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  • richardmitnick 3:03 pm on April 11, 2019 Permalink | Reply
    Tags: , Helical Carotenoid Protein, , , Photoprotection, Photosynthesis   

    From Michigan State University: “MSU researchers discover light absorbing protein in cyanobacteria” 

    Michigan State Bloc

    From Michigan State University

    April 11, 2019

    Igor Houwat
    MSU-DOE Plant Research Laboratory office
    (517) 353-2223


    Cyanobacteria are tiny, hardy organisms. Each cell is 25 times smaller than a human hair. Their collective ability to do photosynthesis is why we have air to breathe and a diverse and complex biosphere.

    Scientists are interested in what makes cyanobacteria great at photosynthesis. Some want to isolate and copy successful processes which would then be repurposed for human usage, like in medicine or for renewable energy.

    One of these processes is photoprotection. It includes a network of proteins that detect surrounding light levels and protect cyanobacteria from damages caused by overexposure to bright light.

    The lab of Cheryl Kerfeld at Michigan State University recently discovered a family of proteins, the Helical Carotenoid Protein, or HCP, that are the evolutionary ancestors of today’s photoprotective proteins. Although ancient, HCP still live on alongside their modern descendants.

    This discovery has opened new avenues to explore photoprotection and for the first time, the Kerfeld lab structurally and biophysically characterizes one of these proteins. They call it HCP2. The study is in the journal BBA-Bioenergetics.

    Structurally, the HCP2 is a monomer when isolated in a solution, but in its crystallized form, it curiously shows up as a dimer.

    “We don’t think that the dimer is the protein’s form when it is in the cyanobacteria,” says Maria Agustina Dominguez-Martin, a post-doc in the Kerfeld lab. “Most likely, HCP2 binds to a yet unknown partner. The dimer situation during crystallization is artificial, because the only available molecules in the environment are others like itself.”

    The scientists try to determine HCP2s functions. It is a good quencher of reactive oxygen species, damaging byproducts of photosynthesis. But since many other proteins can do that as well, Dominguez-Martin doesn’t think that is HCP2’s main function.

    “We have yet to identify a primary function,” Dominguez-Martin says. “The difficulty is that the HCP family is a recent discovery, so we don’t have much basis for comparison.”

    The ability to detect light is key for applications, especially in biotech. One promising area is optogenetics, a technology that uses light to control living cells. Optogenetics systems are like light switches that activate predetermined functions when struck by a light source.

    HCP2 could play a part in such applications. But this is all far down the road.

    “There are 9 evolutionary families of HCP to explore,” Dominguez-Martin said. “That adds up to hundreds of variants with possibly distinctive functions that we have yet to discover. With that in mind, we’re characterizing other proteins from the HCP family to expand our available data set.”

    Because these proteins likely play a role in photoprotection, they may represent a system that scientists could engineer for “smart photoprotection,” reducing wasteful photoprotection which would then help photosynthetic organisms become more efficient.

    See the full article here .


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    Michigan State Campus

    Michigan State University (MSU) is a public research university located in East Lansing, Michigan, United States. MSU was founded in 1855 and became the nation’s first land-grant institution under the Morrill Act of 1862, serving as a model for future land-grant universities.

    MSU pioneered the studies of packaging, hospitality business, plant biology, supply chain management, and telecommunication. U.S. News & World Report ranks several MSU graduate programs in the nation’s top 10, including industrial and organizational psychology, osteopathic medicine, and veterinary medicine, and identifies its graduate programs in elementary education, secondary education, and nuclear physics as the best in the country. MSU has been labeled one of the “Public Ivies,” a publicly funded university considered as providing a quality of education comparable to those of the Ivy League.

    Following the introduction of the Morrill Act, the college became coeducational and expanded its curriculum beyond agriculture. Today, MSU is the seventh-largest university in the United States (in terms of enrollment), with over 49,000 students and 2,950 faculty members. There are approximately 532,000 living MSU alumni worldwide.

  • richardmitnick 1:50 pm on November 7, 2018 Permalink | Reply
    Tags: , , , , , Photosynthesis, , Researchers create most complete high-res atomic movie of photosynthesis to date, , ,   

    From SLAC National Accelerator Lab: “Researchers create most complete high-res atomic movie of photosynthesis to date” 

    From SLAC National Accelerator Lab

    November 7, 2018

    Andrew Gordon
    (650) 926-2282

    In a major step forward, SLAC’s X-ray laser captures all four stable states of the process that produces the oxygen we breathe, as well as fleeting steps in between. The work opens doors to understanding the past and creating a greener future.

    Using SLAC’s X-ray laser, researchers have captured the most complete high-res atomic movie to date of Photosystem II, a key protein complex in plants, algae and cyanobacteria responsible for splitting water and producing the oxygen we breathe. (Gregory Stewart, SLAC National Accelerator Laboratory)

    Despite its role in shaping life as we know it, many aspects of photosynthesis remain a mystery. An international collaboration between scientists at SLAC National Accelerator Laboratory, Lawrence Berkeley National Laboratory and several other institutions is working to change that. The researchers used SLAC’s Linac Coherent Light Source (LCLS) X-ray laser to capture the most complete and highest-resolution picture to date of Photosystem II, a key protein complex in plants, algae and cyanobacteria responsible for splitting water and producing the oxygen we breathe. The results were published in Nature today.


    Explosion of life

    When Earth formed about 4.5 billion years ago, the planet’s landscape was almost nothing like what it is today. Junko Yano, one of the authors of the study and a senior scientist at Berkeley Lab, describes it as “hellish.” Meteors sizzled through a carbon dioxide-rich atmosphere and volcanoes flooded the surface with magmatic seas.

    Over the next 2.5 billion years, water vapor accumulating in the air started to rain down and form oceans where the very first life appeared in the form of single-celled organisms. But it wasn’t until one of those specks of life mutated and developed the ability to harness light from the sun and turn it into energy, releasing oxygen molecules from water in the process, that Earth started to evolve into the planet it is today. This process, oxygenic photosynthesis, is considered one of nature’s crown jewels and has remained relatively unchanged in the more than 2 billion years since it emerged.

    “This one reaction made us as we are, as the world. Molecule by molecule, the planet was slowly enriched until, about 540 million years ago, it exploded with life,” said co-author Uwe Bergmann, a distinguished staff scientist at SLAC. “When it comes to questions about where we come from, this is one of the biggest.”

