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Journal Cover   Science
  [SJR: 12.465]   [H-I: 801]   [2166 followers]  Follow
   Full-text available via subscription Subscription journal
   ISSN (Print) 0036-8075 - ISSN (Online) 1095-9203
   Published by American Association for the Advancement of Science (AAAS) Homepage  [4 journals]
  • [Research Article] The complete structure of the 55S mammalian
           mitochondrial ribosome
    • Authors: Basil J. Greber
      Abstract: Mammalian mitochondrial ribosomes (mitoribosomes) synthesize mitochondrially encoded membrane proteins that are critical for mitochondrial function. Here we present the complete atomic structure of the porcine 55S mitoribosome at 3.8 angstrom resolution by cryo–electron microscopy and chemical cross-linking/mass spectrometry. The structure of the 28S subunit in the complex was resolved at 3.6 angstrom resolution by focused alignment, which allowed building of a detailed atomic structure including all of its 15 mitoribosomal-specific proteins. The structure reveals the intersubunit contacts in the 55S mitoribosome, the molecular architecture of the mitoribosomal messenger RNA (mRNA) binding channel and its interaction with transfer RNAs, and provides insight into the highly specialized mechanism of mRNA recruitment to the 28S subunit. Furthermore, the structure contributes to a mechanistic understanding of aminoglycoside ototoxicity.
      Authors : Basil J. Greber, Philipp Bieri, Marc Leibundgut, Alexander Leitner, Ruedi Aebersold, Daniel Boehringer, Nenad Ban
      PubDate: 2015-04-17
      DOI: 10.1126/science.aaa3872
  • [Report] Subatomic resolution force microscopy reveals internal structure
           and adsorption sites of small iron clusters
    • Authors: Matthias Emmrich
      Abstract: Clusters built from individual iron atoms adsorbed on surfaces (adatoms) were investigated by atomic force microscopy (AFM) with subatomic resolution. Single copper and iron adatoms appeared as toroidal structures and multiatom clusters as connected structures, showing each individual atom as a torus. For single adatoms, the toroidal shape of the AFM image depends on the bonding symmetry of the adatom to the underlying structure [twofold for copper on copper(110) and threefold for iron on copper(111)]. Density functional theory calculations support the experimental data. The findings correct our previous work, in which multiple minima in the AFM signal were interpreted as a reflection of the orientation of a single front atom, and suggest that dual and triple minima in the force signal are caused by dimer and trimer tips, respectively.
      Authors : Matthias Emmrich, Ferdinand Huber, Florian Pielmeier, Joachim Welker, Thomas Hofmann, Maximilian Schneiderbauer, Daniel Meuer, Svitlana Polesya, Sergiy Mankovsky, Diemo Ködderitzsch, Hubert Ebert, Franz J. Giessibl
      PubDate: 2015-04-17
      DOI: 10.1126/science.aaa5329
  • [Report] Quasiparticle mass enhancement approaching optimal doping in a
           high-Tc superconductor
    • Authors: B. J. Ramshaw
      Abstract: In the quest for superconductors with higher transition temperatures (Tc), one emerging motif is that electronic interactions favorable for superconductivity can be enhanced by fluctuations of a broken-symmetry phase. Recent experiments have suggested the existence of the requisite broken-symmetry phase in the high-Tc cuprates, but the impact of such a phase on the ground-state electronic interactions has remained unclear. We used magnetic fields exceeding 90 tesla to access the underlying metallic state of the cuprate YBa2Cu3O6+δ over a wide range of doping, and observed magnetic quantum oscillations that reveal a strong enhancement of the quasiparticle effective mass toward optimal doping. This mass enhancement results from increasing electronic interactions approaching optimal doping, and suggests a quantum critical point at a hole doping of pcrit ≈ 0.18.
      Authors : B. J. Ramshaw, S. E. Sebastian, R. D. McDonald, James Day, B. S. Tan, Z. Zhu, J. B. Betts, Ruixing Liang, D. A. Bonn, W. N. Hardy, N. Harrison
      PubDate: 2015-04-17
      DOI: 10.1126/science.aaa4990
  • [Report] A strong magnetic field in the jet base of a supermassive black
    • Authors: Ivan Martí-Vidal
      Abstract: Active galactic nuclei (AGN) host some of the most energetic phenomena in the universe. AGN are thought to be powered by accretion of matter onto a rotating disk that surrounds a supermassive black hole. Jet streams can be boosted in energy near the event horizon of the black hole and then flow outward along the rotation axis of the disk. The mechanism that forms such a jet and guides it over scales from a few light-days up to millions of light-years remains uncertain, but magnetic fields are thought to play a critical role. Using the Atacama Large Millimeter/submillimeter Array (ALMA), we have detected a polarization signal (Faraday rotation) related to the strong magnetic field at the jet base of a distant AGN, PKS 1830−211. The amount of Faraday rotation (rotation measure) is proportional to the integral of the magnetic field strength along the line of sight times the density of electrons. The high rotation measures derived suggest magnetic fields of at least tens of Gauss (and possibly considerably higher) on scales of the order of light-days (0.01 parsec) from the black hole.
