Research Highlights
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Vol 452|13 March 2008 RESEARCH HIGHLIGHTS Nosing around J. Exp. Biol. 211, 921–934 (2008) The elephant nose fish uses its eponymous if misnamed adaptation — actually a protuberant chin appendage — as an electrical ‘flashlight’, and Jacob Engelmann PIXONNET.COM/ALAMY at the University of Bonn in Germany and his colleagues have shown how. Gnathonemus petersii senses objects through the distortions they cause in an electric field that it creates. The researchers confirm that elephant noses have two different high-acuity sensory regions, known as foveae. One is the actual nasal region, and the other is in its characteristic chin, called a Schnauzenorgan. The highest density of electrical receptors is at the tip of this appendage. EVOLUTION Astronomers expect that many stars THEORETICAL PHYSICS periodically reverse their magnetic polarity, Streetwise weeds but so far only about 20 stars have had Holographic memory Proc. Natl Acad. Sci. USA 105, 3796–3799 (2008) magnetic polarization measurements taken Phys. Rev. A 77, 020302 (2008) City weeds are adapting to their urban more than once. A special type of hologram may provide a environment at a staggering rate, suggests Jean-François Donati of France’s CNRS way to store light’s quantum information. a research team in France. and his colleagues, who made the discovery, Regular holograms store three-dimensional Pierre-Olivier Cheptou and his colleagues estimate that Tau Bootis’s poles flip every information in an interference pattern, often at the CNRS, France’s basic-research agency, year or so. etched on a glass surface. But such a system in Montpellier analysed the dispersal of the won’t work for quantum information, which weed Crepis sancta, which produces two types CHEMISTRY includes fundamental uncertainties that of seed — a light, feathery, wind-dispersed cannot be held in a classical medium. one and a heavy one. The researchers A ring-side seat for chloride Eugene Polzik of the Danish Research found that feathery seeds dispersed along Angew. Chem. Int. Edn doi:10.1002/anie.200704717 Center for Quantum Optics in Copenhagen Montpellier’s city streets have a 55% lower (2008) and his colleagues at St Petersburg University chance of successfully settling in their parent’s Normally, opposites attract, but chemists in Russia determined a way to store light’s local patch than heavy seeds. In patchy, at Indiana University in Bloomington have quantum properties in a cloud of atoms. pavement-dense habitats, weeds release a designed an uncharged organic molecule By entangling the light with atoms at a significantly higher proportion of heavy seeds that can nevertheless attract and hold temperature close to absolute zero, it should than do their country counterparts. negatively charged ions. be possible to store the quantum features of Genetic evaluations suggest that short- Amar Flood and Yongjun Li the light in the atoms’ collective spins. The term evolution has taken place during a made a doughnut-shaped information can then be read from the atoms mere 5–12 generations. molecule from a number of by reversing the process. small building-block ASTRONOMY molecules, using a CHEMICAL BIOLOGY technique called Magnetic flux ‘click chemistry’. Fixing fragile flies Mon. Not. R. Astron. Soc. doi:10.1111/j.1365- The doughnut’s Nature Chem. Biol. doi:10.1038/nchembio.78 (2008) 2966.2008.12946.x (2008) hole snugly fits a A fruitfly model of fragile X syndrome, a The Sun’s magnetic poles are known to chloride (pictured left), and common cause of mental retardation in reverse their polarity every 11 years, but could potentially hold other anions such as humans, has unveiled possible therapeutic it is not alone — another ‘flip-flopper’ has fluoride, depending on building-block size. targets to combat the condition. been identified. Recent mapping of the Anions are held in place by hydrogen Flies lacking a gene called Fmr1 exhibit magnetic field around nearby star Tau bonds. These were thought to be too weak some physical and behavioural features Bootis shows that its polarity to provide a strong attractive pull, but of fragile X syndrome. Stephen Warren at has reversed since the last nitrogen atoms in the doughnut draw Emory University School of Medicine in observation in 2006. some electron density out of the Atlanta, Georgia, and his colleagues found Measurements of C–H bonds, making it more that food enriched with glutamate, which the polarization of attractive to a negative ion. functions as an excitatory neurotransmitter, the light emitted by Tau These molecules could kills mutant embryos. Bootis allow its complicated provide a new regime for The researchers screened a library of 2,000 magnetic structure to be calculated. removing unwanted anions from solution. compounds and characterized nine that 130 NATURE|Vol 452|13 March 2008 RESEARCH HIGHLIGHTS JOURNAL CLUB John Church Centre for Australian Weather and Climate Research, allowed Fmr1 mutants to survive a high- STRUCTURAL BIOLOGY Tasmania, Australia glutamate diet. Three of the compounds Into the groove An oceanographer ponders