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Volume 460 Issue 7255, 30 July 2009

A dye measurement on a Mastigias sp. jellyfish in Jellyfish Lake, Palau. Kakani Katija and John Dabiri used data from experiments like this, combined with a new theoretical model, to show that the contribution of living organisms to ocean mixing via a mechanism described by Sir Charles Darwin - grandson of the Charles Darwin - is the same order of magnitude as that of winds and tides. Photo credit: Kakani Katija.

Authors

Editorial

  • Editorial |

    A report released last week by the US National Academies makes recommendations for tackling the issues surrounding the era of petabyte science.

  • Editorial |

    The vast reserves of US natural gas must be used judiciously to ease the transition to clean energy.

  • Editorial |

    Those wishing to reveal scientific ideas should learn from the engaging style of TED conference talks.

Research Highlights

Journal Club

News

News in Brief

News Feature

  • News Feature |

    A vast supply of energy is racing around the planet far above the surface. Erik Vance meets the engineers trying to bring the power of high-altitude wind down to earth.

    • Erik Vance
  • News Feature |

    Multiphoton microscopy is allowing immunologists to watch infections as they happen. Jeanne Erdmann pulls up a seat.

    • Jeanne Erdmann

Correspondence

Essay

  • Essay |

    The Western public's misapprehension that genius in science is always male and caucasian is partly a legacy of Victorian politics, says Christine MacLeod.

    • Christine MacLeod

Books & Arts

  • Books & Arts |

    Nature regulars give their recommendations for relaxed, inspiring holiday reading and viewing — from climate-change history to Isaac Newton the detective.

    • David Poeppel
    • Mike Brown
    • Adam Kepecs

News & Views

  • News & Views |

    An illusion device, placed near but not enclosing an object of arbitrary shape, manipulates and transforms light scattered off the object so as to give it the appearance of a completely different object.

    • John Pendry
  • News & Views |

    Cavernous chambers, intricate passages, a gate with a curious lock — the structure of an ATP-activated ion channel reveals its architecture. And this intriguing interior design is found in another type of ion channel too.

    • Shai D. Silberberg
    • Kenton J. Swartz
  • News & Views |

    Ocean life is in almost constant motion, and such activity must surely stir things up. Innovative investigations into this concept of 'biogenic mixing' show a role for jellyfish and their brethren.

    • William K. Dewar
  • News & Views |

    Saturn's rotation period has been a mystery. An estimate based on its meteorology comes with implications for our understanding of the planet's atmospheric jet streams and interior structure.

    • Adam P. Showman
  • News & Views |

    Analysis of the platinum-group elements in a particular type of ancient volcanic rock provides clues about Earth's early history as well as a fresh approach to understanding mantle dynamics.

    • Nicholas Arndt
  • News & Views |

    A regulatory protein thought to be crucial for maintaining the muscle stem-cell pool throughout life is shown to be dispensable in the adult. Muscle biologists are left wondering what fundamental things apply as time goes by.

    • Terry Partridge
  • News & Views |

    Violent criminals are imprisoned to keep them under control. Similarly, incarceration in a molecular jail stops white phosphorus from bursting into flames — but on release, it regains its fiery character.

    • Kenneth N. Raymond

Review Article

Article

  • Article |

    P2X receptors are ATP-gated cation channels that are implicated in diverse physiological processes, from synaptic transmission to inflammation to the sensing of taste and pain. The crystal structure of the zebrafish P2X4 channel is now solved in its closed state, revealing some of the molecular underpinnings of ligand-binding, cation entry and channel gating.

    • Toshimitsu Kawate
    • Jennifer Carlisle Michel
    • Eric Gouaux
  • Article |

    Like P2X receptors, acid-sensing ion channels are trimeric in structure; however, they belong to an entirely different family. Here, the structure of an acid-sensing ion channel is presented and compared to the structure of P2X4, suggesting that these functionally distinct channels use similar mechanistic principles.

    • Eric B. Gonzales
    • Toshimitsu Kawate
    • Eric Gouaux

Letter

  • Letter |

    The origin of dwarf spheroidal galaxies is one of the outstanding puzzles of how galaxies form. Previous theories require that they orbit near giant galaxies like the Milky Way, but some dwarfs have been observed in the outskirts of the Local Group. Here, simulations of encounters between dwarf disk galaxies and somewhat larger dwarfs yield results that may account for some of the observed properties of dwarf spheroidals in the Local Group.

    • Elena D'Onghia
    • Gurtina Besla
    • Lars Hernquist
  • Letter |

    The rotation period of a gas giant's magnetic field (the System III reference frame) is commonly used to infer its bulk rotation, but this approach cannot be used for Saturn because its dipole magnetic field is not tilted relative to its rotation axis. Consequently, the surrogate measure of long-wavelength radiation is used to fix the System III rotation period. The period as recently measured by the Cassini spacecraft is up to 7 minutes longer than the value measured 28 years ago by Voyager. Here, a determination of Saturn's rotation period is reported, based on an analysis of potential vorticity.