      Authors : Ivan Martí-Vidal, Sébastien Muller, Wouter Vlemmings, Cathy Horellou, Susanne Aalto
      PubDate: 2015-04-17
      DOI: 10.1126/science.aaa1784
  • [Report] Evidence for mature bulges and an inside-out quenching phase 3
           billion years after the Big Bang
    • Authors: S. Tacchella
      Abstract: Most present-day galaxies with stellar masses ≥1011 solar masses show no ongoing star formation and are dense spheroids. Ten billion years ago, similarly massive galaxies were typically forming stars at rates of hundreds solar masses per year. It is debated how star formation ceased, on which time scales, and how this “quenching” relates to the emergence of dense spheroids. We measured stellar mass and star-formation rate surface density distributions in star-forming galaxies at redshift 2.2 with ~1-kiloparsec resolution. We find that, in the most massive galaxies, star formation is quenched from the inside out, on time scales less than 1 billion years in the inner regions, up to a few billion years in the outer disks. These galaxies sustain high star-formation activity at large radii, while hosting fully grown and already quenched bulges in their cores.
      Authors : S. Tacchella, C. M. Carollo, A. Renzini, N. M. Förster Schreiber, P. Lang, S. Wuyts, G. Cresci, A. Dekel, R. Genzel, S. J. Lilly, C. Mancini, S. Newman, M. Onodera, A. Shapley, L. Tacconi, J. Woo, G. Zamorani
      PubDate: 2015-04-17
      DOI: 10.1126/science.1261094
  • [This Week in Science] Metal clusters really close-up
    • Authors: Phil Szuromi
      Abstract: Author: Phil Szuromi
      Keywords: Surface Structure
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.298-r
  • [This Week in Science] Engineering superenzyme function
    • Authors: Guy Riddihough
      Abstract: Author: Guy Riddihough
      Keywords: Protein Structure
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.298-s
  • [This Week in Science] Red cells need leucine for hemoglobin
    • Authors: Wei Wong
      Abstract: Author: Wei Wong
      Keywords: Physiology
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.298-t
  • [Editors' Choice] Of mice and men
    • Authors: Laura M. Zahn
      Abstract: Author: Laura M. Zahn
      Keywords: Immunogenetics
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.299-a
  • [Editors' Choice] Challenging antimicrobial growth trends
    • Authors: Caroline Ash
      Abstract: Author: Caroline Ash
      Keywords: Antibiotic Resistance
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.299-f
  • [Editors' Choice] Not a panacea
    • Authors: Sacha Vignieri
      Abstract: Author: Sacha Vignieri
      Keywords: Speciation
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.299-g
  • [Review] Evolutionary innovation and ecology in marine tetrapods from the
           Triassic to the Anthropocene
    • Authors: Neil P. Kelley
      Abstract: Many top consumers in today’s oceans are marine tetrapods, a collection of lineages independently derived from terrestrial ancestors. The fossil record illuminates their transitions from land to sea, yet these initial invasions account for a small proportion of their evolutionary history. We review the history of marine invasions that drove major changes in anatomy, physiology, and ecology over more than 250 million years. Many innovations evolved convergently in multiple clades, whereas others are unique to individual lineages. The evolutionary arcs of these ecologically important clades are framed against the backdrop of mass extinctions and regime shifts in ocean ecosystems. Past and present human disruptions to marine tetrapods, with cascading impacts on marine ecosystems, underscore the need to link macroecology with evolutionary change.
      Authors : Neil P. Kelley, Nicholas D. Pyenson
      PubDate: 2015-04-17
      DOI: 10.1126/science.aaa3716
  • [Research Article] Identification and isolation of a dermal lineage with
           intrinsic fibrogenic potential
    • Authors: Yuval Rinkevich
      Abstract: Dermal fibroblasts represent a heterogeneous population of cells with diverse features that remain largely undefined. We reveal the presence of at least two fibroblast lineages in murine dorsal skin. Lineage tracing and transplantation assays demonstrate that a single fibroblast lineage is responsible for the bulk of connective tissue deposition during embryonic development, cutaneous wound healing, radiation fibrosis, and cancer stroma formation. Lineage-specific cell ablation leads to diminished connective tissue deposition in wounds and reduces melanoma growth. Using flow cytometry, we identify CD26/DPP4 as a surface marker that allows isolation of this lineage. Small molecule–based inhibition of CD26/DPP4 enzymatic activity during wound healing results in diminished cutaneous scarring. Identification and isolation of these lineages hold promise for translational medicine aimed at in vivo modulation of fibrogenic behavior.
      Authors : Yuval Rinkevich, Graham G. Walmsley, Michael S. Hu, Zeshaan N. Maan, Aaron M. Newman, Micha Drukker, Michael Januszyk, Geoffrey W. Krampitz, Geoffrey C. Gurtner, H. Peter Lorenz, Irving L. Weissman, Michael T. Longaker
      PubDate: 2015-04-17
      DOI: 10.1126/science.aaa2151
  • [This Week in Science] Microbiome of uncontacted Amerindians
    • Authors: Philip Yeagle
      Abstract: Author: Philip Yeagle
      Keywords: Microbial Ecology
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.298-a
  • [This Week in Science] Massive electrons signify correlations
    • Authors: Jelena Stajic
      Abstract: Author: Jelena Stajic
      Keywords: Superconductivity
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.298-b
  • [This Week in Science] Dilution solves the recalcitrance question
    • Authors: H. Jesse Smith
      Abstract: Author: H. Jesse Smith
      Keywords: Biogeochemistry
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.298-c
  • [This Week in Science] Progress toward fixing a broken back?
