoveries.
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11/14/2007
With support from NAI Teams at the Carnegie Institution of Washington and UC Berkeley, researchers at the American Type Culture Collection and their colleagues have a new paper in PLOS One describing a novel lineage of proteobacteria which are dominant in iron-rich hydrothermal vent sites on the Loihi Seamount near Hawai'i. They form a unique morphological structure which could serve as a fossil biomarker. |
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11/14/2007
Researchers from NAI's University of Hawai'i Team and their colleagues have a new paper in Geobiology reviewing recent work on the climatic, geochemical, and ecological events that preceded animal fossils, considering their portent for metazoan evolution. They also consider recent published research on the nature and chronology of the earliest fossil record of metazoans, and on the molecular-based analysis that yielded dates older than the last 35 million years of the Precambrian for the appearance of major animal groups. |
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10/11/2007
In this week's Science, astrobiologists from NAI's University of Hawai'i Team review the prospects for discovering smaller planets more like Earth, some of which may even have conditions suitable for life. Improved techniques and the ability to monitor fainter stars now enable astronomers to discover smaller planets, particularly planets orbiting much closer to their host star than the Earth is to the Sun. This review article is based on an NAI-supported session at the May, 2007 meeting of the American Astronomical Society. |
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10/11/2007
Researchers from NAI's Carnegie Institution of Washington Team have a paper in this week's Nature describing evidence that Earth's Mesoarchean atmosphere (3.2 and 2.8 Gya) possessed very low amounts oxygen. These findings contrast with prior claims that Earth's atmosphere underwent its first rise in oxygen during the Mesoarchean, and indicate that oxygen first rose above parts per million levels sometime between 2.45 and 2.4 billion years ago. |
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10/9/2007
NAI's Marine Biological Laboratory Team has a new paper in this week's Science detailing aspects of population structure for microbial communities at two neighboring hydrothermal vents. Using environmental DNA sequencing techniques, they found the two populations reflect the geochemical conditions of each vent. |
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9/28/2007
NAI's Astrobiology Drilling Program supported researchers in 2004 to obtain subsurface core samples from the Hamersley Basin in Western Australia. Those samples, representing the time just before the Great Oxidation Event, have been analyzed, and two research papers detailing the results (Anbar, et al. and Kaufman, et al.) appear in September 28, 2007 issue of Science. Both groups found unexpected, correlated changes that reveal the presence of small but significant amounts of O2 in the environment 2.5 billion years ago, ~50-100 milion years before the Great Oxidation Event, and a shift from lower O2 abundance prior to that time. |
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9/13/2007
Norbert Schorghofer of NAI's University of Hawai'i Team has a new paper in this week's Nature describing a climate model he developed which accounts for the advance and retreat of the subsurface martian ice layers. The model reveals forty major ice ages over the past five million years, and explains the present distribution of subsurface ice on Mars. His findings outline expectations of ice stratigraphy at the NASA Mars Phoenix Mission's landing site. |
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8/31/2007
Biomarkers in rocks prior to the rise in Earth's atmospheric oxygen 2.5 billion years ago show cyanobacteria released oxygen at the same levels as today. What was happening to that oxygen? A new paper in this week's Nature from NAI's Penn State Team proposes that the rise of atmospheric oxygen occurred because the predominant sink for oxygen—enhanced submarine volcanism—was abruptly and permanently diminished during the Archaean–Proterozoic transition by a shift from predominantly submarine volcanism to a mix of subaerial and submarine volcanism. |
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8/31/2007
NAI Postdoctoral Fellow Elise Furlan from NAI’s UCLA Team is co-author on a new paper in Nature this week reporting the development of a protoplanetary disk. Using NASA’s Spitzer Space Telescope, observations were made of water vapor within the emerging system’s natal cloud. Lead author Dan Watson of the University of Rochester said, "For the first time, we are seeing water being delivered to the region where planets will most likely form." |
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8/17/2007
