SCIENCE & TECHNOLOGY CONCENTRATES
MOLYBDATE DIANION TRAPS CARBON DIOXIDE AND SPITS OUT FORMATE
STARRY ENVIRONMENT REDEFINED Astronomers have discovered a previously unknown chemical processing factory inside the workings of a newly forming star—a discovery that may change fundamental models of how stars and planetary systems are born (Nature 2014, DOI: 10.1038/nature13000). A team led by Nami Sakai of the University of Tokyo used the Atacama Large Millimeter/ submillimeter Array radio telescopes in Chile to study a nearby star-forming region. The system consists of a flat rotating envelope of gas that is being fed by a stream of gas from interstellar clouds, with a more concentrated rotating disk at the center. The scientists say they discovered a drastic chemical change at the boundary between the envelope and disk. In the larger envelope, they predominantly detected cyclic C3H2, but this compound abruptly diminishes and is suddenly replaced by SO in the disk. The researchers conclude that this An artist’s conception shows a transition results from the sudden change in swirling envelope of gas being environment as the gas hits the rapidly swirlfed by interstellar clouds. The ing disk: The kinetic energy of the gas is conchemical environment abruptly verted to rotational energy and, as a result, a changes at the barrier (blue), lot of heat. They suggest that two unrelated inside which a new star is being formed. processes may be occurring: The C3H2 is destroyed by reaction with O, while SO is ripped off dust grains and liberated as gas. In solar evolutionary models, astronomers had been presuming that an unchanging chemical composition of interstellar clouds served as the starting conditions for forming stars.—EKW NAMI SAKAI
Inexpensive reduction of carbon dioxide to useful chemical reagents would help put a dent in solving Earth’s overabundance problem with the greenhouse gas. Inorganic chemists have turned to the task of designing catalysts for the job, but most of these systems so far involve complex ligands that are costly to synthesize. Taking a simple approach, Ioana Knopf and Christopher C. Cummins of Massachusetts Institute of Technology and their colleagues have identified a soluble molybdate system unencumbered by organic ligands for easy reduction of CO2 (Chem. Sci. 2014, DOI: 10.1039/c4sc00132j). The team found that [MoO4]2– readily binds CO2 at room temperature to irreversibly form a monocarbonate complex. With excess CO2 the complex forms a dicarbonate species, which is the first structurally characterized transition-metal dicarbonate derived from CO2. The researchers also found that the monocarbonate reacts with triethylsilane to produce formate, HCO2–, which is an important reagent in many chemical processes. “While many researchers spend considerable time designing elaborate ligand systems perfectly tuned both sterically and electronically for carbon dioxide fixation applications, this work represents a straightforward and beautifully simple approach to achieving the same sorts of transformations,” observes Christine M. Thomas of Brandeis University, whose group has developed CO2-reduction catalysts.—SR
SYDN EY STRINGHAM/U OF UTAH
and the mechanism of their action had been lacking. Michael D. Shapiro and Eric T. Domyan of the University of Utah and their colleagues have now nailed down the source of the varied pigeon plumage. Mutations in the three genes, in different combinations, THREE GENETIC affect the proportions of the major melanin pigments pheomelanin and eumelanin, MUTATIONS PRODUCE which give feathers their color (Curr. Biol. COLORFUL PIGEONS 2014, DOI: 10.1016/j.cub.2014.01.020). BeDomestic rock pigeons come in myriad colsides aiding in the understanding of pigeon ors—intense red, blue-black, and a variety feathers, the genes are of interest to scienof shades in between. Scientists have known tists because they are also implicated in huthat three genes are responsible for the man conditions such as albinism and in the coloring, but the knowledge of which genes susceptibility to develop skin cancer. In fact, two of the genes, Tyrp1 and Sox10, are potential melanoma treatment targets. The Utah team sequenced genes from pigeon Mutations in three genes cause blood and feather samples, many collectdifferent feather ed from birds at pigeon shows in Utah. pigmentations Understanding the complex interplay of in domestic rock the genes and their mutations in pigeons pigeons, such could give scientists added perspective as these English on human skin problems, the researchers trumpeter pigeons. suggest.—EKW CEN.ACS.ORG
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MICROMOTORS CRUISE INSIDE LIVING CELLS Ever since the 1966 sci-fi movie “Fantastic Voyage,” scientists have envisioned steering tiny rockets through the human bloodstream to deliver drugs to tumors and unclog arteries. During the past decade, some researchers have designed microscale motors, but those objects typically run on toxic fuel or can’t function in high-salt environments, properties that have barred their entry into living systems. Now, researchers led by Thomas E. Mallouk and Tony Jun Huang of Pennsylvania State University have for the first time propelled gold nanorod motors around the innards of living cells (Angew. Chem. Int. Ed. 2014, DOI: 10.1002/ anie.201309629). HeLa cervical cancer cells took up the 3-µm-long, 300-nm-wide rods during a 48-hour incubation period. When the team placed the cells in an ultrasound chamber, acoustic waves scattered off the metallic rods, nudging the micromotors along at a speed of 60 µm per second. “It was
SCIENCE & TECHNOLOGY CONCENTRATES