    • Authors: Stella M. Hurtley
      Abstract: Author: Stella M. Hurtley
      Keywords: Axonal Regeneration
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.298-d
  • [This Week in Science] Resolving whole mitoribosomes
    • Authors: Guy Riddihough
      Abstract: Author: Guy Riddihough
      Keywords: Structural Biology
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.298-e
  • [This Week in Science] Gaze into my eyes
    • Authors: Sacha Vignieri
      Abstract: Author: Sacha Vignieri
      Keywords: Social Evolution
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.298-f
  • [This Week in Science] Stem cells can sort mitochondria by age
    • Authors: L. Bryan Ray
      Abstract: Author: L. Bryan Ray
      Keywords: Stem Cells
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.298-g
  • [This Week in Science] Will the real mutation please stand up?
    • Authors: Yevgeniya Nusinovich
      Abstract: Author: Yevgeniya Nusinovich
      Keywords: Cancer
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.298-h
  • [This Week in Science] Biodiversity protects grassland stability
    • Authors: Andrew M. Sugden
      Abstract: Author: Andrew M. Sugden
      Keywords: Plant Ecology
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.298-i
  • [This Week in Science] Similar shapes inhabit the sea
    • Authors: Sacha Vignieri
      Abstract: Author: Sacha Vignieri
      Keywords: Vertebrate Evolution
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.298-j
  • [This Week in Science] Fibroblasts in fibrosis
    • Authors: Beverly A. Purnell
      Abstract: Author: Beverly A. Purnell
      Keywords: Skin Fibrosis
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.298-k
  • [This Week in Science] The polarized mark of magnetic fields
    • Authors: Margaret M. Moerchen
      Abstract: Author: Margaret M. Moerchen
      Keywords: Active Galaxies
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.298-l
  • [This Week in Science] Eat your heart out, old galaxies
    • Authors: Margaret M. Moerchen
      Abstract: Author: Margaret M. Moerchen
      Keywords: Galaxy Evolution
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.298-m
  • [This Week in Science] Traces of collisions within collisions
    • Authors: Margaret M. Moerchen
      Abstract: Author: Margaret M. Moerchen
      Keywords: Lunar Formation
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.298-n
  • [This Week in Science] Smaller differences and greater extremes
    • Authors: H. Jesse Smith
      Abstract: Author: H. Jesse Smith
      Keywords: Climate Warming
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.298-o
  • [This Week in Science] Disappearing faster around the edges
    • Authors: H. Jesse Smith
      Abstract: Author: H. Jesse Smith
      Keywords: Climate Warming
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.298-p
  • [This Week in Science] Toward broad-spectrum antiviral drugs
    • Authors: Julia Fahrenkamp-Uppenbrink
      Abstract: Author: Julia Fahrenkamp-Uppenbrink
      Keywords: Infectious Disease
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.298-q
  • [Technical Response] Response to Comment on “Local reorganization of
           xanthophores fine-tunes and colors the striped pattern of zebrafish”
    • Authors: Ajeet Pratap Singh
      Abstract: Watanabe and Kondo question our conclusion that the current Turing-type model of color patterning in zebrafish requires modification. In addition to xanthophores and melanophores, iridophores are essential for stripe formation in the body, although not in the fins. A model of predictive value should accommodate the in vivo dynamics and interactions of all three chromatophore types in body stripe formation.
      Authors : Ajeet Pratap Singh, Hans-Georg Frohnhöfer, Uwe Irion, Christiane Nüsslein-Volhard
      PubDate: 2015-04-17
      DOI: 10.1126/science.aaa2804
  • [Letter] Shaping the future of synthetic biology
    • Authors: Todd Kuiken
      Abstract: Author: Todd Kuiken
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.296-a
  • [Letter] Combating the next lethal epidemic
    • Authors: Peter J. Hotez
      Abstract: Author: Peter J. Hotez
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.296-b
  • [Letter] More than a science camp
    • Authors: Luciano Gastón Morosi
      Abstract: Author: Luciano Gastón Morosi
      Keywords: Outside the Tower
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.297-a
  • [Technical Comment] Comment on “Local reorganization of xanthophores
           fine-tunes and colors the striped pattern of zebrafish”
    • Authors: Masakatsu Watanabe
      Abstract: Mahalwar et al. (Reports, 12 September 2014, p. 1362) observed the onset of pigment pattern formation in zebrafish. They concluded that their data do not support our Turing mechanism–based model and presented an essentially different mechanism. Here, we clarify their misunderstanding that may have caused their conclusion and explain past experimental data that do not support their proposed mechanism.
      Authors : Masakatsu Watanabe, Shigeru Kondo
      PubDate: 2015-04-17
      DOI: 10.1126/science.1261947
  • [Perspective] Escape by dilution
    • Authors: Jack J. Middelburg
      Abstract: Earth's oceans contain as much carbon in the form of dissolved organic matter (DOM) as does the biosphere, and more than 200 times that of living marine biomass. Most of the DOM is in the deep sea below 1000 m. Radiocarbon data show that the bulk of the DOM is thousands of years old (1). This long residence of DOM in the deep ocean is intriguing: Prokaryotes (bacteria and archaea) are abundant and active in the deep ocean, and many of them require DOM for energy and carbon. Moreover, molecular biology data show high metabolic diversity in the deep ocean (2). Why does some DOM escape degradation in the deep sea? Nutrient limitation of consumer biomass may explain underutilization of resources in nutrient-low surface waters (3), but this does not apply to the nutrient-rich deep sea. On page 331 of this issue, Arrieta et al. (4) show that DOM is too dilute to be consumed. Author: Jack J. Middelburg
      Keywords: Oceanography
      PubDate: 2015-04-17
      DOI: 10.1126/science.aaa9852
  • [Policy Forum] Improve customs systems to monitor global wildlife trade
    • Authors: Hon-Ki Chan
      Abstract: The volume of international trade in wildlife commodities is immense and, in many cases, is rising (1). Although there are already wildlife trade data sources [e.g., the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) Trade Database and the U.S. Fish and Wildlife Service Law Enforcement Management Information System (LEMIS)], coverage of traded species or countries involved is not comprehensive. This can undermine supply-chain monitoring and fast aggregation of data to inform policy-making (2). We discuss whether widely used, but limited, international customs codes and governance might evolve to address these gaps.