A new paper in Nature this week from NAI's NASA Ames Research Center Team describes a new technique they've developed through which completely new enzymes can be evolved in the laboratory. The process does not require prior understanding of how the enzymes will work, but uses product formation as the sole selection criterion. |
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7/11/2007
An international team of researchers including members of NAI's Virtual Planetary Laboratory Team have, using NASA's Spitzer Space Telescope, detected the presence of water vapor on the hot jupiter HD 189733b. Published in this week's Nature, the study's primary author, Giovanna Tinetti, was a 2003 NAI Postdoctoral Fellow. |
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6/28/2007
Scientists from NAI's University of Arizona Team have studied the outflow of VY Canis Majoris, an oxygen-rich supergiant star. Thier results show that, against expectations, an old, oxygen-rich star can synthesize a chemically varied molecular cocktail. The study is published in this week's Nature, and a News and Views about the paper is also available. |
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6/18/2007
Scientists from NAI's IPTAI Team have a paper out in Geophysical Research Letters detailing a new mechanism for recent methane release on Mars. Their results show that increasing salinity can cause destabilization of subsurface methane hydrates, and that active thermal or pressure fluctuations are not required to account for the presence of methane in the atmosphere. |
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6/14/2007
Scientists from NAI's University of California, Berkeley Team have a new paper out in Nature outlining evidence for the presence of an ancient ocean on Mars. The study points to a large body of liquid water at the pole which could have shifted Mars' spin axis. This shift would have in turn deformed the shoreline of this ocean relative to the rest of the surface topography, in accordance with observations. |
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6/14/2007
Deep inside a flooded mine in Wisconsin, scientists from NAI’s University of California, Berkeley Team have discovered an environment in which bacteria emit proteins that sweep up metal nanoparticles into immobile clumps. Their finding may lead to innovative ways to remediate subsurface metal toxins, and have exciting implications for identifying biosignatures on Earth and other worlds. The research, published in the June 14th issue of Science, was done in collaboration with a team from the U.S. Department of Energy’s Lawrence Berkeley National Laboratory. |
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6/7/2007
A new paper on the evolutionary relationships among New World tropical frogs was published online this week in PNAS. The authors, including members of the NAI Penn State Team, used DNA sequence and molecular clock analyses to further understand the frogs' origin as more likely by dispersal over water from South America, than via land connections with North and South America. |
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6/6/2007
Members of NAI's Michigan State University Alumni Team are part of an international team of scientists characterizing the microbial populations in Antarctic permafrost soils. Based on multiple samples, they describe the presence of diverse populations of both aerobic and anaerobic bacteria, cyanobacteria, green algae, yeasts, and fungi. Based on the documented ages of the permafrost regions—perhaps more than 5 million years old—these findings represent the oldest viable microorganisms discovered in permafrost on Earth. Their paper appears in the April issue of Astrobiology.
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5/2/2007
NAI scientists from the Carnegie Institution of Washington Team and their colleagues have a new paper in Geology outlining their process in resolving the mysterious identity of the Devonian fossil organism Prototaxities as a fungus. The team analyzed carbon isotopic ratios of the fossil relative to plants that lived in the same environment 400 million years ago. |
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4/18/2007
Members of NAI's Virtual Planetary Laboratory Alumni Team and their colleagues have a new paper in the current issue of Astrobiology. They present a critical discussion of M star properties that are relevant for the long- and short-term thermal, dynamical, geological, and environmental stability of conventional liquid water habitable zone (HZ) M star planets. |
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4/17/2007
NAI Postdoctoral Fellow Sean Raymond leads a team of authors from NAI's University of Colorado, Boulder, and University of Arizona Teams, and Virtual Planetary Laboratory and University of Washington Alumni Teams in a new publication in Astrobiology. They present analysis of water delivery and planetary habitability in 5 high-resolution simulations forming 15 terrestrial planets. Their results outline a new model for water delivery to terrestrial planets in dynamically calm systems, which may be very common in the Galaxy.
