New Astrobiology Online Course Starts July 14th

The Coursera Massively Open On-Line Course (MOOC), Emergence of Life, is built upon the pioneering work of Carl Woese, on which the modern synthesis of the Tree of Life has been established.

No prior knowledge is required, just a willingness to learn and a desire to delve into Earth’s 4-billion-year history of Life. The course will traverse from the ancient primordial soup into the expansive and diverse Tree of Life, and how these understandings might point us towards the existence of Life elsewhere in the universe.

The University of Illinois Urbana-Champaign College of Liberal Arts and Sciences, the NASA Astrobiology Institute for Universal Biology, and the Institute for Genomic Biology have partnered to present this educational opportunity, made possible with the contributions of scientific experts from around the world, including Karl Stetter, Norm Pace, Jan Sapp, Mike Russell, and Nigel Goldenfeld.

Please join us in this unique 8-week journey through history, evolution, geologic change, and discovery of the universality of Life! Registration, course information and a 2-minute video overview are available at http://ift.tt/1kdTXQ7.

Source: [University of Illinois, Urbana-Champaign]

via NASA Astrobiology Articles http://ift.tt/1kdU0es

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Starting With the Oceans, Single-Celled Organisms Will Re-Inherit the Earth – Motherboard


Phys.Org

Starting With the Oceans, Single-Celled Organisms Will Re-Inherit the Earth
Motherboard
Trout will die out, whales will fail, but unicellular bacteria and archaea (a type of microorganism) are going to flourish. Animals can only develop and reproduce up to a temperature threshold in the water of about 41 degrees Celsius, or 105 degrees
The key to adaptation limits of ocean dwellers
Scientists uncover the key to adaptation limits of ocean dwellers

via archaea – Google News http://ift.tt/1rWekWR

Archaea: The First Domain of Diversified Life

The study of the origin of diversified life has been plagued by technical and conceptual difficulties, controversy, and apriorism. It is now popularly accepted that the universal tree of life is rooted in the akaryotes and that Archaea and Eukarya are sister groups to each other. However, evolutionary studies have overwhelmingly focused on nucleic acid and protein sequences, which partially fulfill only two of the three main steps of phylogenetic analysis, formulation of realistic evolutionary models, and optimization of tree reconstruction. In the absence of character polarization, that is, the ability to identify ancestral and derived character states, any statement about the rooting of the tree of life should be considered suspect. Here we show that macromolecular structure and a new phylogenetic framework of analysis that focuses on the parts of biological systems instead of the whole provide both deep and reliable phylogenetic signal and enable us to put forth hypotheses of origin. We review over a decade of phylogenomic studies, which mine information in a genomic census of millions of encoded proteins and RNAs. We show how the use of process models of molecular accumulation that comply with Weston’s generality criterion supports a consistent phylogenomic scenario in which the origin of diversified life can be traced back to the early history of Archaea.

via Archaea http://ift.tt/1oRw0oh

More Neanderthal

Neanderthal_modelScientists at the University of Washington’s Department of Genome Sciences, report that they can zero in on remnant Neanderthal DNA in modern humans, identifying specific regions in our genome where that ancient DNA resides, and they can do this even without access to actual Neanderthal DNA samples from fossilized bones. The study published this week[…]

Read more…

via The 23andMe Blog http://bit.ly/MxX77x

Serpentinization of Ocean Crust: Life’s Mother Engine?


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Shelf-like “flange” structures jut from the wall of one of the spires in the Lost City hydrothermal field. Image credit: IFE URI-IAO, Lost City Science Party, and NOAA

In a new study published in Philosophical Transactions of the Royal Society B, NAI-funded scientists advance a theory about life’s origins based on the idea of “reservoir-mediated energy.” This paradigm—in cells—involves constantly filling up and depleting a kind of chemical reservoir that is created by pushing a lot more protons onto one side of a membrane than the other—just like pumping water uphill to fill a lake behind a dam.

Then, mimicking how hydroelectric turbines are driven by water flowing downhill, these protons are only allowed to flow back “downhill” through the membrane by passing through a turbine-like molecular “generator” which creates, instead of high-voltage electricity, a chemical fuel called ATP, the cell’s “gasoline.” All cells then “burn” ATP in order to power their vital processes.

The study looks at how a geochemical process known as serpentinization pioneered this system before life even began, giving it a “free gift!” At the time life arose, the world was almost entirely covered in a weakly-acidic ocean, the atmosphere was rich in CO2, and tectonic processes constantly replenished and destroyed the crusts of the ocean floor, as they still do today. It is the exposure of newly made ocean crust to the ocean, such as what happens at hydrothermal vents, that gives rise to the geochemical magic of serpentinization.

As areas of new ocean crust cool, the still-stressed rock becomes brittle and develops cracks. Cold seawater gravitates down the cracks where it is heated and reacts chemically with rock minerals to form a highly-alkaline solution. This transformed water, or vent fluid, is then driven back to the surface, where, in Hadean times, it reacted with cooler, mildly acidic ocean water. These reactions create precipitates that form massive chimney-like towers similar to chemical gardens.

These highly-structured precipitate-chimneys are comprised of numerous micro-compartments bounded by semi-permeable “mineral membranes.” Across these membranes, a proton (pH) gradient arises between the extremely alkaline emerging vent fluids and the surrounding, relatively acidic ocean.

This pH gradient is almost exactly the same as the gradient that all living cells constantly recreate with the same strength and the same direction: acidic on the outside and alkaline on the inside.

“It is at least highly suggestive that every living thing is constantly and indeed furiously recreating something equivalent to this ancient ‘ocean effluent’ membrane-based proton gradient that serpentinization handed life to start with on the rocky floor of the ancient Hadean ocean,” said co-author Elbert Branscomb of the University of Illinois. “It was, in part, by exploiting that naturally-given, geochemical proton gradient that the engines required to produce the molecular ‘starter kit’ of life got going. So suddenly it’s obvious why we pump protons and use this silly method—we became dependent on this ‘free lunch’ energy system when life was born, developed a lot of fancy machinery for using it, and have never severed that umbilicus since.”

The scientists have developed an experimental system to study serpentinization and look at chemical reactions that pave the way for life in simulated vents. They observe that hydrothermal vent fluids lead to the production of a simple chemical called acetate (similar to vinegar). Acetate can then be transformed into biological molecules.

Their findings could help define chemical signatures to look for when searching for life on icy worlds like Europa and Enceladus.

Source: [UIUC Press Release]

via NASA Astrobiology Articles http://astrobiology.nasa.gov/articles/2013/08/14/serpentinization-of-ocean-crust-lifes-mother-engine/