    A greener future

    Photosystem II is the workhorse responsible for using sunlight to break water down into its atomic components, unlocking hydrogen and oxygen. Until recently, it had only been possible to measure pieces of this process at extremely low temperatures. In a previous paper, the researchers used a new method to observe two steps of this water-splitting cycle [Nature]at the temperature at which it occurs in nature.

    Now the team has imaged all four intermediate states of the process at natural temperature and the finest level of detail yet. They also captured, for the first time, transitional moments between two of the states, giving them a sequence of six images of the process.

    The goal of the project, said co-author Jan Kern, a scientist at Berkeley Lab, is to piece together an atomic movie using many frames from the entire process, including the elusive transient state at the end that bonds oxygen atoms from two water molecules to produce oxygen molecules.

    “Studying this system gives us an opportunity to see how metals and proteins work together and how light controls such kinds of reactions,” said Vittal Yachandra, one of the authors of the study and a senior scientist at Berkeley Lab who has been working on Photosystem II for more than 35 years. “In addition to opening a window on the past, a better understanding of Photosystem II could unlock the door to a greener future, providing us with inspiration for artificial photosynthetic systems that produce clean and renewable energy from sunlight and water.”

    Sample assembly line

    For their experiments, the researchers grow what Kern described as a “thick green slush” of cyanobacteria — the very same ancient organisms that first developed the ability to photosynthesize — in a large vat that is constantly illuminated. They then harvest the cells for their samples.

    At LCLS, the samples are zapped with ultrafast pulses of X-rays [Science] to collect both X-ray crystallography and spectroscopy data to map how electrons flow in the oxygen-evolving complex of photosystem II. In crystallography, researchers use the way a crystal sample scatters X-rays to map its structure; in spectroscopy, they excite the atoms in a material to uncover information about its chemistry. This approach, combined with a new assembly-line sample transportation system [Nature Methods], allowed the researchers to narrow down the proposed mechanisms put forward by the research community over the years.

    Mapping the process

    Previously, the researchers were able to determine the room-temperature structure of two of the states at a resolution of 2.25 angstroms; one angstrom is about the diameter of a hydrogen atom. This allowed them to see the position of the heavy metal atoms, but left some questions about the exact positions of the lighter atoms, like oxygen. In this paper, they were able to improve the resolution even further, to 2 angstroms, which enabled them to start seeing the position of lighter atoms more clearly, as well as draw a more detailed map of the chemical structure of the metal catalytic center in the complex where water is split.

    This center, called the oxygen-evolving complex, is a cluster of four manganese atoms and one calcium atom bridged with oxygen atoms. It cycles through the four stable oxidation states, S0-S3, when exposed to sunlight. On a baseball field, S0 would be the start of the game when a player on home base is ready to go to bat. S1-S3 would be players on first, second, and third. Every time a batter connects with a ball, or the complex absorbs a photon of sunlight, the player on the field advances one base. When the fourth ball is hit, the player slides into home, scoring a run or, in the case of Photosystem II, releasing breathable oxygen.

    The researchers were able to snap action shots of how the structure of the complex transformed at every base, which would not have been possible without their technique. A second set of data allowed them to map the exact position of the system in each image, confirming that they had in fact imaged the states they were aiming for.

    In photosystem II, the water-splitting center cycles through four stable states, S0-S3. On a baseball field, S0 would be the start of the game when a batter on home base is ready to hit. S1-S3 would be players waiting on first, second, and third. The center gets bumped up to the next state every time it absorbs a photon of sunlight, just like how a player on the field advances one base every time a batter connects with a ball. When the fourth ball is hit, the player slides into home, scoring a run or, in the case of Photosystem II, releasing the oxygen we breathe. (Gregory Stewart/SLAC National Accelerator Laboratory)

    Sliding into home

    But there are many other things going on throughout this process, as well as moments between states when the player is making a break for the next base, that are a bit harder to catch. One of the most significant aspects of this paper, Yano said, is that they were able to image two moments in between S2 and S3. In upcoming experiments, the researchers hope to use the same technique to image more of these in-between states, including the mad dash for home — the transient state, or S4, where two atoms of oxygen bond together — providing information about the chemistry of the reaction that is vital to mimicking this process in artificial systems.

    “The entire cycle takes nearly two milliseconds to complete,” Kern said. “Our dream is to capture 50-microsecond steps throughout the full cycle, each of them with the highest resolution possible, to create this atomic movie of the entire process.”

    Although they still have a way to go, the researchers said that these results provide a path forward, both in unveiling the mysteries of how photosynthesis works and in offering a blueprint for artificial sources of renewable energy.

    “It’s been a learning process,” said SLAC scientist and co-author Roberto Alonso-Mori. “Over the last seven years we’ve worked with our collaborators to reinvent key aspects of our techniques. We’ve been slowly chipping away at this question and these results are a big step forward.”

    In addition to SLAC and Berkeley Lab, the collaboration includes researchers from Umeå University, Uppsala University, Humboldt University of Berlin, the University of California, Berkeley, the University of California, San Francisco and the Diamond Light Source.

    Key components of this work were carried out at SLAC’s Stanford Synchrotron Radiation Lightsource (SSRL), Berkeley Lab’s Advanced Light Source (ALS) and Argonne National Laboratory’s Advanced Photon Source (APS). LCLS, SSRL, APS, and ALS are DOE Office of Science user facilities. This work was supported by the DOE Office of Science and the National Institutes of Health, among other funding agencies.




    See the full article here .

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    SLAC Campus
    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

  • richardmitnick 11:44 am on September 28, 2018 Permalink | Reply
    Tags: Astrobiology Grand Tour, , , , Community of microbial mats living on top. They are some of the Earth’s earliest ecosystems., , First oxygen-producing bacteria-cyanobacteria, , Karijini National Park, Living stromatolites of Shark Bay, , , Photosynthesis, , Pilbara in Western Australia, Pilbara is also where the oldest mineral on Earth –a zircon dated at 4.4 billion years old — was discovered four years ago in the Jack Hills region, State of Western Australia, Stromatolites literally mean “layered rocks”, The most important contribution of stromatolites – terraforming the Earth, These ancient life forms left behind geological footprints reminding us they were here first, Time-Traveling in the Australian Outback in Search of Early Earth   

    From Many Worlds: “Time-Traveling in the Australian Outback in Search of Early Earth” 

    NASA NExSS bloc


    Many Words icon

    From Many Worlds

    Nicholas Siegler, Chief Technologist for NASA’s Exoplanet Exploration Program at the Jet Propulsion Laboratory with the help of doctoral student Markus Gogouvitis, at the University of New South Wales, Australia and Georg-August-University in Gottingen, Germany.

