Hot off the presses! Dec 03 Nature

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Latest Articles Include:

• Climatologists under pressure
  - Nature 462(7273):545 (2009)
  Stolen e-mails have revealed no scientific conspiracy, but do highlight ways in which climate researchers could be better supported in the face of public scrutiny.
• Statistical physics: Chess obeys the law
  - Nature 462(7273):546 (2009)
  
• Immunology: Timely defence
  - Nature 462(7273):546 (2009)
  
• Biology: Beetle-juice antifreeze
  - Nature 462(7273):546 (2009)
  
• Environmental chemistry: Plucking pollutants
  - Nature 462(7273):546 (2009)
  
• Genetics: One on one
  - Nature 462(7273):546 (2009)
  
• Neuroscience: Brain's immune connection
  - Nature 462(7273):546 (2009)
  
• Ecology: Diverse recovery
  - Nature 462(7273):547 (2009)
  
• Genetics: Immune impediment
  - Nature 462(7273):547 (2009)
  
• Astronomy: A black hole draws near
  - Nature 462(7273):547 (2009)
  
• Neuroscience: Rude awakening
  - Nature 462(7273):547 (2009)
  
• Journal club
  - Nature 462(7273):547 (2009)
  
• News briefing: 3 December 2009
  - Nature 462(7273):548 (2009)
  The week in science This article is best viewed as a PDF. Policy|Research|Events|People|Business watch|The week ahead|Number crunch|Sound bites China will cut its carbon intensity — the amount of carbon dioxide emitted relative to its economic output — by 40–45% from 2005 levels by 2020, China's State Council decreed on 26 November. The announcement came the day after US President Barack Obama pledged to reduce emissions by 17% by 2020 compared with 2005 levels. See page 550 for more. The Australian Liberal Party, the main opposition to Prime Minister Kevin Rudd's governing Labor Party, elected climate-change sceptic Tony Abbott as its leader on 1 December. The move has jeopardized Rudd's attempt to pass legislation on an emissions-trading scheme before the United Nations Climate Change Conference in Copenhagen next week. Abbott replaces Malcolm Turnbull, who backed amended cap-and-trade legislation, triggering sceptics in his party to try to oust him last week. President Mahmoud Ahmadinejad has ratified an order calling on the Atomic Energy Organization of Iran to draw up plans for ten gas-centrifuge enrichment plants similar to the one already being constructed in Natanz. The directive comes just days after the International Atomic Energy Agency in Vienna urged the Islamic republic to halt its enrichment activities. The death toll from AIDS has topped 25 million people, but new HIV infections are dropping sharply, according to a report released on 24 November by the Joint United Nations Programme on HIV/AIDS and the World Health Organization (WHO). In 2008, some 2.7 million people became infected with the virus, but the rate of infection has dropped by 17% over the past eight years. Meanwhile, the WHO recommended on 30 November that the widely used antiretroviral drug stavudine be phased out because of its "long-term, irreversible" side effects, which include nerve damage. The Spanish government announced on 26 November which universities would benefit from the inaugural round of a €150-million (US$226-million) annual programme to bolster teaching and research in the country. See page 552 for more. The Nuclear Power Corporation of India has ordered a probe into what it believes to be sabotage that exposed 55 workers at its Kaiga plant in southwestern India to radiation last week. The workers were treated for poisoning after drinking from a water cooler contaminated with tritium — a radioactive isotope of hydrogen. Anil Kakodkar, chairman of the Atomic Energy Commission of India, says the tritium may have been introduced into the cooler in a "malevolent act" by a disgruntled employee. Japanese researchers have launched protests against budget cuts proposed by the country's new government. The move coincides with the end of hearings on 27 November to help government-appointed working groups recommend where the axe should fall. See page 557 for more. Just ten days after it was restarted, the Large Hadron Collider (LHC) has become the world's highest-energy particle accelerator. On 30 November, the giant machine, located at CERN, Europe's premier high-energy physics laboratory near Geneva, Switzerland, accelerated two beams of protons to energies of 1.18 teraelectronvolts (TeV). That beats the previous record of 0.98 TeV set by the Tevatron at Fermi National Accelerator Laboratory in Batavia, Illinois. The LHC hopes to reach energies of 3.5 TeV by early 2010. NASA's decade-old Quick Scatterometer or QuikSCAT satellite can no longer fulfil its main mission of measuring global wind speeds and direction after the failure of its key instrument. The satellite's radar dish antenna stopped spinning on 23 November. Data from the satellite, which was designed to last only two years, were used by weather forecasters worldwide. Global sea levels could rise by 1.4 metres by 2100 — around twice as much as predicted by the Intergovernmental Panel on Climate Change in 2007 — owing to the melting of ice sheets in western Antarctica, according to an international review of the continent's climate published on 1 December. The Scientific Committee on Antarctic Research predicts that Antarctica will warm by around 3 °C by 2100 in part because the hole in the ozone layer above the continent, which has shielded the continent from global warming, is healing. See go.nature.com/9BAguz for a copy of the report. Reining in greenhouse-gas emissions could improve public health, says an international task force publishing in The Lancet. The team, led by epidemiologist Andrew Haines at the London School of Hygiene and Tropical Medicine, found that an Indian programme to replace 150 million indoor biomass-burning stoves with low-emissions stoves could, for example, save 12,500 disability-adjusted life-years as well as the equivalent of 0.1–0.2 megatonnes of carbon dioxide per million people in a year (P. Wilkinson et al. Lancet doi:10.1016/S0140-6736(09)61713-X; 2009). See go.nature.com/4BcJ6v for more. M. VATSYAYANA/AFP/GETTY IMAGES Local authorities have delayed plans to open the site of the Union Carbide factory in Bhopal, India, that was responsible for a chemical leak that killed thousands of people 25 years ago this week. The state government of Madyha Pradesh said in early November that it would allow visitors to tour the plant in a bid to reassure people that it was now safe, amid protests from victims' groups (above). But the state's Gas Relief and Rehabilitation Minister Babulal Gaur said last week that the opening would be pushed back until after municipal elections in December, in line with rules forbidding major policy announcements in the run-up to the polls. A. KATRIN PURKISS/REX FEATURES Leszek Borysiewicz (pictured), chief executive of Britain's Medical Research Council (MRC), will step down in October 2010 to become vice-chancellor of the University of Cambridge, UK. He will leave a full year before his term was due to expire, prompting concerns over the council's future. See page 553 for more. Ireland's Máire Geoghegan-Quinn is to be the European Union's next commissioner for research and innovation. Geoghegan-Quinn, appointed on 27 November, is currently a member of the European Court of Auditors. If approved by the European Parliament, she will take up office in January and succeed Slovenia's Janez Potočnik, who will take over the directorate for the environment. The new climate directorate will be headed by Danish environment minister Connie Hedegaard, who will preside over the Copenhagen climate summit this month. Germany's Günther Oettinger has been named as energy commissioner. US President Barack Obama has created a panel to make policy recommendations on bioethical issues. Political theorist Amy Gutmann, president of the University of Pennsylvania in Philadelphia, will chair the Presidential Commission for the Study of Bioethical Issues. Its vice-chair will