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Volume 453 Issue 7192, 8 May 2008

The duck-billed platypus (Ornithorhynchus anatinus) is a unique egg-laying mammal, with lactation, venom and a bill. It even has an electro-sensory system for foraging underwater. Platypuses are monotremes descended from the most basal branch of the mammalian lineage and combine aspects of both reptilian and mammalian biology. Now an international consortium reports the sequence and analysis of the platypus genome. It is an amalgam of reptilian, mammalian and its own unique characteristics that provides clues to the function and evolution of all mammalian genomes. This has helped uncover the origins of genomic imprinting; platypus venom proteins were co-opted independently from the same gene families that provided reptile venom; milk protein genes are conserved; and immune gene family expansions are directly related to platypus biology. As well as providing an invaluable resource for comparative genomics, the sequence will be important for monotreme conservation. The cover image (by D. Parer & E. Parer-Cook) shows the unique bill with electro-sensory pits, eye and ear opening behind the eye.

Editorial

  • Editorial |

    Two years on, a National Academies report on US competitiveness struggles to make an impact.

  • Editorial |

    Whether in music or in nature, noise can be full of riches. The trick is to recognize the treasures.

Research Highlights

Journal Club

News

  • News |

    Doctors used to try out their surgical skills on animals before being allowed to work on patients. Now just a handful of US medical schools still have animal labs. Meredith Wadman asks if they've lost a vital tool.

    • Meredith Wadman
  • News |

    NASA's Mars strategy goes from "follow the water" to "arrive at the ice".

    • Eric Hand
  • News |

    Valérie Pecresse has been a member of the French National Assembly (Yvelines department) since 2002. She rose to prominence as the combative spokeswoman for Nicolas Sarkozy's centre-right UMP party during the 2007 presidential race, after which she was appointed minister for higher education and research.

    • Declan Butler

News in Brief

Correction

News Feature

  • News Feature |

    A new way to analyse seismic vibrations is bringing order out of noise to help predict volcanic eruptions or create detailed images of Earth's interior. Rachel Courtland reports.

    • Rachel Courtland
  • News Feature |

    The inner life of a cell is noisy. Helen Pearson discovers how the resulting randomness makes life more challenging - and richer.

    • Helen Pearson

Correspondence

Books & Arts

Essay

  • Essay |

    At the heart of any scientific explanation of music is an understanding of how and why it affects us. In the first of a nine-part essay series, Philip Ball explores just how far we can hope to achieve a full scientific theory of music.

    • Philip Ball

News & Views

  • News & Views |

    Fifteen-year oscillations in Saturn's equatorial stratosphere bear a striking resemblance to the shorter-term oscillations seen on Earth and Jupiter — akin to notes played on a cello, a violin and a viola.

    • Timothy E. Dowling
  • News & Views |

    Although enzymes are superb catalysts, their range of reactions is limited to those that support life. Their repertoire could be expanded by a method that allows artificial enzymes to be made from scratch.

    • Giovanna Ghirlanda
  • News & Views |

    A clever device uses the quantum statistics of electron tunnelling to match image patterns. The circuit is low-power, works at room temperature — and could point to a way forward for silicon electronics.

    • Robert M. Westervelt
  • News & Views |

    Uncontrollable outside influences undermine the whole enterprise of quantum computing. Nailing down the sources of this 'decoherence' in a solid-state system is a step towards solving the problem.

    • Philip C. E. Stamp
  • News & Views |

    With two catalytic activities and many substrates, how does HIV's reverse transcriptase enzyme know what to do to which substrate? Zooming in on the enzyme's molecular interactions provides tantalizing clues.

    • Eddy Arnold
    • Stefan G. Sarafianos

News and Views Q&A

  • News and Views Q&A |

    Most polymers consist of long molecular chains made up of many units connected by covalent bonds — but supramolecular polymers are different. The strikingly dynamic properties of these materials arise from the reversible bonds that hold their chains together, and open up the prospect of many new applications.

    • Tom F. A. de Greef
    • E. W. Meijer

Article

  • Article | | Open Access

    Platypuses are monotremes and combine aspects of both reptilian and mammalian behaviour. An international consortium reports the genome sequence and analysis of Ornithorhynchus anatinus and as expected, parts of the genome look more like mammals, whereas other parts more like reptiles or even chickens.

    • Wesley C. Warren
    • LaDeana W. Hillier
    • Richard K. Wilson
  • Article |

    HIV-1 reverse transcriptase (RT) is an important drug target. RT has two activities, DNA synthesis, and cleavage of a DNA–RNA hybrid. These activities require that RT bind to both DNA and RNA. Single-molecule technology is used to show that the enzyme binds to RNA and DNA in different orientations, and provide insight into how it can flip between these orientations and activities without dissociating from the substrate.

    • Elio A. Abbondanzieri
    • Gregory Bokinsky
    • Xiaowei Zhuang
  • Article |

    A computational protein design was used to generate eight enzymes that were able to catalyse the Kemp elimination, a model reaction for proton transfer from carbon. Directed evolution was used to enhance the catalytic activity of the designed enzymes, demonstrating that the combination of computational protein design and directed evolution is a highly effective strategy to create novel enzymes.

    • Daniela Röthlisberger
    • Olga Khersonsky
    • David Baker

Letter

  • Letter |

    Both Earth and Jupiter have equatorial oscillations in their atmospheres. An analysis of over two decades of observations of Saturn's stratospheric emission finds a similar oscillation. The period is 14.8 ± 1.2 terrestrial years, roughly half of Saturn's year, suggesting the influence of seasonal forcing, as is the case with the Earth's semi-annual oscillation.