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4/11/2007
Differently colored plants may live on extra-solar planets, according to two new papers in the current issue of Astrobiology authored by members of NAI's Virtual Planetary Laboratory Alumni Team and their colleagues. They took previously simulated planetary atmospheric compositions for Earth-like planets orbiting various star types (including M stars), generated spectra, and found that photosynthetic pigments may peak in absorbance in the blue for some star types, and red-orange and near-infrared for others. Their results also suggest that, under water, organisms would still be able to survive ultraviolet flares from young M stars and acquire adequate light for growth - which greatly increases the scope for habitability in these systems. |
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4/10/2007
Multidisciplinary work from members of NAI's SETI Institute Team and a host of collaborators across the NAI re-examines what is known at present about the potential for a terrestrial planet forming within, or migrating into, the classic liquid–surface–water habitable zone close to an M dwarf star. Their new paper, published in the current issue of Astrobiology, presents the summary conclusions of an interdisciplinary workshop sponsored by NAI and convened at the SETI Institute in 2005. |
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4/9/2007
New work from NAI NASA Ames Research Center Team members and their colleagues published recently in PNAS suggests that the cause for much of the extended red emission, or ERE, is due to closed-shell cationic polycyclic aromatic hydrocarbon, or PAH, dimers. Their work sheds light on the processes involved in carbonaceous dust evolution in the interstellar medium. |
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3/5/2007
NAI's Marine Biological Laboratory and Carnegie Institution of Washington Teams are contributing authors on a new paper in Earth and Planetary Science Letters presenting a new model for the evolution of Proterozoic deep seawater composition based on rare earth elements. Their data suggest transitional, suboxic conditions in the deep ocean (vs. sulfidic), which likely limited nutrient concentrations in seawater and, consequently, may have constrained biological evolution. |
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2/27/2007
New research from NAI's SETI Institute Team published online in Icarus today outlines the empirical range of salt concentrations permitted for Europa’s ocean. Solutions within the range imply high, near-saturation salt concentrations and require a Europan ice shell of less than 15 km thick, with a best fit at 4 km ice thickness. The paper examines the implications for subsurface habitability. |
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2/26/2007
Researchers from NAI's Carnegie Institution of Washington and NASA Goddard Space Flight Center Teams have a new paper in Nature describing the infrared spectrum of exoplanet HD 209458b as obtained by the NASA Spitzer Space Telescope. Scientists from NAI's University of Arizona and Alumni Virtual Planetary Laboratory Teams are contributing authors on a similar paper in Astrophysical Journal Letters which details the spectrum of exoplanet HD 189733b. Both sets of results show relatively flat spectra, with no significant absorption by water or methane, in contrast with the predictions of most atmospheric models. One spectral feature of HD 209458b is attributed to silicate clouds. The Nature paper features the work of an NAI Summer Undergraduate Intern at the Goddard Center for Astrobiology. Both papers were the subject of a recent NASA News conference. |
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2/8/2007
Researchers from NAI's University of Colorado, Boulder Team recently reported in Earth and Planetary Science Letters their new biogeochemical model relating to the Great Oxidation Event. With ion microprobe data for individual sulfides from water-lain sedimentary units in the 2.45–2.22 Ga Huronian Supergroup, the team proposes a new model where enhanced weathering rates during interglacial thawing stimulated blooms of oxygenic photosynthesis, the demise of methane, and ultimately the irreversible rise in atmospheric oxygen between the first and second Huronian glaciations. The paper's lead author was also the recipient of an NAI Research Scholarship in 2004. |
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2/7/2007
A team of researchers including members of NAI's University of Colorado, Boulder Team have provided the first direct field evidence supporting the theory that high concentrations of greenhouse gases could have helped avoid global freezing on the early Earth. They analyzed iron carbonates from 3.75-3.8 billion year old rocks in northern Québec, and conclude that the atmosphere of early Earth contained high levels of CO2. Their paper appears in a recent issue of Earth and Planetary Science Letters. |
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12/21/2006
Scientists from NAI's University of California, Berkeley Team report in this week's Science on their use of shotgun sequencing to uncover three novel archea present in all biofilms growing in pH 0.5 to 1.5 solutions within the Richmond Mine, California. Their results inform the problem of characterizing microbial communities and lineages which are difficult to cultivate. |
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12/21/2006
