"I am curious about what effect an asteroid impact, like the one that killed the dinosaurs, would have on the orbit of the earth."
Content with the tag: “proceedings of the national academy of sciences (journal)”
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New World Frogs
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.
June 6, 2007 / Posted by: Shige Abe
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NASA Astrobiologists Elected to National Academy of Sciences
Congratulations are due to astrobiologists Donald E. Canfield and Paul G. Falkowski for their election to the distinguished ranks of membership in the National Academy of Sciences.
May 1, 2007 / Posted by: Shige Abe
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PAH's Responsible for "Red Glow"
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.
April 8, 2007 / Posted by: Shige Abe
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Snowball Earth and the Origin of Photosynthesis
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...
December 20, 2006 / Posted by: Shige Abe
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Organic Hazes on Early Earth and Titan
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.
November 6, 2006 / Posted by: Shige Abe
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NASA Study Shows Titan and Early Earth Atmospheres are Similar
Organic haze in the atmosphere of Saturn’s moon, Titan, is similar to haze in early Earth’s air — haze that may have helped nourish life on our planet— according to a NASA Astrobiology Institute study released Nov. 6, 2006.
November 5, 2006 / Posted by: Shige Abe
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Romer's Gap Confirmed
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.”
October 24, 2006 / Posted by: Shige Abe
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Photosynthesis in the late Archean
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...
October 16, 2006 / Posted by: Shige Abe
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Microbial Diversity in the Deep Sea
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
July 31, 2006 / Posted by: Shige Abe
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Strategies for Evolutionary Success - Sulfolipids
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...
July 4, 2006 / Posted by: Shige Abe
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Microbial Biodiversity in Cuatro Cienegas
A new study published by former NAI Team Arizona State University members documents the extensive microbial biodiversity of one Earth’s rare ecosystems. “An endangered oasis of aquatic microbioal biodiversity in the Chihuahuan desert” is available in PNAS .
April 18, 2006 / Posted by: Shige Abe
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Timelines for the Evolution of Cyanobacteria
Former NAI Principal Investigator, Andy Knoll of Harvard University, and colleagues discuss the evolution of cyanobacteria in their new paper, “The evolutionary diversification of cyanobacteria: Molecular-phylogenetic and paleontological perspectives” in the April 4th issue of PNAS. The evolutionary timeline has implications for the rise of atmospheric oxygen on Earth.
Image courtesy of Micro*scope
April 17, 2006 / Posted by: Shige Abe
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A Window into the Subsurface Microbial Population
A new paper this week in PNAS highlights a collaboration between NAI Lead Teams at Penn State, University of Rhode Island, UCLA, and the Marine Biological Laboratory. Their research reveals that heterotrophic Archea dominate the scene in a variety of biogeochemically distinct sedimentary regions, and may constitute a significant portion of the prokaryotic biomass in Earth’s subsurface. Ecosystem-level carbon budgets suggest that community turnover times are on the order of 100-2,000 years.
February 27, 2006 / Posted by: Shige Abe
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Life in the Deep Subseafloor
In a new study published in this week’s PNAS, researchers from NAI’s University of Rhode Island Lead Team report the vertical and geographical distribution of microbes in deeply buried marine sediments of the Pacific Ocean Margin. Sediment cores from the Peru and Cascadia Margins were obtained, and thousands of clones were studied to describe the nature of the biomass in areas with and without methane hydrates. The data suggest that prokaryotic communities from methane hydrate-bearing sediment cores are...
February 21, 2006 / Posted by: Shige Abe
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Update on the Human-Chimpanzee Divergence
Researchers from NAI’s Pennsylvania State University Lead Team and their colleagues at Arizona State University published this week in PNAS their research constraining the divergence of humans and chimpanzees. Using the largest data set yet and improved computational methods for the molecular clock calculations, the study narrows the gap from between 3 and 13 million years ago to between 5 and 7 million years ago.
December 18, 2005 / Posted by: Shige Abe
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