    These living stromatolites at Shark Bay, Australia are descendants of similar microbial/sedimentary forms once common around the world. They are among the oldest known repositories of life. Most stromatolites died off long ago, but remain at Shark Bay because of the high salinity of the water. (Tourism, Western Australia)

    This past July I joined a group of geologists, geochemists, microbiologists, and fellow astronomers on a tour of some of the best-preserved evidence for early life.

    Entitled the Astrobiology Grand Tour, it was a trip led by Dr. Martin Van Kranendonk, a structural geologist from the University of New South Wales, who had spent more than 25 years surveying Australia’s Pilbara region. Along with his graduate students he had organized a ten-day excursion deep into the outback of Western Australia to visit some of astrobiology’s most renowned sites.

    The trip would entail long, hot days of hiking through unmaintained trails on loose surface rocks covered by barb-like bushes called spinifex. As I was to find out, nature was not going to give up its secrets easily. And there were no special privileges allocated to astrophysicists from New Jersey [? no mention of anyone from New Jersey].

    The route of our journey back in time. (Google Earth/Markus Gogouvitis /Martin Van Kranendonk)

    The state of Western Australia, almost four times the size of the American state of Texas but with less than a tenth of the population (2.6 million), is the site of many of astrobiology’s most heralded sites. For more than three billion years, it has been one of the most stable geologic regions in the world.

    It has been ideal for geological preservation due to its arid conditions, lack of tectonic movement, and remoteness. The rock records have in many places survived and are now able to tell their stories (to those who know how to listen).

    The classic red rocks of the Pilbara in Western Australia, with the needle sharp spinifex bushes in the foreground. (Nick Siegler, NASA/JPL-Caltech)

    Our trip began with what felt like a pilgrimage. We left Western Australia’s largest city Perth and headed north for Shark bay. It felt a bit like a pilgrimage because the next morning we visited one of modern astrobiology’s highlights – the living stromatolites of Shark Bay.

    Stromatolites literally mean “layered rocks”. It’s not the rocks that are alive but rather the community of microbial mats living on top. They are some of the Earth’s earliest ecosystems.

    We gazed over these living microbial communities aloft on their rock perches and marveled at their exceptional longevity — the species has persisted for over three billion years. Their ancestors had survived global mass extinctions, planet-covering ice glaciers, volcanic activity, and all sorts of predators. Once these life forms took hold they were not going to let go.

    The stromatolites forming today in the shallow waters of Shark Bay, Australia are built by colonies of microbes that capture ocean sediments. (University of Wisconsin-Madison)

    The photosynthetic bacteria that built ancient stromatolites played a central role of our trip for three reasons:

    Their geological footprints allowed scientists to date the evolution of early life and at times gain insight into the environments in which they grew.
    They eventually harbored the first oxygen-producing bacteria and played a central role in creating our oxygen-rich atmosphere.
    By locating ever-increasingly older microbial fossils we observed a lower limit to the age of the first life forms.. Given photosynthesis is not a simple process, the first life forms must have been simpler. Speculating, perhaps a few hundred million years earlier so that the first life form on Earth may have originated at four billion years ago.

    When viewed under a microscope, you can see the mats are made of millions of single cell bacteria and archaea, among the simplest life forms we know. Within these relatively thin regions are multiple layers of specialized microbial communities that live interdependently.

    Bacteria in the top layer evolved to harvest sunlight to live and grow via photosynthesis. Their waste products include oxygen as well as important nutrients for many different bacterial species within underlying layers. And this underlying layer’s waste product would do the same for the layer beneath it, perfectly recycling each other’s waste. The oldest forms of life that we know of had learned to co-exist together in a chemically interdependent environment.

    Broken piece of a living stromatolite, which was was remarkably spongy and smelled slightly salty, indicative of the hypersaline bay that has contributed to their survival by making bacteria and other organisms undesirable. What was actually most remarkable of the visit to Hamelin pool was how quiet it was. There were no seagulls and other birds because of the hypersaline environment. They had gone elsewhere for their meals. (Nick Siegler, NASA/JPL-Caltech)

    We saw ripped up portions of the mats that washed upon the shore at Hamelin pool in Shark Bay. A whole ecosystem held in one’s hand. Thousands of millions of years ago ancient relatives of these microbes thrived in shallow waters all around our planet, and left behind fossilized remains. But due to the evolution of grazing organisms these microbial structures are nowadays constrained to very specific environments. In the case of Shark Bay, the very high salt contents of this inlet have warded off most predators providing the microbes with a safe haven to live.

    Ironically, the rocks, which help identify these ancient life forms, at the time were just a nuisance for the living microbes.

    Small fine grains of sedimentary rock carried along in the daily tides would occasionally get stuck in the sticky mucus the microbes would secrete. In addition, the photosynthetic bacteria found at Shark Bay may have been inadvertently making their own rock by depleting the carbon dioxide in the surrounding water as part of photosynthesis and precipitating carbonate, adding to the grains of sediment trapped within the sticky top layer.

    Over time, the grains from both the sedimentary and precipitated rocks would cover the surface and block the sunlight for which these organisms had evolved to depend on. As an evolutionary tour de force, the photosynthetic microbes learned to migrate upward, leaving the newly formed rock layers behind.

    These secondary rock fossils today showcase visually observable crinkly, frequently conical shapes, in stark contrast to abiotic sedimentary rocks. These ancient life forms left behind geological footprints reminding us they were here first.

    Now to the most important contribution of stromatolites – terraforming the Earth.

    Living in shallow water, the top most layer of the Shark Bay microbial mats are known to host cyanobacteria, photosynthetic bacteria that produce oxygen as a byproduct. Scientists don’t know what the first bacteria produced as they harnessed the energy of the Sun. But they do know that they eventually started producing oxygen.

    In the evolution of life that eventually led to all plants and animals, this was one of the great events. More than 2.5 billion years ago, ancient bacteria began diligently producing oxygen in the oceans. Earth’s atmosphere began to irreversibly shift from its original, oxygen-free existence, to an oxic one, initiating the formation of our ozone layer and paving the way for the evolution of more complex life. Our planet has been terraformed by micro-organisms!

    It was in the Karijini National Park where we went back in time (2.4 billion years) and observed an extraordinary piece of evidence for the early production of oxygen in Earth’s oceans, a time before oxygen made a strong presence in our atmosphere.

