Nature is a weekly international journal publishing the finest peer-reviewed research in all fields of science and technology on the basis of its originality, importance, interdisciplinary interest, timeliness, accessibility, elegance and surprising conclusions. Nature also provides rapid, authoritative, insightful and arresting news and interpretation of topical and coming trends affecting science, scientists and the wider public. http://www.nature.com/nature/current_issue/ Nature Publishing Group en © 2006 Nature Publishing Group Nature 0028-0836 1476-4679 © 2006 Nature Publishing Group permissions@nature.com http://www.nature.com/includes/rj_globnavimages/nature_logo.gif http://www.nature.com/nature/ http://dx.doi.org/10.1038/7077xiiia A large international effort reveals secrets hidden in the Milky Way. Making the paperJames Hinton doi:10.1038/7077xiiia Nature 439, xiii (2006) 2006-02-08 Nature 2006-02-08 439 7077 Authors xiii xiii http://dx.doi.org/10.1038/7077xiiib News & views authorFor every immune challenge there is an opposing immune response. But scientists are using immune reactions to one challenge to treat a completely separate challenge. In the paper on page 682, scientists look at how one particluar response — a Abstractions doi:10.1038/7077xiiib Nature 439, xiii (2006) 2006-02-08 Nature 2006-02-08 439 7077 Authors xiii xiii http://dx.doi.org/10.1038/7077xiiic A numerical perspective on Nature authors.At the International Centre for Genetic Engineering and Biotechnology (ICGEB) in New Delhi, India, Amit Sharma runs a small research group focused on structural analyses of malaria parasite proteins. Collaborating with the European Molecular Biology Laboratory in Grenoble, QuantifiedIndia doi:10.1038/7077xiiic Nature 439, xiii (2006) 2006-02-08 Nature 2006-02-08 439 7077 Authors xiii xiii http://dx.doi.org/10.1038/439633a The physical sciences are strongly favoured in President Bush's 2007 budget request — but researchers can't count their chickens yet. Physics fights back doi:10.1038/439633a Nature 439, 633 (2006) 2006-02-08 Nature 2006-02-08 439 7077 Editorial 633 633 http://dx.doi.org/10.1038/439633b Only biologists can effectively police the misuse of biological agents. Network of concern doi:10.1038/439633b Nature 439, 633 (2006) 2006-02-08 Nature 2006-02-08 439 7077 Editorial 633 634 http://dx.doi.org/10.1038/439634a A framework is required for investigations into scientific misconduct in Japan. Japan's research conduct doi:10.1038/439634a Nature 439, 634 (2006) 2006-02-08 Nature 2006-02-08 439 7077 Editorial 634 634 http://dx.doi.org/10.1038/439636a Optics: Longest laserPhys. Rev. Lett.96, 023902 (2006)A fibre-optic system that could dramatically cut signal power losses in telecommunications has been created by a group led by Sergei Turitsyn and Juan Diego Ania-Castañón at the University of Aston in Birmingham, UK.The Research highlights doi:10.1038/439636a Nature 439, 636 (2006) 2006-02-08 Nature 2006-02-08 439 7077 Research Highlights 636 637 http://dx.doi.org/10.1038/439638a Original manuscript could settle old scores. Dealer unearths Hooke's Royal Society notes Jim Giles doi:10.1038/439638a Nature 439, 638 (2006) 2006-02-08 Nature 2006-02-08 439 7077 News 638 639 http://dx.doi.org/10.1038/439638b Abstinence campaigners claim success over AIDS. Drop in HIV infection rate used to justify focus on morality Erika Check doi:10.1038/439638b Nature 439, 638 (2006) 2006-02-08 Nature 2006-02-08 439 7077 News 638 639 http://dx.doi.org/10.1038/439639a Astronomers remain divided over definition. Possible planets left with no name Mark Peplow doi:10.1038/439639a Nature 439, 639 (2006) 2006-02-08 Nature 2006-02-08 439 7077 News 639 639 http://dx.doi.org/10.1038/439640a On the Record“Old octopuses become what we call senescent, or senile... and sometimes their actions are very inappropriate.”Jim Cosgrove of the Royal British Columbia Museum speculates about why an octopus recently attacked a small research submarine.“Please note that from now on, Orion's Sidelines doi:10.1038/439640a Nature 439, 640 (2006) 2006-02-08 Nature 2006-02-08 439 7077 News 640 640 http://dx.doi.org/10.1038/439640b Island hosts double boost for evolutionary theory. One place, one parent, two species Michael Hopkin doi:10.1038/439640b Nature 439, 640 (2006) 2006-02-08 Nature 2006-02-08 439 7077 News 640 641 http://dx.doi.org/10.1038/439640c European Research Council faces problematic beginning. Political strife set to delay EU funds Quirin Schiermeier doi:10.1038/439640c Nature 439, 640 (2006) 2006-02-08 Nature 2006-02-08 439 7077 News 640 641 http://dx.doi.org/10.1038/439642a University bids to save meteorites for science. Space rocks wanted: cash paid Rex Dalton doi:10.1038/439642a Nature 439, 642 (2006) 2006-02-08 Nature 2006-02-08 439 7077 News 642 642 http://dx.doi.org/10.1038/439642b Cloak of anonymity shed by new publication. Journal lays bare remarks from peer reviewers Emma Marris doi:10.1038/439642b Nature 439, 642 (2006) 2006-02-08 Nature 2006-02-08 439 7077 News 642 642 http://dx.doi.org/10.1038/439643a US targets roles of genes and environment in diseaseThe US National Institutes of Health was this week set to announce two ambitious projects in genetics.The Genes and Environment Initiative and the Genetic Association Information Network (GAIN) are both aimed at identifying the genetic News in brief doi:10.1038/439643a Nature 439, 643 (2006) 2006-02-08 Nature 2006-02-08 439 7077 News in Brief 643 643 http://dx.doi.org/10.1038/439644a Energy and competitiveness are the buzzwords in George W. Bush's proposal for spending in