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Volume 452 Issue 7186, 27 March 2008

Recent advances in crystallography and cryo-electron microscopy have increased our current under-standing of the ribosomeã‚â’s role in protein synthesis, the translation of the information encoded by messenger RNA code into a poly-peptide. Now in a technical tour de force, Jin-Der Wen et al. have used optical tweezers to follow the translation of a single mRNA by an E. coli ribosome one codon at a time. An mRNA (yellow on the cover) is tracked as it is unwound and translated. Translation, it turns out, is not a continuous process but occurs through successive translocation-and-pause cycles. Each cycle consists of a translocation step of three nucleotides in less than 0.1 s, then a pause of a few seconds. These are the first direct real-time observations of the physical steps of the ribosome machine along the mRNA during translation. The resulting single-molecule assay can address problems in translation not accessible using traditional bulk methods, including translational gene regulation and the fidelity of translation. [Article p. 598] Graphic by Laura Lancaster and Courtney Hodges, using Ribbons (Carson, 1997).

Editorial

  • Editorial |

    Arthur C. Clarke's technological prescience deserves to be honoured; his endless optimism needs to be cherished.

  • Editorial |

    Science coverage is on the wane when public scrutiny of science is more important than ever.

  • Editorial |

    Stem-cell research is in danger of falling foul of haste.

Research Highlights

Journal Club

News

News in Brief

  • News in Brief |

    Scribbles on the margins of science.

News

News in Brief

News Feature

  • News Feature |

    Chemists have long wanted to recreate photosynthesis in the lab — and to improve on its efficiency at converting sunlight into fuel. Katharine Sanderson reports on their latest efforts.

    • Katharine Sanderson
  • News Feature |

    The 'Doomsday vault' buried in the Arctic ice will provide a backup for the world's seeds. But more needs to be done to safeguard food diversity, says Michael Hopkin.

    • Michael Hopkin

Correspondence

Books & Arts

News & Views

  • News & Views |

    In the fable of the tortoise and the hare, the reptilian slowcoach beats its fleet-footed rival in a race. A zinc catalyst recreates this story by giving a less reactive chemical group a turn of speed over a rival group.

    • Gorka Peris
    • Scott J. Miller
  • News & Views |

    Circadian activity in the brain regulates the movement of blood stem cells into and out of the bone marrow. Perhaps this process is testing the suitability of these cell 'tenants' for their new home — the remodelling bone.

    • David T. Scadden
  • News & Views |

    Observations of intensely bright star-forming galaxies both close by and in the far Universe seem to emphasize their similarities. But look a little closer, and telling differences emerge.

    • Yu Gao
  • News & Views |

    Spintronics is an emerging branch of electronics that exploits electrons' spin, rather than charge. In carbon nanotubes, the coupling of this spin with electron motion could offer a desirable way to control quantum information.

    • Arne Brataas
  • News & Views |

    To store information, the brain modulates synapses, which mediate communication between neurons. A closer look hints that subcellular changes in response to groups of synapses facilitate this process.

    • Nelson Spruston

Article

  • Article |

    In this paper gene expression is treated as a quantitative trait in both blood and adipose tissue, and associations between specific genetic loci and body mass index are identified using a molecular network approach.

    • Valur Emilsson
    • Gudmar Thorleifsson
    • Kari Stefansson
  • Article |

    Standard approaches to identify the genetic changes that lead to disease are reversed by examination of genetic networks for perturbations that are associated with disease states, and following up candidate genes from there. This begins with three genes in mice that lead to obesity when mutated, demonstrating that complex genetic–environmental traits can be dissected with this new approach.

    • Yanqing Chen
    • Jun Zhu
    • Eric E. Schadt
  • Article |

    A newly discovered mechanism for synaptic plasticity whereby higher-order information can be stored in the forward propagation of local dendritic branch spikes is described. It is reported that coupling between branches and the soma is not static as previously thought, but that an associative form of branch plasticity allows neurons to encode the spatio-temporal correlation of inputs.

