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Research Highlights and New Publications... |
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 Unlikely life thriving at Antarctica's Blood Falls
Anbar group analyzes samples...
An unmapped reservoir of briny liquid chemically similar to sea water, but hidden under an inland Antarctic glacier, appears to support microbial life in a cold, dark, oxygen-poor environment- a most unexpected setting to be teeming with life.
"A Contemporary Microbially Maintained Subglacial Ferrous "Ocean"", Jill A. Mikucki, Ann Pearson,David T. Johnston, Alexandra V. Turchyn, James Farquhar, Daniel P. Schrag, Ariel D. Anbar, John C. Priscu, Peter A. Lee, Science 17 April 2009: Vol. 324. no. 5925, pp. 397 - 400 DOI: 10.1126/science.1167350
 Link to the Abstract
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 Scanning tunneling microscopy (STM) helps with DNA sequencing...Stuart Lindsay, Otto Sankey and colleagues have recently published in Nature Nanotechnology...
Hydrogen bonding has a ubiquitous role in electron transport and in molecular recognition, with DNA base pairing being the best-known example. Scanning tunnelling microscope images and measurements of the decay of tunnel current as a molecular junction is pulled apart by the scanning tunnelling microscope tip are sensitive to hydrogen-bonded interactions. Here, Lindsay and coworkers show that these tunnel-decay signals can be used to measure the strength of hydrogen bonding in DNA base pairs. Junctions that are held together by three hydrogen bonds per base pair (for example, guanine-cytosine interactions) are stiffer than junctions held together by two hydrogen bonds per base pair (for example, adenine-thymine interactions). Similar, but less pronounced effects are observed on the approach of the tunnelling probe, implying that attractive forces that depend on hydrogen bonds also have a role in determining the rise of current. These effects provide new mechanisms for making sensors that transduce a molecular recognition event into an electronic signal.
"Tunnelling readout of hydrogen-bonding-based recognition", Shuai Chang, Jin He, Ashley Kibel, Myeong Lee, Otto Sankey, Peiming Zhang& Stuart Lindsay, Nature Nanotechnology. Published online: 22 March 2009 | doi:10.1038/nnano.2009.48
 Link to the Abstract
Full story on biodesign website
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CREDIT: K. SUTLIFF/SCIENCE |
Allen and Williams' research highlighted in Science...
ORIGINS: On the Origin of Photosynthesis
Mitch Leslie
Science March 2009: Vol. 323. no. 5919, pp. 1286 - 1287
Where would we be without photosynthesis? In the third essay in Science's series in honor of the Year of Darwin, Mitch Leslie details researchers' efforts to piece together how and when organisms first began to harness light's energy.
An excerpt from the article follows...
Biochemists James Allen and JoAnn Williams of Arizona State University, Tempe, and colleagues are working out how a bacterial reaction center could have evolved photosystem II's appetite for electrons. Taking a hands-on approach, they have been tinkering with the reaction center of the purple bacterium Rhodobacter sphaeroides to determine if they can make it more like photosystem II. First they targeted bacterio- chlorophyll, the bacterial version of chlorophyll that's at the core of the reaction center, and altered the number of hydrogen bonds. Adding hydrogen bonds hiked the molecule's greed for electrons, they found. The water-cleaving portion of photosystem II sports four manganese atoms that become oxidized, or lose electrons. So the team equipped the bacterial reaction center with one atom of the metal. In this modified version, the added manganese also underwent oxidation, the researchers reported in 2005. James Allen says that their creations aren't powerful enough to split water. But eventually, they hope to engineer a reaction center that can oxidize less possessive molecules, such as hydrogen peroxide, that would have been present on the early Earth. Even if the researchers never replicate photosystem II, "if we define the intermediate stages, we've accomplished a lot," he says.
Link to the full article |
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 Gust, Moore and Moore publish in the Chem. Soc. Rev.'s 2009 Renewable Energy issue, reviewing the latest developments in renewable energy research
Biology and technology for photochemical fuel production Michael Hambourger, Gary F. Moore, David M. Kramer, Devens Gust, Ana L. Moore and Thomas A. Moore Sunlight is the ultimate energy source for the vast majority of life on Earth, and organisms have evolved elegant machinery for energy capture and utilization. Solar energy, whether converted to wind, rain, biomass or fossil fuels, is also the primary energy source for human-engineered energy transduction systems. This tutorial review draws parallels between biological and technological energy systems. Aspects of biology that might be advantageously incorporated into emerging technologies are highlighted, as well as ways in which technology might improve upon the principles found in biological systems. Emphasis is placed upon artificial photosynthesis, as well as the use of protonmotive force in biology.