the next fiscal year. But will the president's push really benefit researchers? Physics wins the US budget race Geoff Brumfiel Emma Marris doi:10.1038/439644a Nature 439, 644 (2006) 2006-02-08 Nature 2006-02-08 439 7077 Special Report 644 645 http://dx.doi.org/10.1038/439646a Show us the moneyThe world's most advanced economies are losing their scientific edge, some analysts claim. Fearing, that weak research budgets will lead to weak economies, lawmakers on both sides of the Atlantic are preparing to pour billions of dollars into research and development The scientific balance of power doi:10.1038/439646a Nature 439, 646 (2006) 2006-02-08 Nature 2006-02-08 439 7077 Special Report 646 647 http://dx.doi.org/10.1038/439648a Fractal analysis has been used to assess the authenticity of paintings purporting to be the work of Jackson Pollock. Alison Abbott reports. Fractals and artIn the hands of a master Alison Abbott doi:10.1038/439648a Nature 439, 648 (2006) 2006-02-08 Nature 2006-02-08 439 7077 News Feature 648 650 http://dx.doi.org/10.1038/439652a Less than a month ago, investigators at Seoul National University in South Korea announced that cloning researcher Woo Suk Hwang had lied when he claimed his team cloned human embryos with relative ease and produced stem cells from them. The news was a significant setback for cloning researchers. In this special section, Nature looks at how biologists are regrouping. Carina Dennis asks how they can get cloning to work given a very limited supply of eggs and Phyllida Brown looks at whether we will need therapeutic cloning at all, if immunologists can stop our bodies fighting transplants (see page 655). And on page 658, one of Hwang's closest rivals admits it may not continue its cloning quest. CloningMining the secrets of the egg Carina Dennis doi:10.1038/439652a Nature 439, 652 (2006) 2006-02-08 Nature 2006-02-08 439 7077 News Feature 652 655 http://dx.doi.org/10.1038/439655a Less than a month ago, investigators at Seoul National University in South Korea announced that cloning researcher Woo Suk Hwang had lied when he claimed his team cloned human embryos with relative ease and produced stem cells from them. The news was a significant setback for cloning researchers. In this special section, Nature looks at how biologists are regrouping. Carina Dennis asks how they can get cloning to work given a very limited supply of eggs and Phyllida Brown looks at whether we will need therapeutic cloning at all, if immunologists can stop our bodies fighting transplants (see page 655). And on page 658, one of Hwang's closest rivals admits it may not continue its cloning quest. CloningDo we even need eggs? Phyllida Brown doi:10.1038/439655a Nature 439, 655 (2006) 2006-02-08 Nature 2006-02-08 439 7077 News Feature 655 657 http://dx.doi.org/10.1038/439658a Advanced Cell Technology plans to tread cautiously on the ground left vacant by the collapse of a South Korean scientist's claims to have cloned a human embryo, as David Cyranoski reports. No end in sight for stem-cell odyssey doi:10.1038/439658a Nature 439, 658 (2006) 2006-02-08 Nature 2006-02-08 439 7077 Business 658 659 http://dx.doi.org/10.1038/439659a Roche reboundSwiss drug giant Roche reported sales surging by 20% in 2005, to reach 35.5 billion Swiss francs (US$27.8 billion). The numbers were driven by the Basel-based company's portfolio of cancer drugs, whose sales rose by 42% — and by strong demand for Tamiflu, In brief doi:10.1038/439659a Nature 439, 659 (2006) 2006-02-08 Nature 2006-02-08 439 7077 Business 659 659 http://dx.doi.org/10.1038/439659b This week Wood Mackenzie, an Edinburgh-based research and consulting firm, reviews recent trends in biotechnology stocks.After a flat close to 2005, the Nasdaq biotechnology index moved forward in January, with most of the rise attributable to a flurry of recent clinical trials results and Market watch doi:10.1038/439659b Nature 439, 659 (2006) 2006-02-08 Nature 2006-02-08 439 7077 Business 659 659 http://dx.doi.org/10.1038/439660a SirYour News Feature “A sea change” (Nature439, 256–260; 2006) states that evidence for the huge effects on climate of past thermohaline shutdowns is “near indisputable”. You then claim that the best such evidence is the coincidence of Climate may not be linked with circulation slowdown Eric Steig doi:10.1038/439660a Nature 439, 660 (2006) 2006-02-08 Nature 2006-02-08 439 7077 Correspondence 660 660 http://dx.doi.org/10.1038/439660b SirYour News story “Croatian scientists call for openness over funding” (Nature439, 7; 2006) brings attention to the funding of technology-development projects in Croatia. The petition discussed in this story was signed by only 26 scientists inside Croatia (the other No unfairness in funding of Croatian minister's project Stjepan Risović doi:10.1038/439660b Nature 439, 660 (2006) 2006-02-08 Nature 2006-02-08 439 7077 Correspondence 660 660 http://dx.doi.org/10.1038/439660c SirJennifer Devine and colleagues in their Brief Communication “Deep-sea fishes qualify as endangered” (Nature439, 29; 2006) state: “At one time it was presumed from the vastness of the oceans that fishing would not drive species to extinction.” Indeed, the Dwindling fish numbers already of concern in 1883 David W. Sims Alan J. Southward doi:10.1038/439660c Nature 439, 660 (2006) 2006-02-08 Nature 2006-02-08 439 7077 Correspondence 660 660 http://dx.doi.org/10.1038/439660d SirIn addition to the concerns expressed in your Editorial “Enough, already” (Nature438, 712; 2005), about the planned increase in plutonium stored at Lawrence Livermore National Laboratory (LLNL), numerous other problems exist which do not lend themselves to ready fixes. Problems at plutonium lab need more than a quick fix Martha Priebat doi:10.1038/439660d Nature 439, 660 (2006) 2006-02-08 Nature 2006-02-08 439 7077 Correspondence 660 660 http://dx.doi.org/10.1038/439661a How much has genetics contributed to advances in medicine? A healthy dose of genetics Uta Francke doi:10.1038/439661a Nature 439, 661 (2006) 2006-02-08 Nature 2006-02-08 439 7077 Books and Arts 661 662 http://dx.doi.org/10.1038/439662a In T. H. White's The Once and Future King (G. P. Putnam, 1958), Merlin educates a young King Arthur by transmogrifying him into other creatures. Sometimes Arthur is an ant, and considers everything in the world only as ‘done’ or ‘not done’. Sometimes he In the minds of animals Scott Creel doi:10.1038/439662a Nature 439, 662 (2006) 2006-02-08 Nature 2006-02-08 439 7077 Books and Arts 662 663 http://dx.doi.org/10.1038/439663a Even when advanced in years, Lady Sarah Cowper (1644–1720) was still a keen observer, especially of other women. After meeting with “Lady W.” she confided to her diary that W. had “rent her face with painting. She is at least as old as I am A ship, gradually lowering sail Douwe Draaisma doi:10.1038/439663a Nature 439, 663 (2006) 2006-02-08 Nature 2006-02-08 439 7077 Books and Arts 663 664 http://dx.doi.org/10.1038/439664a A short film playing with concepts of quantum physics makes it big. Science in culture: Nuclear-powered image Alison Abbott doi:10.1038/439664a Nature 439, 664 (2006) 2006-02-08 Nature 2006-02-08 439 7077 Books and Arts 664 664 http://dx.doi.org/10.1038/439665a A newly discovered species of dinosaur, characterized by a wonderfully elaborate head crest, is the oldest known member of the lineage that culminated in Tyrannosaurus rex more than 90 million years later. PalaeontologyA Jurassic tyrant is crowned Thomas R. Holtz Jr doi:10.1038/439665a Nature 439, 665 (2006) 2006-02-08 Nature 2006-02-08 439 7077 News and Views 665 666 http://dx.doi.org/10.1038/439666a Chameleon-like nanoparticles of gold can be used to indicate the presence of various biomolecules. Adding aptamers — DNA strands that bind only to specific molecules — to the mix opens up further possibilities. Chemical biologyAptamers in nanoland Michael Famulok Günter Mayer doi:10.1038/439666a Nature 439, 666 (2006) 2006-02-08 Nature 2006-02-08 439 7077 News and Views 666 669 http://dx.doi.org/10.1038/439667a 50 YEARS AGO“The ‘Queen-Substance’ of Honeybees and the Ovary-inhibiting Hormone of Crustaceans” — In the course of work on the social organization of honeybee communities, it has been found that worker honeybees obtain a substance (‘queen-substance’) from their queens which, if obtained in sufficient 50 & 100 years ago doi:10.1038/439667a Nature 439, 667 (2006) 2006-02-08 Nature 2006-02-08 439 7077 News and Views 667 667 http://dx.doi.org/10.1038/439669a During persistent infections, the immune cells responsible for killing infected cells and maintaining inflammation gradually stop functioning, allowing the pathogen to thrive. But can this process be reversed? ImmunologyExhausted T cells perk up Matthew A. Williams Michael J. Bevan doi:10.1038/439669a Nature 439, 669 (2006) 2006-02-08 Nature 2006-02-08 439 7077 News and Views 669 670 http://dx.doi.org/10.1038/439670a It is not difficult to be impressed by the grandeur of high mountainous regions, but it is difficult to reconstruct how the elevation of such regions evolved. A study of the Tibetan plateau does just that. Earth scienceThe rise and growth of Tibet Andreas Mulch C. Page Chamberlain doi:10.1038/439670a Nature 439, 670 (2006) 2006-02-08 Nature 2006-02-08 439 7077 News and Views 670 671 http://dx.doi.org/10.1038/439671a Conventionally, conduction in silicon is enhanced by doping — adding impurities that change the material's electronic structure. But exploiting surface effects in thin silicon films may offer yet other opportunities. Semiconductor physicsTransport news John J. Boland doi:10.1038/439671a Nature 439, 671 (2006) 2006-02-08 Nature 2006-02-08 439 7077 News and Views 671 673 http://dx.doi.org/10.1038/439673a If elephants never forget, the memories of mammoths need a little prompting. Nevertheless, inventive approaches to the extraction and sequencing of DNA from mammoths preserved in Siberian permafrost are allowing direct access to the deeper memories of elephant evolution.There has been much debate about EvolutionMemories of mammoths Henry Gee doi:10.1038/439673a Nature 439, 673 (2006) 2006-02-08 Nature 2006-02-08 439 7077 News and Views 673 673 http://dx.doi.org/10.1038/439675a This huge eruption slowed sea-level rise and ocean warming well into the following century.We have analysed a suite of 12 state-of-the-art climate models and show that ocean warming and sea-level rise in the twentieth century were substantially reduced by the colossal eruption in 1883 of the volcano Krakatoa in the Sunda strait, Indonesia. Volcanically induced cooling of the ocean surface penetrated into deeper layers, where it persisted for decades after the event. This remarkable effect on oceanic thermal structure is longer lasting than has previously been suspected and is sufficient to offset a large fraction of ocean warming and sea-level rise caused by anthropogenic influences. Volcanoes and climateKrakatoa's signature persists in the ocean P. J. Gleckler T. M. L. Wigley B. D. Santer J. M. Gregory K. AchutaRao K. E. Taylor doi:10.1038/439675a Nature 439, 675 (2006) 2006-02-08 Nature 2006-02-08 439 7077 Brief Communications 675 675 http://dx.doi.org/10.1038/nature04506 