      Authors : Hon-Ki Chan, Huarong Zhang, Feng Yang, Gunter Fischer
      Keywords: Conservation
      PubDate: 2015-04-17
      DOI: 10.1126/science.aaa3141
  • [Book Review] The fever on the farm
    • Authors: Delia Grace
      Abstract: At the turn of the twentieth century, innovations in agriculture and infrastructure created opportunities for livestock diseases to emerge and spread in the United States. Arresting Contagion offers a penetrating glimpse into the behavioral economics that defined early animal disease control efforts, a story complete with setbacks and victories, heroes and villains. Reviewer Delia Grace applauds this comprehensive history, and recommends it those who are grappling with the resurgence in zoonotic diseases brought about by the rapid expansion of the livestock sector in developing countries and elsewhere. Author: Delia Grace
      Keywords: Animal Disease Control
      PubDate: 2015-04-17
      DOI: 10.1126/science.aaa7672
  • [Book Review] The evolution of evolution
    • Authors: Jim Endersby
      Abstract: The question of how species evolved was debated long before the time of Charles Darwin, a fact frequently forgotten by scientists and historians. These early theories are revived in a meticulously researched history, authored by Niles Eldredge, who developed the theory of punctuated equilibrium with the late Stephen Jay Gould. Reviewer Jim Endersby applauds this ambitious attempt to unearth these long-forgotten theories, but questions the author's determination to inform current evolutionary debates with historical theories. Author: Jim Endersby
      Keywords: History of Science
      PubDate: 2015-04-17
      DOI: 10.1126/science.aaa5821
  • [Books et al.] Books Received
    • Abstract: A listing of books received at Science during the week ending 10 April 2015.
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.295-b
  • [Perspective] Mitoribosome oddities
    • Authors: Roland Beckmann
      Abstract: Eukaryotic cells contain two separate translation machineries for protein synthesis—one in the cytosol and one in mitochondria. This situation is attributable to the evolutionary history of eukaryotic cells, which originate from a merger of two formerly independent cells—the host cell and the bacterial endosymbiont—with each contributing a full-fledged protein synthesis system. However, during the past 1.5 billion years, the two translation machineries have evolved very differently. That of the host cell, which acts in the cytosol, synthesizes almost all cellular proteins, including most mitochondrial proteins. By contrast, in mitochondria—the descendants of the bacterial endosymbionts—ribosomes (mitoribosomes) are now highly specialized for the synthesis of a very small number (13 in humans) of membrane proteins that function in energy production. It has been assumed that mitoribosomes are still similar to those of bacteria. Now, advances in high-resolution cryo–electron microscopy have allowed fascinating insights into the molecular structure of mitoribosomes, as reported by Greber et al. (1) on page 303 of this issue and by Amunts et al. (2). It is clear that the mitoribosome differs dramatically from the “canonical” cytosolic ribosome of bacteria and eukaryotes (see the figure).
      Authors : Roland Beckmann, Johannes M. Herrmann
      Keywords: Structural Biology
      PubDate: 2015-04-17
      DOI: 10.1126/science.aab1054
  • [Perspective] Systemically treating spinal cord injury
    • Authors: Amanda P. Tran
      Abstract: Spinal cord injury is a debilitating condition. Axons of nerve cells are severed, resulting in a range of deficits, including the loss of voluntary movements and sensation. Failure of axonal regeneration after such an injury may be partly explained by a decreased intrinsic capacity for neuron growth, especially at the lesion site (1). On page 347 in this issue, Ruschel et al. (2) show that this inhibition can be overcome with a small molecule that can be injected into the body cavity, cross the bloodbrain barrier, and reach the central nervous system. The drug, epothilone B, stabilizes microtubules in extending axons, thereby promoting spinal cord regeneration.
      Authors : Amanda P. Tran, Jerry Silver
      Keywords: Neuroscience
      PubDate: 2015-04-17
      DOI: 10.1126/science.aab1615
  • [Perspective] Nanoplasmonic sensing and detection
    • Authors: Mark I. Stockman
      Abstract: Measuring minute amounts of chemical and biological objects in the environment and in living organisms is one of the most common and important tasks in chemistry, biology, medicine, environmental monitoring, transportation, homeland security, and defense. Although the existing methods of sensing and detection are numerous and powerful, they are not without shortcomings: insufficient sensitivity; long detection times; necessity for enzymatic, fluorescent, or radioactive labeling; high costs, and so on. Optical spectroscopic methods have the advantage of being fast, noncontact, and relatively inexpensive, but they are not necessarily sensitive enough. Author: Mark I. Stockman
      Keywords: Applied Optics
      PubDate: 2015-04-17
      DOI: 10.1126/science.aaa6805
  • [Perspective] Combating emerging viral threats
    • Authors: Elena Bekerman
      Abstract: Although hundreds of viruses are known to cause human disease, antiviral therapies are approved for fewer than 10. Most approved antiviral drugs target viral enzymes, most commonly proteases and polymerases. Such direct acting antivirals (DAAs) have shown considerable success in the treatment of HIV and hepatitis C virus (HCV) infections. However, this approach does not scale easily and is limited particularly with respect to emerging and reemerging viruses against which no vaccines or antiviral therapies are approved.
