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Volume 467 Issue 7318, 21 October 2010

More than half of the global population lives in cities. This press of people is a breeding ground for some of the world’s greatest problems: pollution, poverty, disease and crime. Yet humankind is sometimes at its best in cities - and, as the series of News Feature and Comment pieces in this issue demonstrates, science is important to cities and cities to science. Cover credit: Oliver Munday.

Editorial

  • IPCC members last week considered the best way to quantify uncertainty. They are not alone in needing to do so — the media must also take a firm line when it comes to scientific reporting.

    Editorial

    Advertisement

  • Scientists researching problems such as water management should focus more on urban areas.

    Editorial
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World View

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Research Highlights

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Seven Days

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News

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News Feature

  • With the majority of the human population now living in cities, Nature takes a look at the implications for scientists.

    News Feature
  • The explosion in urban population looks set to continue through the twenty-first century, presenting challenges and opportunities for scientists.

    News Feature
  • After winning a Nobel prize for helping to protect the planet, Mario Molina is tackling a much more difficult problem — trying to clean up Mexico City.

    • Jeff Tollefson
    News Feature
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Comment

  • Scientists should do the research to help mayors prepare for a warming world, say Cynthia Rosenzweig, William Solecki, Stephen A. Hammer and Shagun Mehrotra.

    • Cynthia Rosenzweig
    • William Solecki
    • Shagun Mehrotra
    Comment
  • It is time for a science of how city growth affects society and environment, say Luis Bettencourt and Geoffrey West.

    • Luis Bettencourt
    • Geoffrey West
    Comment
  • As the data deluge swells, statisticians are evolving from contributors to collaborators. Sallie Ann Keller urges funders, universities and associations to encourage this shift.

    • Sallie Ann Keller
    Comment
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Books & Arts

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Correspondence

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News & Views

  • A female can develop a diabetes-like disease due to a high fat content in her father's diet before she was conceived. Epigenetic modifications of the father's sperm DNA might underlie this peculiar observation. See Letter p.963

    • Michael K. Skinner
    News & Views
  • The use of templates to control the morphology of nanostructures is a powerful but inflexible technique. A template that is remodelled during synthesis suggests fresh opportunities for fabricating new nanostructures.

    • Younan Xia
    • Byungkwon Lim
    News & Views
  • A galaxy has smashed the record for the most distant object ever observed. The object sheds light on the nature of the sources that stripped electrons from hydrogen atoms during the reionization epoch. See Letter p.940

    • Michele Trenti
    News & Views
  • Proteins that pump a wide range of toxic compounds out of cells are ubiquitous in nature, but crystal structures for one family of these transporters have remained elusive. Until now. See Letter p.991

    • Hendrik W. van Veen
    News & Views
  • The origin of the diffuse aurora, whose beauty and intensity pale beside those of the famous aurora borealis, has remained controversial. A convincing explanation for this auroral display is now at hand. See Letter p.943

    • Patrick T. Newell
    News & Views
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Hypothesis

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Article

  • DEAD-box helicases use ATP hydrolysis to unwind duplex RNA and facilitate RNA or RNA–protein remodelling. One such helicase is Mss116, which targets a particular group II intron in RNA. Here, single-molecule fluorescence was used to monitor the effect of Mss16 on a minimal construct containing this intron. The data show that Mss16 stimulates the sampling of different folded states of the RNA. Moreover, the helicase promotes RNA folding through discrete ATP-independent and ATP-dependent steps.

    • Krishanthi S. Karunatilaka
    • Amanda Solem
    • David Rueda
    Article
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Letter

  • Until now, the most distant spectroscopically confirmed galaxies known in the Universe were at redshifts of z = 8.2 and z = 6.96. It is now reported that the galaxy UDFy-38135539 is at a redshift of z = 8.5549 ± 0.0002. The finding has implications for our understanding of the timing, location and nature of the sources responsible for reionization of the Universe after the Big Bang.

    • M. D. Lehnert
    • N. P. H. Nesvadba
    • S. Basa
    Letter
  • Earth's diffuse aurora occurs over a broad latitude range, and is mainly caused by the precipitation of low-energy electrons originating in the central plasma sheet. Theory suggests that two classes of magnetospheric plasma waves — electrostatic electron cyclotron harmonic waves and whistler-mode chorus waves — could be responsible for the electron scattering that leads to diffuse auroral precipitation. Here it is found that scattering by chorus is the dominant cause of the most intense diffuse precipitation.

    • Richard M. Thorne
    • Binbin Ni
    • Nigel P. Meredith
    Letter
  • Electrophoresis is a motion of charged dispersed particles relative to a fluid in a uniform electric field. Here it is described how an anisotropic fluid — a nematic liquid crystal — can lead to motion of both charged and neutral particles, even when they are perfectly symmetrical, in any type of electric field. The phenomenon is caused by a distortion in the orientation of the liquid crystals around the particles. The approach could see applications in, for example, display technologies and colloidal assembly and disassembly.

    • Oleg D. Lavrentovich
    • Israel Lazo
    • Oleg P. Pishnyak
    Letter
  • Climate change is expected to intensify the global hydrological cycle and to alter evapotranspiration, but direct observational constraints are lacking at the global scale. Now a data-driven, machine-learning technique and a suite of process-based models have been used to show that from 1982 to 1997 global evapotranspiration increased by about 7.1 millimetres per year per decade. But since 1998 this increase has ceased, probably because of moisture limitation in the Southern Hemisphere.