be materials scientist James Wagner, president of Emory University in Atlanta, Georgia. The commission is expected to produce more policy guidance and be wider ranging than President George W. Bush's bioethics advisory council. See page 553 for more. SOURCE: PHARMAVISION Companies are racing to produce treatments that exploit RNA interference (RNAi), a natural process that silences gene expression in cells. PharmaVision, a biomedical consultancy based in Chichester, UK, estimates that the market for RNAi therapies could be worth more than US$2.9 billion by 2020. But no RNAi therapy has yet completed phase III clinical trials. Results from a phase Ib trial of an RNAi therapy developed by a consortium including TransDerm of Santa Cruz, California, were published on 24 November (S. A. Leachman et al. Mol. Ther. doi:10.1038/mt.2009.273; 2009). A patient treated for pachyonychia congenita, a rare inherited skin disorder, saw some benefit after a series of RNAi injections into lesions on the sole of one foot. But the injections are too painful to treat the disease in the long term and many cancers, for example, cannot be treated by direct injection of an RNAi product. Delivery is not the only problem facing RNAi. In May, a treatment for wet age-related macular degeneration was ditched by Allergan, a biotech company based in Irvine, California, after the therapy failed to improve patients' vision. With concern growing over the side effects of RNAi-based treatments, firms must now "conclusively prove the mechanism of action of their products", says PharmaVision consultant Cheryl Barton. The American Society for Cell Biology meets in San Diego, California. → www.ascb.org Governments attempt to reach a deal on greenhouse-gas emissions at the United Nations Climate Change Conference in Copenhagen. → http://en.cop15.dk and www.nature.com/roadtocopenhagen NASA's Wide-field Infrared Survey Explorer is scheduled to launch from Vandenberg Air Force Base in California. → go.nature.com/EDqMqP Amount of GDP that will be lost each year by the European Union if global temperatures rise by 2.5 °C Source: European Commission Joint Research Centre John Prescott, the Council of Europe's rapporteur on climate change, presses home the urgency of getting a climate deal in Copenhagen this month. There are currently no comments.
• China's climate target: is it achievable?
  - Nature 462(7273):550 (2009)
  The world's top emitter pledges cuts, but "substantial societal reforms" are needed to make them. Reuters Climate analysts are praising China's promise to slash the country's emissions — even as they wonder if the target is achievable or ambitious enough. Last week, China's State Council announced that the country will cut its carbon intensity — carbon emissions per unit of gross domestic product (GDP) — by 40–45% from 2005 levels by 2020. "It is a very welcome decision," says Fatih Birol, chief economist at the International Energy Agency in Paris. "If the target is met, it would have significant implications for China and the rest of the world." Yet some think that the target is not far-reaching enough given China's booming economy and its track record of improving energy efficiency. The country reduced its energy intensity — energy consumption per unit of GDP — by 47% between 1990 and 2005, and looks likely to cut it by another 20% from 2005 levels by the end of next year. Carbon intensity can drop faster than energy intensity if clean-energy sources are brought into the mix. Online collection Xie Zhenhua, deputy director of China's National Development and Reform Commission, says that China has picked low-hanging fruit by closing energy-inefficient factories and power plants. In China, industry accounts for an unusually large share — 50% — of energy consumption. "The further we go, the more challenging and costly it will get," he says. If China sticks to current policies, it will reduce its carbon intensity by about 30% by 2020, says Zou Ji, an environmental economist at Renmin University in Beijing. "To get extra mileage and reach the 40–45% target, China will have to instigate substantial social and economic reforms across the board," he says. Indeed, the China Council for International Cooperation on Environment and Development (CCICED), a joint Chinese and international advisory board to the state government, recently laid out a road map to a low-carbon economy. It includes recommendations in such wide-ranging areas as energy pricing, industrial development, technological innovation, tax systems, land use and urban planning. "The daunting challenge that China faces cannot be underestimated," says Zou. "The concern is not only whether China is willing to make that step forward but whether its development state will allow a smooth economic transition." Emissions peak The new pledge will be included in China's next five-year plan along with policies to help it shift towards a low-carbon economy. The target puts China on a path for emissions to peak around 2030, says Knut Alfsen, head of research at the Center for International Climate and Environmental Research in Oslo, and an author on the CCICED report. That peak, he says, "will take place at a level where emissions per capita are only half of what we have in the developed world today". China's announcement came the day after US President Barack Obama pledged to cut his country's emissions by 17% from 2005 levels by 2020. It is the first time that the world's top two emitters have offered specific targets at the same time for controlling their emissions. "It's very important for the two countries to put numbers on the table," says Jim Watson, a policy researcher at the University of Sussex in Brighton, UK. In recent weeks other developing countries have made ambitious pledges. South Korea has promised a 30% cut below a business-as-usual scenario, and Brazil at least a 36% cut by 2020. Both would be modest cuts compared with 2005 emissions. India followed China's announcement by saying it would "be willing to sign on to an ambitious global target for emissions reductions or limiting temperature increase" — but with the catch that "this must be accompanied by an equitable burden-sharing paradigm". China and India, along with Brazil, South Africa and Sudan, last weekend reiterated developing countries' insistence that developed nations help bear the cost of climate change, including facilitating technology transfer (see page 555). So far, the European Union has pledged the most aggressive emissions cuts in the developed world, of 20% from 1990 levels by 2020, to be increased to 30% below if rich non-EU nations follow suit. The US target announced last week would be equivalent to a 3% reduction from 1990 levels. Obama must also work with the Democrat-­dominated Congress to pass climate legislation that would make its targets binding. The 17% cut he announced last week is in agreement with a bill passed by the House of Representatives earlier this year. The Senate is expected to vote on its own version of climate legislation early in 2010. The Environmental Protection Agency has the authority to regulate carbon dioxide emissions if Congress does not act. ADVERTISEMENT Meanwhile, the Australian parliament has been trying to pass a climate ruling that would cut emissions by up to 25% from 2000 levels by 2020. But on 1 December, the main opposition party elected a new leader who has vowed to oppose the bill, throwing its future into jeopardy. Australia has the highest emissions per capita of any developed nation. China, if it sticks to its plans, may end up leading the way for developing countries. Compared with current levels, the new target would avoid 1 gigatonne of carbon dioxide emissions — equivalent to a quarter of what the world would need to do to limit global temperature rise to 2 °C over pre-industrial times. "China would champion the fight against global warming," says Birol. page 555, www.nature.com/roadtocopenhagen There are currently no comments.