      Authors : Elena Bekerman, Shirit Einav
      Keywords: Infectious Disease
      PubDate: 2015-04-17
      DOI: 10.1126/science.aaa3778
  • [Perspective] A scar is born: Origins of fibrotic skin tissue
    • Authors: Rachel Sennett
      Abstract: Tissues rely on fibroblasts to produce and distribute extracellular matrix (ECM) proteins that provide crucial structure and organization for other resident cells. Although their presence is imperative to normal tissue morphogenesis and maintenance, these mesenchymal cells are frequently overlooked as “merely” ubiquitous supportive cells or uniformly vilified because of their role in aberrant connective tissue deposition that can occur during wound healing or reactive fibrosis. Consequently, the study by Rinkevich et al. on page 302 of this issue (1), teasing apart the embryonic origins, molecular profiles, and functional capacities of discrete fibroblast lineages within adult skin, turns a thought-provoking spotlight on these unassuming cells and paves the way for future studies with potentially important clinical implications.
      Authors : Rachel Sennett, Michael Rendl
      Keywords: Developmental Biology
      PubDate: 2015-04-17
      DOI: 10.1126/science.aab0120
  • [Editors' Choice] Interfering in an aggregation pathway
    • Authors: Valda Vinson
      Abstract: Author: Valda Vinson
      Keywords: Protein Folding
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.299-b
  • [Editors' Choice] Shocking aluminum into a warm dense state
    • Authors: Jelena Stajic
      Abstract: Author: Jelena Stajic
      Keywords: Physics
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.299-c
  • [Editors' Choice] Out with tradition and in with inquiry
    • Authors: Melissa McCartney
      Abstract: Author: Melissa McCartney
      Keywords: Education
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.299-d
  • [Editors' Choice] Keeping the cell nucleus pumped up
    • Authors: Guy Riddihough
      Abstract: Author: Guy Riddihough
      Keywords: Cell Biology
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.299-e
  • [Perspective] Dogs hijack the human bonding pathway
    • Authors: Evan L. MacLean
      Abstract: Tens of thousands of years ago, a wolflike predator gave rise to a more docile lineage, which soon became our trusted fireside companions (1). How did dogs become so embedded in human societies? Why do we feel genuine friendship, love, and social attachment in our relationships with dogs? On page 333 in this issue, Nagasawa et al. (2) reveal a powerful mechanism through which dogs win our hearts—and we win theirs in return.
      Authors : Evan L. MacLean, Brian Hare
      Keywords: Evolution
      PubDate: 2015-04-17
      DOI: 10.1126/science.aab1200
  • [Feature] How the wolf became the dog
    • Authors: David Grimm
      Abstract: Scientists who study canine origins seem to fight about everything: where dogs arose, when this happened, and even the best way to find these answers. But there's one thing most of them agree on: how dogs became domesticated. Dogs, the thinking now goes, domesticated themselves, with the tamest wolves able to approach ancient human campsites and feast on leftover carcasses. New findings from an unprecedented collaboration of geneticists and archaeologists are adding insight into how dogs became domesticated, as is a new study, which shows that dogs have hijacked the same hormonal pathway human mothers use to bond with their infants. Author: David Grimm
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.277
  • [Feature] Dawn of the dog
    • Authors: David Grimm
      Abstract: Dogs were the first thing humans domesticated—before any plant, before any other animal. Yet scientists have argued for years over where and when they arose. Some studies suggest that canines evolved in Europe, others Asia, with time frames ranging from 15,000 to more than 30,000 years ago. Now, an unprecedented collaboration of archaeologists and geneticists has brought the warring camps together for the first time. The group is analyzing thousands of bones from around the world, employing new techniques, and trying to put aside years of bad blood and bruised egos. If it succeeds, it will uncover the history of man's oldest friend—and solve one of the greatest mysteries of domestication. Author: David Grimm
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.274
  • [In Depth] Japan accelerator poised to go fully operational
    • Authors: Dennis Normile
      Abstract: Shut down after a radiation leak in May 2013, Japan's premier particle accelerator could soon resume full operations if it passes an inspection of new safety features scheduled for 17 April. The Japan Proton Accelerator Research Complex (J-PARC) in Tokai, 110 kilometers northeast of Tokyo, features a 50 giga-electronvolt synchrotron that provides streams of protons for three separate experimental facilities. One focuses on materials and life sciences; another is dedicated to a long-baseline neutrino experiment; the third supports studies of subatomic particles called hadrons. The leak put a halt to all operations. Work on materials and life sciences and neutrinos resumed in spring 2014 after J-PARC bolstered safety procedures. Research in the Hadron Experimental Facility, where the leak occurred, was further delayed by the installation of new vapor barriers and exhaust fan filters and the adoption of other countermeasures to contain radiation. The halt in experiments has delayed groundbreaking research, though some groups were affected more than others. Author: Dennis Normile
      Keywords: Particle Physics
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.273
  • [In Depth] For toilets, money matters
    • Authors: Jocelyn Kaiser
      Abstract: About 1 billion people in the developing world still walk out to a field, the bushes, or an open waterway to defecate instead of using a latrine. That has contributed to high rates of diarrheal disease. The problem is particularly acute in India, where Prime Minister Narendra Modi has vowed to build 111 million toilets as part of a plan to end open defecation by October 2019. But exactly how to get there is surprisingly controversial. Now, a large, controlled experiment, conducted in India's neighbor Bangladesh and published online this week in Science, finds that the key to getting people to build hygienic latrines is to subsidize the cost. Although other experts say these results are important, some caution that building toilets doesn't always mean people will use them or be healthier. Author: Jocelyn Kaiser
      Keywords: Sanitation
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.272