"Biology and technology for photochemical fuel production", Michael Hambourger, Gary F. Moore, David M. Kramer, Devens Gust, Ana L. Moore and Thomas A. Moore, Chem. Soc. Rev., 2009, 38, 25 - 35, DOI: 10.1039/b800582f
Link to Abstract
"Engineered and Artificial Photosynthesis: Human Ingenuity Enters the Game", Devens Gust, David Kramer, Ana Moore , Thomas A. Moore, and Wim Vermaas , MRS BULLETIN, VOLUME 33 • APRIL 2008, p383.
Link to the full article |
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 Buseck and Adachi publish in a special issue of Elements on nanoparticles in the environment ...
The most continuous and intimate contact the average person has with nanoparticles is almost surely through the air, which is replete with them. Nanoparticles are being generated continuously and in large numbers by vehicles and industries in urban areas and by vegetation and sea spray in rural areas. Volcanoes are sporadic sources of huge numbers. Nanoparticles have large surface area to volume ratios and react rapidly in the atmosphere, commonly growing into particles large enough to interact with radiation and to have serious consequences for visibility and local, regional, and global climate. They also have potentially significant health effects.
The figure on the right shows nanoparticles from biomass burning. Also a photograph of a region of biomass burning, taken near Mexico City (top left). Gases emitted from the fires cooled rapidly and condensed or accumulated as nanoparticles. A low- magnification transmission electron micrograph is shown (bottom left) of biomass-burning particles collected from an airplane and deposited on a substrate of lacey carbon (fibers). This is enlarged to the right and shows nanoparticles trapped within a larger organic particle and therefore observable (red arrows). Other aerosol particles are indicated by white arrows. The compositions were determined using energy dispersive X-ray spectrometry. The sample was collected from aircraft during an international atmospheric campaign called MILAGRO, sponsored by NSF, NASA, DOE, and various other national and international agencies as part of a program to study emissions from tropical megacities. The photo was taken by Kouji Adachi.
"Nanoparticles in the atmosphere", P.R. Buseck and K. Adachi,Elements 4, 389-394, 2008. |
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| Byrne and Angell publish article on biomolecules "out of water"...
In a contribution currently in press Chemical Communications, Nolene Byrne and Austen Angell give another example how use of protic ionic liquid solvents for biomolecule studies can produce interesting phenomena. Although there is only one molecule of water for every two ions present in these solvents, the dissolved proteins behave in many cases as if they are in normal aqueous buffer - except that they seem to be more stable against aggregation. In the present communication these authors show that, also as in aqueous solutions, change of solution conditions to more acidic states can lead to fibril formation. These are the same sort of amyloid fibril that cause Parkinson's and Jacob Kreutz "folding" diseases. However, now, with the right choice of ionic liquids, the fibrils can be readily redissolved. The authors even show that in some cases, most of the original bioactivity can be restored.
"Formation and dissolution of hen egg white lysozyme amyloid fibrils in protic ionic liquids", Nolene Byrne and C. Austen Angell, Chem. Commun., 2009, 1046
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Movie showing the 3D architecture of nanotubes formed with 5 nm and 10 nm AuNPs (gold particles).
Play Video |
Hao Yan and Yan Liu's group publish in this week's Science on the self-assembly of DNA tubules...
DNA tubes are known to form through either self-association of multi-helix DNA bundle structures or closing up of 2D DNA tile lattices. By the attachment of single-stranded DNA to gold nanoparticles, nanotubes of various 3D architectures can form, ranging in shape from stacked rings to single spirals, double spirals, and nested spirals. The nanoparticles are active elements that control the preference for specific tube conformations through size-dependent steric repulsion effects. For example, one can control the tube assembly to favor stacked-ring structures using 10-nanometer gold nanoparticles. Electron tomography reveals a left-handed chirality in the spiral tubes, double-wall tube features, and conformational transitions between tubes.
The future of the nanotechnology field depends on our ability to reliably and reproducibly assemble nanoparticles into 3D structures we can use to develop new technologies. According to Hao Yan and Yan Liu at Arizona State University, the greatest challenges in this burgeoning field include control over nanoscale 3D structure and imaging these tiny materials.
"Control of Self-Assembly of DNA Tubules Through Integration of Gold Nanoparticles", Jaswinder Sharma, Rahul Chhabra, Anchi Cheng, Jonathan Brownell, Yan Liu, and Hao Yan Science 2 January 2009: 112-116.
Link to Abstract
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