affect the inhibitory neurotransmitter, the difficulty of accurately GABA. Treating mutants with GABA Mol. Cell 29, 525–531 (2008) estimating abyssal-ocean relieved glutamate toxicity, and restored Genes are often marked for silencing by warming. several features, including normal courtship the addition of methyl groups to DNA. behaviour and some brain morphology. This type of modification is recognized Estimating how much oceans are by transcriptional regulators such as the warming and where within them FOOD SCIENCE repressor MeCP2, but not in the way heat is stored is a fascinating generally predicted, according to research challenge for me and my fellow The origins of la louche by Adrian Bird and Malcolm Walkinshaw at oceanographers. So far, most Langmuir 24, 1701–1706 (2008) the University of Edinburgh, UK, and their studies comparing observations Part of the allure of aniseed-flavoured spirits collaborators. and models of changing ocean such as absinthe (pictured below), ouzo Previous studies predicted that a temperatures have focused on the and pastis is the mysterious ‘louche’ — their hydrophobic patch in the MeCP2 protein upper 1 kilometre of water. But what transformation from clear to cloudy and made contact with methylated DNA. However, about the abyssal depths, from opalescent with the addition of water. The structural analysis of how the two molecules about 3,000 metres to the bottom? effect comes from the formation of insoluble, bind together suggests that hydrogen bonding Are changes in those waters milky droplets of anise-flavoured oil. of MeCP2 with the water-containing groove in really so slow as to be essentially Details of the process are murky, however. the DNA double helix is crucial. irrelevant to atmospheric warming? Erik van der Linden of Wageningen The research also reveals how a mutation The most comprehensive University in the Netherlands and his common in Rett syndrome, an autism surface-to-bottom measurements colleagues made the first direct measurement spectrum disorder, might disrupt this binding. of ocean temperature were of the oil droplets’ interfacial collected by research ships over tension, which determines how many months during the World fast they grow. These rates, and Ocean Circulation Experiment in their dependence on ethanol the 1990s. By comparing these concentration, differ from those observations with more recent ones predicted by conventional theory. from the World Climate Research PIXONNET.COM/ALAMY Because this ‘spontaneous Programme’s CLIVAR Project, Greg emulsification’ is being explored Johnson and his colleagues have for various purposes, including shown that the Pacific Ocean’s the production of drug-loaded abyssal waters have warmed during nanoparticles and microcapsules, the past two decades (G. C. Johnson the discrepancy is more than just a et al. J. Clim. 20, 5365–5375; 2007). puzzle for barflies. Although the temperature increase is small — up to about GEOLOGY 0.01 °C — compared with the much larger changes in the upper Glacier slimming 1,000 metres of the ocean, it has Geology 36, 223–226 (2008) OPTICS occurred over a thickness of several Satellites have documented the rapid decline kilometres, implying a huge quantity of the West Antarctic ice sheet during the How to make a black hole of heat storage. The deep warming past two decades, with thinning of more than Science 319, 1367–1370 (2008) is strongest in the south-west a metre per year. But pre-satellite — let alone Researchers have created an analogue of a Pacific, where newly ventilated prehistoric — data are harder to come by. black hole in a lab, using light trapped in an abyssal waters enter from the south. Joanne Johnson from the British Antarctic optical fibre. This optical black hole affects The Pacific warming, and abyssal Survey in Cambridge, UK, and her colleagues light in ways equivalent to the intense gravity warming elsewhere, means that we used rocks to gain insight into the history of at a black hole’s ‘event horizon’, beyond which should start considering abyssal glaciers by the Amundsen Sea Embayment. no light can escape. waters when estimating sea-level They suggest that, for most of the past Pulses of light travelling down the fibre rise and the climate’s sensitivity 10,000 years, these glaciers have been thinning affect the fibre’s light-carrying properties to increasing greenhouse-gas at rates of just a few centimetres per year. in a manner analogous to the bending of concentrations. There is plenty to The team took samples from nunataks space-time by gravity. The leading edge of a find out: how does the heat reach — rocky peaks that poke through the ice and pulse then acts like an event horizon when abyssal waters? Is the warming sometimes, like dipsticks, contain evidence of it catches up with slower light up ahead. human-induced? Designing historical glacier heights. The thinning rates, Meanwhile, the pulse’s trailing edge becomes and implementing an adequate which the researchers established by isotopic equivalent to a white-hole event horizon, abyssal-water-observing system is dating of quartz grains from within seven where no light can enter.