Researchers decode genetics of rare photosynthetic bacteriumFebruary 11, 2008TEMPE, Ariz. - A bacterium that harvests far-red light by making a rare form of chlorophyll (chlorophyll d) has revealed its genetic secrets, according to a team of researchers who recently sequenced the bacteria's genome. The researchers, from Arizona State University and Washington University, St. Louis, report in the current online edition (Feb. 4) of the Proceedings of the National Academy of Sciences, that they have sequenced the genome of the cyanobacterium, Acaryochloris marina, which through its production of chlorophyll d can absorb "red edge," near infrared long wavelength light -- light that is invisible to the naked eye. Acaryochloris marina has a massive genome (8.3 million base pairs) and is among the largest of 55 cyanobacterial strains in the world. It is the first chlorophyll-d containing organism to be sequenced. The advance has applications in plant research, said Jeffrey Touchman, an assistant professor ASU's School of Life Sciences and lead author of the paper, "Niche adaptation and genome expansion in the chlorophyll d-producing cyanobacterium Acaryochloris marina."
"Chlorophyll d harvests light from a spectrum of light that few other organisms can, and that enables this organism to carve out its own special niche in the environment to pick up far-red light," Touchman explained. "The agricultural implications could be significant. One could imagine the transfer of this biochemical mechanism to other plants where they could then use a wider range of the light spectrum and become sort of 'plant powerhouses,' deriving increased energy by employing this new photosynthetic pigment." There is a bioenergy link to this work, said Touchman, who is a member of ASU's Center for Bioenergy and Photosynthesis. It could be used for crops that are turned into fuels or to generate biomass. Touchman worked with Robert Blankenship of Washington University on the sequencing project, which involved collaborators from Australia and Japan. Touchman also has an appointment with Translational Genomics Research Institute (TGen), Scottsdale, Ariz., where he operates a high-throughput DNA sequencing facility. The work is supported by the National Science Foundation. Blankenship said with every gene of Acaryochloris marina now sequenced and annotated, the immediate goal is to find the enzyme that causes a chemical structure change in chlorophyll d, making it different from the more common chlorophyll a, and b, but also from about nine other forms of chlorophyll. "The synthesis of chlorophyll by an organism is complex, involving 17 different steps in all," Blankenship said. "Someplace near the end of this process, an enzyme transforms a vinyl group to a formyl group to make chlorophyll d. This transformation of chemical forms is not known in any other chlorophyll molecules." Touchman and Blankenship said they have some candidate genes they will test. They plan to insert these genes into an organism that only makes chlorophyll a. If the organism learns to synthesize chlorophyll d with one of the genes, the mystery of chlorophyll d synthesis will be solved, and then the excitement will begin. The researchers said harvesting solar power through plants or other organisms that would be genetically altered with the chlorophyll d gene could make them "solar power factories" that generate and store solar energy. Consider a seven-foot tall corn plant genetically tailored with the chlorophyll d gene to be expressed at the very base of the stalk. While the rest of the plant synthesized chlorophyll a, absorbing short wave light, the base is absorbing "red edge" light in the 710 nanometer range. Energy could be stored in the base without competing with any other part of the plant for photosynthesis, as the rest only makes chlorophyll a. Also, the altered corn using the chlorophyll d gene could become a super plant because of its enhanced ability to harness energy from the Sun. That model is similar to how Acaryochloris marina actually operates in the South Pacific, specifically Australia's Great Barrier Reef. Discovered just 11 years ago, the cyanobacterium lives in a symbiotic relationship with a sponge-like marine animal popularly called a sea squirt. The Acaryochloris marina lives beneath the sea squirt, which is a marine animal that lives attached to rocks just below the surface of the water. The cyanobacterium absorbs "red edge" light through the tissues of the sea squirt. The genome, said Blankenship, is "fat and happy. Acaryochloris marina lies down there using far red light that no one else can use. The organism has never been under very strong selection pressure to maintain a modest genome size. It's in kind of a sweet spot. Living in this environment is what allowed it to have such dramatic genome expansion." Touchman said that once the gene that causes the late-step chemical transformation is found and inserted successfully into other plants or organisms, that it could potentially represent a five percent increase in available light for organisms to use. "We now have the complete genetic information of a novel organism that makes this type of pigment that no other organism does," he said. "We don't yet know what every gene does, but this presents a fertile area for future studies. When we find the chlorophyll-d enzyme and then look into transferring it into other organisms, we'll be working to extend the range of potentially useful radiation from our Sun." Arizona State University Science News and Science Current Events Tag Cloud This tag cloud is a visual representation of term frequencies of random science news topics with common terms grouped together and emphasized by their display size. Flavanols Nanospheres Pathogens Fat Flavonoids Neuroblastoma Anesthetics Puberty Cervical Cancer Hepatocellular Carcinoma Infection Beetle Osteoporosis Periodontal Disease Aggression Palliative Care Post-traumatic Stress Disorder Mental Retardation Diamond Human Evolution Incontinence Neurological Disease DNA Walking Elephants
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Related Chlorophyll Current Events and Chlorophyll News Articles First step to converting solar energy using 'artificial leaf' An international team of researchers has modified chlorophyll from an alga so that it resembles the extremely efficient light antennae of bacteria. Breakthrough made in assessing marine phytoplankton health Researchers from Oregon State University, NASA and other organizations said today that they have succeeded for the first time in measuring the physiology of marine phytoplankton through satellite measurements of its fluorescence - an accomplishment that had been elusive for years. NASA satellite detects red glow to map global ocean plant health Researchers have conducted the first global analysis of the health and productivity of ocean plants, as revealed by a unique signal detected by a NASA satellite. Scientists find black gold amidst overlooked data About half of the oil in the ocean bubbles up naturally from the seafloor, with Earth giving it up freely like it was of no value. Likewise, NASA satellites collect thousands of images and 1.5 terrabytes of data every year, but some of it gets passed over because no one thinks there is a use for it. Engineering algae to make fuel instead of sugar In pursuing cleaner energy there is such a thing as being too green. Unicellular microalgae, for instance, can be considered too green. Plants grow bigger and more vigorously through changes in their internal clocks Hybrid plants, like corn, grow bigger and better than their parents because many of their genes for photosynthesis and starch metabolism are more active during the day, report researchers from The University of Texas at Austin in a new study published in the journal Nature. U.Va. Engineers Aim to Solve 'Burning' Computer Problem f you've balanced a laptop computer on your lap lately, you probably noticed a burning sensation. That's because ever-increasing processing speeds are creating more and more heat, which has to go somewhere -- in this case, into your lap. Climate change causing significant shift in composition of coastal fish communities A detailed analysis of data from nearly 50 years of weekly fish-trawl surveys in Narragansett Bay and adjacent Rhode Island Sound has revealed a long-term shift in species composition, which scientists attribute primarily to the effects of global warming. Berkeley Researchers Identify Photosynthetic Dimmer Switch In a study of the molecular mechanisms by which plants protect themselves from oxidation damage should they absorb too much sunlight during photosynthesis, a team of researchers has discovered a molecular "dimmer switch" that helps control the flow of solar energy moving through the system of light harvesting proteins. ESA contributes to ocean carbon cycle research The Earth's oceans play a vital role in the carbon cycle, making it imperative that we understand marine biological activity enough to predict how our planet will react to the extra 25 000 million tonnes of carbon dioxide humans are pumping into the atmosphere annually. More Chlorophyll Current Events and Chlorophyll News Articles |
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