  • [In Depth] Moon-forming impact left scars in distant asteroids
    • Authors: Eric Hand
      Abstract: Not too long after the planets began forming, a Mars-sized object slammed into Earth, creating the debris that would coalesce into the moon. But some of the debris escaped all the way out to the asteroid belt. Collisions there left shock-heating signatures that can still be detected billions of years later in meteorites that have fallen to Earth. Planetary scientists have found that a significant number of these altered meteorites have ages clustering at 105 million years after the solar system's birth—the true age of the moon-forming impact, they say. The result is an independent check on different estimates for the moon's age, and it suggests that the asteroid belt could be witness to other ancient disruptions in the inner solar system. Author: Eric Hand
      Keywords: Planetary Science
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.271
  • [In Depth] U.S. lays out its ambitions for leadership in the Arctic
    • Authors: Carolyn Gramling
      Abstract: Next week, the United States will become chair of the eight-nation Arctic Council, an intergovernmental forum that aims to foster cooperation on research and policy in the far north. The United States has released an ambitious, climate- and conservation-focused agenda for its 2-year chairmanship that includes pushing for more research on black carbon, which accelerates melting in the region, and on emissions of the potent greenhouse gas methane from the seabed and permafrost, as well as creating a network of marine protected areas in the Arctic and equipping Arctic villages with renewable energy sources. Environmental groups have hailed the agenda, but some observers warn against too lofty expectations for what it might mean for policy changes among the "Arctic 8." Author: Carolyn Gramling
      Keywords: Arctic Policy
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.270
  • [In Depth] Women best men in study of tenure-track hiring
    • Authors: Rachel Bernstein
      Abstract: Cornell University psychologists believe they have crossed one factor off the list of obstacles to women in academia: the hiring committee. A new study reports that, when faculty members rated hypothetical candidates for a tenure-track faculty position, a highly qualified woman is twice as likely to be hired as an equally qualified man. The results run counter to widely held perceptions and suggest that this is a good time for women in STEM (science, technology, engineering, and mathematics). Some observers, however, worry that the study does not reproduce real-world hiring and that it may leave an incorrect impression about gender parity in STEM fields. Author: Rachel Bernstein
      Keywords: Faculty Hiring
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.269
  • [In Depth] Meager snows spell trouble ahead for salmon
    • Authors: Robert F. Service
      Abstract: Warm winter temperatures in the mountains of the western United States this past winter sharply reduced the region's snowpack, which normally reaches its high point at this time each year. That snow typically serves as a vital water storage reservoir that is slowly released as the snow melts over the dry summer months. Without this snowmelt, stream flows are expected to drop sharply this summer, which in turn is expected to cause water temperatures to rise to a level unhealthy for migrating salmon. As a result, fisheries biologists expect a looming calamity for endangered salmon stocks this year. Author: Robert F. Service
      Keywords: Conservation
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.268
  • [Editorial] One Arctic
    • Authors: Fran Ulmer
      Abstract: This month, the United States takes over the chairmanship of the Arctic Council, a position it last held in 1998. Since then, global interest in the Arctic has increased, and the council has evolved considerably. What has spurred that interest, and what will the council focus on under U.S. leadership? Author: Fran Ulmer
      PubDate: 2015-04-17
      DOI: 10.1126/science.aab3119
  • [In Brief] This week's section
    • Abstract: In science news around the world, the World Health Organization calls for the public release of clinical trials data, Brazil approves the first commercial planting of genetically modified eucalyptus trees, a review panel convened by the Scientific Committee of the International Whaling Commission gives Japanese research whaling a thumbs-down, and the death of monkeys at a Harvard University primate research facility prompts an investigation. Also, a thoracic surgeon who famously transplanted artificial tracheae into patients—and then faced misconduct charges—has been cleared in one of two investigations. And biomedical engineer Joshua Resnikoff discusses Labconscious, a blog he created to help scientists green their labs.
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.264
  • [New Products] New Products
    • Abstract: A weekly roundup of information on newly offered instrumentation, apparatus, and laboratory materials of potential interest to researchers.
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.358-a
  • [Podcast] Science Podcast: 17 April Show
    • Abstract: On this week's show: The human-dog bond, a roundup of daily news stories.
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.358-b
  • [Working Life] En pointe
    • Authors: Elisabeth Pain
      Abstract: Author: Elisabeth Pain
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.366
  • [Report] Systemic administration of epothilone B promotes axon
           regeneration after spinal cord injury
    • Authors: Jörg Ruschel
      Abstract: After central nervous system (CNS) injury, inhibitory factors in the lesion scar and poor axon growth potential prevent axon regeneration. Microtubule stabilization reduces scarring and promotes axon growth. However, the cellular mechanisms of this dual effect remain unclear. Here, delayed systemic administration of a blood-brain barrier–permeable microtubule-stabilizing drug, epothilone B (epoB), decreased scarring after rodent spinal cord injury (SCI) by abrogating polarization and directed migration of scar-forming fibroblasts. Conversely, epothilone B reactivated neuronal polarization by inducing concerted microtubule polymerization into the axon tip, which propelled axon growth through an inhibitory environment. Together, these drug-elicited effects promoted axon regeneration and improved motor function after SCI. With recent clinical approval, epothilones hold promise for clinical use after CNS injury.
