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

    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
    houwatig@msu.edu

    1

    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 9:16 am on August 21, 2018 Permalink | Reply
    Tags: , Building phylogenetic trees, Chronograms, Cyanobacteria, , , , Investigating Earth’s earliest life, Kelsey Moore, , ,   

    From MIT News: Women in STEM- “Investigating Earth’s earliest life” Kelsey Moore 

    MIT News
    MIT Widget

    From MIT News

    August 18, 2018
    Fatima Husain

    1
    Kelsey Moore. Image: Ian MacLellan

    Graduate student Kelsey Moore uses genetic and fossil evidence to study the first stages of evolution on our planet.

    In the second grade, Kelsey Moore became acquainted with geologic time. Her teachers instructed the class to unroll a giant strip of felt down a long hallway in the school. Most of the felt was solid black, but at the very end, the students caught a glimpse of red.

    That tiny red strip represented the time on Earth in which humans have lived, the teachers said. The lesson sparked Moore’s curiosity. What happened on Earth before there were humans? How could she find out?

    A little over a decade later, Moore enrolled in her first geoscience class at Smith College and discovered she now had the tools to begin to answer those very questions.

    Moore zeroed in on geobiology, the study of how the physical Earth and biosphere interact. During the first semester of her sophomore year of college, she took a class that she says “totally blew my mind.”

    “I knew I wanted to learn about Earth history. But then I took this invertebrate paleontology class and realized how much we can learn about life and how life has evolved,” Moore says. A few lectures into the semester, she mustered the courage to ask her professor, Sara Pruss in Smith’s Department of Geosciences, for a research position in the lab.

    Now a fourth-year graduate student at MIT, Moore works in the geobiology lab of Associate Professor Tanja Bosak in MIT’s Department of Earth, Atmospheric, and Planetary Sciences. In addition to carrying out her own research, Moore, who is also a Graduate Resident Tutor in the Simmons Hall undergraduate dorm, makes it a priority to help guide the lab’s undergraduate researchers and teach them the techniques they need to know.

    Time travel

    “We have a natural curiosity about how we got here, and how the Earth became what it is. There’s so much unknown about the early biosphere on Earth when you go back 2 billion, 3 billion, 4 billion years,” Moore says.

    Moore studies early life on Earth by focusing on ancient microbes from the Proterozoic, the period of Earth’s history that spans 2.5 billion to 542 million years ago — between the time when oxygen began to appear in the atmosphere up until the advent and proliferation of complex life. Early in her graduate studies, Moore and Bosak collaborated with Greg Fournier, the Cecil and Ida Green Assistant Professor of Geobiology, on research tracking cyanobacterial evolution. Their research is supported by the Simons Collaboration on the Origins of Life.

    An image of Cyanobacteria, Tolypothrix

    The question of when cyanobacteria gained the ability to perform oxygenic photosynthesis, which produces oxygen and is how many plants on Earth today get their energy, is still under debate. To track cyanobacterial evolution, MIT researchers draw from genetics and micropaleontology. Moore works on molecular clock models, which track genetic mutations over time to measure evolutionary divergence in organisms.

    Clad with a white lab coat, lab glasses, and bright purple gloves, Moore sifts through multiple cyanobacteria under a microscope to find modern analogs to ancient cyanobacterial fossils. The process can be time-consuming.

    “I do a lot of microscopy,” Moore says with a laugh. Once she’s identified an analog, Moore cultures that particular type of cyanobacteria, a process which can sometimes take months. After the strain is enriched and cultured, Moore extracts DNA from the cyanobacteria. “We sequence modern organisms to get their genomes, reconstruct them, and build phylogenetic trees,” Moore says.

    By tying information together from ancient fossils and modern analogs using molecular clocks, Moore hopes to build a chronogram — a type of phylogenetic tree with a time component that eventually traces back to when cyanobacteria evolved the ability to split water and produce oxygen.

    Moore also studies the process of fossilization, on Earth and potentially other planets. She is collaborating with researchers at NASA’s Jet Propulsion Laboratory to help them prepare for the upcoming Mars 2020 rover mission.

    “We’re trying to analyze fossils on Earth to get an idea for how we’re going to look at whatever samples get brought back from Mars, and then to also understand how we can learn from other planets and potentially other life,” Moore says.

    After MIT, Moore hopes to continue research, pursue postdoctoral fellowships, and eventually teach.