• Battle lines drawn over e-mail leak
  - Nature 462(7273):551 (2009)
  Climatologists remain sanguine over incident. As the blogosphere continues to buzz with discussion about e-mails leaked from the Climatic Research Unit (CRU) at the University of East Anglia (UEA) in Norwich, UK, climatologists are insisting that the controversy will not discredit their science, or hamper a global climate deal. CRU confirmed on 20 November that more than 1,000 e-mails and documents had been copied from its servers and distributed on the Internet (see Nature 462, 397; 2009). Since then, climate sceptics have seized on the material, citing the contents of selected e-mails as evidence that the case for anthropogenic global warming has been over-stated, and US Senator James Inhofe (Republican, Oklahoma) has promised an investigation into the affair. Yet climate experts say the broader impact of the leak will be minimal. "Any suggestions that these e-mails will affect public and policy-makers' understanding of climate science give far too much credence to blog chatter and boastful spin," says Peter Frumhoff, director of science and policy at the Union of Concerned Scientists in Cambridge, Massachusetts. Some, however, are pointing out that certain e-mails highlight a tendency for scientists to respond to critics either by retreating into an ivory tower, or by attempting to quiet dissenting voices. In an open letter posted on http://climateaudit.org, Judith Curry, a climatologist at Georgia Institute of Technology, Atlanta, wrote last week: "Scientists need to consider carefully skeptical arguments and either rebut them or learn from them. Trying to suppress them or discredit the skeptical researcher or blogger is not an ethical strategy and one that will backfire in the long run." The UEA has launched an independent inquiry into both the security breach and whether CRU has dealt appropriately with the deluge of requests for raw climate data it has received under the UK Freedom of Information Act (see Nature 460, 787; 2009). It has also pointed out that more than 95% of the raw data used in CRU climate models has been publicly available for several years. "Science and science institutions should be transparent, but they are not a 24-hour help service for climate sceptics who lack fundamental scientific and technical skills." "Only openness will make the buzz go away. If only the vaguest impression lingers on that studies have been cooked up or that facts have been hidden it will feed conspiracy theories for ages." "Given the overwhelming scientific evidence for climate change, we should deal less and less with climate sceptics. Otherwise we should also deal with folks who think Elvis Presley is still alive, that Earth is less than 6,000 years old and that we cannot possibly have descended from monkeys." "It is important that scientists make their studies completely transparent, but the least ethical way to accuse others is to highlight a sentence and ignore the context in which this sentence has been written." "It is possible that climate science has become too partisan, too centralized. The tribalism that some of the leaked e-mails display is something more usually associated with social organization within pre-modern cultures; it is not attractive when we find it at work inside science." "I doubt that negotiations in Copenhagen will be influenced by this unfortunate incident." Image credits: (From top) Univ. Bern; F. Bimmer/AP; U. Dahl/Technische Universität Berlin; M. Trezzini, Keystone/AP; JPL/NASA; J. Straube/Bellona UPDATE: Phil Jones, the director of the Climatic Research Unit (CRU) at the University of East Anglia, stepped aside from his post on 1 December. In a statement he said: "What is most important is that CRU continues its world-leading research with as little interruption and diversion as possible. After a good deal of consideration I have decided that the best way to achieve this is by stepping aside from the director's role" while the university conducts an independent review of data security and its responses to Freedom of Information requests. There are currently no comments.
• Spanish awards rekindle old rivalries
  - Nature 462(7273):552 (2009)
  An ambitious effort to develop Spanish universities into campuses that are among Europe's best has stoked some long-standing regional rivalries. On 26 November, the government announced which universities would benefit from the inaugural round of an annual programme called the Campus of International Excellence, administered jointly by the Ministry of Science and Innovation and the Ministry of Education. There are currently no comments.
• US bioethics commission promises policy action
  - Nature 462(7273):553 (2009)
  Five months after abruptly dismantling the bioethics advisory council left by his predecessor, US President Barack Obama last week created a new bioethics commission that will move beyond the issues that consumed previous panels, such as stem cells and cloning. Based within the Department of Health and Human Services, the Presidential Commission for the Study of Bioethical Issues is explicitly charged with recommending legislative and regulatory action and promises to have more influence on policy. There are currently no comments.
• British medical research chief quits midterm
  - Nature 462(7273):553 (2009)
  The early departure of the head of Britain's Medical Research Council (MRC) has prompted concern for the future of the funding body. Leszek Borysiewicz announced on 26 November that he will quit as chief executive of the MRC on 1 October 2010 — a year before his four-year term was due to expire — to become vice-chancellor at the University of Cambridge, UK. There are currently no comments.
• Technology transfer on the table
  - Nature 462(7273):555 (2009)
  Climate summit will seek ways to help developing nations build a low-carbon energy infrastructure. To tackle climate change, poor countries may need green technologies, such as these wind turbines in India.A. Dave/Reuters Cutting global carbon emissions and slowing climate change will require a massive dissemination of clean-energy technology from rich nations to the developing world. And although negotiators remain deadlocked over goals for cutting emissions (see page 550), they are converging on a framework for speeding up the spread of the necessary technologies. Several proposals for this will be on the table when delegates from 192 countries gather in Copenhagen for the climate summit next week, but two elements seem to be gathering momentum in the run-up discussions. The first is the idea of a centralized technology-transfer body under the United Nations climate convention. The second is a network of regional centres, or some kind of technology corps, to help poor nations implement sustainable-development plans. Online collection Both proposals sidestep the issue of access to patented technology, the focus of a long-running dispute between rich and poor nations. Instead, they would help poor countries address an array of mundane but in many ways more pernicious issues, such as energy infrastructure, government policy and workforce development, that hinder their ability to absorb new technologies. Blueprints for a solar thermal power station, for instance, aren't much use without qualified engineers to build and run it and power lines to carry the electricity — challenges even for industrialized nations. "You have to come back to the basic question about how technology is flowing to the developing world, and it's primarily flowing through transactions within the business community," says Björn Stigson, president of the World Business Council for Sustainable Development in Geneva, Switzerland. Government policies, local economics and workforce issues can all affect those deals, he says. "The biggest bottleneck is availability of human resources." Exactly how this new framework would function, what kind of authority it would have and how much money it would command remain to be worked out. But poor and rich countries alike support the general idea, says Kunihiko Shimada, a Japanese delegate who has stepped aside as a negotiator in order to co-chair the technology-transfer group at the UN climate talks. "We need a proliferation of efforts and institutions, because we don't know what is going to work." Shimada acknowledges that negotiators in Copenhagen could still get bogged down in the debate over access to the patented technologies found in everything from the latest solar panels to low-emission coal-plant prototypes. Developing countries have to varying degrees called for compulsory licensing, which would force companies to put certain patents in the public domain, or for a fund to purchase patented technologies, which would then be put in the public sphere. Industrialized countries are resisting such proposals, declaring that intellectual property is crucial to driving innovation. In fact, little is known about how patents affect technological diffusion in the energy industry, when any given 'technology', such as a wind turbine or a clean coal plant, might contain dozens or hundreds of patents, many of which originated in other industries. "We are flying blind," says Bernice Lee, a researcher who has been studying the issue at Chatham House, a think tank in London. Lee recently headed a Chatham House analysis of nearly 57,000 patents in six energy sectors, which found that the 30 most-cited patents in each sector took two to three decades to hit the mass market. That lag time will need to be halved by 2025 if the world is to meet its climate goals, according to the report. In order to disperse crucial technologies more quickly and widely, Chatham House recommends expanding global demonstration programmes for high-risk sectors such as carbon capture and storage, coordinating technology standards, and accelerating international collaboration on research and development. ADVERTISEMENT All of these functions could be promoted through a technology-transfer body under the UN climate convention, although few think that will be enough to get the job done. "We need a proliferation of efforts and institutions, because we don't know what is going to work," says Michael Levi, a climate expert at the Council on Foreign Relations in New York City. "What we can't afford is to focus on a single mechanism and then find out over the course of a decade that it doesn't work very well." The developing world, for its part, can't simply wait for the rich countries to equip it for a low-carbon future, says Shane Tomlinson, a researcher with the London-based advocacy group E3G, which promotes sustainable development. One proposal under discussion would require countries to create their own sustainable-development strategies, perhaps in concert with plans for adapting to climate change, to be eligible for international aid. "It's a balanced approach between top–down strategic prioritization and bottom–up low-carbon development plans that is really key to getting the marketplace right," Tomlinson says. "We really do need both." www.nature.com/roadtocopenhagen There are currently no comments.