    Banded iron formation at Karajini National Park. (Nick Siegler, NASA-JPL/Caltech)

    We saw a massive gorge with steep vertical walls carved out by flowing water. As oxygen production by early bacteria increased below the water surface it would react with dissolved iron ions (early oceans were iron-rich) causing iron oxides to precipitate and settle to the bottom.

    For reasons not entirely understood — perhaps related to seasonal or temperature effects– the amount of new oxygen temporarily decreased and iron ion remained soluble in the oceans and other types of sediments accumulated, carbonates, slate, and shale. And then, just as before, the oxygen reappeared creating a new layer of precipitated iron.

    The result was a banded sedimentary rock, a litmus test to a changing world, where oxygen would be the reactive ingredient leading to larger and more complex life forms. As the oxygen production no longer cycled, the oxygen went on to saturate the ocean and then accumulated in the Earth’s atmosphere eventually to the levels we have today.

    Banded iron formation at Karajini. (Nick Siegler, NASA-JPL/Caltech)

    After a day of looking down at rocks and spinifex it was both a relief and a joy to look up at the glorious Western Australian night sky. Far away from the light pollution of modern cities, each night would greet us with an awe-inspiring starlit sky. It never got old to remember we are part of a vast network of stars suspended in an infinite space.

    The nights would start with the appearance of Venus well before sundown followed shortly by the innermost planet Mercury and then Jupiter and Saturn. It didn’t take long after sunset to see the renowned Southern Cross. Mars joined the evening as well, perfectly appearing on the arc called the ecliptic.

    But nothing stirred the group more than the emergence of the swath of stars of the Milky Way, the disk of our home galaxy where its spiral arms all lie. The nights would be so clear that one could actually see the dark clouds of gas and dust that block large portions of the galaxy’s stars from shining through. We partook in the well-known tradition connecting individual points of light to form exotic creatures like scorpions and centaurs. But we also we followed the inverted approach of the Aborigines and connected the dark patches. Only then did we see the emu of the Milky Way. I would never have thought of connecting the darkness.

    The night sky appeared even more special knowing that each of its stellar members likely host planetary systems like our own. How many of them host life? Maybe even civilizations? The numbers are in their favor.

    At the half-way point of our trip we hiked to an ancient granite region in the red rocks of the Pilbara which contain the world’s largest concentration of Pleistocene rock art also known as petroglyphs. These etchings are believed to be 6,000 to 20, 000 years old.

    The artists used no pigments, but rather rocks to pound/chisel shapes into the desert varnish, a thin dark film (possibly of microbial origin) that typically covers exposed rock surfaces in hyper arid regions. We came across many stylized male and female figures with highlighted genitalia as well as animals such as emus and kangaroos. Little is known about the people who created these art works. They left no clues to their origin or fate.

    Rock art by aboriginal people done 6,000 to 20,000 years ago. The shapes were etched into an existing varnish on the rock. (Nick Siegler, NASA-JPL/Caltech)

    Pilbara is also where the oldest mineral on Earth –a zircon dated at 4.4 billion years old — was discovered four years ago in the Jack Hills region. Because of the geological history of the region, it is a frequent (if hardscrabble) site where many geologists and geochemists specializing in ancient Earth do their work.

    In the last several days of the tour we encountered ever-increasing older evidence of stromatolites extending out to circa 3.5 billion years, about 75% of the history of the Earth. I expected the quality of the stromatolites to degrade as we went back in time and it looked like I was right until I saw a remarkably large rock in a locality called the Strelley Pool Formation. The rock measuring approximately 1.5 meters in all three directions gave a rare view of ancient stromatolites from all sides and an unequivocal interpretation of past life.

    The shapes of the embedded rocks formed by the microbial mats from the top view clearly show the elliptical areas where the bacteria inched upwards to acquire sunlight. Regions between the conical stromatolites were filled in by carbonate sediments in ancient shallow waters. These were later chemically altered to silica-rich rocks through alteration and etching of minerals by fluids. Silicified rocks are very weather-resistant, making them a great medium to preserve fossils for billions of years.

    The side views of the stromatolite-laden rock revealed the expected conical layered shapes we saw in younger rocks (and in the living stromatolites of Shark Bay). Everything we had learned about stromatolite structures was clearly visible in this circa 3.43 billion year old example. It is astounding to realize that complex phototrophic (light-eating) organisms, even if not yet oxygen producing, were around during the deposition of the Strelley Pool Formation.

    Detail of Strelley Pool stromatolite fossil. (Nick Siegler, NASA-JPL/Caltech)

    It is not unreasonable to speculate that the earliest life forms are even older by perhaps a few more hundred million years or so. There is evidence for even more ancient stromatolites in Greenland (3.7 billion years old) and isotope carbon evidence, with considerable controversy, in Nuvvuagittuq greenstone belt in northern Quebec, Canada (4.28 billion years old). Hence, life on Earth may have emerged within 500 million years from its formation. That is astonishingly rapid.

    Was Earth an exception or the rule? What does that say for possible life on exoplanets?

    Our tour came to an end on July 11. We had traveled over 1,600 miles through Australia’s outback, from Western Australia’s biggest city Perth, all the way up to Port Hedland at the north coast. We were privileged to see the country in ways that very few people get a chance to, and to be steeped in the multidisciplinary sciences of astrobiology while seeing some of its iconic ground.

    I had seen some of the earliest evidence for life and the pivotal effect it had on our environment. For those 10 days I learned what it was like to be a time traveler.

    See the full article here .


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    About Many Worlds

    There are many worlds out there waiting to fire your imagination.

    Marc Kaufman is an experienced journalist, having spent three decades at The Washington Post and The Philadelphia Inquirer, and is the author of two books on searching for life and planetary habitability. While the “Many Worlds” column is supported by the Lunar Planetary Institute/USRA and informed by NASA’s NExSS initiative, any opinions expressed are the author’s alone.

    This site is for everyone interested in the burgeoning field of exoplanet detection and research, from the general public to scientists in the field. It will present columns, news stories and in-depth features, as well as the work of guest writers.