    “I really love research. So why stop? I’m going to keep going,” Moore says. She says she wants to teach in an institution that emphasizes giving research opportunities to undergraduate students.

    “Undergrads can be overlooked, but they’re really intelligent people and they’re budding scientists,” Moore says. “So being able to foster that and to see them grow and trust that they are capable in doing research, I think, is my calling.”

    Geology up close

    To study ancient organisms and find fossils, Moore has traveled across the world, to Shark Bay in Australia, Death Valley in the United States, and Bermuda.

    “In order to understand the rocks, you really have to get your nose on the rocks. Go and look at them, and be there. You have to go and stand in the tidal pools and see what’s happening — watch the air bubbles from the cyanobacteria and see them make oxygen,” Moore says. “Those kinds of things are really important in order to understand and fully wrap your brain around how important those interactions are.”

    And in the field, Moore says, researchers have to “roll with the punches.”

    “You don’t have a nice, beautiful, pristine lab set up with all the tools and equipment that you need. You just can’t account for everything,” Moore says. “You have to do what you can with the tools that you have.”

    Mentorship

    As a Graduate Resident Tutor, Moore helps to create supporting living environments for the undergraduate residents of Simmons Hall.

    Each week, she hosts a study break in her apartment in Simmons for her cohort of students — complete with freshly baked treats. “[Baking] is really relaxing for me,” Moore says. “It’s therapeutic.”

    “I think part of the reason I love baking so much is that it’s my creative outlet,” she says. “I know that a lot of people describe baking as like chemistry. But I think you have the opportunity to be more creative and have more fun with it. The creative side of it is something that I love, that I crave outside of research.”

    Part of Moore’s determination to research, trek out in the field, and mentor undergraduates draws from her “biggest science inspiration” — her mother, Michele Moore, a physics professor at Spokane Falls Community College in Spokane, Washington.

    “She was a stay-at-home mom my entire childhood. And then when I was in middle school, she decided to go and get a college degree,” Moore says. When Moore started high school, her mother earned her bachelor’s degree in physics. Then, when Moore started college, her mother earned her PhD. “She was sort of one step ahead of me all the time, and she was a big inspiration for me and gave me the confidence to be a woman in science.”

    See the full article here .


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    Please help promote STEM in your local schools.


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    The mission of MIT is to advance knowledge and educate students in science, technology, and other areas of scholarship that will best serve the nation and the world in the twenty-first century. We seek to develop in each member of the MIT community the ability and passion to work wisely, creatively, and effectively for the betterment of humankind.

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  • richardmitnick 10:30 am on August 12, 2018 Permalink | Reply
    Tags: A billion-year-old lake could help find alien life, Cyanobacteria, , , , Oxygenization   

    From METI and McGill via Futurity: “A billion-year-old lake could help find alien life” 

    1

    METI (Messaging Extraterrestrial Intelligence) International has announced plans to start sending signals into space

    McGill University

    McGill University

    From METI International and McGill University

    via

    1

    Futurity

    July 18th, 2018 [Just appeared in social media.]
    Justin Dupuis-McGill

    1
    Credit: Getty Images

    A sample of ancient oxygen from a 1.4 billion-year-old evaporative lake deposit in Ontario provides fresh evidence of what the Earth’s atmosphere and biosphere were like leading up to the emergence of animal life, according to new research.

    The findings, which appear in the journal Nature, represent the oldest measurement of atmospheric oxygen isotopes by nearly a billion years. The results support previous research suggesting that oxygen levels in the air during this time in Earth history were a tiny fraction of what they are today due to a much less productive biosphere.

    “It has been suggested for many decades now that the composition of the atmosphere has significantly varied through time,” says Peter Crockford, a postdoctoral researcher at Princeton University and Israel’s Weizmann Institute of Science who led the study as a PhD student at McGill University. “We provide unambiguous evidence that it was indeed much different 1.4 billion years ago.”

    2
    An image of the history of life and atmospheric oxygen on Earth over its 4.6 billion year history. The magnifying glass shows a picture of cyanobacteria that would have dominated life on Earth across much of the Proterozoic beginning around 2.4 billion years ago. On the far right is an image of the Earth that highlights vegetation on the continents and cholorphyll concentrations in the ocean. What the new study shows is that these colors would have been much less vibrant in Earth’s deep past due to a smaller biosphere. (Credit: McGill)

    The study provides the oldest gauge yet of what earth scientists refer to as “primary production,” in which micro-organisms at the base of the food chain—algae, cyanobacteria, and the like—produce organic matter from carbon dioxide and pour oxygen into the air.