Using atmospheric chemical models of a Snowball Earth, scientists from NAI's Alumni Virtual Planetary Laboratory Team show that, during long and severe glacial intervals, a weak hydrological cycle coupled with photochemical reactions involving water vapor would give rise to the sustained production of hydrogen peroxide. The peroxide, upon release from melting ice into the oceans and atmosphere at the end of the snowball event, could mediate global oxidation events. Their results are published in the December 12th issue of PNAS. |
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12/14/2006
Researchers from NAI's Carnegie Institution of Washington Team have published in Science their findings of a novel archaeon who's ability to fix nitrogen at 92 degrees Celcius has officially increased the upper limit of biological nitrogen fixation by 28 degrees Celcius. The hyperthermophilic methanogen was isolated from a hydrothermal vent. Thier findings could reveal a broader range of conditions for life in the subseafloor biosphere. |
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12/14/2006
A special issue of Science (Dec 15) includes several papers reporting on various aspects of Stardust sample analysis including an organics survey, isotopic and elemental compositions, mineralogy and petrology, and infrared spectroscopy. Many NAI researchers contributed to this comprehensive analytical campaign, including members of NAI's Teams at the Carnegie Institution of Washington, NASA's Ames Research Center and Goddard Space Flight Center, and NAI's Alumni Team at the University of Washington. |
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12/11/2006
An international team of researchers including NAI Postdoctoral Fellow Evgenya Shkolnik of the University of Hawai'i Team publish their observation in this month's Royal Astronomical Society Letters of a magnetic field at the surface of star Tau Bootis, which is orbited by a giant planet every three days. The magnetic field's intensity is similar to that of the Sun, but the star and the planet are tidally locked, possibly producing the observed magnetic knots. |
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11/27/2006
The December 2006 issue of Geobiology is a collection of papers focusing on the history of Earth's biogeochemistry, from the earliest sedimentary rocks in Greenland to the late Proterozoic. The rise of atmospheric oxygen provides a thematic link. The papers in this issue, edited by David Catling and Roger Buick of NAI's University of Washington Alumni Team, grew out of a session of the Earth System Processes 2 conference in Calgary, Canada, 8–11 August 2005, sponsored by the NAI. |
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11/20/2006
Robert Hazen, from NAI's Carnegie Institution of Washington Team, published his 2005 Presidential Address to the Mineralogical Society of America in this month's American Mineralogist. The address reviews the role of mineral surfaces on the self-assembly of lipids, the polymerization of amino acids and nucleic acids, and the selective adsorption of organic species, including chiral molecules, onto mineral surfaces. |
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11/7/2006
Researchers from NAI's Unviersity of Colorado, Boulder and University of Arizona Teams have published a new study in PNAS this week about the atmospheres of both present day Titan and early Earth. For Titan, their experiments modeled conditions measured by the Huygens probe from NASA's Cassini mission, and CO2 was added to model the early Earth conditions. They conclude that organize haze can form over a wide range of methane and carbon dioxide concentrations. |
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10/25/2006
Peter Ward from NAI's Alumni Team at the University of Washington and his collaborators have a new paper out in PNAS this week providing supportive evidence for Romer's Gap. Their results link this gap in vertebrate terrestrialization with a low atmospheric oxygen interval. This paper supports Ward's new book on the evolution of effective respiratory systems, entitled "Out of Thin Air." |
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10/20/2006
In this week's Science, researchers from NAI's Indiana, Princeton, Tennessee Astrobiology Initiative (IPTAI) and Carnegie Institution of Washington Teams report that they have found an extant microbial biome at 2.8km depth in a South African mine. Analyses showed thermophilic sulfate reducers existing "with no apparent reliance on photosynthetically derived substrates." |
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10/17/2006
Researchers from NAI's UCLA, Carnegie Institution of Washington, and NASA Goddard Space Flight Center Teams published this week in Science Express what may well be the first "Interstellar Weather Report." Focusing on the innermost planet orbiting the star Upsilon Andromeda b, a hot Jupiter, the team used NASA's Spitzer Space Telescope to make measurements indicating that the temperature variation between the planets light and dark sides is 2,550 degrees Fahrenheit. |
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10/17/2006
A new study on carbon isotopes in sedimentary rocks from Western Australia by researchers from NAI's Penn State and Carnegie Institution of Washington Teams supports the idea that small, shallow pools of water containing photosynthetic microbes existed on the early Earth ~ 2.72 Gya, about 300 million years before the rise of oxygen in the atmosphere. Their findings suggest a "global-scale expansion" of these habitats, and a progression away from anaerobic ecosystems and toward photosynthetic communities before the oxygenation of the atmosphere. This work was published in the early edition of this week's PNAS. |
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10/4/2006
Members of the Former University of Rhode Island Team, have published their latest findings on the production of ethane and propane in the deep subsurface in this week'sPNAS.
