Research articles

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  • 'Blue straggler' stars lie on or near the main sequence of star clusters and are sufficiently massive that they should have evolved into white dwarfs long ago. Statistical evidence indicates that in globular star clusters the blue stragglers probably form from binary stars. Here, 76 per cent of the blue stragglers in the open cluster NGC 188 are found to be currently in binary systems, a three times higher frequency than that among normal solar-type main-sequence stars.

    • Robert D. Mathieu
    • Aaron M. Geller
    Letter
  • A longstanding aim in molecular-scale electronics is to create a true transistor analogue in which charge transport through a molecule is directly controlled by external modulation of the molecular orbitals. The observation of such a solid-state molecular device is now reported. The data demonstrate that true molecular transistors can be created, and clear the way for molecularly engineered electronic devices.

    • Hyunwook Song
    • Youngsang Kim
    • Takhee Lee
    Letter
  • Coastal ecosystems are sensitive to changes in the quantity and lability of terrigenous dissolved organic matter (DOM) delivered by rivers. The lability of DOM is thought to decrease with age, but this view stems from work in watersheds where terrestrial plant and soil sources dominate streamwater DOM. Here, glaciated watersheds on the Gulf of Alaska are shown to be a source of old but labile dissolved organic matter, suggesting that glacial runoff is an important source of labile reduced carbon to marine ecosystems.

    • Eran Hood
    • Jason Fellman
    • Durelle Scott
    Letter
  • As the climate changes, species will have to move if they are to remain in an area with the same average temperature. Here, this required movement — termed the velocity of temperature change — is quantified. The results indicate management strategies for minimizing biodiversity loss from climate change and suggest that montane landscapes may effectively shelter many species into the next century.

    • Scott R. Loarie
    • Philip B. Duffy
    • David D. Ackerly
    Letter
  • Non-small-cell lung cancers with activating mutations in the epidermal growth factor receptor (EGFR) often show a clinical response to EGFR kinase inhibitors but tend to develop drug-resistance mutations, including the gatekeeper T790M mutation. Here, a new class of EGFR inhibitors is developed; these agents are 30- to 100-fold more potent against EGFR with the T790M mutation, and up to 100-fold less potent against wild-type EGFR, than current EGFR inhibitors.

    • Wenjun Zhou
    • Dalia Ercan
    • Pasi A. Jänne
    Letter
  • Although magnetic fields have an important role in the evolution of gas clouds in the Galaxy, the strength and orientation of the field in the interstellar medium near the heliosphere has been poorly constrained, with previous estimates varying widely and based on indirect observational inferences or modelling. Measurements of the deflection of the solar wind plasma flows in the heliosheath are now used to determine the magnetic field strength and orientation in the interstellar medium.

    • M. Opher
    • F. Alouani Bibi
    • T. I. Gombosi
    Letter
  • 'Blue straggler' stars lie on or near the main sequence of star clusters and are sufficiently massive that they should have evolved into white dwarfs long ago. Two possible mechanisms have been proposed for their formation: mass transfer between binary companions and stellar mergers resulting from direct collisions between two stars. Here, two distinct parallel sequences of blue stragglers are reported in the globular cluster M 30, one arising from the evolution of close binaries, the other from direct collisions.

    • F. R. Ferraro
    • G. Beccari
    • S. Bovinelli
    Letter
  • Non-volcanic tremor was discovered nearly a decade ago; however, a thorough explanation of the geologic process responsible for tremor generation has yet to be determined. A robust correlation is now identified between extremely small, tidally induced shear stress parallel to the San Andreas fault and non-volcanic tremor activity near Parkfield, California. Such tremor may represent shear failure on a critically stressed fault in the presence of near-lithostatic pore pressure.

    • Amanda M. Thomas
    • Robert M. Nadeau
    • Roland Bürgmann
    Letter
  • The ATP-dependent chromatin assembly factor (ACF) generates and maintains nucleosome spacing by constantly moving a nucleosome towards the longer flanking DNA faster than the shorter flanking DNA. But how the enzyme moves back and forth between both sides of a nucleosome to accomplish bidirectional movement is unknown. Nucleosome movement is now shown to depend cooperatively on two ACF molecules, indicating that ACF functions as a dimer of ATPases.

    • Lisa R. Racki
    • Janet G. Yang
    • Geeta J. Narlikar
    Article
  • There are now nearly 1,000 completed bacterial and archaeal genomes available, but as most of them were chosen for sequencing on the basis of their physiology, the data are limited by a highly biased phylogenetic distribution. To explore the value added by choosing microbial genomes for sequencing on the basis of their evolutionary relationships, the genomes of 56 species of Bacteria and Archaea selected to maximize phylogenetic coverage are now sequenced and analysed.