    • Martin Jung
    • Markus Reichstein
    • Ke Zhang
    Letter
  • The Palaeocene–Eocene thermal maximum (PETM) is a well-known abrupt warming that occurred at about 55.8 Myr ago and is usually thought to have been caused by a large release of greenhouse gases, as recorded in a large carbon isotope excursion. Yet some marine evidence suggests that in fact the warming came first. Here it is shown that continental warming of about 5 °C preceded the excursion in the Bighorn Basin, Wyoming. Thus the PETM seems to have been caused by at least two separate warming events.

    • Ross Secord
    • Philip D. Gingerich
    • Kenneth G. MacLeod
    Letter
  • Climate change is expected to shift the latitudinal and altitudinal ranges of species, but the low latitude or low altitude edge does not necessarily move as fast as the high edge. Here, demographic data on two tundra plants have been used to show that changed demographic rates at the lower edge are compensating for the warming climate, but that this effect will not last and a tipping point will be reached as temperatures get warmer.

    • Daniel F. Doak
    • William F. Morris
    Letter
  • Here it is shown that the consumption of a high-fat diet by male rats has an intergenerational effect: it leads to the dysfunction of pancreatic β-cells in female offspring. Relative to controls, these offspring showed an early onset of impaired insulin secretion and glucose tolerance, which worsened with time. The results add to our understanding of the complex genetic and environmental factors that are leading to the global epidemic of obesity and type 2 diabetes.

    • Sheau-Fang Ng
    • Ruby C. Y. Lin
    • Margaret J. Morris
    Letter
  • CD4+ T cells that selectively produce interleukin (IL)-17 (TH17 cells) are essential for host defence and autoimmunity. It has been thought that IL-6 and transforming growth factor (TGF)-β1 are the factors responsible for initiating the specification of TH17 cells. Here, however, it is shown that TH17 differentiation can occur in the absence of TGF-β signalling. IL-6, IL-23 and IL-1β effectively induced IL-17 production in naive precursors. These data reveal an alternative mode for TH17 differentiation and the importance of IL-23.

    • Kamran Ghoreschi
    • Arian Laurence
    • John J. O’Shea
    Letter
  • Here it is shown that the end products of lipid oxidation — ω-(2-carboxyethyl) pyrrole and other related pyrroles — are generated during inflammation and wound healing, and accumulate at high levels in ageing tissues in mice and in highly vascularized tumours in murine and human melanomas. These carboxyalkylpyrroles are recognized by Toll-like receptor 2 on endothelial cells, setting off a chain of events that leads to the growth of new blood vessels.

    • Xiaoxia Z. West
    • Nikolay L. Malinin
    • Tatiana V. Byzova
    Letter
  • Two forms of X-chromosome inactivation ensure the selective silencing of female sex chromosomes in mouse embryos. Imprinted silencing begins with the detection of Xist RNA expression on the paternal X chromosome at about the four-cell stage of development. Later, a random form of inactivation silences either the paternal or the maternal X chromosome. Here it is shown that maternal deposits of the ubiquitin ligase Rnf12/RLIM are required for the imprinted form of X-chromosome inactivation.

    • JongDae Shin
    • Michael Bossenz
    • Ingolf Bach
    Letter
  • Bacterial chromosomes often carry integrated genetic elements (such as plasmids and prophages) that contribute to the evolutionary fitness of the host bacterium. In Vibrio cholerae, a prophage encodes cholera toxin. Here, the events that led to the acquisition of phage DNA have been reconstructed, revealing the cooperative interactions between multiple filamentous phages that contributed to the emergence of virulent V. cholerae strains.

    • Faizule Hassan
    • M. Kamruzzaman
    • Shah M. Faruque
    Letter
  • The aberrant expression of microRNAs and of the enzymes that control their processing has been reported in tumours, but the mechanisms involved are not clear. It is now shown that TAp63, a member of the p53 family of tumour suppressors, suppresses tumorigeneis and metastasis by directly controlling the expression of Dicer (a microRNA-processing enzyme) and Dicer-regulated microRNAs.

    • Xiaohua Su
    • Deepavali Chakravarti
    • Elsa R. Flores
    Letter
  • Transporter proteins from the MATE (multidrug and toxic compound extrusion) family are involved in metabolite transport in plants, and in multiple-drug resistance in bacteria and mammals. Here, the X-ray crystal structure of a MATE transporter from Vibrio cholerae is reported. The structure is in an outward-facing conformation, and reveals a cation-binding site near to residues previously deemed essential for transport.

    • Xiao He
    • Paul Szewczyk
    • Geoffrey Chang
    Letter
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Feature

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Column

  • To get a job these days, don't rely on your adviser — use your own networking skills, says Peter Fiske.

    • Peter Fiske
    Column
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Career Brief

  • Singapore aims to attract local and international young scientific talent.

    Career Brief
  • Doctoral and postdoctoral scholarships in Argentina aim to boost science research pipeline.

    Career Brief
  • Speakers exhort legislators to fund young scientists.

    Career Brief
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Futures

  • A vision to behold.

    • Elizabeth Counihan
    Futures
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