    An image of Cyanobacteria, Tolypothrix

    Our planet, 1.4 billion years ago

    “This study shows that primary production 1.4 billion years ago was much less than today,” says senior coauthor Boswell Wing, an associate professor of geological sciences at the University of Colorado at Boulder who helped supervise Crockford’s work at McGill.

    “This means that the size of the global biosphere had to be smaller, and likely just didn’t yield enough food—organic carbon—to support a lot of complex macroscopic life,” says Wing.

    To come up with these findings, Crockford teamed up with colleagues who had collected pristine samples of ancient salts, known as sulfates, found in a sedimentary rock formation north of Lake Superior.

    The work also sheds new light on a stretch of Earth’s history known as the “boring billion” because it yielded little apparent biological or environmental change.

    “Subdued primary productivity during the mid-Proterozoic era—roughly 2 billion to 800 million years ago—has long been implied, but no hard data had been generated to lend strong support to this idea,” notes study coauthor Galen Halverson, an associate professor of earth and planetary sciences.

    “That left open the possibility that there was another explanation for why the middle Proterozoic ocean was so uninteresting, in terms of the production and deposit of organic carbon.” Crockford’s data “provide the direct evidence that this boring carbon cycle was due to low primary productivity.”

    Beyond Earth

    The findings could also help inform astronomers’ search for life outside our own solar system.

    “For most of Earth history our planet was populated with microbes, and projecting into the future they will likely be the stewards of the planet long after we are gone,” says Crockford.

    “Understanding the environments they shape not only informs us of our own past and how we got here, but also provides clues to what we might find if we discover an inhabited exoplanet,” he says.

    Researchers from Rice University; Yale University; the University of California, Riverside; Lakehead University in Thunder Bay, Ontario; and Louisiana State University also contributed to the work.

    Funding from the Natural Sciences and Engineering Research Council of Canada, the Fonds de recherche du Québec—Nature et Technologies, and the University of Colorado Boulder supported the research.

    Article part from McGill

    Billion-year-old lake deposit yields clues to Earth’s ancient biosphere

    18 July 2018

    Contact Information

    Peter Crockford
    peter.crockford@weizmann.ac.il

    Secondary Contact Information

    Justin Dupuis
    Media Relations Office
    justin.dupuis@mcgill.ca
    Office Phone:
    514-398-6751

    3
    No caption or credit.

    A sample of ancient oxygen, teased out of a 1.4 billion-year-old evaporative lake deposit in Ontario, provides fresh evidence of what the Earth’s atmosphere and biosphere were like during the interval leading up to the emergence of animal life.

    The findings, published in the journal Nature [link is above] , represent the oldest measurement of atmospheric oxygen isotopes by nearly a billion years. The results support previous research suggesting that oxygen levels in the air during this time in Earth history were a tiny fraction of what they are today due to a much less productive biosphere.

    “It has been suggested for many decades now that the composition of the atmosphere has significantly varied through time,” says Peter Crockford, who led the study as a PhD student at McGill University. “We provide unambiguous evidence that it was indeed much different 1.4 billion years ago.”

    The study provides the oldest gauge yet of what earth scientists refer to as “primary production,” in which micro-organisms at the base of the food chain – algae, cyanobacteria, and the like – produce organic matter from carbon dioxide and pour oxygen into the air.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    The primary objectives and purposes of METI International are to:

    Conduct scientific research and educational programs in Messaging Extraterrestrial Intelligence (METI) and the Search for Extraterrestrial Intelligence (SETI).

    Promote international cooperation and collaboration in METI, SETI, and astrobiology.

    Understand and communicate the societal implications and relevance of searching for life beyond Earth, even before detection of extraterrestrial life.

    Foster multidisciplinary research on the design and transmission of interstellar messages, building a global community of scholars from the natural sciences, social sciences, humanities, and arts.

    Research and communicate to the public the many factors that influence the origins, evolution, distribution, and future of life in the universe, with a special emphasis on the last three terms of the Drake Equation: (1) the fraction of life-bearing worlds on which intelligence evolves, (2) the fraction of intelligence-bearing worlds with civilizations having the capacity and motivation for interstellar communication, and (3) the longevity of such civilizations.