    About NExSS

    The Nexus for Exoplanet System Science (NExSS) is a NASA research coordination network dedicated to the study of planetary habitability. The goals of NExSS are to investigate the diversity of exoplanets and to learn how their history, geology, and climate interact to create the conditions for life. NExSS investigators also strive to put planets into an architectural context — as solar systems built over the eons through dynamical processes and sculpted by stars. Based on our understanding of our own solar system and habitable planet Earth, researchers in the network aim to identify where habitable niches are most likely to occur, which planets are most likely to be habitable. Leveraging current NASA investments in research and missions, NExSS will accelerate the discovery and characterization of other potentially life-bearing worlds in the galaxy, using a systems science approach.
    The National Aeronautics and Space Administration (NASA) is the agency of the United States government that is responsible for the nation’s civilian space program and for aeronautics and aerospace research.

    President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA’s predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

    Since that time, most U.S. space exploration efforts have been led by NASA, including the Apollo moon-landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program (LSP) which provides oversight of launch operations and countdown management for unmanned NASA launches. Most recently, NASA announced a new Space Launch System that it said would take the agency’s astronauts farther into space than ever before and lay the cornerstone for future human space exploration efforts by the U.S.

    NASA science is focused on better understanding Earth through the Earth Observing System, advancing heliophysics through the efforts of the Science Mission Directorate’s Heliophysics Research Program, exploring bodies throughout the Solar System with advanced robotic missions such as New Horizons, and researching astrophysics topics, such as the Big Bang, through the Great Observatories [Hubble, Chandra, Spitzer, and associated programs. NASA shares data with various national and international organizations such as from the [JAXA]Greenhouse Gases Observing Satellite.

  • richardmitnick 8:00 am on March 9, 2018 Permalink | Reply
    Tags: , , , , Photosynthesis   

    From astrobio.net: “Photosynthesis originated a billion years earlier than we thought, study shows” 

    Astrobiology Magazine

    Astrobiology Magazine

    Mar 7, 2018

    This plate is a culture of Synechocystis sp. PCC 6803, a type of unicellular Cyanobacteria. Credit: Elsevier

    Ancient microbes may have been producing oxygen through photosynthesis a billion years earlier than we thought, which means oxygen was available for living organisms very close to the origin of life on earth. In a new article in Heliyon, a researcher from Imperial College London studied the molecular machines responsible for photosynthesis and found the process may have evolved as long as 3.6 billion years ago.

    The author of the study, Dr. Tanai Cardona, says the research can help to solve the controversy around when organisms started producing oxygen – something that was vital to the evolution of life on earth. It also suggests that the microorganisms we previously believed to be the first to produce oxygen – cyanobacteria – evolved later, and that simpler bacteria produced oxygen first.

    “My results mean that the process that sustains almost all life on earth today may have been doing so for a lot longer than we think,” said Dr. Cardona. “It may have been that the early availability of oxygen was what allowed microbes to diversify and dominate the world for billions of years. What allowed microbes to escape the cradle where life arose and conquer every corner of this world, more than 3 billion years ago.”

    Photosynthesis is the process that sustains complex life on earth – all of the oxygen on our planet comes from photosynthesis. There are two types of photosynthesis: oxygenic and anoxygenic. Oxygenic photosynthesis uses light energy to split water molecules, releasing oxygen, electrons and protons. Anoxygenic photosynthesis use compounds like hydrogen sulfide or minerals like iron or arsenic instead of water, and it does not produce oxygen.

    This image is the crystal structure of Photosystem I (PDB ID: 1JB0). Credit: Elsevier

    Previously, scientists believed that anoxygenic evolved long before oxygenic photosynthesis, and that the earth’s atmosphere contained no oxygen until about 2.4 to 3 billion years ago. However, the new study suggests that the origin of oxygenic photosynthesis may have been as much as a billion years earlier, which means complex life would have been able to evolve earlier too.

    Dr. Cardona wanted to find out when oxygenic photosynthesis originated. Instead of trying to detect oxygen in ancient rocks, which is what had been done previously, he looked deep inside the molecular machines that carry out photosynthesis – these are complex enzymes called photosystems. Oxygenic and anoxygenic photosynthesis both use an enzyme called Photosystem I. The core of the enzyme looks different in the two types of photosynthesis, and by studying how long ago the genes evolved to be different, Dr. Cardona could work out when oxidative photosynthesis first occurred.

    He found that the differences in the genes may have occurred more than 3.4 billion years ago – long before oxygen was thought to have first been produced on earth. This is also long before cyanobacteria – microbes that were thought to be the first organisms to produce oxygen – existed. This means there must have been predecessors, such as early bacteria, that have since evolved to carry out anoxygenic photosynthesis instead.

    “This is the first time that anyone has tried to time the evolution of the photosystems,” said Dr. Cardona. “The result hints towards the possibility that oxygenic photosynthesis, the process that have produced all oxygen on earth, actually started at a very early stage in the evolutionary history of life – it helps solve one of the big controversies in biology today.”

    One surprising finding was that the evolution of the photosystem was not linear. Photosystems are known to evolve very slowly – they have done so since cyanobacteria appeared at least 2.4 billion years ago. But when Dr. Cardona used that slow rate of evolution to calculate the origin of photosynthesis, he came up with a date that was older than the earth itself. This means the photosystem must have evolved much faster at the beginning – something recent research suggests was due to the planet being hotter.

    “There is still a lot we don’t know about why life is the way it is and how most biological process originated,” said Dr. Cardona. “Sometimes our best educated guesses don’t even come close to representing what really happened so long ago.”

    Dr. Cardona hopes his findings may also help scientists who are looking for life on other planets answer some of their biggest questions.

    See the full article here .

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  • richardmitnick 9:01 am on August 15, 2017 Permalink | Reply
    Tags: Chloroplasts, , Eukaryotes, Photosynthesis,   

    From U Bristol: “The origin of the chloroplast” 

    University of Bristol

    14 August 2017
    No writer credit found

    A new study, led by the University of Bristol, has shed new light on the origin, timing and habitat in which the chloroplast first evolved.

    Chloroplast. Kristian Peters — Fabelfroh

    The Earth’s biosphere is fuelled by photosynthesis. During this fundamental process algae and plants capture sunlight and transform carbon dioxide into carbohydrates, splitting water and releasing oxygen. Photosynthesis takes place in green specialised subunits within a cell known as chloroplasts.

    Scientists have known that algae and land plants evolved after a more complex organism with a nucleus known knows as eukaryotes; this ancient eukaryote swallowed a photosynthesising bacteria which are commonly known as blue-green algae or cyanobacterium.

    Cyanobacteria. flickr.

    While, it is accepted that cyanobacteria, are the ancestors of the chloroplast, it is unclear which of the cyanobacteria are closest related to the chloroplast, when this association first appeared in geological terms, and in which type of habitat this association first took place.