      Authors : Jörg Ruschel, Farida Hellal, Kevin C. Flynn, Sebastian Dupraz, David A. Elliott, Andrea Tedeschi, Margaret Bates, Christopher Sliwinski, Gary Brook, Kristina Dobrindt, Michael Peitz, Oliver Brüstle, Michael D. Norenberg, Armin Blesch, Norbert Weidner, Mary Bartlett Bunge, John L. Bixby, Frank Bradke
      PubDate: 2015-04-17
      DOI: 10.1126/science.aaa2958
  • [Report] Direct observation of structure-function relationship in a
           nucleic acid–processing enzyme
    • Authors: Matthew J. Comstock
      Abstract: The relationship between protein three-dimensional structure and function is essential for mechanism determination. Unfortunately, most techniques do not provide a direct measurement of this relationship. Structural data are typically limited to static pictures, and function must be inferred. Conversely, functional assays usually provide little information on structural conformation. We developed a single-molecule technique combining optical tweezers and fluorescence microscopy that allows for both measurements simultaneously. Here we present measurements of UvrD, a DNA repair helicase, that directly and unambiguously reveal the connection between its structure and function. Our data reveal that UvrD exhibits two distinct types of unwinding activity regulated by its stoichiometry. Furthermore, two UvrD conformational states, termed “closed” and “open,” correlate with movement toward or away from the DNA fork.
      Authors : Matthew J. Comstock, Kevin D. Whitley, Haifeng Jia, Joshua Sokoloski, Timothy M. Lohman, Taekjip Ha, Yann R. Chemla
      PubDate: 2015-04-17
      DOI: 10.1126/science.aaa0130
  • [Business Office Feature] Proteomics: Diving Deep into Cell Signaling
    • Authors: Caitlin Smith
      Abstract: New proteomics tools enable researchers to dive deeply into signaling networks, allowing them to tease out interactions among key molecules. But this comes with a new challenge of increased complexity. Can cell signaling scientists balance the bewildering complexity that comes with the discovery power of proteomics technology?Read the Feature (Full-Text HTML)Read the Feature (PDF)Read New Products (PDF) Author: Caitlin Smith
      Keywords: Business Office Feature
      PubDate: 2015-04-17
      DOI: 10.1126/science.348.6232.355
  • [Report] Anthropogenic environmental changes affect ecosystem stability
           via biodiversity
    • Authors: Yann Hautier
      Abstract: Human-driven environmental changes may simultaneously affect the biodiversity, productivity, and stability of Earth’s ecosystems, but there is no consensus on the causal relationships linking these variables. Data from 12 multiyear experiments that manipulate important anthropogenic drivers, including plant diversity, nitrogen, carbon dioxide, fire, herbivory, and water, show that each driver influences ecosystem productivity. However, the stability of ecosystem productivity is only changed by those drivers that alter biodiversity, with a given decrease in plant species numbers leading to a quantitatively similar decrease in ecosystem stability regardless of which driver caused the biodiversity loss. These results suggest that changes in biodiversity caused by drivers of environmental change may be a major factor determining how global environmental changes affect ecosystem stability.
      Authors : Yann Hautier, David Tilman, Forest Isbell, Eric W. Seabloom, Elizabeth T. Borer, Peter B. Reich
      PubDate: 2015-04-17
      DOI: 10.1126/science.aaa1788
  • [Report] Asymmetric apportioning of aged mitochondria between daughter
           cells is required for stemness
    • Authors: Pekka Katajisto
      Abstract: By dividing asymmetrically, stem cells can generate two daughter cells with distinct fates. However, evidence is limited in mammalian systems for the selective apportioning of subcellular contents between daughters. We followed the fates of old and young organelles during the division of human mammary stemlike cells and found that such cells apportion aged mitochondria asymmetrically between daughter cells. Daughter cells that received fewer old mitochondria maintained stem cell traits. Inhibition of mitochondrial fission disrupted both the age-dependent subcellular localization and segregation of mitochondria and caused loss of stem cell properties in the progeny cells. Hence, mechanisms exist for mammalian stemlike cells to asymmetrically sort aged and young mitochondria, and these are important for maintaining stemness properties.
      Authors : Pekka Katajisto, Julia Döhla, Christine L. Chaffer, Nalle Pentinmikko, Nemanja Marjanovic, Sharif Iqbal, Roberto Zoncu, Walter Chen, Robert A. Weinberg, David M. Sabatini
      PubDate: 2015-04-17
      DOI: 10.1126/science.1260384
  • [Report] Engineering of a superhelicase through conformational control
    • Authors: Sinan Arslan
      Abstract: Conformational control of biomolecular activities can reveal functional insights and enable the engineering of novel activities. Here we show that conformational control through intramolecular cross-linking of a helicase monomer with undetectable unwinding activity converts it into a superhelicase that can unwind thousands of base pairs processively, even against a large opposing force. A natural partner that enhances the helicase activity is shown to achieve its stimulating role also by selectively stabilizing the active conformation. Our work provides insight into the regulation of nucleic acid unwinding activity and introduces a monomeric superhelicase without nuclease activities, which may be useful for biotechnological applications.