• Japan budget threat sparks backlash
  - Nature 462(7273):557 (2009)
  Japanese scientists have mobilized a huge national and international protest against the budget-slashing policies of their new government. The criticisms came as government-appointed working groups of roughly 20 people — with few scientists among them — reached the final week of hearings that are recommending budget cuts for 220 government-funded projects, including many major research initiatives. There are currently no comments.
• Dirty pigs beat disease
  - Nature 462(7273):558 (2009)
  Immune system gets a boost from early exposure to bacteria. Outdoor pigs had more 'friendly' gut bacteria than indoor pigs.D. BURTON/NATUREPL.COM Living like a pig could be good for you, according to research showing that dirty piglets pick up 'friendly' bacteria that help them to develop robust immune systems later in life. The results provide support for the hygiene hypothesis, which suggests that a lack of exposure to microbes in early life can affect development of the immune system and increase susceptibility to certain disorders, such as allergies and inflammatory bowel disease. Denise Kelly, a gut immunologist at the University of Aberdeen, UK, who worked on the study, says that the results provide the first direct link between early exposure to microbes, immune health and gene expression (I. E. Mulder et al. BMC Biol. 7, 79; 2009). Until now, she says, that link had been circumstantial. "There has been a lot of hearsay around gut microbiota and how it influences immune function and susceptibility to diseases and allergies." Although many researchers now accept the hygiene hypothesis, says Jean-François Bach, an immunologist at the University of Paris Descartes, there are still questions about how it works, including what role the microbiota has in the gut and how infection helps to protect against disease. "This paper shows that the first days of life are very important," he adds. The researchers took 54 piglets and divided them equally between an outdoor environment, an indoor environment and isolated conditions in which they were fed antibiotics daily. The scientists then killed piglets on day 5 (neonatal stage), day 28 (weaning age) and day 56 (nearing maturity) to study their gut tissue and faeces. The study found that 90% of bacteria in the guts of the outdoor piglets came from the phylum Firmicutes. Most of these were Lactobacillaceae, a family of bacteria known for their ability to limit intestinal pathogens such as Escherichia coli and Salmonella species. By contrast, Firmicutes made up less than 70% of the gut flora in indoor pigs and slightly more than 50% of that in isolated pigs. Pigs from these cleaner environments also had much smaller proportions of bacteria from the Lactobacillaceae. Kelly's team also found that the differences in gut microbes affected the expression of genes associated with the piglets' immune systems. Animals raised in the isolated environment expressed more genes involved in inflammatory immune responses and cholesterol synthesis, whereas genes linked with infection-fighting T cells were expressed in the outdoor-bred pigs. Glenn Gibson, a food microbiologist at the University of Reading, UK, says that previous studies have suggested that immune responses are linked to organisms in the gut. "This study takes a step forwards by tallying the gene-expression response into this," he says. However, he adds, because the study was carried out in pigs, there is no way to be certain that the results are relevant to humans. ADVERTISEMENT Jonathan Rhodes, a gastroenterologist at the Royal Liverpool University Hospital in Liverpool, UK, points out that people with chronic inflammation of the digestive tract, known as Crohn's disease, have reduced numbers of Firmicutes, as did the cleaner piglets. But, he adds, patients with Crohn's also have reduced overall bacterial diversity, similar to the outdoor pigs, suggesting that the results might not extrapolate directly to human disease. Kelly argues, however, that the comparable organ sizes of humans and pigs, and the similarities between the microorganisms found in their guts, makes pigs good model animals for such studies. There are currently no comments.
• Correction
  - Nature 462(7273):558 (2009)
  The News Feature 'Reflecting the past' (Nature 462, 30–32; 2009) suggested that wolves from reintroduction programmes might find their way to the Oostvaardersplassen reserve. In fact, the closest wolves are expanding from eastern Europe without human help. In addition, what was described as cattle 'wallows' are better termed 'scratching pits', as the cattle use their hooves to make them rather than rolling on their backs. There are currently no comments.
• Underwater acoustics: The neutrino and the whale
  - Nature 462(7273):560 (2009)
  To the dock workers and sailors at the port of Catania, in Eastern Sicily, it all looked very suspicious. About once a month during 2005 and 2006, two strangers would walk out to a large wooden cabin at the end of a pier, unlock the door, and remove a small box. There are currently no comments.
• Behaviour: Flies on film
  - Nature 462(7273):562 (2009)
  At full speed, the altercation would have looked like nothing — a brief contact, fractions of a second long, between two flies. But slowed to 1/20th of normal speed it has all the flash and dazzle of an elaborate professional wrestling move. There are currently no comments.
• World view: A tale of two sciences
  - Nature 462(7273):566 (2009)
  The main laboratory of the Toxics Use Reduction Institute (TURI) at the University of Massachusetts Lowell looks more like a 1940s factory machine shop than a state-of-the-art research facility. Yet despite its low-tech feel, TURI could revolutionize the way the United States deals with chemicals in the environment. There are currently no comments.
• Carbon emissions: the poorest forest dwellers could suffer
  - Nature 462(7273):567 (2009)
  Debate on the carbon-credit system known as REDD ('reducing emissions from deforestation and forest degradation') has focused on technical and methodological obstacles and on sourcing carbon finance. The impact of the system on the world's 350 million tropical forest dwellers calls for closer scrutiny.
• Carbon emissions: dry forests may be easier to manage
  - Nature 462(7273):567 (2009)
  You discuss in an Editorial (Nature 462, 11; 2009) the promise of the emissions trading scheme REDD, whereby tropical countries will be rewarded for increased sequestration by forests.
• King Canute and the wisdom of forest conservation
  - Nature 462(7273):567 (2009)
  Copenhagen is where the world's nations are meeting this month to attend the all-important climate summit. It was also the capital of King Canute's empire and, by a quirk of history, it was Canute who drafted the first forest-conservation legislation almost 1,000 years ago, as king of England (John Manwood A Treatise of the Lawes of the Forest Societie of Stationers, London; 1615).