    Offer programs to the public and to the scholarly community that foster increased awareness of the challenges facing our civilization’s longevity, while encouraging individual and community activities that support the sustainability of human culture on multigenerational timescales, which is essential for long-term METI and SETI research.

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

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

    Astrobiology Magazine

    Astrobiology Magazine

    Mar 7, 2018
    https://www.elsevier.com

    1
    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.

    2
    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, Cyanobacteria, Eukaryotes, ,   

    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.

    1
    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.

    2
    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: , , , , Cyanobacteria, , Microbial Communities Thrive by Transferring Electrons, , Syntrophic anaerobic photosynthesis   

    From EMSL: “Microbial Communities Thrive by Transferring Electrons” 

    EMSL

    EMSL

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

    Alice Dohnalkova
    EMSL
    Alice.Dohnalkova@pnnl.gov

    1
    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.

    Summary

    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.

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    Quanta scanning electron microscope

    3
    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 10:09 am on May 22, 2017 Permalink | Reply
    Tags: , , , , Cyanobacteria, Getting Real About the Oxygen Biosignature,   

    From Many Worlds: “Getting Real About the Oxygen Biosignature” 

    NASA NExSS bloc

    NASA NExSS

    Many Words icon

    Many Worlds

    2017-05-22
    Marc Kaufman

    1
    Oxygen, which makes up about 21 percent of the Earth atmosphere, has been embraced as the best biosignature for life on faraway exoplanets. New research shows that detecting distant life via the oxygen biosignature is not so straight-forward, though it probably remains the best show we have. (NASA)

    I remember the first time I heard about the atmospheres of distant exoplanets and how could and would let us know whether life was present below.

    The key was oxygen or its light-modified form, ozone. Because both oxygen and ozone molecules bond so quickly with other molecules — think rust or iron oxide on Mars, silicon dioxide in the Earth’s crust — it was said that oxygen could only be present in large and detectable quantities if there was a steady and massive source of free oxygen on the planet.

    On Earth, this of course is the work of photosynthesizers such as planets, algae and cyanobacteria, which produce oxygen as a byproduct.

    2
    An image of Cyanobacteria, Tolypothrix.
    Date 22 January 2013
    Author Matthewjparker

    No other abiotic, or non-biological, ways were known at the time to produce substantial amounts of atmospheric oxygen, so it seemed that an oxygen signal from afar would be a pretty sure sign of life.

    But with the fast growth of the field of exoplanet atmospheres and the very real possibility of having technology available in the years ahead that could measure the components of those atmospheres, scientists have been busy modelling exoplanet formations, chemistry and their atmospheres.

    One important goal has been to search for non-biological ways to produce large enough amounts of atmospheric oxygen that might fool us into thinking that life has been found below.

    And in recent years, scientists have succeeded in poking holes in the atmospheric oxygen-means-life scenario.

    3
    Oxygen bonds quickly with many other molecules. That means has to be resupplied regularly to be present as O2 in an atmosphere . On Earth, O2 is mostly a product of biology, but elsewhere it might be result of non-biological processes. Here is an image of oxygen bubbles in water.

    Especially researchers at the University of Washington’s Virtual Planetary Laboratory (VPL) have come up with numerous ways that exoplanets atmospheres can be filled (and constantly refilled) with oxygen that was never part of plant or algal or bacteria photo-chemistry.

    In other words, they found potential false positives for atmospheric oxygen as a biosignature, to the dismay of many exoplanet scientists.

    In part because she and her own team were involved in some of these oxygen false-positive papers, VPL director Victoria Meadows set out to review, analyze and come to some conclusions about what had become the oxygen-biosignature problem.

    The lengthy paper (originally planned for 6 pages but ultimately 34 pages because research from so many disciplines was coming in) was published last month in the journal Astrobiology. It seeks to both warn researchers about the possibilities of biosignature false-positives based on oxygen detection, and then it assures them that there are ways around the obstacles.

    “There was this view in the community that oxygen could only be formed by photosynthesis, and that no other process could make O2,” Meadows told me. “It was a little simplistic. We now see the rich complexity of what we are looking at, and are thinking about the evolutionary paths of these planets.