    • P. L. Read
    • T. E. Dowling
    • G. Schubert
  • Letter |

    A simple underlying mechanism for the random assembly of granular particles, analogous to crystalline ordering, remains unknown. Here however, three-dimensional measurements of packings of polydisperse emulsion droplets are used to build a statistical model where the complexity of the global packing can be understood in terms of two simple, local parameters — the available space around a particle and the ratio of contacts to neighbours.

    • Maxime Clusel
    • Eric I. Corwin
    • Jasna Brujić
  • Letter |

    The feedback between the terrestrial carbon cycle and climate is one of the largest uncertainties in current projections of future climate, with the long-term sensitivity of carbon in peatlands remaining unclear. The combination of non-disturbing in situ measurements of carbon dioxide respiration rates and isotopic composition of respired CO2 in subarctic peatland experiments now shows that warming accelerates respiration rates of these subsurface carbon reservoirs to a much larger extent than was previously thought.

    • Ellen Dorrepaal
    • Sylvia Toet
    • Rien Aerts
  • Letter |

    Komatiites are ancient volcanic rocks, mostly from the Archaean era, that formed through high degrees of partial melting of the mantle and therefore provide reliable information on bulk mantle compositions. Here it is shown that most early Archaean komatiites from the Barberton greenstone belt of South Africa and the Pilbara craton of Western Australia are depleted in platinum group elements (PGEs) relative to late Archaean and younger komatiites, and the variations of this depletion with time suggests that PGE-enriched cosmic material was progressively mixed into the deep mantle.

    • Wolfgang D. Maier
    • Stephen J. Barnes
    • R. Hugh Smithies
  • Letter |

    Sir Charles Darwin, grandson of the famous evolutionary pioneer, was a physicist who suggested that swimming animals might contribute significantly to the mixing of water in the ocean. Here, observations of swimming jellyfish are used to create and validate a theoretical model for the relative contributions of Darwinian mixing and turbulent wake mixing. The contribution of living organisms to ocean mixing is found to be substantial — in the same order of magnitude as winds and tides.

    • Kakani Katija
    • John O. Dabiri
  • Letter |

    The myogenic determinant Pax7 is thought to have a critical role in adult muscle stem cells (satellite cells), but a formal demonstration has been lacking in vivo. Here it is shown that, unexpectedly, when Pax7 is inactivated in adult mice, mutant satellite cells are not compromised in muscle regeneration. Multiple time points of gene inactivation reveal that Pax7 is only required up to the juvenile period, indicating an age-dependent change in the genetic requirement for muscle stem cells.

    • Christoph Lepper
    • Simon J. Conway
    • Chen-Ming Fan
  • Letter |

    Mutations in the presenilin genes are associated with familial cases of Alzheimer's disease, but the precise site and nature of the synaptic dysfunction remain unknown. Using a genetic approach to selectively inactivate presenilins in a mouse model, it has been possible to demonstrate that they act in the presynaptic compartment to control the activity-dependent efficacy of neurotransmitter release, a process essential for neuronal computation, learning and memory.

    • Chen Zhang
    • Bei Wu
    • Jie Shen
  • Letter |

    Macrophages possess several substances with which they can kill bacteria, including reactive oxygen species, nitric oxide, and antimicrobial proteins. Here, macrophage elastase, an enzyme implicated in several disease processes including emphysema, is shown to have direct antimicrobial activity against Gram-positive and Gram-negative bacteria.

    • A. McGarry Houghton
    • William O. Hartzell
    • Steven D. Shapiro
  • Letter |

    During development of the vertebrate nervous system, a switch in the subunit composition of the BAF chromatin-remodelling complex occurs when cells lose multipotency and begin to develop stable connections that will persist for a lifetime. Here, the switch in BAF subunits is shown to be mediated by two microRNAs that are selectively expressed in post-mitotic neurons.

    • Andrew S. Yoo
    • Brett T. Staahl
    • Gerald R. Crabtree
  • Letter |

    Female mammals undergo silencing of most genes on one of their two X chromosomes in a process termed X-chromosome inactivation (XCI). In placental mammals, the non-coding RNA Xist is thought to trigger XCI. Here it is demonstrated that silencing of the paternal X chromosome (Xp) is able to initiate in the absence of paternal Xist; Xist is, however, required to stabilize silencing along the Xp.

    • Sundeep Kalantry
    • Sonya Purushothaman
    • Terry Magnuson

Corrigendum

Prospects

  • Prospects |

    Can religious belief really be reconciled with a life in science? Gene Russo contemplates the contradictions.

    • Gene Russo

News

Careers Q&A

  • Careers Q&A |

    Inaugural chief of the Division of Biomedical Informatics at the University of California, San Diego.

Postdoc Journal

  • Postdoc Journal |

    Feeling the effects of the economic downturn.

    • Julia Boughner

Career Brief

Futures

Brief Communications Arising

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