Science news

• At UN climate talks some worry about Brexit, Trump impacts

  26-05-2016 22:22
  BONN, Germany (AP) — Climate negotiators ended their first talks after last year's landmark Paris Agreement on Thursday with some delegates expressing concern about the potential impact of upcoming votes in the U.S. and Britain.
  
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• [Working Life] Three strikes and research is out

  26-05-2016 21:39
  Author: Michael J. Orsini
  
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• [This Week in Science] Unwinding DNA and unleasing inflammation

  26-05-2016 21:39
  Author: Kristen L. Mueller
  
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• [This Week in Science] The promise of digital markets

  26-05-2016 21:39
  Author: Julia Fahrenkamp-Uppenbrink
  
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• [This Week in Science] The fuel for fungal enzymes

  26-05-2016 21:39
  Author: Nicolas S. Wigginton
  
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• [This Week in Science] Rhythm remodeling traced to tiny RNA

  26-05-2016 21:39
  Author: Megan Frisk
  
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• [This Week in Science] Quantum cats here and there

  26-05-2016 21:39
  Author: Ian S. Osborne
  
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• [This Week in Science] Precise control from a metal-free catalyst

  26-05-2016 21:39
  Author: Jake Yeston
  
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• [This Week in Science] Phosphorylation cues exit from mitosis

  26-05-2016 21:39
  Author: L. Bryan Ray
  
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• [This Week in Science] Narrowing down genetic loci of interest

  26-05-2016 21:39
  Author: Laura M. Zahn
  
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• [This Week in Science] Genes and microbes converge in colitis

  26-05-2016 21:39
  Author: Kristen L. Mueller
  
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• [This Week in Science] From neutral to new

  26-05-2016 21:39
  Author: H. Jesse Smith
  
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• [This Week in Science] Forcing the spindle to the cell center

  26-05-2016 21:39
  Author: Beverly A. Purnell
  
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• [This Week in Science] Evidence for ice ages on Mars

  26-05-2016 21:39
  Author: Keith T. Smith
  
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• [This Week in Science] Designing better estrogens

  26-05-2016 21:39
  Author: Wei Wong
  
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• [This Week in Science] Cold atoms do geometry

  26-05-2016 21:39
  Author: Jelena Stajic
  
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• [This Week in Science] Calcium signals the making of symbiosis

  26-05-2016 21:39
  Author: Pamela J. Hines
  
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• [This Week in Science] A radical route to ophiobolin rings

  26-05-2016 21:39
  Author: Jake Yeston
  
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• [This Week in Science] A new metal scavenger for bacteria

  26-05-2016 21:39
  Author: Nicolas S. Wigginton
  
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• [Research Article] Topoisomerase 1 inhibition suppresses inflammatory genes and protects from death by inflammation

  26-05-2016 21:39
  The host innate immune response is the first line of defense against pathogens and is orchestrated by the concerted expression of genes induced by microbial stimuli. Deregulated expression of these genes is linked to the initiation and progression of diseases associated with exacerbated inflammation. We identified topoisomerase 1 (Top1) as a positive regulator of RNA polymerase II transcriptional activity at pathogen-induced genes. Depletion or chemical inhibition of Top1 suppresses the host res
  
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• [Report] Organocatalyzed atom transfer radical polymerization driven by visible light

  26-05-2016 21:39
  Atom transfer radical polymerization (ATRP) has become one of the most implemented methods for polymer synthesis, owing to impressive control over polymer composition and associated properties. However, contamination of the polymer by the metal catalyst remains a major limitation. Organic ATRP photoredox catalysts have been sought to address this difficult challenge but have not achieved the precision performance of metal catalysts. Here, we introduce diaryl dihydrophenazines, identified through
  
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• [Report] Nuclear-localized cyclic nucleotide–gated channels mediate symbiotic calcium oscillations

  26-05-2016 21:39
  Nuclear-associated Ca2+ oscillations mediate plant responses to beneficial microbial partners—namely, nitrogen-fixing rhizobial bacteria that colonize roots of legumes and arbuscular mycorrhizal fungi that colonize roots of the majority of plant species. A potassium-permeable channel is known to be required for symbiotic Ca2+ oscillations, but the calcium channels themselves have been unknown until now. We show that three cyclic nucleotide–gated channels in Medicago truncatula are required f
  
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• [Report] New particle formation in the free troposphere: A question of chemistry and timing