    4
    Artist’s impression of the exoplanet GJ 1132 b, which orbits the red dwarf star GJ 1132. Earlier this year, astronomers managed to detect the atmosphere of this Earth-sized planet and have determined that water and methane are likely prevalent in the atmosphere. (Max Planck Institute for Astronomy)

    “What I see is a maturing of the field. We have models that show plausible ways for oxygen to be produced without biology, but that doesn’t mean that oxygen is no longer an important biosignature.

    “It is very important. But it has to be seen and understood in the larger context of what else is happening on the planet and its host star.”

    Before moving forward, perhaps we should look back a bit at the history of oxygen on Earth.

    For substantial parts of our planet’s history there was only minimal oxygen in the atmosphere, and life survived in an anaerobic environment. When exactly oxygen went from a small percentage of the atmosphere to 21 percent of the atmosphere is contested, but there is broader agreement about the source of the O2 in the atmosphere. The source was photosynthesis, most importantly coming from cyanobacteria in the oceans.

    As far back as four billion years ago, photosynthesis occurred on Earth based on the capturing of the energy of near infrared light by sulfur-rich organisms, but it did not involve the release of oxygen as a byproduct.

    5
    A chart showing the percentage rise in oxygen in Earth’s atmosphere over the past 3.8 billion years. The great oxidation event occurred some 2.3 billion years ago, but it took more than a billion additional years for the build-up to have much effect on the composition of the planet’s atmosphere.

    Then came the the rise of cyanobacteria in the ocean and their production of oxygen. With their significantly expanded ability to use photosynthesis, this bacterium was able to generate up to 16 times more energy than its counterparts, which allowed it to out-compete and explode in reproduction.

    It took hundreds of millions of years more, but that steady increase in the cyanobacteria population led to what is called the “Great Oxidation Event” of some 2.3 billion years ago, when oxygen levels began to really climb in Earth’s atmosphere. They did level off and remained well below current levels for another billion years, but then shot up in the past billion years.

    As Meadows (and others) point out, this means that life existed on Earth for at least two billion years years without producing a detectable oxygen biosignature. It’s perhaps the ultimate false negative.

    But as biosignatures go, oxygen offers a lot. Because it bonds so readily with other elements and compounds, it remains unbonded or “free” O2 only if it is being constantly produced. On Earth, the mode of production is overwhelmingly photosynthesis and biology. What’s more, phototrophs — organism that manufacture their own food from inorganic substances using light for energy — often produce reflections and seasonally dependent biosignatures that can serve as secondary confirmations of biology as the source for abundant O2 in an atmosphere.

    So in a general way, it makes perfect sense to think that O2 in the atmosphere of an exoplanet would signify the presence of photosynthesis and life.

    The problem arises because other worlds out there orbiting stars very different than our own can have quite different chemical and physical dynamics and evolutionary histories, with results at odds with our world.

    For instance, when it comes to the non-biological production of substantial amounts of oxygen that could collect in the atmosphere, the dynamics involved could include the following:

    Perhaps the trickiest false positive involves the possible non-biological release of O2 via the photolysis of water — the breaking apart of H2O molecules by light. On Earth, the water vapor in the atmosphere condenses into liquids after reaching a certain height and related temperature, and ultimately falls back down to the surface. How and why that happens is related to the presence of large amounts of nitrogen in our atmosphere.

    But what if an exoplanet atmosphere doesn’t have a lot of an element like nitrogen that allows the water to condense? Then the water would rise into the stratosphere, where it would be subject to intense UV light,. The molecule would be split, and an H atom would fly off into space — leaving behind large amounts of oxygen that had nothing to do with life. This conclusion was reached by Robin Wordsworth and Raymond Pierrehumbert of the University of Chicago and was published by the The Astrophysical Journal.

    Another recently proposed mechanism to generate high levels of abiotic oxygen, first described by Rodrigo Luger and Rory Barnes of Meadow’s VPL team, focuses on the effects of the super-luminous phase of young stars on any rocky planets that might be orbiting them.

    Small-mass M dwarfs in particular can burn much brighter when they are young, exposing potential planets around those stars to very high levels of radiation for as long as one billion years.

    Modeling suggests that during this super-luminous phase a terrestrial planet that forms within what will become the main sequence habitable zone around an M dwarf star may lose up to several Earth ocean equivalents of water due to evaporation and hydrodynamic escape, and this can lead to generation of large amounts of abiotic O2 via the same H2O photolysis process.