Zinc ions (red) stable to heat and induce a cytochrome organic solvents protein (space-filling than the native representation) to protein and that form a stable array its light-driven that can be used to redox activity can control nanoparticle growth. be used to control inorganic nanocrystal growth. Stable arrays of other proteins and enzymes with different functions could also potentially be used. Manuel A. Navia of Oxford Bioscience Partners, who developed cross-linked enzyme crystals, says the new technology “still has a ways to go, but I am both curious and excited about the never-before-seen polymers and other interesting materials it could eventually be used to create.”—SB
DAVID GOODSELL/PROTEIN DATA BANK
Plant shoots get their directive to grow and branch from a family of hormones called cytokinins that are produced in the root system. How these chemical messages make that journey has been a mystery. A team of researchers led by Chang-Jun Liu of Brookhaven National Laboratory has now discovered a transport protein called PROTEIN ARRAY GUIDES ABCG14 that’s responsible for relaying the messages (Nat. Commun. 2014, DOI: NANOCRYSTAL GROWTH 10.1038/ncomms4274). Cytokinins, includTwo years ago, F. Akif Tezcan of the Univering trans-zeatin, are pivotal in governing sity of California, San Diego, and coworkers overall plant size and can extend plant showed that an electron-transfer protein photosynthesis by delaying leaf aging could self-assemble via zinc ion coordinaand death. For those reasons, the tion into one- and two-dimensional arrays team argues that their findings (C&EN, March 12, 2012, page 9). At the HO “may open new avenues NH time, nanotechnologist Chengde Mao of for modifying variPurdue University commented that applious important crops N N cations of the work could include using the agriculturally, bioN metal-linked protein arrays “as templates technologically, and N H for nanofabrication.” Tezcan, Jeffrey D. horticulturally to intrans-Zeatin Brodin, and coworkers have now demoncrease yields and reduce strated just that (Proc. Natl. Acad. Sci. USA fertilizer requirements.” 2014, DOI: 10.1073/pnas.1319866111). The Working with a model Arabidopsis plant, researchers show that a cytochrome prothe researchers used an array of biochemitein in a metal-based array is much more cal and genetic techniques to determine that ABCG14 is expressed in root cell membranes. They also determined that the protein is responsible for exporting cytokinins from the root cells to the plant xylem, an important thoroughfare by which plants transport water and some nutrients to their extremities.—SE
CATALYTIC DUO COMBATS BLOOD CLOTS Blood clots that form on implanted medical devices such as catheters and heart valves can curtail the lifetimes of the devices and possibly lead to health complications. Antithrombotic agents could prevent such clots, but scientists have yet to find a suitable way to provide a long-lasting, steady supply of those agents. As a possible solution, Teng Xue, Xiangfeng Duan, and Yu Huang of UCLA; Mark E. Meyerhoff of the University of Michigan; and coworkers have developed a catalytic system that generates the antithrombotic agent nitroxyl (HNO) from species commonly found in blood (Nat. Commun. 2014, DOI: 10.1038/ ncomms4200). The system consists of the enzyme glucose oxidase and the molecular CEN.ACS.ORG
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catalyst hemin, both attached to graphene. Glucose oxidase catalyzes the oxidation of glucose, a reaction that generates a local supply of hydrogen peroxide. Hemin then uses hydrogen peroxide to oxidize l-arginine to form nitroxyl. The researchers embedded the catalytic system in a polymer film and showed that platelets don’t adhere to the film after three days in blood plasma. Such films could be used as long-lasting coatings for medical devices, the researchers propose.—CHA
FUSION FUEL FINALLY YIELDS EXCESS ENERGY The two main purposes of the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory are to explore fusion energy and enable experiments to ensure the safety and viability of the U.S. nuclear weapons arsenal. Completed in 2009, the $3.5 billion facility missed a 2012 deadline to ignite a self-sustaining fusion reaction that would yield more energy than was put in to start it. NIF researchers now report reaching an important milestone toward ignition: Experiments now produce more energy than went into the deuterium-tritium fuel (Nature 2014, DOI: 10.1038/nature13008). NIF experimental “shots” involve aiming 192 lasers with a combined 1.8 MJ of energy at a pencil-eraser-sized gold cylinder called a hohlraum. The hohlraum converts the laser light into X-rays, which interact with a 2-mm-diameter spherical plastic shell called an ablator. The deuterium-tritium fuel inside the ablator then implodes and turns into helium nuclei and neutrons, releasing energy. The challenge for NIF scientists has been to keep the implosion from ripping itself apart. The best shot reported so far produced 17.3 kJ, or about double the amount of energy that made In the NIF reaction it from the chamber, 192 laser lasers into the beams blast a target the fuel. Possible size of a pencil eraser. approaches to further improve the yield include changing the hohlraum geometry and the ablator material, says LLNL physicist Debra A. Callahan.—JK LLNL
PLANT GROWTH REGULATOR HITCHES A PROTEIN RIDE
interesting to see their erratic motion inside the cells,” Mallouk says. The rods zipped forward for short distances before crashing into organelles and changing direction. VIDEO ONLINE According to Mallouk, the team would like to better understand this propulsion mechanism as well as the mechanical and chemical effects the motors have when bumping along.—LKW