The work stems from cores drilled on Leg 201 of the Ocean Drilling Program, February-March 2002. The Ocean Drilling Program is succeeded by the Integrated Ocean Drilling Program which concluded it's "Exploring Subseafloor Life" workshop this week in Vancouver. |
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9/8/2006
Collaborators from NAI's Teams at NASA Goddard Space Flight Center, University of Colorado, Boulder, and Penn State as well as the former Virtual Planetary Lab Team have a paper this week in Science discussing the possible formation of "Exotic Earths." Their models have simulated terrestrial planet growth during and after inward giant planet migration. Their results cause them to speculate that more than a third of the known systems of giant planets may harbor Earth-like planets. |
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8/24/2006
Most geologists agree that Earth's atmosphere was oxygen-free until 2.4 billion years ago. But the latest research from NAI's Pennsylvania State University team provides new evidence for alternative viewpoints. Ohmoto et al have published their latest results in this week's Nature. Ohmoto's team took samples from western Australia as a part of NAI's Astrobiology Drilling Program.
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8/18/2006
Pennsylvania State University Team members, Matt Hurtgen and colleagues, have just published a new paper in Earth and Planetary Science Letters on continental glaciers in the Neoproterozoic. |
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8/1/2006
NAI PI of the Marine Biological Laboratory Team, Mitch Sogin, and his team have published a new paper in PNAS documenting astonishing new findings of microbial diversity in the deep sea. The findings are the result of a new DNA technique called "454 tag sequencing."
Image courtesy of Micro*scope |
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7/25/2006
Scientists from NAI's UCLA and University of Colorado, Boulder Teams recently published their new geologic and geochemical analysis of the ancient rocks on Akilia Island in West Greenland which were the subject of a controversial Nature paper ten years ago. This new study includes a thorough geologic map of the area, and, using the ion-microprobe to analyze carbon inclusions in the rock, outlines a carbon isotopic ratio indicative of life's signature. Their work appears in the current issue of the American Journal of Science. |
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7/25/2006
Researchers from NAI's University of Washington, University of Colorado, Boulder, and Virtual Planetary Laboratory Teams have developed models testing planet formation in four known systems, 55 Cancri, HD 38529, HD 37124 and HD 74156. Placing Mars to Moon-sized planet embryos between giant planets and allowing them to evolve for 100 million years, they found terrestrial planets formed readily in 55 Cancri, sometimes with substantial water and orbits in the system's habitable zone. They found HD 38529 is likely to support an asteroid belt and Mars-sized or smaller bodies but no notable terrestrial planets. No planets formed in HD 37124 and HD 74156. The paper was published in a recent issue of The Astrophysical Journal. |
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7/5/2006
Researchers from NAI's University of Rhode Island Team and their colleagues have studied the use of phosphorus vs. sulfur in the membrane lipid sythesis pathways of organisms resident in the ocean's subtropical gyres. Their data show that the dominant organism in the phytoplankton, a cyanobacterium, has evolved a "sulfur-for-phosphorus" strategy; producing a membrane lipid containing sulfate and sugar instead of phosphate. This adaptation may have been a major event in Earth's early history when the relative availability of sulfate and phosphate was different than in today's oceans. Their paper appears in the June 6th issue of PNAS. |
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7/5/2006
NAI's Virtual Planetary Laboratory Team have explored the possibility of detecting exovegetation on terrestrial planets orbiting M stars. They estimated the red-shift of this surface feature using leaf optical property spectra with a three photon photosynthetic scheme. The authors have produced a model wherein a pigment-derived surface signature such as exovegetation could be detected, but would be dependent upon the extent of the vegetation on the surface, cloud cover, and viewing angle. Their paper is in the current issue of The Astrophysical Journal. |
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6/19/2006
Researchers from NAI's NASA Goddard Space Flight Center Team and their colleagues publish their analysis of two meteorites in the current issue of Meteoritics and Planetary Science. Their study revealed a suite of amino acids present in the meteorites that are not present in the Antarctic ice on which they were found. |
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6/19/2006
Andrey Bekker of NAI's Carnegie Institution of Washington Team and his colleagues have an article in press for Precambrian Research which details the carbon isotope record for the carbonate platform in the Great Lakes area. Observed carbon isotope values from the Lake Superior area may correspond to those from Griqualand West Basin, South Africa, supporting the notion of three global glaciations in the Paleoproterozoic Era. |
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6/14/2006