The elevation history of the Tibetan plateau provides direct insight into the tectonic processes associated with continent–continent collisions. Here we present oxygen-isotope-based estimates of the palaeo-altimetry of late Eocene and younger deposits of the Lunpola basin in the centre of the plateau, which indicate that Palaeo-altimetry of the late Eocene to Miocene Lunpola basin, central Tibet David B. Rowley Brian S. Currie doi:10.1038/nature04506 Nature 439, 677 (2006) Nature 439 7077 Article 677 681 http://dx.doi.org/10.1038/nature04444 Functional impairment of antigen-specific T cells is a defining characteristic of many chronic infections, but the underlying mechanisms of T-cell dysfunction are not well understood. To address this question, we analysed genes expressed in functionally impaired virus-specific CD8 T cells present in mice chronically infected Restoring function in exhausted CD8 T cells during chronic viral infection Daniel L. Barber E. John Wherry David Masopust Baogong Zhu James P. Allison Arlene H. Sharpe Gordon J. Freeman Rafi Ahmed doi:10.1038/nature04444 Nature 439, 682 (2006) 2005-12-28 Nature 2005-12-28 439 7077 Article 682 687 http://dx.doi.org/10.1038/nature04316 Plants counteract fluctuations in water supply by regulating all aquaporins in the cell plasma membrane. Channel closure results either from the dephosphorylation of two conserved serine residues under conditions of drought stress, or from the protonation of a conserved histidine residue following a drop in Structural mechanism of plant aquaporin gating Susanna Törnroth-Horsefield Yi Wang Kristina Hedfalk Urban Johanson Maria Karlsson Emad Tajkhorshid Richard Neutze Per Kjellbom doi:10.1038/nature04316 Nature 439, 688 (2006) 2005-12-07 Nature 2005-12-07 439 7077 Article 688 694 http://dx.doi.org/10.1038/nature04467 The source of Galactic cosmic rays (with energies up to 1015 eV) remains unclear, although it is widely believed that they originate in the shock waves of expanding supernova remnants. At present the best way to investigate their acceleration and propagation is by observing the γ-rays produced when cosmic rays interact with interstellar gas. Here we report observations of an extended region of very-high-energy (> 1011 eV) γ-ray emission correlated spatially with a complex of giant molecular clouds in the central 200 parsecs of the Milky Way. The hardness of the γ-ray spectrum and the conditions in those molecular clouds indicate that the cosmic rays giving rise to the γ-rays are likely to be protons and nuclei rather than electrons. The energy associated with the cosmic rays could have come from a single supernova explosion around 104 years ago. Discovery of very-high-energy γ-rays from the Galactic Centre ridge F. Aharonian A. G. Akhperjanian A. R. Bazer-Bachi M. Beilicke W. Benbow D. Berge K. Bernlöhr C. Boisson O. Bolz V. Borrel I. Braun F. Breitling A. M. Brown P. M. Chadwick L.-M. Chounet R. Cornils L. Costamante B. Degrange H. J. Dickinson A. Djannati-Ataï L. O'C. Drury G. Dubus D. Emmanoulopoulos P. Espigat F. Feinstein G. Fontaine Y. Fuchs S. Funk Y. A. Gallant B. Giebels S. Gillessen J. F. Glicenstein P. Goret C. Hadjichristidis D. Hauser M. Hauser G. Heinzelmann G. Henri G. Hermann J. A. Hinton W. Hofmann M. Holleran D. Horns A. Jacholkowska O. C. de Jager B. Khélifi S. Klages Nu. Komin A. Konopelko I. J. Latham R. Le Gallou A. Lemière M. Lemoine-Goumard N. Leroy T. Lohse A. Marcowith J. M. Martin O. Martineau-Huynh C. Masterson T. J. L. McComb M. de Naurois S. J. Nolan A. Noutsos K. J. Orford J. L. Osborne M. Ouchrif M. Panter G. Pelletier S. Pita G. Pühlhofer M. Punch B. C. Raubenheimer M. Raue J. Raux S. M. Rayner A. Reimer O. Reimer J. Ripken L. Rob L. Rolland G. Rowell V. Sahakian L. Saugé S. Schlenker R. Schlickeiser C. Schuster U. Schwanke M. Siewert H. Sol D. Spangler R. Steenkamp C. Stegmann J.-P. Tavernet R. Terrier C. G. Théoret M. Tluczykont C. van Eldik G. Vasileiadis C. Venter P. Vincent H. J. Völk S. J. Wagner doi:10.1038/nature04467 Nature 439, 695 (2006) Nature 439 7077 Letter 695 698 http://dx.doi.org/10.1038/nature04401 Strong discrete aurorae on Earth are excited by electrons, which are accelerated along magnetic field lines towards the planet. Surprisingly, electrons accelerated in the opposite direction have been recently observed. The mechanisms and significance of this anti-earthward acceleration are highly uncertain because only earthward acceleration was traditionally considered, and observations remain limited. It is also unclear whether upward acceleration of the electrons is a necessary part of the auroral process or simply a special feature of Earth's complex space environment. Here we report anti-planetward acceleration of electron beams in Saturn's magnetosphere along field lines that statistically map into regions of aurora. The energy spectrum of these beams is qualitatively similar to the ones observed at Earth, and the energy fluxes in the observed beams are comparable with the energies required to excite Saturn's aurora. These beams, along with the observations at Earth and the barely understood electron beams in Jupiter's magnetosphere, demonstrate that anti-planetward acceleration is a universal feature of aurorae. The energy contained in the beams shows that upward acceleration is an essential part of the overall auroral process. Anti-planetward auroral electron beams at Saturn J. Saur B. H. Mauk D. G. Mitchell N. Krupp K. K. Khurana S. Livi S. M. Krimigis P. T. Newell D. J. Williams P. C. Brandt A. Lagg E. Roussos M. K. Dougherty doi:10.1038/nature04401 Nature 