    • Dongying Wu
    • Philip Hugenholtz
    • Jonathan A. Eisen
    Letter Open Access
  • The ATP-dependent chromatin assembly factor (ACF) generates regularly spaced nucleosomes, but the mechanism by which ACF mobilizes nucleosomes remains poorly understood. Here, single-molecule FRET is used to monitor the remodelling of individual nucleosomes by ACF in real time; the study reveals previously unknown remodelling intermediates and dynamics, and indicates that ACF is a highly processive and bidirectional nucleosome translocase.

    • Timothy R. Blosser
    • Janet G. Yang
    • Xiaowei Zhuang
    Article
  • Multiple somatic rearrangements are often found in cancer genomes, but the underlying processes of rearrangement and the effects of this are unclear. A paired-end sequencing strategy is now used to map somatic rearrangements in human breast cancer genomes. More rearrangements in some breast cancers are found than previously recognized, including frequent tandem duplications that may reflect a specific defect in DNA maintenance.

    • Philip J. Stephens
    • David J. McBride
    • Michael R. Stratton
    Article
  • A mesenchymal phenotype is the hallmark of tumour aggressiveness in human malignant glioma, but the regulatory programs responsible for implementing the associated molecular signature are largely unknown. Reverse-engineering and an unbiased interrogation of a glioma-specific regulatory network now reveal the transcription factors that activate expression of mesenchymal genes in malignant glioma.

    • Maria Stella Carro
    • Wei Keat Lim
    • Antonio Iavarone
    Article
  • The small coding capacity of the influenza A virus demands that the virus use the host cellular machinery for many aspects of its life cycle. An integrated systems approach, based on genome-wide RNA interference screening, is now used to identify 295 cellular cofactors required for early-stage influenza virus replication. Knowledge of these host cell requirements provides further targets that could be pursued for antiviral drug development.

    • Renate König
    • Silke Stertz
    • Sumit K. Chanda
    Letter
  • To elucidate regulatory mechanisms involved in reprogramming to generate pluripotent cells from somatic cells, this study generates interspecies heterokaryons (fused mouse ES cells and human fibroblasts) that induce reprogramming efficiently, rapidly and without cell division. SiRNA–mediated knockdown reveals that AID is required for active DNA demethylation and initiation of nuclear reprogramming towards pluripotency in human somatic cells.

    • Nidhi Bhutani
    • Jennifer J. Brady
    • Helen M. Blau
    Article
  • If broken chromosomes arising from DNA double-strand breaks are left unrepaired or incorrectly repaired, they can lead to genomic changes that may result in cell death or cancer. DNA-dependent protein kinase (DNA-PK), which comprises the DNA-PK catalytic subunit (DNA-PKcs) and the heterodimer Ku70/Ku80, has a major role in the repair of double-strand breaks. The crystal structure of human DNA-PKcs is now presented, in which the overall fold is clearly visible.

    • Bancinyane L. Sibanda
    • Dimitri Y. Chirgadze
    • Tom L. Blundell
    Letter
  • Innate immune responses are important in the early phases of infection; for example, natural killer cells are innate lymphocytes that rapidly exhibit cytotoxic activities against virus-infected cells and produce various cytokines. Here, a new type of innate lymphocyte is found in a novel lymphoid structure associated with adipose tissues in the peritoneal cavity. These cells, termed FALC (fat-associated lymphoid cluster) cells, produce TH2 cytokines and support B1 cells.

    • Kazuyo Moro
    • Taketo Yamada
    • Shigeo Koyasu
    Letter
  • MCL1 — essential for the survival of stem and progenitor cells of multiple lineages — is unique among pro-survival BCL2 family members in that it is rapidly turned over through the action of ubiquitin ligases. Abnormally high levels of MCL1 are expressed in some cancers, but the mechanism of MCL1 overexpression is not well understood. The deubiquitinase USP9X is now shown to stabilize MCL1 and thereby promote cell survival; this makes it a potential therapeutic target.

    • Martin Schwickart
    • XiaoDong Huang
    • Vishva M. Dixit
    Letter
  • Optical near-field microscopies can achieve spatial resolutions beyond the diffraction limit, but they cannot match the atomic-scale resolution of electron microscopy. Here, the development of photon-induced near-field electron microscopy — an ingenious blend of these two imaging modalities — opens the way for direct space-time imaging of localized fields at interfaces and visualization of phenomena related to photonics, plasmonics and nanostructures.

    • Brett Barwick
    • David J. Flannigan
    • Ahmed H. Zewail
    Letter
  • Universal patterns can be observed in many collective human activities, including violence. However, the possibility of universal patterns ranging across wars in the size distribution or timing of within-conflict events has barely been explored. Here, the sizes and timing of violent events within different insurgent conflicts are shown to exhibit remarkable similarities, and a unified model of human insurgency — with an interesting resemblance to financial market models — is proposed.

    • Juan Camilo Bohorquez
    • Sean Gourley
    • Neil F. Johnson
    Letter