Using NASA's FUSE spacecraft, scientists from NAI's Carnegie Institution of Washington Team have discovered abundant amounts of carbon gas in a dusty disk surrounding the young star Beta Pictoris. While planets may have already formed, the prevalence of carbon gas in the disk indicates that the planets could be carbon-rich worlds of graphite and methane, potentially resembling the early conditions of our own Solar System. The authors suggest that either carbon-rich asteroids or comets, unlike any in our own solar system, have vaporized, or that bodies outgassing carbon-bearing species such as methane are responsible for the observation. Their work is published in this week's Nature. |
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6/14/2006
Roger Buick from NAI's University of Washington Team and his colleagues report in the current issue of Geology their analysis of oil-bearing fluid inclusions in 2.45 billion year old rocks from Canada. They assert that the oil is derived from an overlying formation, becoming trapped in the host rock before 2.2 billion years ago - prior to the Great Oxidation Event. Abundant biomarkers for cyanobacteria and eukaryotes were identified in the study, suggesting that aqueous environments at the time had become sufficiently oxygenated for sterol biosynthesis to occur, and implying that organisms had the ability to survive "snowball Earth" glaciations. |
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6/7/2006
The cover of this week's Nature belongs to Abigail Allwood of the Australian Centre for Astrobiology, one of NAI's International Partners. She and her colleagues put forward the latest research on the ancient rocks of the Pilbara Craton in Western Australia, which points to evidence of life on Earth 3.43 billion years ago. Their description of a shallow marine environment, and identification of seven stromatolite morphotypes makes a strong argument for early life. NAI supported Allwood's work with a 2005 NAI Research Scholarship. |
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6/7/2006
Alan Boss of NAI's Carnegie Institution of Washington Team published in the current issue of the Astrophysical Journal a new look at the origin of super-Earths orbiting M dwarf stars. The core accretion mechanism of giant planet formation has been used to explain the presence of these planets. Boss' new work shows they could also have been formed by the disk instability mechanism. |
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6/6/2006
Researchers from NAI's NASA Ames Research Center and University of Colorado, Boulder Teams published in the current issue of Astrobiology their study of the petrology and mineral chemistry of a cold spring in Northern California. They propose that the serpentinization process can provide a source of energy for chemosynthetic organisms, and outline criteria to aid in the identification of serpentinizing terranes on Mars. |
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5/31/2006
An alternative theory for the origin and evolution of life is proposed by scientists from NAI's Pennsylvania State University Team in the current issue of Molecular Biology and Evolution. The theory, centering on the concept that an energy-conservation pathway was the major force which powered and directed the early evolution of the cell, provides insight into the evolution of the microbial production of methane. |
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5/31/2006
Researchers from NAI's Indiana Princeton Tennessee Astrobiology Initiative Team published their theory on the origin of the detected atmospheric methane on Mars in the current issue of Astrobiology. Measurements of deep fracture water samples from South Africa led to a model which distinguishes between abiogenic and microbial methane sources based upon their isotopic composition, and couples microbial methane production to molecular hydrogen generation by water radiolysis. The authors also propose an instrument for future missions to Mars which, with measurements over time, could distinguish mechanisms for methane emissions. |
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5/18/2006
Researchers at NAI's University of Colorado, Boulder and Marine Biological Laboratory Team published their analysis of biodiversity in hypersaline microbial mats in a recent issue of Applied and Environmental Microbiology. Bacteria dominated the mat in unprecedented diversity representing 752 species, including 15 novel candidate phyla. |
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5/18/2006
Researchers from NAI's Pennsylvania State University Team published their functional and phylogenetic analysis of protein WrbA function this week in The Journal of Bacteriology. Comparing 30 sequences including that of Archaeoglobus fulgidus, a hyperthermophilic archeabacterium, this study demonstrates the ability for this enzyme to protect against oxidative stress through quinone oxidoreductase activity. |
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5/9/2006
Researchers at NAI's Carnegie Institution of Washington Team published this week in Science their new study of the interstellar chemistry record in both meteorites and interplanetary dust particles. They show that isotopic compositions in meteories meet and exceed those in found in IDP's, demonstrating the capability of both to preserve primitive organics. |
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5/3/2006
Scientists on NAI's Pennsylvania State University Team published new findings recently in Nature demonstrating a single early origin of the venom system in snakes and lizards. Their molecular biology and toxinological analyses show that the snakes, iguanians and anguimorphs form a single clade, pointing toward the proposed common origin. |
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4/19/2006
A new study published by former NAI Team Arizona State University members documents the extensive microbial biodiversity of one Earth's rare ecosystems. "An endan |