    This new study shows that the chloroplast lineage split from their closest cyanobacterial ancestor more than 2.1 billion years ago in low salinity environments.

    It took another 200 million years for the chloroplast and the eukaryotic host to be intimately associated into a symbiotic relationship. This evolutionary study also revealed that marine algae groups diversified much later on at around 800 – 750 million years ago.

    The study’s lead author, Dr Patricia Sanchez-Baracaldo, a Royal Society Research Fellow at the University of Bristol’s School of Geographical Sciences, said: “The results of this study imply that complex organisms such as algae first evolved in freshwater environments, and later colonised marine environments – these results also have huge implications to understanding the carbon cycle.

    “Genomic data and sophisticated evolutionary methods can now be used to draw a more complete picture of early life on land; complementing what has been previously inferred from the fossil record.”

    Professor Davide Pisani from the Schools of Biological and Earth Sciences said: “Our planet is a beautiful place and it exists in such a sharp contrast with the rest of the solar system. Think about those beautiful satellite pictures where you see the green of the forests and the blue/green tone of the water.

    “Well, Earth was not like that before photosynthesis. Before photosynthesis it was an alien place, uninhabitable by humans. Here we made some big steps to clarify how Earth become the planet we know today, and I think that that is just wonderful.”

    Professor Andrew H. Knoll from Harvard University added: “Integrating observations from molecular biology, paleontology and environmental history provides new perspectives on the deep, and deeply intertwined history of Earth and life.”

    Science paper:

    Early photosynthetic eukaryotes inhabited low salinity habitats by P. Sánchez-Baracaldo. J. Raven, D. Pisani and A. Knoll in PNAS .

    See the full article here .

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    Bristol is one of the most popular and successful universities in the UK and was ranked within the top 50 universities in the world in the QS World University Rankings 2018.

    The University of Bristol is at the cutting edge of global research. We have made innovations in areas ranging from cot death prevention to nanotechnology.

    The University has had a reputation for innovation since its founding in 1876. Our research tackles some of the world’s most pressing issues in areas as diverse as infection and immunity, human rights, climate change, and cryptography and information security.

    The University currently has 40 Fellows of the Royal Society and 15 of the British Academy – a remarkable achievement for a relatively small institution.

    We aim to bring together the best minds in individual fields, and encourage researchers from different disciplines and institutions to work together to find lasting solutions to society’s pressing problems.

    We are involved in numerous international research collaborations and integrate practical experience in our curriculum, so that students work on real-life projects in partnership with business, government and community sectors.

  • richardmitnick 4:50 pm on June 17, 2017 Permalink | Reply
    Tags: , , , , , , Microbial Communities Thrive by Transferring Electrons, Photosynthesis, Syntrophic anaerobic photosynthesis   

    From EMSL: “Microbial Communities Thrive by Transferring Electrons” 



    February 03, 2017 [Blew right by tis when it first came out. Glad to see they re-issued it.]
    Haluk Beyenal
    Washington State University

    Alice Dohnalkova

    New cooperative photosynthesis studied for applications to waste treatment and bioenergy production. No image credit.

    The Science

    Photosynthetic bacteria are major primary producers on Earth, using sunlight to convert inorganic compounds in the environment into more complex organic compounds that fuel all living systems on the planet. A team of researchers recently discovered a new microbial metabolic process, which they termed syntrophic anaerobic photosynthesis, and which could represent an important, widespread form of carbon metabolism in oxygen-depleted zones of poorly mixed freshwater lakes.

    The Impact

    The discovery of syntrophic anaerobic photosynthesis reveals new possibilities for bioengineering microbial communities that could be used for waste treatment and bioenergy production.


    Almost all life on Earth relies directly or indirectly on primary production—the conversion of inorganic compounds in the environment into organic compounds that store chemical energy and fuel the activity of organisms. Nearly half the global primary productivity occurs through photosynthetic carbon dioxide (CO2) fixation by sulfur bacteria and cyanobacteria. In oxygen-depleted environments, photosynthetic bacteria use inorganic compounds such as water, hydrogen gas and hydrogen sulfide to provide electrons needed to convert CO2 into organic compounds. These organic compounds also make their way into the food web, where they support the growth of heterotrophs—organisms that cannot manufacture their own food. A recent study revealed a new metabolic process, called syntrophic anaerobic photosynthesis, in which photosynthetic and heterotrophic bacteria cooperate to support one another’s growth in oxygen-depleted environments. Researchers from Washington State University, Pacific Northwest National Laboratory (PNNL), China University of Geoscience, and Southern Illinois University made this discovery using the Quanta scanning electron microscope and the FEI Tecnai T-12 cryo-transmission electron microscope at EMSL, the Environmental Molecular Sciences Laboratory, a DOE Office of Science user facility.

    Quanta scanning electron microscope

    FEI Tecnai T-12 cryo-transmission electron microscope

    Their analysis revealed that a heterotrophic bacterial species, Geobacter sulfurreducens, directly transfers electrons to a photosynthetic bacterial species, Prosthecochloris aestuarii, which uses electrons to fix CO2 into cell material. At the same time, donating electrons allows G. sulfurreducens to support its own metabolic needs by converting acetate into CO2 and water. This potentially widespread, symbiotic form of metabolism, which links anaerobic photosynthesis directly to anaerobic respiration, could be harnessed to develop new strategies for waste treatment and bioenergy production.

    P.T. Ha, S.R. Lindemann, L. Shi, A.C. Dohnalkova, J.K. Fredrickson, M.T. Madigan and H. Beyenal, “Syntrophic anaerobic photosynthesis via direct interspecies electron transfer.” 2017 Nature Communications doi:10.1038/ncomms13924

    See the full article here .

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    EMSL campus

    Welcome to EMSL. EMSL is a national scientific user facility that is funded and sponsored by DOE’s Office of Biological & Environmental Research. As a user facility, our scientific capabilities – people, instruments and facilities – are available for use by the global research community. We support BER’s mission to provide innovative solutions to the nation’s environmental and energy production challenges in areas such as atmospheric aerosols, feedstocks, global carbon cycling, biogeochemistry, subsurface science and energy materials.

    A deep understanding of molecular-level processes is critical to gaining a predictive, systems-level understanding of the impacts of aerosols and terrestrial systems on climate change; making clean, affordable, abundant energy; and cleaning up our legacy wastes. Visit our Science page to learn how EMSL leads in these areas, through our Science Themes.