    Non-biological oxygen can also build up on an exoplanet, according to a number of researchers, if the host star sends out a higher proportion of far ultraviolet light than near ultraviolet. The dynamics of photo-chemistry are such, they argue, that the excess far ultraviolet radiation would split CO2 to an extent that O2 would build up in the atmosphere.

    There are other potential scenarios that would produce an oxygen false positive, and almost all of them involve radiation from the host star driving chemistry in the planet’s atmosphere, with the planetary environment then allowing O2 to build up. While some of these false positive mechanisms can produce enough oxygen to make a big impact on their planets, some may not produce enough to even be seen by telescopes currently being planned.

    As Meadows tells it, it was Shawn Domagal-Goldman of NASA Goddard and VPL who first brought the issue of oxygen false-positives to her attention. It was back in 2010 after he found an anomaly in his photo-chemical code results regarding atmospheric oxygen and exoplanets, and followed it. Since that initial finding, several other VPL researchers discovered new ways to produce O2 without life, and often while undertaking research focused on a different scientific goal.

    Six years later, when she was writing up a VPL annual report, it jumped out that the group (and others) had found quite a few potential oxygen false positives — a significant development in the field of biosignature detection and interpretation. That’s when she decided that an analysis and summary of the findings would be useful and important for the exoplanet community. “Never let it be said that administrative tasks can’t lead to inspiration!” she wrote to me.

    While Meadows does not downplay the new challenges to defining oxygen and ozone as credible biosignatures, she does say that these new understandings can be worked around.

    Some of that involves targeting planets and stars for observation that don’t have the characteristics known to produce abiotic oxygen. Some involves finding signatures of this abiotic oxygen that can be identified and then used to discard potential false positives. And perhaps most telling, the detection of methane alongside free oxygen in an exoplanet atmosphere would be considered a powerful signature of life.

    The official goal of Meadows’ VPL is to wrestle with this question: “How would we determine if an extrasolar planet were able to support life or had life on it already?”

    This has led her to a highly interdisciplinary approach, bringing together fifty researchers from twenty institutions. In addition to its leading role in the NASA Astrobiology Institute, the VPL is also part of a broad NASA initiative to bring together scientists from different locales and disciplines to work on issues and problems of exoplanet research — the Nexus for Exoplanet System Science, or NExSS.

    Given this background and these approaches, it is hardly surprising that Meadows would be among the first to see the oxygen-false positive issue in both scientific and collective terms.

    “I wanted the community to have some place to go to when thinking about O2 false positives,” she said. “We’re learning now about the complexity and richness of exoplanets, and this is essential for preparing to do the best job possible {in terms of looking for signs of life on exoplanets} when we get better and better observations to work with.”

    “This story needed to be told now. Forewarned is forearmed.”

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

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

    physdotorg
    phys.org

    August 5, 2016
    No writer credit found

    1
    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.

    1
    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 9:00 pm on May 16, 2016 Permalink | Reply
    Tags: , Cyanobacteria, , ,   

    From Rice: “Oxygen atmosphere recipe = tectonics + continents + life” 

    Rice U bloc

    Rice University

    Rice-led study offers new answer to why Earth’s atmosphere became oxygenated

    May 16, 2016
    Jade Boyd

    Earth scientists from Rice University, Yale University and the University of Tokyo are offering a new answer to the long-standing question of how our planet acquired its oxygenated atmosphere.

    Based on a new model that draws from research in diverse fields including petrology, geodynamics, volcanology and geochemistry, the team’s findings* were published online this week in Nature Geoscience. They suggest that the rise of oxygen in Earth’s atmosphere was an inevitable consequence of the formation of continents in the presence of life and plate tectonics.

    “It’s really a very simple idea, but fully understanding it requires a good bit of background about how the Earth works,” said study lead author Cin-Ty Lee, professor of Earth science at Rice. “The analogy I most often use is the leaky bathtub. The level of water in a bathtub is controlled by the rate of water flowing in through the faucet and the efficiency by which water leaks out through the drain. Plants and certain types of bacteria produce oxygen as a byproduct of photosynthesis. This oxygen production is balanced by the sink: reaction of oxygen with iron and sulfur in the Earth’s crust and by back-reaction with organic carbon. For example, we breathe in oxygen and exhale carbon dioxide, essentially removing oxygen from the atmosphere. In short, the story of oxygen in our atmosphere comes down to understanding the sources and sinks, but the 3-billion-year narrative of how this actually unfolded is more complex.”