      Authors : Sinan Arslan, Rustem Khafizov, Christopher D. Thomas, Yann R. Chemla, Taekjip Ha
      PubDate: 2015-04-17
      DOI: 10.1126/science.aaa0445
  • [Report] The weakening summer circulation in the Northern Hemisphere
    • Authors: Dim Coumou
      Abstract: Rapid warming in the Arctic could influence mid-latitude circulation by reducing the poleward temperature gradient. The largest changes are generally expected in autumn or winter, but whether significant changes have occurred is debated. Here we report significant weakening of summer circulation detected in three key dynamical quantities: (i) the zonal-mean zonal wind, (ii) the eddy kinetic energy (EKE), and (iii) the amplitude of fast-moving Rossby waves. Weakening of the zonal wind is explained by a reduction in the poleward temperature gradient. Changes in Rossby waves and EKE are consistent with regression analyses of climate model projections and changes over the seasonal cycle. Monthly heat extremes are associated with low EKE, and thus the observed weakening might have contributed to more persistent heat waves in recent summers.
      Authors : Dim Coumou, Jascha Lehmann, Johanna Beckmann
      PubDate: 2015-04-17
      DOI: 10.1126/science.1261768
  • [Report] Volume loss from Antarctic ice shelves is accelerating
    • Authors: Fernando S. Paolo
      Abstract: The floating ice shelves surrounding the Antarctic Ice Sheet restrain the grounded ice-sheet flow. Thinning of an ice shelf reduces this effect, leading to an increase in ice discharge to the ocean. Using 18 years of continuous satellite radar altimeter observations, we have computed decadal-scale changes in ice-shelf thickness around the Antarctic continent. Overall, average ice-shelf volume change accelerated from negligible loss at 25 ± 64 cubic kilometers per year for 1994–2003 to rapid loss of 310 ± 74 cubic kilometers per year for 2003–2012. West Antarctic losses increased by ~70% in the past decade, and earlier volume gain by East Antarctic ice shelves ceased. In the Amundsen and Bellingshausen regions, some ice shelves have lost up to 18% of their thickness in less than two decades.
      Authors : Fernando S. Paolo, Helen A. Fricker, Laurie Padman
      PubDate: 2015-04-17
      DOI: 10.1126/science.aaa0940
  • [Report] Dilution limits dissolved organic carbon utilization in the deep
    • Authors: Jesús M. Arrieta
      Abstract: Oceanic dissolved organic carbon (DOC) is the second largest reservoir of organic carbon in the biosphere. About 72% of the global DOC inventory is stored in deep oceanic layers for years to centuries, supporting the current view that it consists of materials resistant to microbial degradation. An alternative hypothesis is that deep-water DOC consists of many different, intrinsically labile compounds at concentrations too low to compensate for the metabolic costs associated to their utilization. Here, we present experimental evidence showing that low concentrations rather than recalcitrance preclude consumption of a substantial fraction of DOC, leading to slow microbial growth in the deep ocean. These findings demonstrate an alternative mechanism for the long-term storage of labile DOC in the deep ocean, which has been hitherto largely ignored.
      Authors : Jesús M. Arrieta, Eva Mayol, Roberta L. Hansman, Gerhard J. Herndl, Thorsten Dittmar, Carlos M. Duarte
      PubDate: 2015-04-17
      DOI: 10.1126/science.1258955
  • [Report] Oxytocin-gaze positive loop and the coevolution of human-dog
    • Authors: Miho Nagasawa
      Abstract: Human-like modes of communication, including mutual gaze, in dogs may have been acquired during domestication with humans. We show that gazing behavior from dogs, but not wolves, increased urinary oxytocin concentrations in owners, which consequently facilitated owners’ affiliation and increased oxytocin concentration in dogs. Further, nasally administered oxytocin increased gazing behavior in dogs, which in turn increased urinary oxytocin concentrations in owners. These findings support the existence of an interspecies oxytocin-mediated positive loop facilitated and modulated by gazing, which may have supported the coevolution of human-dog bonding by engaging common modes of communicating social attachment.
      Authors : Miho Nagasawa, Shouhei Mitsui, Shiori En, Nobuyo Ohtani, Mitsuaki Ohta, Yasuo Sakuma, Tatsushi Onaka, Kazutaka Mogi, Takefumi Kikusui
      PubDate: 2015-04-17
      DOI: 10.1126/science.1261022
  • [Report] Dating the Moon-forming impact event with asteroidal meteorites
    • Authors: W. F. Bottke
      Abstract: The inner solar system’s biggest and most recent known collision was the Moon-forming giant impact between a large protoplanet and proto-Earth. Not only did it create a disk near Earth that formed the Moon, it also ejected several percent of an Earth mass out of the Earth-Moon system. Here, we argue that numerous kilometer-sized ejecta fragments from that event struck main-belt asteroids at velocities exceeding 10 kilometers per second, enough to heat and degas target rock. Such impacts produce ~1000 times more highly heated material by volume than do typical main belt collisions at ~5 kilometers per second. By modeling their temporal evolution, and fitting the results to ancient impact heating signatures in stony meteorites, we infer that the Moon formed ~4.47 billion years ago, which is in agreement with previous estimates.
      Authors : W. F. Bottke, D. Vokrouhlický, S. Marchi, T. Swindle, E. R. D. Scott, J. R. Weirich, H. Levison
      PubDate: 2015-04-17
      DOI: 10.1126/science.aaa0602
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