• No quick switch to low-carbon energy
  - Nature 462(7273):568 (2009)
  In the first of two pieces on reducing greenhouse-gas emissions, Gert Jan Kramer and Martin Haigh analyse historic growth in energy systems to explain why deploying alternative technologies will be a long haul.
• Let the global technology race begin
  - Nature 462(7273):570 (2009)
  In the second of two pieces on decarbonization, Isabel Galiana and Christopher Green argue that fostering a technology revolution, not setting emissions targets, is the key to stabilizing the climate.
• Freezes, floes and the future
  - Nature 462(7273):572 (2009)
  The story of Earth's glaciers and ice caps is key to understanding climate science, but this kaleidoscopic account lacks a strong narrative, argues Johannes Oerlemans.
• Gail Wight, artist of science
  - Nature 462(7273):573 (2009)
  The artist Gail Wight has examined X-rays with neuroscientists, pored over skeletal remains alongside archaeologists and thawed insects with animal behaviourists.Wight, an associate professor in the Department of Art and Art History at Stanford University in California, likens her role in these short-term apprenticeships to that of a "lurker".
• The Internet of the ancient world
  - Nature 462(7273):574 (2009)
  The time is 8.00 p.
• Plant biology: Signal advance for abscisic acid
  - Nature 462(7273):575 (2009)
  The hunt for the receptor for abscisic acid, initially marked by false starts and lingering doubts, has met with success. Converging studies now reveal the details of how this plant hormone transmits its message.
• Biological chemistry: Dehydrated but unharmed
  - Nature 462(7273):576 (2009)
  The weakest interactions of protein complexes are thought to be lost when such assemblies are removed from their natural, watery environments. Not so, reveals a study in the vacuum chamber of a mass spectrometer.
• 50 & 100 years ago
  - Nature 462(7273):577 (2009)
  Composition with an Electronic Computer. By Prof. L.
• Astrophysics: Different stellar demise
  - Nature 462(7273):579 (2009)
  A decades-old theory of stellar evolution — that the most massive stars end their life in a peculiar type of explosion termed a pair-instability supernova — finally seems to have been confirmed by observations.
• Neuroscience: Unbearable lightness of touch
  - Nature 462(7273):580 (2009)
  Following inflammation or nerve injury, stimuli that are normally perceived as innocuous can evoke persistent pain. A population of neurons that contributes to this syndrome has now been identified.
• Structural biology: Steps in the right direction
  - Nature 462(7273):581 (2009)
  The ring-shaped helicase enzyme Rho moves along RNA using ATP as an energy source. Coordinating ATP hydrolysis with nucleic-acid binding seems to determine the direction and mechanism of helicase movement.
• Atomic physics: Neutral atoms put in charge
  - Nature 462(7273):584 (2009)
  An elegant experiment shows that atoms subjected to a pair of laser beams can behave like electrons in a magnetic field, as demonstrated by the appearance of quantized vortices in a neutral superfluid.
• Cell biology: Stairway to the proteasome
  - Nature 462(7273):585 (2009)
  The study of fast and intricate enzyme reactions requires methods that have the speed and sophistication to match. Such an approach reveals the way in which proteins are tagged with ubiquitin for destruction.
• Forcing cells to change lineages
  - Nature 462(7273):587 (2009)
  The ability to produce stem cells by induced pluripotency (iPS reprogramming) has rekindled an interest in earlier studies showing that transcription factors can directly convert specialized cells from one lineage to another. Lineage reprogramming has become a powerful tool to study cell fate choice during differentiation, akin to inducing mutations for the discovery of gene functions. The lessons learnt provide a rubric for how cells may be manipulated for therapeutic purposes.
• Direct cell reprogramming is a stochastic process amenable to acceleration
  Hanna J Saha K Pando B van Zon J Lengner CJ Creyghton MP van Oudenaarden A Jaenisch R - Nature 462(7273):595 (2009)
  Direct reprogramming of somatic cells into induced pluripotent stem (iPS) cells can be achieved by overexpression of Oct4, Sox2, Klf4 and c-Myc transcription factors, but only a minority of donor somatic cells can be reprogrammed to pluripotency. Here we demonstrate that reprogramming by these transcription factors is a continuous stochastic process where almost all mouse donor cells eventually give rise to iPS cells on continued growth and transcription factor expression. Additional inhibition of the p53/p21 pathway or overexpression of Lin28 increased the cell division rate and resulted in an accelerated kinetics of iPS cell formation that was directly proportional to the increase in cell proliferation. In contrast, Nanog overexpression accelerated reprogramming in a predominantly cell-division-rate-independent manner. Quantitative analyses define distinct cell-division-rate-dependent and -independent modes for accelerating the stochastic course of reprogramming, and! suggest that the number of cell divisions is a key parameter driving epigenetic reprogramming to pluripotency.
• A gate–latch–lock mechanism for hormone signalling by abscisic acid receptors
  Melcher K Ng LM Zhou XE Soon FF Xu Y Suino-Powell KM Park SY Weiner JJ Fujii H Chinnusamy V Kovach A Li J Wang Y Li J Peterson FC Jensen DR Yong EL Volkman BF Cutler SR Zhu JK Xu HE - Nature 462(7273):602 (2009)
  Abscisic acid (ABA) is a ubiquitous hormone that regulates plant growth, development and responses to environmental stresses. Its action is mediated by the PYR/PYL/RCAR family of START proteins, but it remains unclear how these receptors bind ABA and, in turn, how hormone binding leads to inhibition of the downstream type 2C protein phosphatase (PP2C) effectors. Here we report crystal structures of apo and ABA-bound receptors as well as a ternary PYL2–ABA–PP2C complex. The apo receptors contain an open ligand-binding pocket flanked by a gate that closes in response to ABA by way of conformational changes in two highly conserved -loops that serve as a gate and latch. Moreover, ABA-induced closure of the gate creates a surface that enables the receptor to dock into and competitively inhibit the PP2C active site. A conserved tryptophan in the PP2C inserts directly between the gate and latch, which functions to further lock the receptor in a closed conformation. Togeth! er, our results identify a conserved gate–latch–lock mechanism underlying ABA signalling.
• Structural basis of abscisic acid signalling
  Miyazono KI Miyakawa T Sawano Y Kubota K Kang HJ Asano A Miyauchi Y Takahashi M Zhi Y Fujita Y Yoshida T Kodaira K Yamaguchi-Shinozaki K Tanokura M - Nature 462(7273):609 (2009)
  The phytohormone abscisic acid (ABA) mediates the adaptation of plants to environmental stresses such as drought and regulates developmental signals such as seed maturation. Within plants, the PYR/PYL/RCAR family of START proteins receives ABA to inhibit the phosphatase activity of the group-A protein phosphatases 2C (PP2Cs), which are major negative regulators in ABA signalling. Here we present the crystal structures of the ABA receptor PYL1 bound with (+)-ABA, and the complex formed by the further binding of (+)-ABA-bound PYL1 with the PP2C protein ABI1. PYL1 binds (+)-ABA using the START-protein-specific ligand-binding site, thereby forming a hydrophobic pocket on the surface of the closed lid. (+)-ABA-bound PYL1 tightly interacts with a PP2C domain of ABI1 by using the hydrophobic pocket to cover the active site of ABI1 like a plug. Our results reveal the structural basis of the mechanism of (+)-ABA-dependent inhibition of ABI1 by PYL1 in ABA signalling.