439, 699 (2006) Nature 439 7077 Letter 699 702 http://dx.doi.org/10.1038/nature04501 The widely used ‘silicon-on-insulator’ (SOI) system consists of a layer of single-crystalline silicon supported on a silicon dioxide substrate. When this silicon layer (the template layer) is very thin, the assumption that an effectively infinite number of atoms contributes to its physical properties no longer applies, and new electronic, mechanical and thermodynamic phenomena arise, distinct from those of bulk silicon. The development of unusual electronic properties with decreasing layer thickness is particularly important for silicon microelectronic devices, in which (001)-oriented SOI is often used. Here we show—using scanning tunnelling microscopy, electronic transport measurements, and theory—that electronic conduction in thin SOI(001) is determined not by bulk dopants but by the interaction of surface or interface electronic energy levels with the ‘bulk’ band structure of the thin silicon template layer. This interaction enables high-mobility carrier conduction in nanometre-scale SOI; conduction in even the thinnest membranes or layers of Si(001) is therefore possible, independent of any considerations of bulk doping, provided that the proper surface or interface states are available to enable the thermal excitation of ‘bulk’ carriers in the silicon layer. Electronic transport in nanometre-scale silicon-on-insulator membranes Pengpeng Zhang Emma Tevaarwerk Byoung-Nam Park Donald E. Savage George K. Celler Irena Knezevic Paul G. Evans Mark A. Eriksson Max G. Lagally doi:10.1038/nature04501 Nature 439, 703 (2006) Nature 439 7077 Letter 703 706 http://dx.doi.org/10.1038/nature04465 Corrosion destroys more than three per cent of the world's GDP. Recently, the electrochemical decomposition of metal alloys has been more productively harnessed to produce porous materials with diverse technological potential. High-resolution insight into structure formation during electrocorrosion is a prerequisite for an atomistic understanding and control of such electrochemical surface processes. Here we report atomic-scale observations of the initial stages of corrosion of a Cu3Au(111) single crystal alloy within a sulphuric acid solution. We monitor, by in situ X-ray diffraction with picometre-scale resolution, the structure and chemical composition of the electrolyte/alloy interface as the material decomposes. We reveal the microscopic structural changes associated with a general passivation phenomenon of which the origin has been hitherto unclear. We observe the formation of a gold-enriched single-crystal layer that is two to three monolayers thick, and has an unexpected inverted (CBA-) stacking sequence. At higher potentials, we find that this protective passivation layer dewets and pure gold islands are formed; such structures form the templates for the growth of nanoporous metals. Our experiments are carried out on a model single-crystal system. However, the insights should equally apply within a crystalline grain of an associated polycrystalline electrode fabricated from many other alloys exhibiting a large difference in the standard potential of their constituents, such as stainless steel (see ref. 5 for example) or alloys used for marine applications, such as CuZn or CuAl. Initial corrosion observed on the atomic scale F. U. Renner A. Stierle H. Dosch D. M. Kolb T.-L. Lee J. Zegenhagen doi:10.1038/nature04465 Nature 439, 707 (2006) Nature 439 7077 Letter 707 710 http://dx.doi.org/10.1038/nature04555 Most terrestrial carbon sequestration at mid-latitudes in the Northern Hemisphere occurs in seasonal, montane forest ecosystems. Winter respiratory carbon dioxide losses from these ecosystems are high, and over half of the carbon assimilated by photosynthesis in the summer can be lost the following winter. The amount of winter carbon dioxide loss is potentially susceptible to changes in the depth of the snowpack; a shallower snowpack has less insulation potential, causing colder soil temperatures and potentially lower soil respiration rates. Recent climate analyses have shown widespread declines in the winter snowpack of mountain ecosystems in the western USA and Europe that are coupled to positive temperature anomalies. Here we study the effect of changes in snow cover on soil carbon cycling within the context of natural climate variation. We use a six-year record of net ecosystem carbon dioxide exchange in a subalpine forest to show that years with a reduced winter snowpack are accompanied by significantly lower rates of soil respiration. Furthermore, we show that the cause of the high sensitivity of soil respiration rate to changes in snow depth is a unique soil microbial community that exhibits exponential growth and high rates of substrate utilization at the cold temperatures that exist beneath the snow. Our observations suggest that a warmer climate may change soil carbon sequestration rates in forest ecosystems owing to changes in the depth of the insulating snow cover. Winter forest soil respiration controlled by climate and microbial community composition Russell K. Monson David L. Lipson Sean P. Burns Andrew A. Turnipseed Anthony C. Delany Mark W. Williams Steven K. Schmidt doi:10.1038/nature04555 Nature 439, 711 (2006) Nature 439 7077 Letter 711 714 http://dx.doi.org/10.1038/nature04511 The tyrannosauroid fossil record is mainly restricted to Cretaceous sediments of Laurasia, although some very fragmentary Jurassic specimens have been referred to this group. Here we report a new basal tyrannosauroid, Guanlong wucaii gen. et