    • Attila Losonczy
    • Judit K. Makara
    • Jeffrey C. Magee
  • Article |

    Circulating haematopoetic stem cells and their progenitors exhibit robust circadian fluctuations, peaking 5 hours after the initiation of light and reaching a nadir 5 hours after darkness. Circadian oscillations are markedly altered when mice are subjected to continuous light or to a 'jet lag' (defined as a shift of 12 h). Data also suggests that circadian, neurally driven haematopoetic stem cells release during the animal's resting period may promote regeneration of the stem cell niche, and possibly of other tissues.

    • Simón Méndez-Ferrer
    • Daniel Lucas
    • Paul S. Frenette

Letter

  • Letter |

    Based on a detailed set of electronic transport measurements on high-quality, clean single walled carbon nanotubes, direct signatures of electron spin-orbit coupling are observed. The findings may lead to new design principles for the realization of qubits in nanotubes. Furthermore, the observed spin-orbit coupling may prove to be a valuable tool as a mechanism for all-electrical control of spins in carbon nanotubes.

    • F. Kuemmeth
    • S. Ilani
    • P. L. McEuen
  • Letter |

    Organocatalysts are useful in a wide range of useful transformations, including a carbon–carbon bond forming process known as the Mannich reaction. But these reactions always failed when the simplest possible substrate, acetaldehyde, was used. This paper has now filled this gap in the market by devising effective organocatalytic conditions for Mannich reactions with acetaldehyde, greatly expanding the chemical 'toolkit' of organic chemists.

    • Jung Woon Yang
    • Carley Chandler
    • Benjamin List
  • Letter |

    Molybdenum and total organic carbon data from black shales is used to gain insights into the redox state of the ocean. The data suggests mild oxidative weathering of the continents before 2,200 Myr ago, but weathering becomes more persistent and vigorous at 2,150 Myr ago, 200 million years after the initial rise in atmospheric oxygen. Limited availability of molybdenum after 1,800 Myr ago may have acted as a negative nutrient feedback limiting the spatial and temporal extent of sulphidic conditions.

    • C. Scott
    • T. W. Lyons
    • A. D. Anbar
  • Letter |

    Near the Faroe Islands in the North Atlantic, the majority of basalt is intruded into the continent–ocean transition, rather than extruded onto the surface. This melt is intruded into the lower-crust as sills, which cross-cut the continental fabric, rather than as an 'underplate' of 100% melt, as has often been assumed.

    • R. S. White
    • L. K. Smith
    • V. J. Tymms
  • Letter |

    The discovery of a human lower jaw associated with stone tools and animal bones from the Sima del Elefante in northern Spain is reported. The finds have been dated to between 1.1 and 1.2 million years using a variety of dating techniques, making the site the oldest and most accurately dated record of human occupation in Europe.

    • Eudald Carbonell
    • José M. Bermúdez de Castro
    • Juan L. Arsuaga

    Collection:

  • Letter |

    As more genetic sequence data are generated, evolutionary biology questions about inheritance and phenotypes can be examined with sophisticated analyses. This paper examines pleiotropy, or multiple effects from one genetic mutation, on the skeletal characteristics of mice. It is concluded there is no 'cost of complexity' for higher organisms.

    • Günter P. Wagner
    • Jane P. Kenney-Hunt
    • James M. Cheverud
  • Letter |

    Despite marked behavioural differences between the sexes, surprisingly few anatomic features have been observed that differentiate the male and female brain in any species. But this study unveils a sexual dimorphism in the neuronal circuit responding to a pheromone, which induces different courtship behaviours in male and female fruitflies. The single neuron tracing technique that has been developed to do so should be useful to study the nervous systems of other genetically tractable species.

    • Sandeep Robert Datta
    • Maria Luisa Vasconcelos
    • Richard Axel

Prospects

Special Report

  • Special Report |

    Vaccines are no longer 'worthy but dull'. A heady mix of funding and breakthroughs is bringing this once-quiet area to life, says Virginia Gewin.

    • Virginia Gewin

Futures

  • Futures |

    Never work with children or animals.

    • Elizabeth Counihan

Authors

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