• Detection of sequential polyubiquitylation on a millisecond timescale
  - Nature 462(7273):615 (2009)
  The pathway by which ubiquitin chains are generated on substrate through a cascade of enzymes consisting of an E1, E2 and E3 remains unclear. Multiple distinct models involving chain assembly on E2 or substrate have been proposed. However, the speed and complexity of the reaction have precluded direct experimental tests to distinguish between potential pathways. Here we introduce new theoretical and experimental methodologies to address both limitations. A quantitative framework based on product distribution predicts that the really interesting new gene (RING) E3 enzymes SCFCdc4 and SCF-TrCP work with the E2 Cdc34 to build polyubiquitin chains on substrates by sequential transfers of single ubiquitins. Measurements with millisecond time resolution directly demonstrate that substrate polyubiquitylation proceeds sequentially. Our results present an unprecedented glimpse into the mechanism of RING ubiquitin ligases and illuminate the quantitative parameters that underlie ! the rate and pattern of ubiquitin chain assembly.
• Extreme particle acceleration in the microquasar Cygnus X-3
  Tavani M Bulgarelli A Piano G Sabatini S Striani E Evangelista Y Trois A Pooley G Trushkin S Nizhelskij NA McCollough M Koljonen KI Pucella G Giuliani A Chen AW Costa E Vittorini V Trifoglio M Gianotti F Argan A Barbiellini G Caraveo P Cattaneo PW Cocco V Contessi T D'Ammando F Monte ED De Paris G Di Cocco G Di Persio G Donnarumma I Feroci M Ferrari A Fuschino F Galli M Labanti C Lapshov I Lazzarotto F Lipari P Longo F Mattaini E Marisaldi M Mastropietro M Mauri A Mereghetti S Morelli E Morselli A Pacciani L Pellizzoni A Perotti F Picozza P Pilia M Prest M Rapisarda M Rappoldi A Rossi E Rubini A Scalise E Soffitta P Vallazza E Vercellone S Zambra A Zanello D Pittori C Verrecchia F Giommi P Colafrancesco S Santolamazza P Antonelli A Salotti L - Nature 462(7273):620 (2009)
  Super-massive black holes in active galaxies can accelerate particles to relativistic energies1, producing jets with associated -ray emission. Galactic 'microquasars', which are binary systems consisting of a neutron star or stellar-mass black hole accreting gas from a companion star, also produce relativistic jets, generally together with radio flares2. Apart from an isolated event detected3 in Cygnus X-1, there has hitherto been no systematic evidence for the acceleration of particles to gigaelectronvolt or higher energies in a microquasar, with the consequence that we are as yet unsure about the mechanism of jet energization. Here we report four -ray flares with energies above 100 MeV from the microquasar Cygnus X-3 (an exceptional X-ray binary4, 5, 6 that sporadically produces radio jets7, 8, 9). There is a clear pattern of temporal correlations between the -ray flares and transitional spectral states of the radio-frequency and X-ray emission. Particle acceleration! occurred a few days before radio-jet ejections for two of the four flares, meaning that the process of jet formation implies the production of very energetic particles. In Cygnus X-3, particle energies during the flares can be thousands of times higher than during quiescent states.
• Supernova 2007bi as a pair-instability explosion
  - Nature 462(7273):624 (2009)
  Stars with initial masses such that 10 Minitial 100, where is the solar mass, fuse progressively heavier elements in their centres, until the core is inert iron. The core then gravitationally collapses to a neutron star or a black hole, leading to an explosion—an iron-core-collapse supernova1, 2. By contrast, extremely massive stars with Minitial 140 (if such exist) develop oxygen cores with masses, Mcore, that exceed 50, where high temperatures are reached at relatively low densities. Conversion of energetic, pressure-supporting photons into electron–positron pairs occurs before oxygen ignition and leads to a violent contraction which triggers a nuclear explosion3, 4, 5 that unbinds the star in a pair-instability supernova. Transitional objects with 100 < Minitial < 140 may end up as iron-core-collapse supernovae following violent mass ejections, perhaps as a result of brief episodes of pair instability, and may already have been identified6, 7, 8. Here we rep! ort observations of supernova SN 2007bi, a luminous, slowly evolving object located within a dwarf galaxy. We estimate the exploding core mass to be Mcore 100, in which case theory unambiguously predicts a pair-instability supernova. We show that >3 of radioactive 56Ni was synthesized during the explosion and that our observations are well fitted by models of pair-instability supernovae9, 10. This indicates that nearby dwarf galaxies probably host extremely massive stars, above the apparent Galactic stellar mass limit11, which perhaps result from processes similar to those that created the first stars in the Universe.
• Synthetic magnetic fields for ultracold neutral atoms
  - Nature 462(7273):628 (2009)
  Neutral atomic Bose condensates and degenerate Fermi gases have been used to realize important many-body phenomena in their most simple and essential forms1, 2, 3, without many of the complexities usually associated with material systems. However, the charge neutrality of these systems presents an apparent limitation—a wide range of intriguing phenomena arise from the Lorentz force for charged particles in a magnetic field, such as the fractional quantum Hall effect in two-dimensional electron systems4, 5. The limitation can be circumvented by exploiting the equivalence of the Lorentz force and the Coriolis force to create synthetic magnetic fields in rotating neutral systems. This was demonstrated by the appearance of quantized vortices in pioneering experiments6, 7, 8, 9 on rotating quantum gases, a hallmark of superfluids or superconductors in a magnetic field. However, because of technical issues limiting the maximum rotation velocity, the metastable nature of th! e rotating state and the difficulty of applying stable rotating optical lattices, rotational approaches are not able to reach the large fields required for quantum Hall physics10, 11, 12. Here we experimentally realize an optically synthesized magnetic field for ultracold neutral atoms, which is evident from the appearance of vortices in our Bose–Einstein condensate. Our approach uses a spatially dependent optical coupling between internal states of the atoms, yielding a Berry's phase13 sufficient to create large synthetic magnetic fields, and is not subject to the limitations of rotating systems. With a suitable lattice configuration, it should be possible to reach the quantum Hall regime, potentially enabling studies of topological quantum computation.