sp. nov., from the lower Upper Jurassic of the Junggar Basin, northwestern China. G. wucaii is the oldest known tyrannosauroid and shows several unexpectedly primitive pelvic features. Nevertheless, the limbs of G. wucaii share several features with derived coelurosaurs, and it possesses features shared by other coelurosaurian clades. This unusual combination of character states provides an insight into the poorly known early radiation of the Coelurosauria. Notably, the presumed predatory Guanlong has a large, fragile and highly pneumatic cranial crest that is among the most elaborate known in any non-avian dinosaur and could be comparable to some classical exaggerated ornamental traits among vertebrates. A basal tyrannosauroid dinosaur from the Late Jurassic of China Xing Xu James M. Clark Catherine A. Forster Mark A. Norell Gregory M. Erickson David A. Eberth Chengkai Jia Qi Zhao doi:10.1038/nature04511 Nature 439, 715 (2006) Nature 439 7077 Letter 715 718 http://dx.doi.org/10.1038/nature04325 Sympatric speciation, the formation of species in the absence of geographical barriers, remains one of the most contentious concepts in evolutionary biology. Although speciation under sympatric conditions seems theoretically possible, empirical studies are scarce and only a few credible examples of sympatric speciation exist. Here we present a convincing case of sympatric speciation in the Midas cichlid species complex (Amphilophus sp.) in a young and small volcanic crater lake in Nicaragua. Our study includes phylogeographic, population-genetic (based on mitochondrial DNA, microsatellites and amplified fragment length polymorphisms), morphometric and ecological analyses. We find, first, that crater Lake Apoyo was seeded only once by the ancestral high-bodied benthic species Amphilophus citrinellus, the most common cichlid species in the area; second, that a new elongated limnetic species (Amphilophus zaliosus) evolved in Lake Apoyo from the ancestral species (A. citrinellus) within less than ∼10,000 yr; third, that the two species in Lake Apoyo are reproductively isolated; and fourth, that the two species are eco-morphologically distinct. Sympatric speciation in Nicaraguan crater lake cichlid fish Marta Barluenga Kai N. Stölting Walter Salzburger Moritz Muschick Axel Meyer doi:10.1038/nature04325 Nature 439, 719 (2006) Nature 439 7077 Letter 719 723 http://dx.doi.org/10.1038/nature04432 In studying the genomes of extinct species, two principal limitations are typically the small quantities of endogenous ancient DNA and its degraded condition, even though products of up to 1,600 base pairs (bp) have been amplified in rare cases. Using small overlapping polymerase chain reaction products, longer stretches of sequences or even whole mitochondrial genomes can be reconstructed, but this approach is limited by the number of amplifications that can be performed from rare samples. Thus, even from well-studied Pleistocene species such as mammoths, ground sloths and cave bears, no DNA sequences of more than about 1,000 bp have been reconstructed. Here we report the complete mitochondrial genome sequence of the Pleistocene woolly mammoth Mammuthus primigenius. We used about 200 mg of bone and a new approach that allows the simultaneous retrieval of multiple sequences from small amounts of degraded DNA. Our phylogenetic analyses show that the mammoth was more closely related to the Asian than to the African elephant. However, the divergence of mammoth, African and Asian elephants occurred over a short time, corresponding to only about 7% of the total length of the phylogenetic tree for the three evolutionary lineages. Multiplex amplification of the mammoth mitochondrial genome and the evolution of Elephantidae Johannes Krause Paul H. Dear Joshua L. Pollack Montgomery Slatkin Helen Spriggs Ian Barnes Adrian M. Lister Ingo Ebersberger Svante Pääbo Michael Hofreiter doi:10.1038/nature04432 Nature 439, 724 (2006) 2005-12-18 Nature 2005-12-18 439 7077 Letter 724 727 http://dx.doi.org/10.1038/nature04445 The Bicoid (Bcd) gradient in Drosophila has long been a model for the action of a morphogen in establishing embryonic polarity. However, it is now clear that bcd is a unique feature of higher Diptera. An evolutionarily ancient gene, orthodenticle (otd), has a bcd-like role in the beetle Tribolium. Unlike the Bcd gradient, which arises by diffusion of protein from an anteriorly localized messenger RNA, the Tribolium Otd gradient forms by translational repression of otd mRNA by a posteriorly localized factor. These differences in gradient formation are correlated with differences in modes of embryonic patterning. Drosophila uses long germ embryogenesis, where the embryo derives from the entire anterior–posterior axis, and all segments are patterned at the blastoderm stage, before gastrulation. In contrast, Tribolium undergoes short germ embryogenesis: the embryo arises from cells in the posterior of the egg, and only anterior segments are patterned at the blastoderm stage, with the remaining segments arising after gastrulation from a growth zone. Here we describe the role of otd in the long germband embryo of the wasp Nasonia vitripennis. We show that Nasonia otd maternal mRNA is localized at both poles of the embryo, and resulting protein gradients pattern both poles. Thus, localized Nasonia otd has two major roles that allow long germ development. It activates anterior targets at the anterior of the egg in a manner reminiscent of the Bcd gradient, and it is required for pre-gastrulation expression of posterior gap genes. Localized maternal orthodenticle