    Lee co-authored the study with Laurence Yeung and Adrian Lenardic, both of Rice, and with Yale’s Ryan McKenzie and the University of Tokyo’s Yusuke Yokoyama. The authors’ explanations are based on a new model that suggests how atmospheric oxygen was added to Earth’s atmosphere at two key times: one about 2 billion years ago and another about 600 million years ago.

    Today, some 20 percent of Earth’s atmosphere is free molecular oxygen, or O2. Free oxygen is not bound to another element, as are the oxygen atoms in other atmospheric gases like carbon dioxide and sulfur dioxide. For much of Earth’s 4.5-billion-year history, free oxygen was all but nonexistent in the atmosphere.

    “It was not missing because it is rare,” Lee said. “Oxygen is actually one of the most abundant elements on rocky planets like Mars, Venus and Earth. However, it is one of the most chemically reactive elements. It forms strong chemical bonds with many other elements, and as a result, it tends to remain locked away in oxides that are forever entombed in the bowels of the planet — in the form of rocks. In this sense, Earth is no exception to the other planets; almost all of Earth’s oxygen still remains locked away in its deep rocky interior.”

    Lee and colleagues showed that around 2.5 billion years ago, the composition of Earth’s continental crust changed fundamentally. Lee said the period, which coincided with the first rise in atmospheric oxygen, was also marked by the appearance of abundant mineral grains known as zircons.

    “The presence of zircons is telling,” he said. “Zircons crystallize out of molten rocks with special compositions, and their appearance signifies a profound change from silica-poor to silica-rich volcanism. The relevance to atmospheric composition is that silica-rich rocks have far less iron and sulfur than silica-poor rocks, and iron and sulfur react with oxygen and form a sink for oxygen.

    1
    A view of Earth’s atmosphere taken from the International Space Station in 2003. (Photo courtesy of ISS Expedition 7 Crew, EOL, NASA)

    “Based on this, we believe the first rise in oxygen may have been due to a substantial reduction in the efficiency of the oxygen sink,” Lee said. “In the bathtub analogy, this is equivalent to partially plugging the drain.”

    Lee said the study suggests that the second rise in atmospheric oxygen was related to a change in production — analogous to turning up the flow from the faucet.

    “The bathtub analogy is simple and elegant, but there’s an added complication that must be taken into account,” he said. “That is because oxygen production is ultimately tied to the global carbon cycle — the cycling of carbon between the Earth, the biosphere, the atmosphere and oceans.”

    Lee said the model showed that Earth’s carbon cycle has never been at a steady state because carbon slowly leaks out as carbon dioxide from Earth’s deep interior to the surface through volcanic activity. Carbon dioxide is one of the key ingredients for photosynthesis.

    “On long, geologic timescales, carbon is removed from the atmosphere by the production of condensed forms of carbon, such as organic carbon and minerals called carbonate,” he said. “For most of Earth’s history, most of this carbon has been deposited not in the deep ocean but rather on the margins of continents. The implications are profound because carbon deposited on continents does not return to Earth’s deep interior. Instead, it amplifies carbon inputs into the atmosphere when the continents are subsequently perturbed by volcanism.”

    Lee said the team’s model showed that volcanic activity and other geologic inputs of carbon into the atmosphere may have increased with time, and because oxygen production is tied to carbon production, oxygen production also must increase. The model showed that the second rise in atmospheric oxygen had to occur late in Earth’s history.

    “Exactly when is model-dependent, but what is clear is that the formation of continental crust naturally leads to two rises in atmospheric oxygen, just as we see in the fossil record,” Lee said.

    Exactly what caused the composition of the crust to change during the first oxygenation event remains a mystery, but Lee said the team believes it may have been related to the onset of plate tectonics, where the Earth’s surface, for the first time, became mobile enough to sink back down into Earth’s deep interior.

    The tectonic plates of the world were mapped in 1996, USGS.
    The tectonic plates of the world were mapped in 1996, USGS.

    Lee said the team’s new model is not without controversy. For example, the model predicts that production of carbon dioxide must increase with time, a finding that goes against the conventional wisdom that carbon fluxes and atmospheric carbon dioxide levels have steadily decreased over the last 4 billion years.

    “The change in flux described by our model happens over extremely long time periods, and it would be a mistake to think that these processes that are bringing about any of the atmospheric changes are occurring due to anthropomorphic climate change,” he said. “However, our work does suggest that Earth scientists and astrobiologists may need to revisit what we think we know about Earth’s early history.”