• Controlling photonic structures using optical forces
  Wiederhecker GS Chen L Gondarenko A Lipson M - Nature 462(7273):633 (2009)
  The use of optical forces to manipulate small objects is well known. Applications include the manipulation of living cells by optical tweezers1 and optical cooling in atomic physics2. The miniaturization of optical systems (to the micro and nanoscale) has resulted in very compliant systems with masses of the order of nanograms, rendering them susceptible to optical forces3, 4, 5, 6. Optical forces have been exploited to demonstrate chaotic quivering of microcavities7, optical cooling of mechanical modes8, 9, 10, 11, actuation of a tapered-fibre waveguide and excitation of the mechanical modes of silicon nano-beams12, 13. Despite recent progress in this field14, 15, 16, 17, it is challenging to manipulate the optical response of photonic structures using optical forces; this is because of the large forces that are required to induce appreciable changes in the geometry of the structure. Here we implement a resonant structure whose optical response can be efficiently stat! ically controlled using relatively weak attractive and repulsive optical forces. We demonstrate a static mechanical deformation of up to 20 nanometres in a silicon nitride structure, using three milliwatts of continuous optical power. Because of the sensitivity of the optical response to this deformation, such optically induced static displacement introduces resonance shifts spanning 80 times the intrinsic resonance linewidth.
• Half-precessional dynamics of monsoon rainfall near the East African Equator
  - Nature 462(7273):637 (2009)
  External climate forcings—such as long-term changes in solar insolation—generate different climate responses in tropical and high latitude regions1. Documenting the spatial and temporal variability of past climates is therefore critical for understanding how such forcings are translated into regional climate variability. In contrast to the data-rich middle and high latitudes, high-quality climate-proxy records from equatorial regions are relatively few2, 3, 4, especially from regions experiencing the bimodal seasonal rainfall distribution associated with twice-annual passage of the Intertropical Convergence Zone. Here we present a continuous and well-resolved climate-proxy record of hydrological variability during the past 25,000 years from equatorial East Africa. Our results, based on complementary evidence from seismic-reflection stratigraphy and organic biomarker molecules in the sediment record of Lake Challa near Mount Kilimanjaro, reveal that monsoon rainfall! in this region varied at half-precessional (11,500-year) intervals in phase with orbitally controlled insolation forcing. The southeasterly and northeasterly monsoons that advect moisture from the western Indian Ocean were strengthened in alternation when the inter-hemispheric insolation gradient was at a maximum; dry conditions prevailed when neither monsoon was intensified and modest local March or September insolation weakened the rain season that followed. On sub-millennial timescales, the temporal pattern of hydrological change on the East African Equator bears clear high-northern-latitude signatures, but on the orbital timescale it mainly responded to low-latitude insolation forcing. Predominance of low-latitude climate processes in this monsoon region can be attributed to the low-latitude position of its continental regions of surface air flow convergence, and its relative isolation from the Atlantic Ocean, where prominent meridional overturning circulation more tig! htly couples low-latitude climate regimes to high-latitude bou! ndary conditions.
• Common dependence on stress for the two fundamental laws of statistical seismology
  - Nature 462(7273):642 (2009)
  Two of the long-standing relationships of statistical seismology are power laws: the Gutenberg–Richter relation1 describing the earthquake frequency–magnitude distribution, and the Omori–Utsu law2 characterizing the temporal decay of aftershock rate following a main shock. Recently, the effect of stress on the slope (the b value) of the earthquake frequency–magnitude distribution was determined3 by investigations of the faulting-style dependence of the b value. In a similar manner, we study here aftershock sequences according to the faulting style of their main shocks. We show that the time delay before the onset of the power-law aftershock decay rate (the c value) is on average shorter for thrust main shocks than for normal fault earthquakes, taking intermediate values for strike-slip events. These similar dependences on the faulting style indicate that both of the fundamental power laws are governed by the state of stress. Focal mechanisms are known for only ! 2 per cent of aftershocks. Therefore, c and b values are independent estimates and can be used as new tools to infer the stress field, which remains difficult to measure directly.
• Regulation of adaptive behaviour during fasting by hypothalamic Foxa2
  - Nature 462(7273):646 (2009)
  The lateral hypothalamic area is considered the classic 'feeding centre', regulating food intake, arousal and motivated behaviour through the actions of orexin and melanin-concentrating hormone (MCH)1, 2, 3. These neuropeptides are inhibited in response to feeding-related signals and are released during fasting. However, the molecular mechanisms that regulate and integrate these signals remain poorly understood. Here we show that the forkhead box transcription factor Foxa2, a downstream target of insulin signalling4, 5, 6, regulates the expression of orexin and MCH. During fasting, Foxa2 binds to MCH and orexin promoters and stimulates their expression. In fed and in hyperinsulinemic obese mice, insulin signalling leads to nuclear exclusion of Foxa2 and reduced expression of MCH and orexin. Constitutive activation of Foxa2 in the brain (Nes-Cre/+;Foxa2T156Aflox/flox genotype) results in increased neuronal MCH and orexin expression and increased food consumption, metabo! lism and insulin sensitivity. Spontaneous physical activity of these animals in the fed state is significantly increased and is similar to that in fasted mice. Conditional activation of Foxa2 through the T156A mutation expression in the brain of obese mice also resulted in improved glucose homeostasis, decreased fat and increased lean body mass. Our results demonstrate that Foxa2 can act as a metabolic sensor in neurons of the lateral hypothalamic area to integrate metabolic signals, adaptive behaviour and physiological responses.
• Injury-induced mechanical hypersensitivity requires C-low threshold mechanoreceptors
  Seal RP Wang X Guan Y Raja SN Woodbury CJ Basbaum AI Edwards RH - Nature 462(7273):651 (2009)
  Mechanical pain contributes to the morbidity associated with inflammation and trauma, but primary sensory neurons that convey the sensation of acute and persistent mechanical pain have not been identified. Dorsal root ganglion (DRG) neurons transmit sensory information to the spinal cord using the excitatory transmitter glutamate1, a process that depends on glutamate transport into synaptic vesicles for regulated exocytotic release. Here we report that a small subset of cells in the DRG expresses the low abundance vesicular glutamate transporter VGLUT3 (also known as SLC17A8). In the dorsal horn of the spinal cord, these afferents project to lamina I and the innermost layer of lamina II, which has previously been implicated in persistent pain caused by injury2. Because the different VGLUT isoforms generally have a non-redundant pattern of expression3, we used Vglut3 knockout mice to assess the role of VGLUT3+ primary afferents in the behavioural response to somatosenso! ry input. The loss of VGLUT3 specifically impairs mechanical pain sensation, and in particular the mechanical hypersensitivity to normally innocuous stimuli that accompanies inflammation, nerve injury and trauma. Direct recording from VGLUT3+ neurons in the DRG further identifies them as a poorly understood population of unmyelinated, low threshold mechanoreceptors (C-LTMRs)4, 5. The analysis of Vglut3-/- mice now indicates a critical role for C-LTMRs in the mechanical hypersensitivity caused by injury.