patterns anterior and posterior in the long germ wasp Nasonia Jeremy A. Lynch Ava E. Brent David S. Leaf Mary Anne Pultz Claude Desplan doi:10.1038/nature04445 Nature 439, 728 (2006) Nature 439 7077 Letter 728 732 http://dx.doi.org/10.1038/nature04258 Our capacity to process and respond behaviourally to multiple incoming stimuli is very limited. To optimize the use of this limited capacity, attentional mechanisms give priority to behaviourally relevant stimuli at the expense of irrelevant distractors. In visual areas, attended stimuli induce enhanced responses and an improved synchronization of rhythmic neuronal activity in the gamma frequency band (40–70 Hz). Both effects probably improve the neuronal signalling of attended stimuli within and among brain areas. Attention also results in improved behavioural performance and shortened reaction times. However, it is not known how reaction times are related to either response strength or gamma-band synchronization in visual areas. Here we show that behavioural response times to a stimulus change can be predicted specifically by the degree of gamma-band synchronization among those neurons in monkey visual area V4 that are activated by the behaviourally relevant stimulus. When there are two visual stimuli and monkeys have to detect a change in one stimulus while ignoring the other, their reactions are fastest when the relevant stimulus induces strong gamma-band synchronization before and after the change in stimulus. This enhanced gamma-band synchronization is also followed by shorter neuronal response latencies on the fast trials. Conversely, the monkeys' reactions are slowest when gamma-band synchronization is high in response to the irrelevant distractor. Thus, enhanced neuronal gamma-band synchronization and shortened neuronal response latencies to an attended stimulus seem to have direct effects on visually triggered behaviour, reflecting an early neuronal correlate of efficient visuo-motor integration. Gamma-band synchronization in visual cortex predicts speed of change detection Thilo Womelsdorf Pascal Fries Partha P. Mitra Robert Desimone doi:10.1038/nature04258 Nature 439, 733 (2006) 2005-12-21 Nature 2005-12-21 439 7077 Letter 733 736 http://dx.doi.org/10.1038/nature04417 In mammals, sperm cells become motile during ejaculation and swim up the female reproductive tract. Before fertilization and to overcome various barriers, their motility must be hyperactivated, a motion that is characterized by vigorous asymmetric tail beating. Hyperactivation requires an increase in calcium in the flagella, a process that probably involves plasmalemmal ion channels. Numerous attempts in the past two decades to understand sperm cell channels have been frustrated by the difficulty of measuring spermatozoan transmembrane ion currents. Here, by using a simple approach to patch-clamp spermatozoa and to characterize whole-spermatozoan currents, we describe a constitutively active flagellar calcium channel that is strongly potentiated by intracellular alkalinization. This current is not present in spermatozoa lacking the sperm-specific putative ion channel protein, CatSper1. This plasma membrane protein of the six transmembrane-spanning ion channel superfamily is specifically localized to the principal piece of the sperm tail and is required for sperm cell hyperactivation and male fertility. Our results identify CatSper1 as a component of the key flagellar calcium channel, and suggest that intracellular alkalinization potentiates CatSper current to increase intraflagellar calcium and induce sperm hyperactivation. Whole-cell patch-clamp measurements of spermatozoa reveal an alkaline-activated Ca2+ channel Yuriy Kirichok Betsy Navarro David E. Clapham doi:10.1038/nature04417 Nature 439, 737 (2006) Nature 439 7077 Letter 737 740 http://dx.doi.org/10.1038/nature04443 Molecular processes that govern pathogenic features of erythrocyte invasion and cytoadherence in malaria are reliant on Plasmodium-specific Duffy-binding-like domains (DBLs). These cysteine-rich modules recognize diverse host cell-surface receptors during pathogenesis. DBLs of parasite erythrocyte-binding proteins mediate invasion, and those from the antigenically variant P. falciparum erythrocyte membrane protein 1 (PfEMP1) have been implicated in cytoadherence. The simian and human malarial parasites, P. knowlesi and P. vivax, invade human erythrocytes exclusively through the host DARC receptor (Duffy antigen receptor for chemokines). Here we present the crystal structure of the P. knowlesi DBL domain (Pkα-DBL), which binds to DARC during invasion of human erythrocytes. Pkα-DBL retains the overall fold observed in DBLs from P. falciparumerythrocyte-binding antigen (EBA)-175 (ref. 4). Mapping the residues that have previously been implicated in binding highlights a fairly flat but exposed site for DARC recognition in subdomain 2 of Pkα-DBL; this is in sharp contrast to receptor recognition by EBA-175 (ref. 4). In Pkα-DBL, the residues that contact DARC and the clusters of residues under immune pressure map to opposite surfaces of the DBL, and suggest a possible mechanism for immune evasion by P. vivax. Our comparative structural analysis of Pkα-DBL and P. falciparum EBA-175 provides a framework for the understanding of malaria parasite DBLs, and may affect the development of new prophylactic and therapeutic strategies. Structural basis for Duffy recognition by the malaria parasite Duffy-binding-like domain Saurabh Kumar Singh Rachna Hora Hassan Belrhali Chetan E. Chitnis Amit Sharma doi:10.1038/nature04443 Nature 439, 741 (2006) 2005-12-21 Nature 2005-12-21 439 7077 Letter 741 744 http://dx.doi.org/10.1038/nature04295 There is concern that variola virus, the aetiological agent of smallpox, may be used as a biological weapon. For this reason several countries are now stockpiling (vaccinia virus-based) smallpox vaccine. Although the preventive use of smallpox vaccination has been well documented, little is known about its efficacy when used after exposure to the virus. Here we compare the effectiveness of (1) post-exposure smallpox vaccination and (2) antiviral treatment with either cidofovir (also called HPMPC or Vistide) or with a related acyclic nucleoside phosphonate analogue (HPMPO–DAPy) after lethal intratracheal infection of cynomolgus monkeys (Macaca fascicularis) with monkeypox virus (MPXV). MPXV causes a disease similar to human smallpox and this animal model can be used to measure differences in the protective efficacies of classical and new-generation candidate smallpox vaccines. We show that initiation of antiviral treatment 24 h after lethal intratracheal MPXV infection, using either of the antiviral agents and applying various systemic treatment regimens, resulted in significantly reduced mortality and reduced numbers of cutaneous monkeypox lesions. In contrast, when monkeys were vaccinated 24 h after MPXV infection, using a standard human dose of a currently recommended smallpox vaccine (Elstree-RIVM), no significant reduction in mortality was observed. When antiviral therapy was terminated 13 days after infection, all surviving animals had virus-specific serum antibodies and antiviral T lymphocytes. These data show that adequate preparedness for a biological threat involving smallpox should include the possibility of treating exposed individuals with antiviral compounds such as cidofovir or other selective anti-poxvirus drugs. Antiviral treatment is more effective than smallpox vaccination upon lethal monkeypox virus infection Koert J. Stittelaar Johan Neyts Lieve Naesens Geert van Amerongen Rob F. van Lavieren Antonin Holý Erik De Clercq Hubert G. M. Niesters Edwin Fries Chantal Maas Paul G. H. Mulder Ben A. M. van der Zeijst Albert D. M. E. Osterhaus doi:10.1038/nature04295 Nature 439, 745 (2006) 2005-12-11 Nature 2005-12-11 439 7077 Letter 745 748 http://dx.doi.org/10.1038/nature04434 The foundation of western civilization owes much to the high fertility of bread wheat, which results from the stability of its polyploid genome. Despite possessing multiple sets of related chromosomes, hexaploid (bread) and tetraploid (pasta) wheat both behave as diploids at meiosis. Correct pairing of homologous chromosomes is controlled by the Ph1locus. In wheat hybrids, Ph1 prevents pairing between related chromosomes. Lack of Ph1 activity in diploid relatives of wheat suggests that Ph1 arose on polyploidization. Absence of phenotypic variation, apart from dosage effects, and the failure of ethylmethane sulphonate treatment to yield mutants, indicates that Ph1 has a complex structure. Here we have localized Ph1 to a 2.5-megabase interstitial region of wheat chromosome 5B containing a structure consisting of a segment of subtelomeric heterochromatin that inserted into a cluster of cdc2-related genes after polyploidization. The correlation of the presence of this structure with Ph1 activity in related species, and the involvement of heterochromatin with Ph1 (ref. 6) and cdc2 genes with meiosis, makes the structure a good candidate for the Ph1 locus. Molecular characterization of Ph1 as a major chromosome pairing locus in polyploid wheat Simon Griffiths Rebecca Sharp Tracie N. Foote Isabelle Bertin Michael Wanous Steve Reader Isabelle Colas Graham Moore doi:10.1038/nature04434 Nature 439, 749 (2006) Nature 439 7077 Letter 749 752 http://dx.doi.org/10.1038/nature04412 The N-end rule states that the half-life of a protein is determined by the nature of its amino-terminal residue. Eukaryotes and prokaryotes use N-terminal destabilizing residues as a signal to target proteins for degradation by the N-end rule pathway. In eukaryotes an E3 ligase, N-recognin, recognizes N-end rule substrates and mediates their ubiquitination and degradation by the proteasome. In Escherichia coli, N-end rule substrates are degraded by the AAA + chaperone ClpA in complex with the ClpP peptidase (ClpAP). Little is known of the molecular mechanism by which N-end rule substrates are initially selected for proteolysis. Here we report that the ClpAP-specific adaptor, ClpS, is essential for degradation of N-end rule substrates by ClpAP in bacteria. ClpS binds directly to N-terminal destabilizing residues through its substrate-binding site distal to the ClpS–ClpA interface, and targets these substrates to ClpAP for degradation. Degradation by the N-end rule pathway is more complex than anticipated and several other features are involved, including a net positive charge near the N terminus and an unstructured region between the N-terminal signal and the folded protein substrate. Through interaction with this signal, ClpS converts the ClpAP machine into a protease with exquisitely defined specificity, ideally suited to regulatory proteolysis. ClpS is an essential component of the N-end rule pathway in Escherichia coli A. Erbse R. Schmidt T. Bornemann J. Schneider-Mergener A. Mogk R. Zahn D. A. Dougan B. Bukau doi:10.1038/nature04412 Nature 439, 753 (2006) Nature 439 7077 Letter 753 756 http://dx.doi.org/10.1038/439762a The true value of history. Photons do not lie Euan Nisbet doi:10.1038/439762a Nature 439, 762 (2006) 2006-02-08 Nature 2006-02-08 439 7077 Futures 762 762