    • Glenn S. Orton
    • Padma A. Yanamandra-Fisher
    • Eric Tollestrup
  • Letter |

    The middle atmospheres of planets are driven by a combination of radiative heating and cooling, mean meridional motions, and vertically propagating waves (which originate in the deep troposphere). This paper reports infrared observations showing that Saturn has an equatorial oscillation like Earth's and Jupiter's, as well as a mid-latitude subsidence that may be associated with the equatorial motion.

    • T. Fouchet
    • S. Guerlet
    • F. M. Flasar
  • Letter |

    Molecular magnets are a class of molecule containing multiple magnetic ions whose spins are tightly coupled to give a single 'collective' spin. But it has remained an open question whether the quantum spin states of these molecular entities are sufficiently long-lived to permit useful computation. Pronounced quantum oscillations between the spin states of one such molecular magnet have been observed, indicating that quantum coherence is long-lived.

    • S. Bertaina
    • S. Gambarelli
    • B. Barbara
  • Letter |

    Zeolitic imidazolate frameworks (ZIFs) are porous crystalline materials where organic imidazolate links connect to transition metals to form a tetrahedral framework. Intriguingly, many different ZIF structures can be created by simply adjusting the link-link interactions. Links that result in two new materials with structures of a scale and complexity rarely seen before have now been designed: huge and complex cages within the pore network contain up to 264 vertices, and are constructed from as many as 7,524 atoms.

    • Bo Wang
    • Adrien P. Côté
    • Omar M. Yaghi
  • Letter |

    In 2005, there was a pronounced drought in the western Amazonian rainforest, which seems to have been associated with a period of unusually warm sea-surface temperatures in the North Atlantic. This event can be better understood with reference to the gradient in sea-surface temperatures across the equatorial Atlantic, of which the northern temperature anomalies are just a factor. By incorporating the effects of atmospheric aerosols into the model, the observed variations in this temperature gradient over the past century are reproduced, and it is predicted that the sea-surface conditions conductive to the droughts experienced in 2005 will become much more common.

    • Peter M. Cox
    • Phil P. Harris
    • Carlos A. Nobre
  • Letter |

    Using a data set consisting of 400,000 records covering 3,000 Pyrenean species, it is shown that sampling and scale effects alone can give rise to many conflicting species-richness patterns. Rather than a monotonic decreasing pattern of richness with altitude, a hump-shaped pattern corresponding to a mid-altitudinal richness peak is identified. Apart from sampling issues, it is argued that global reduction in natural lowland habitats also hampers our ability to detect universal patterns in biodiversity.

    • D. Nogués-Bravo
    • M. B. Araújo
    • C. Rahbek
  • Letter |

    The neuronal repressor protein REST (also known as NRSF) maintains self renewal and pluripotency in embryonic stem cells through suppression of the miRNA-21, and is therefore a newly identified member of the transcriptional network maintaining stem cells in a pluripotent state. Knocking down its activity by using of siRNA or deletion of one allele caused loss of self renewal and led the cells to express differentiated markers.

    • Sanjay K. Singh
    • Mohamedi N. Kagalwala
    • Sadhan Majumder
  • Letter |

    Multipotent progenitor cells are like stem cells in their ability to form many kinds of differentiated cells, but they are not able to self renew and thus have a limited lifespan. This paper reports that by mutating only three genes, it is possible to convert multipotent progenitor cells into long-term renewing cells. It is shown that these three genes normally prevent progenitors from self renewing, and suggest a mechanism by which mutations in progenitor cells could cause cancer.

    • Omobolaji O. Akala
    • In-Kyung Park
    • Michael F. Clarke
  • Letter |

    Only a limited amount of information can be stored in short-term memory, but it is unclear whether we store high-quality representations of a small number of items or a larger number of items whose representation is of lower quality. Visual working memory is studied, particularly both the number of representations and the resolution of each representation, with the results favouring the idea that we store a smaller number of objects, with relatively discrete, fixed-resolution representations.

    • Weiwei Zhang
    • Steven J. Luck
  • Letter |

    Apoptotic cells are engulfed by phagocytes in a process that involves the GTPase Rab5. This paper shows that Rab5 promotes phagosome maturation, and Rab5 activation is induced by the guanine nucleotide exchange factor Gapex-5, which is recruited to phagosomes via microtubules.

    • Masahiro Kitano
    • Michio Nakaya
    • Michiyuki Matsuda
  • Letter |

    By testing variants of the budding yeast phosphate response (PHO) genes, it is shown that the affinity of DNA binding sites that are accessible to a transcription factor determines the threshold for promoter activation, and that the binding sites within nucleosomal regions serve to influence the maximal expression of a gene once the nucleosomes are remodelled. Thus nucleosomes can decouple a promoter's threshold of activation from its dynamic range.

    • Felix H. Lam
    • David J. Steger
    • Erin K. O’Shea

Prospects

Regions

  • Regions |

    Specialist research centres are springing up in Canada's biggest city, nourished by government funds that also attract high-calibre scientists. Kurt Kleiner reports.

    • Kurt Kleiner

Movers

Networks and Support

Career View

  • Career View |

    I strive to find the best hummus — and the best experimental approach.

    • Zachary Lippman

Futures

Authors

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