    Team’s in Our DNA. We approach science differently than many institutions. We believe in – and have proven – the value of drawing together members of the scientific community and assembling the people, resources and facilities to solve problems. It’s in our DNA, since our founder Dr. Wiley’s initial call to create a user facility that would facilitate “synergism between the physical, mathematical, and life sciences.” We integrate experts across disciplines; experiment with theory; and our user program proposal calls with other user facilities.

    We proudly provide an enriched, customized experience that allows users to connect with our people and capabilities in an environment where we focus on solving problems. We collaborate with researchers from academia, government labs and industry, and from nearly all 50 states and from other countries.

  • richardmitnick 11:30 am on August 5, 2016 Permalink | Reply
    Tags: , Better understanding of light harvesting may benefit agriculture, , Photosynthesis,   

    From phys.org: “Better understanding of light harvesting may benefit agriculture” 


    August 5, 2016
    No writer credit found

    Credit: Australian Nuclear Science and Technology Organisation (ANSTO)

    Research at ANSTO has helped to reveal insights into a molecular mechanism for harvesting light in extreme conditions. These insights may ultimately lead to previously inaccessible regions of the electromagnetic spectrum becoming available for agricultural production or splitting of water into hydrogen in technological applications of photosynthetic machinery.

    A collaboration between researchers in Australia and Europe, the research has been published in Biochimica et Biophysica Acta. The study investigated light harvesting in the far-red region of the electromagnetic spectrum under extreme conditions.

    Experiments on the Quokka instrument using small angle neutron scattering (SANS) showed that cyanobacteria adjust to low light conditions dynamically by reconfiguring part of the phycobilisome, a protein complex identified with an important role in light harvesting.

    Cyanobacteria, commonly known as blue green algae, are micro-organisms related to bacteria that are capable of photosynthesis (an important biochemical process where light is converted into chemical energy such as glucose).

    Instrument scientist Chris Garvey said SANS was used to measure distances between the membranes of the phycobilisome in a living cyanobacteria, which live in low light conditions and absorb far red light (extreme red in the visible spectrum).

    The ability to harvest far red light is important for these organisms as in their habitat it is a predominant source of energy/photons.

    Novel complementary chromatic acclimation model for H. hongdechloris. Thylakoid membranes with phycoblisomes from WL-grown cells and remodeled thylakoid membranes with red-shifted phycobilisomes from FRL-grown cells. Remodeled red-shifted phycobilisomes mainly consist of an APC core with alternative peptides.WL = white light; FRL = far-red light. Credit: Australian Nuclear Science and Technology Organisation (ANSTO)

    “What is really interesting about these organisms is that they can harness an extreme region of the spectrum (red light) and turn it into chemical potential energy,” said Garvey.

    It appears the way cyanobacteria might be able to do this is by changing the structure of the phycobilisome complex in response to the environmental conditions.

    A difference in the size of the space between thyalkaloid membranes is associated with a new light absorption and energy transfer mechanism enhancing the capture of far red light.

    “Quokka is particularly good at discerning membrane organisation inside living cells. The bumps or peaks in the measurements revealed differences in the spaces between the membranes,” said Garvey.

    “The peaks in the angular distribution of scattered neutrons can be converted to distances at the nanometre scale. The membranes are clearly farther apart in white light,” said Garvey.

    The structure of the phycobilisome, which is located within the cyanobacterium’s chloroplasts, comprises a series of subunits, or rods attached to a core. The remodelled complex may lack rods.

    “We are thinking of ways we might test that,” said Garvey.

    Quokka data complemented spectral characterisation, biochemical analyses and imaging using electron microscopy also undertaken in the study.

    “There are real experimental advantages in using SANS on Quokka. You can take measurements on a living organism, such as the cyanobacteria, rather than the complex processing of preparing a sample for electron microscopy,” said Garvey, who uses SANS to probe cellular systems.

    “We think this approach will become a major area of photosynthesis research—understanding the physiological response to different ambient conditions and in particular the packing of membranes in a cell, measuring distances and linking this to the storage of energy by the cell.”

    This particular species of cyanobacteria have an unusual type of chlorophyll known as chlorophyll f that was discovered in stromatolites in coastal Western Australia (see photo above) by one of the paper’s co-authors, Prof Min Chen of the University of Sydney.

    Prof Chen and collaborators suggested in a paper in Science announcing the discovery, that specific molecular changes to the structure of chlorophyll allowed photosynthetic organisms to survive in almost any environment on Earth.

    Chen and collaborators found that cyanobacterium could photosynthesise using light just outside the visible spectrum – at 710nm, in the infrared region —using a modified chlorophyll molecule.

    The results of the recent research were recently presented at a conference, Photosynthesis Research for Sustainability 2016, which was held in Russia.

    Garvey attended the conference and described to photosynthesis experts how deuteration may complement neutron based techniques for studies of cellular structure and physiology.

    Deuteration minimises the hydrogen content of samples, replacing hydrogen with deuterium to improve the information content of the SANS technique.

    “Our biodeuteration laboratories can produce deuterated biomass in samples such as algae, the outstanding question is which biomolecules are being deuterated” said Garvey.

    The cyanobacteria, Halomicronema hongdechloris, were biodeuterated for neutron scattering experiments on Quokka.

    See the full article here .

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    About Phys.org in 100 Words

    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

  • richardmitnick 5:18 am on February 10, 2015 Permalink | Reply
    Tags: , , , Photosynthesis,   

    From phys.org: “Bionic leaf: Researchers use bacteria to convert solar energy into liquid fuel” 


    Plant cells with visible chloroplasts (from a moss, Plagiomnium affine) Credit: Wikipedia

    Harvesting sunlight is a trick plants mastered more than a billion years ago, using solar energy to feed themselves from the air and water around them in the process we know as photosynthesis.

    Scientists have also figured out how to harness solar energy, using electricity from photovoltaic cells to yield hydrogen that can be later used in fuel cells. But hydrogen has failed to catch on as a practical fuel for cars or for power generation in a world designed around liquid fuels.

    Now scientists from a team spanning Harvard University’s Faculty of Arts and Sciences, Harvard Medical School and the Wyss Institute for Biologically Inspired Engineering at Harvard University have created a system that uses bacteria to convert solar energy into a liquid fuel. Their work integrates an “artificial leaf,” which uses a catalyst to make sunlight split water into hydrogen and oxygen, with a bacterium engineered to convert carbon dioxide plus hydrogen into the liquid fuel isopropanol.