• Exceptional structured noncoding RNAs revealed by bacterial metagenome analysis
  - Nature 462(7273):656 (2009)
  Estimates of the total number of bacterial species1, 2, 3 indicate that existing DNA sequence databases carry only a tiny fraction of the total amount of DNA sequence space represented by this division of life. Indeed, environmental DNA samples have been shown to encode many previously unknown classes of proteins4 and RNAs5. Bioinformatics searches6, 7, 8, 9, 10 of genomic DNA from bacteria commonly identify new noncoding RNAs (ncRNAs)10, 11, 12 such as riboswitches13, 14. In rare instances, RNAs that exhibit more extensive sequence and structural conservation across a wide range of bacteria are encountered15, 16. Given that large structured RNAs are known to carry out complex biochemical functions such as protein synthesis and RNA processing reactions, identifying more RNAs of great size and intricate structure is likely to reveal additional biochemical functions that can be achieved by RNA. We applied an updated computational pipeline17 to discover ncRNAs that rival ! the known large ribozymes in size and structural complexity or that are among the most abundant RNAs in bacteria that encode them. These RNAs would have been difficult or impossible to detect without examining environmental DNA sequences, indicating that numerous RNAs with extraordinary size, structural complexity, or other exceptional characteristics remain to be discovered in unexplored sequence space.
• In vitro reconstitution of an abscisic acid signalling pathway
  Fujii H Chinnusamy V Rodrigues A Rubio S Antoni R Park SY Cutler SR Sheen J Rodriguez PL Zhu JK - Nature 462(7273):660 (2009)
  The phytohormone abscisic acid (ABA) regulates the expression of many genes in plants; it has critical functions in stress resistance and in growth and development1, 2, 3, 4, 5, 6, 7. Several proteins have been reported to function as ABA receptors8, 9, 10, 11, 12, 13, and many more are known to be involved in ABA signalling3, 4, 14. However, the identities of ABA receptors remain controversial and the mechanism of signalling from perception to downstream gene expression is unclear15, 16. Here we show that by combining the recently identified ABA receptor PYR1 with the type 2C protein phosphatase (PP2C) ABI1, the serine/threonine protein kinase SnRK2.6/OST1 and the transcription factor ABF2/AREB1, we can reconstitute ABA-triggered phosphorylation of the transcription factor in vitro. Introduction of these four components into plant protoplasts results in ABA-responsive gene expression. Protoplast and test-tube reconstitution assays were used to test the function of var! ious members of the receptor, protein phosphatase and kinase families. Our results suggest that the default state of the SnRK2 kinases is an autophosphorylated, active state and that the SnRK2 kinases are kept inactive by the PP2Cs through physical interaction and dephosphorylation. We found that in the presence of ABA, the PYR/PYL (pyrabactin resistance 1/PYR1-like) receptor proteins can disrupt the interaction between the SnRK2s and PP2Cs, thus preventing the PP2C-mediated dephosphorylation of the SnRK2s and resulting in the activation of the SnRK2 kinases. Our results reveal new insights into ABA signalling mechanisms and define a minimal set of core components of a complete major ABA signalling pathway.
• The abscisic acid receptor PYR1 in complex with abscisic acid
  Santiago J Dupeux F Round A Antoni R Park SY Jamin M Cutler SR Rodriguez PL Márquez JA - Nature 462(7273):665 (2009)
  The plant hormone abscisic acid (ABA) has a central role in coordinating the adaptive response in situations of decreased water availability as well as the regulation of plant growth and development. Recently, a 14-member family of intracellular ABA receptors, named PYR/PYL/RCAR1, 2, 3, has been identified. These proteins inhibit in an ABA-dependent manner the activity of a family of key negative regulators of the ABA signalling pathway: the group-A protein phosphatases type 2C (PP2Cs)4, 5, 6. Here we present the crystal structure of Arabidopsis thaliana PYR1, which consists of a dimer in which one of the subunits is bound to ABA. In the ligand-bound subunit, the loops surrounding the entry to the binding cavity fold over the ABA molecule, enclosing it inside, whereas in the empty subunit they form a channel leaving an open access to the cavity, indicating that conformational changes in these loops have a critical role in the stabilization of the hormone–receptor com! plex. By providing structural details on the ABA-binding pocket, this work paves the way for the development of new small molecules able to activate the plant stress response.
• Hidden alternative structures of proline isomerase essential for catalysis
  - Nature 462(7273):669 (2009)
  A long-standing challenge is to understand at the atomic level how protein dynamics contribute to enzyme catalysis. X-ray crystallography can provide snapshots of conformational substates sampled during enzymatic reactions1, while NMR relaxation methods reveal the rates of interconversion between substates and the corresponding relative populations1, 2. However, these current methods cannot simultaneously reveal the detailed atomic structures of the rare states and rationalize the finding that intrinsic motions in the free enzyme occur on a timescale similar to the catalytic turnover rate. Here we introduce dual strategies of ambient-temperature X-ray crystallographic data collection and automated electron-density sampling to structurally unravel interconverting substates of the human proline isomerase, cyclophilin A (CYPA, also known as PPIA). A conservative mutation outside the active site was designed to stabilize features of the previously hidden minor conformation! . This mutation not only inverts the equilibrium between the substates, but also causes large, parallel reductions in the conformational interconversion rates and the catalytic rate. These studies introduce crystallographic approaches to define functional minor protein conformations and, in combination with NMR analysis of the enzyme dynamics in solution, show how collective motions directly contribute to the catalytic power of an enzyme.
• Remote triggering of fault-strength changes on the San Andreas fault at Parkfield
  - Nature 462(7273):674 (2009)
  Nature 461, 636–639 (2009) In Figure 2a of this Letter, in the key, the green line was inadvertently labelled 'SMN' instead of 'CCRB'. Also, in Figure 2c, the y-axis label should be 'Recurrence interval (d)' and not 'Recurrence index (d)'. The correct figure is shown below.
• El Niño in a changing climate
  - Nature 462(7273):674 (2009)
  Nature 461, 511–514 (2009) In Figure 4 of this letter, the key for the 20C3M ensemble (red line) and the SRESA1B ensemble (blue line) were inadvertently mislabelled. The correct figure is shown below.
• Integration of neuronal clones in the radial cortical columns by EphA and ephrin-A signalling
  - Nature 462(7273):674 (2009)
  Nature 461, 524–528 (2009) On page 1 of this Letter, Efna2 was inadvertently listed as Efna1 when describing the triple knockout mouse (knockout for Efna2, Efna3 and Efna5). Also, in the online-only Methods section of this Letter, the triple knockout mouse (Efna2/a3/a5) was inadvertently written as Epha2/a3/a5.
• Microscopy: Ever-increasing resolution
  - Nature 462(7273):675 (2009)
  Overcoming the limitations of spatial and temporal resolution to image within a cell is no easy feat. Kelly Rae Chi examines the latest diffraction-busting technologies.
• Microscopy: Breaking the light barrier
  - Nature 462(7273):676 (2009)
  In 1873, German physicist Ernst Abbe proposed that diffraction fundamentally limited the resolution that any microscope could achieve to around half the wavelength of light. And, despite many advances, microscopes didn't threaten to challenge this law of physics for more than a century.
• Microscopy: Table of suppliers
  - Nature 462(7273):679 (2009)
  Table 1
• Press '1' to begin
  - Nature 462(7273):688 (2009)
  The art of conversation.