    This work is the result of an ongoing study of the global carbon cycle funded by the National Science Foundation and administered by Rice University.

    [Note mentioned in this article, the activity of cyanobacteria which were the creatures which released the oxygen we breathe.]

    *Science paper:
    Two-step rise of atmospheric oxygen linked to the growth of continents

    See the full article here .

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    Rice U campus

    In his 1912 inaugural address, Rice University president Edgar Odell Lovett set forth an ambitious vision for a great research university in Houston, Texas; one dedicated to excellence across the range of human endeavor. With this bold beginning in mind, and with Rice’s centennial approaching, it is time to ask again what we aspire to in a dynamic and shrinking world in which education and the production of knowledge will play an even greater role. What shall our vision be for Rice as we prepare for its second century, and how ought we to advance over the next decade?

    This was the fundamental question posed in the Call to Conversation, a document released to the Rice community in summer 2005. The Call to Conversation asked us to reexamine many aspects of our enterprise, from our fundamental mission and aspirations to the manner in which we define and achieve excellence. It identified the pressures of a constantly changing and increasingly competitive landscape; it asked us to assess honestly Rice’s comparative strengths and weaknesses; and it called on us to define strategic priorities for the future, an effort that will be a focus of the next phase of this process.

     
  • richardmitnick 4:39 pm on December 29, 2014 Permalink | Reply
    Tags: , , Cyanobacteria,   

    From PNNL Lab: “The Quality of Light” 

    PNNL BLOC

    PNNL Lab

    December 2014

    Optimizing production rates of cyanobacteria that have a “bright” future in biofuel synthesis

    Results: Rapidly growing bacteria that live in the ocean and can manufacture their own food hold promise as host organisms for producing chemicals, biofuels, and medicine. Researchers at Pacific Northwest National Laboratory (PNNL) and The Pennsylvania State University are closely studying one of these photosynthetic species of fast-growing cyanobacteria using advanced tools developed at PNNL to determine the optimum environment that contributes to record growth and productivity. Their work on how the cyanobacteria respond to different wavelengths of light, as critical resources, recently was featured in Frontiers in Microbiology.

    c
    PNNL and The Pennsylvania State University are studying Synechococcus, a promising cyanobacterium (the yellow-orange cells) that could be used to determine optimum growing conditions for biofuels.
    No image credit

    Why It Matters: Using biofuels based on cyanobacteria on an industrial scale could lower pollution levels from fossil fuels, provide a sustainable source of energy, and curb energy dependence. The challenge has been to find the right organism that can be cost-effectively grown quickly enough to meet industrial demand. The strain of cyanobacteria researchers studied, Synechococcus sp. PCC 7002, grows at rates that rank among the fastest reported for photosynthetic microorganisms. With a better understanding of how the cyanobacterium adapts to changing environmental conditions, researchers are able to optimize growth and productivity.

    2
    Scientists at PNNL compare culturing conditions in samples generated from a novel cultivation approach: binary cultivation in photobioreactors. The approach uses binary cultivation inside photobioreactors to facilitate growth by creating a closed system where the metabolic by-products of one organism are used to fuel metabolism in the other.

    “Understanding the fundamental underpinnings that determine growth rates of cyanobacteria provides an insight into the biological blueprint of photosynthetic organisms,” said PNNL’s Dr. Alex Beliaev, the lead scientist on the project.

    Dr. Hans Bernstein, a Linus Pauling Postdoctoral Fellow at PNNL who helped lead the study, added, “A deeper understanding of the basic biology for this organism is helping us develop solutions for efficient renewable energy production and will ultimately help us develop novel technologies based on microbial communities.”

    See the full article here.

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    Pacific Northwest National Laboratory (PNNL) is one of the United States Department of Energy National Laboratories, managed by the Department of Energy’s Office of Science. The main campus of the laboratory is in Richland, Washington.

    PNNL scientists conduct basic and applied research and development to strengthen U.S. scientific foundations for fundamental research and innovation; prevent and counter acts of terrorism through applied research in information analysis, cyber security, and the nonproliferation of weapons of mass destruction; increase the U.S. energy capacity and reduce dependence on imported oil; and reduce the effects of human activity on the environment. PNNL has been operated by Battelle Memorial Institute since 1965.

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