    The findings are published Feb. 9 in PNAS. The co-first authors are Joseph Torella, a recent PhD graduate from the HMS Department of Systems Biology, and Christopher Gagliardi, a postdoctoral fellow in the Harvard Department of Chemistry and Chemical Biology.

    Pamela Silver, the Elliott T. and Onie H. Adams Professor of Biochemistry and Systems Biology at HMS and an author of the paper, calls the system a bionic leaf, a nod to the artificial leaf invented by the paper’s senior author, Daniel Nocera, the Patterson Rockwood Professor of Energy at Harvard University.

    “This is a proof of concept that you can have a way of harvesting solar energy and storing it in the form of a liquid fuel,” said Silver, who is Core Faculty at the Wyss Institute. “Dan’s formidable discovery of the catalyst really set this off, and we had a mission of wanting to interface some kinds of organisms with the harvesting of solar energy. It was a perfect match.”

    Silver and Nocera began collaborating two years ago, shortly after Nocera came to Harvard from MIT. They shared an interest in “personalized energy,” or the concept of making energy locally, as opposed to the current system, which in the example of oil means production is centralized and then sent to gas stations. Local energy would be attractive in the developing world.

    “It’s not like we’re trying to make some super-convoluted system,” Silver said. “Instead, we are looking for simplicity and ease of use.”

    In a similar vein, Nocera’s artificial leaf depends on catalysts made from materials that are inexpensive and readily accessible.

    “The catalysts I made are extremely well adapted and compatible with the growth conditions you need for living organisms like a bacterium,” Nocera said.

    In their new system, once the artificial leaf produces oxygen and hydrogen, the hydrogen is fed to a bacterium called Ralstonia eutropha. An enzyme takes the hydrogen back to protons and electrons, then combines them with carbon dioxide to replicate—making more cells.

    Next, based on discoveries made earlier by Anthony Sinskey, professor of microbiology and of health sciences and technology at MIT, new pathways in the bacterium are metabolically engineered to make isopropanol.

    “The advantage of interfacing the inorganic catalyst with biology is you have an unprecedented platform for chemical synthesis that you don’t have with inorganic catalysts alone,” said Brendan Colón, a graduate student in systems biology in the Silver lab and a co-author of the paper. “Solar-to-chemical production is the heart of this paper, and so far we’ve been using plants for that, but we are using the unprecedented ability of biology to make lots of compounds.”

    The same principles could be employed to produce drugs such as vitamins in small amounts, Silver said.

    The team’s immediate challenge is to increase the bionic leaf’s ability to translate solar energy to biomass by optimizing the catalyst and the bacteria. Their goal is 5 percent efficiency, compared to nature’s rate of 1 percent efficiency for photosynthesis to turn sunlight into biomass.

    “We’re almost at a 1 percent efficiency rate of converting sunlight into isopropanol,” Nocera said. “There have been 2.6 billion years of evolution, and Pam and I working together a year and a half have already achieved the efficiency of photosynthesis.”

    See the full article here.

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    About Phys.org in 100 Words

    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

  • richardmitnick 9:10 am on March 29, 2014 Permalink | Reply
    Tags: , , Photosynthesis   

    From Argonne Lab: “Photosynthesis, reimagined” 

    News from Argonne National Laboratory

    March 27, 2014
    Jared Sagoff

    Using water as fuel has been a recurrent theme of science fiction since the days of Jules Verne. A recent discovery, however, may bring it one step closer to science fact by mimicking the very first steps of the photosynthetic water-splitting pathway.

    Scientists at the U.S. Department of Energy’s Argonne National Laboratory in collaboration with researchers from Arizona State University have found a way to imitate Photosystem II, the first protein complex in the long chain of reactions that use energy from the sun to create usable fuel. The result was reported in the journal Nature Chemistry.

    Argonne scientists in collaboration with researchers from Arizona State University have found a way to imitate Photosystem II, the first protein complex in the long chain of reactions that use energy from the sun to create usable fuel.

    Photosystem II uses energized electrons to split water into oxygen, protons and the electrons that are necessary to complete the photosynthetic process.

    Once light strikes an electron in a chlorophyll molecule at the heart of photosystem II, the excited electron moves to a higher energy state, leaving behind a positively charged region called a “hole,” which is in then filled by other electrons that are stripped from water by a special enzyme. The excited electron then travels through a number of “electron carrier” proteins like a baton being passed among relay racers.

    However, the motion of an electron brings with it a negative charge. The protein compensates for this by transferring a positively-charged proton as well. When both steps happen, the “baton exchange” is complete and charge separation happens successfully.

    “The problem is that even though we know exactly how these reactions occur in nature, it’s extremely difficult to replicate them in the laboratory because the protein environment is so hard to imitate,” said Argonne nanoscientist Tijana Rajh.

    In this experiment, Rajh and her colleagues used facilities at Argonne’s Center for Nanoscale Materials to create an organic/inorganic hybrid based around a titanium dioxide nanoparticle. This hybrid performed the same elementary steps of charge separation as in the natural system, including the transfer of both electrons and protons facilitated by the protein environment.

    The researchers were able to follow and compare these first steps by using electron paramagnetic resonance (EPR) spectroscopy, which is similar to the techniques used in MRI machines in doctors’ offices – however, it looks at electron spins instead of those of atomic nuclei.

    “There are three parts to doing this kind of research: synthesizing the material, performing EPR experiments and making theoretical calculations,” Rajh said.

    “EPR is the optimal technique for studying photochemical reactions because it’s the only technique that lets us see both the electrons and the holes,” said Argonne chemist Oleg Poluektov.

    In the future, Rajh and Poluektov hope to generate a more perfect imitation of the biological system. “We’re trying to mimic a natural solution that’s cheap, stable, and efficient. Right now, we can only do two out of three,” Rajh said.

    Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America’s scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science.

    The Center for Nanoscale Materials at Argonne National Laboratory is one of the five DOE Nanoscale Science Research Centers (NSRCs), premier national user facilities for interdisciplinary research at the nanoscale, supported by the DOE Office of Science. Together the NSRCs comprise a suite of complementary facilities that provide researchers with state-of-the-art capabilities to fabricate, process, characterize and model nanoscale materials, and constitute the largest infrastructure investment of the National Nanotechnology Initiative. The NSRCs are located at DOE’s Argonne, Brookhaven, Lawrence Berkeley, Oak Ridge and Sandia and Los Alamos National Laboratories. For more information about the DOE NSRCs, please visit the Office of Science website.
    See the full article here.

    Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science

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