8 items with the tag “oxygenic photosynthesis

  • Thermodynamic Efficiency of Electron-Transfer Reactions in the Chlorophyll D-Containing Cyanobacterium, Acharyochloris Marina
    NAI 2009 VPL at University of Washington Annual Report

    Photosynthesis is the only known process that produces planetary-scale biosignatures – atmospheric oxygen and the color of photosynthetic pigments — and it is expected to be successful on habitable extrasolar planets as well, due to the ubiquity of starlight as an energy source. How might photosynthetic pigments adapt to alternative environments? Could oxygenic photosynthesis occur at much longer wavelengths than the red? This project is approaching these questions by studying a recently discovered cyanobacterium, Acaryochloris marina, which performs oxygenic photosynthesis in environments depleted in visible light but enriched in far-red/near-infrared light. A. marina is the only known organism to have chlorophyll d (Chl d) to use photons in the far-red and near-infrared, whereas all other oxygenic photosynthetic organisms use chlorophyll a (Chl a) to utilize red photons. Whether A. marina is operating more efficiently or less than Chl a-utilizing organisms will indicate what wavelengths are the ultimate limit for oxygenic photosynthesis. We have been conducting lab measurements of energy storage in whole A. marina cells using pulsed, time-resolved photoacoustics (PTRPA, or PA), a laser technique that allows us to control the wavelength, amount, and timing of energy received by a sample of cells.

    ROADMAP OBJECTIVES: 3.2 4.2 5.1 5.3 6.2 7.2
  • Postdoctoral Fellow Report: Steven Mielke
    NAI 2009 VPL at University of Washington Annual Report

    This project seeks to resolve the long-wavelength limit of oxygenic photosynthesis in order to constrain the range of extrasolar environments in which spectral signatures of biogenic oxygen might be found, and thereby guide future planet detecting and characterizing observatories.

    ROADMAP OBJECTIVES: 5.1 6.1 6.2 7.2
  • Thermodynamic Efficiency of Electron-Transfer Reactions in the Chlorophyll D-Containing Cyanobacterium, Acharyochloris Marina
    NAI 2010 VPL at University of Washington Annual Report

    Photosynthesis produces planetary-scale biosignatures – atmospheric oxygen and the color of photosynthetic pigments. It is expected to be successful on habitable extrasolar planets as well, due to the ubiquity of starlight as an energy source. How might photosynthetic pigments adapt to alternative environments? Could oxygenic photosynthesis occur at much longer wavelengths than the red? This project is approaching these questions by using a laser technique to study the recently discovered cyanobacterium, Acaryochloris marina, which uses the chlorophyll d pigment to perform its photosynthesis at wavelengths longer than those used by the much more prevalent chlorophyll a. Whether A. marina is operating more efficiently or less than Chl a-utilizing organisms will indicate what wavelengths are the ultimate limit for oxygenic photosynthesis.

    ROADMAP OBJECTIVES: 3.2 4.2 5.1 5.3 6.2 7.2
  • Postdoctoral Fellow Report: Steven Mielke
    NAI 2010 VPL at University of Washington Annual Report

    This project seeks to resolve the long-wavelength limit of oxygenic photosynthesis in order to constrain the range of extrasolar environments in which spectral signatures of biogenic oxygen might be found, and thereby guide future planet detecting and characterizing observatories.

    ROADMAP OBJECTIVES: 5.1 6.1 6.2 7.2
  • Postdoctoral Fellow Report: Steven Mielke
    NAI 2011 VPL at University of Washington Annual Report

    This project seeks to resolve the long-wavelength limit of oxygenic photosynthesis in order to constrain the range of extrasolar environments in which spectral signatures of biogenic oxygen might be found, and thereby guide future planet detecting and characterizing observatories.

    ROADMAP OBJECTIVES: 5.1 6.1 6.2 7.2
  • The Long Wavelength Limit for Oxygenic Photosynthesis
    NAI 2011 VPL at University of Washington Annual Report

    Photosynthesis is process where plants and bacteria use solar energy to produce sugar and oxygen. It is also the only known process that produces signs of life (biosignatures) on a planetary scale. And, because starlight (or solar energy) is one of the most common sources of energy, it is expected that photosynthesis will be successful on habitable extrasolar planets. Our team is studying how photosynthetic pigments – the molecules that make photosynthesis possible – might function in unique or extreme environments on other planets. In our experiments, we use a bacteria called Acaryochloris marina to study how different photosynthetic pigments work. This bacterium is useful for our research because it uses a pigment known as chlorophyll d instead of chlorophyll a, which is more common on our planet. Chrolophyll a works well in Earth’s environment but, by studying chlorophyll d, we can begin to understand how photosynthesis might work on planets with different environments than Earth. So far, our research is revealing that photosynthesis can occur quite efficiently in environments that are very different from our planet.

    ROADMAP OBJECTIVES: 3.2 4.2 5.1 5.3 6.2 7.2
  • Unicellular Protists of the Neoproterozoic
    NAI 2012 Massachusetts Institute of Technology Annual Report

    We investigated 1) how microbial processes shape some sedimentary rocks, 2) how microbial processes influence the isotopic composition of sulfur-rich minerals that are used to understand the evolution of oxygen and the cycling of carbon in the past, 3) searched for fossils of organisms that lived between 716 and 635 million years ago, surviving times when ice covered entire oceans, even at the equator and 4) used these fossils, recovered from limestone rocks, to understand the cycling of carbon during this unusual time.

    ROADMAP OBJECTIVES: 4.1 4.2 5.1 6.1 7.1