  26-05-2016 21:39
  New particle formation (NPF) is the source of over half of the atmosphere’s cloud condensation nuclei, thus influencing cloud properties and Earth’s energy balance. Unlike in the planetary boundary layer, few observations of NPF in the free troposphere exist. We provide observational evidence that at high altitudes, NPF occurs mainly through condensation of highly oxygenated molecules (HOMs), in addition to taking place through sulfuric acid–ammonia nucleation. Neutral nucleation is more t
  
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• [Report] Gene-microbiota interactions contribute to the pathogenesis of inflammatory bowel disease

  26-05-2016 21:39
  Inflammatory bowel disease (IBD) is associated with risk variants in the human genome and dysbiosis of the gut microbiome, though unifying principles for these findings remain largely undescribed. The human commensal Bacteroides fragilis delivers immunomodulatory molecules to immune cells via secretion of outer membrane vesicles (OMVs). We reveal that OMVs require IBD-associated genes, ATG16L1 and NOD2, to activate a noncanonical autophagy pathway during protection from colitis. ATG16L1-deficien
  
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• [Report] Extracellular electron transfer systems fuel cellulose oxidative degradation

  26-05-2016 21:39
  Ninety percent of lignocellulose-degrading fungi contain genes encoding lytic polysaccharide monooxygenases (LPMOs). These enzymes catalyze the initial oxidative cleavage of recalcitrant polysaccharides after activation by an electron donor. Understanding the source of electrons is fundamental to fungal physiology and will also help with the exploitation of LPMOs for biomass processing. Using genome data and biochemical methods, we characterized and compared different extracellular electron sour
  
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• [Report] Experimental reconstruction of the Berry curvature in a Floquet Bloch band

  26-05-2016 21:39
  Topological properties lie at the heart of many fascinating phenomena in solid-state systems such as quantum Hall systems or Chern insulators. The topology of the bands can be captured by the distribution of Berry curvature, which describes the geometry of the eigenstates across the Brillouin zone. Using fermionic ultracold atoms in a hexagonal optical lattice, we engineered the Berry curvature of the Bloch bands using resonant driving and show a full momentum-resolved measurement of the ensuing
  
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• [Report] Enantioselective synthesis of an ophiobolin sesterterpene via a programmed radical cascade

  26-05-2016 21:39
  Cyclase enzymes weave simple polyprenyl chains into the elaborate polycyclic ring systems of terpenes, a sequence that is often difficult to emulate under abiotic conditions. Here we report a disparate synthetic approach to complex terpenes whereby simple prenyl-derived chains are cyclized using radical, rather than cationic, reaction pathways. This strategy allowed us to efficiently forge the intricate 5-8-5 fused ring systems found in numerous complex natural product classes and also enabled a
  
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• [Report] Cyclin-dependent kinase 1–dependent activation of APC/C ubiquitin ligase

  26-05-2016 21:39
  Error-free genome duplication and segregation are ensured through the timely activation of ubiquitylation enzymes. The anaphase-promoting complex or cyclosome (APC/C), a multisubunit E3 ubiquitin ligase, is regulated by phosphorylation. However, the mechanism remains elusive. Using systematic reconstitution and analysis of vertebrate APC/Cs under physiological conditions, we show how cyclin-dependent kinase 1 (CDK1) activates the APC/C through coordinated phosphorylation between Apc3 and Apc1. P
  
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• [Report] CRISPR-directed mitotic recombination enables genetic mapping without crosses

  26-05-2016 21:39
  Linkage and association studies have mapped thousands of genomic regions that contribute to phenotypic variation, but narrowing these regions to the underlying causal genes and variants has proven much more challenging. Resolution of genetic mapping is limited by the recombination rate. We developed a method that uses CRISPR (clustered, regularly interspaced, short palindromic repeats) to build mapping panels with targeted recombination events. We tested the method by generating a panel with rec
  
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• [Report] Bloch state tomography using Wilson lines

  26-05-2016 21:39
  Topology and geometry are essential to our understanding of modern physics, underlying many foundational concepts from high-energy theories, quantum information, and condensed-matter physics. In condensed-matter systems, a wide range of phenomena stem from the geometry of the band eigenstates, which is encoded in the matrix-valued Wilson line for general multiband systems. Using an ultracold gas of rubidium atoms loaded in a honeycomb optical lattice, we realize strong-force dynamics in Bloch ba
  
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• [Report] Biosynthesis of a broad-spectrum nicotianamine-like metallophore in Staphylococcus aureus

  26-05-2016 21:39
  Metal acquisition is a vital microbial process in metal-scarce environments, such as inside a host. Using metabolomic exploration, targeted mutagenesis, and biochemical analysis, we discovered an operon in Staphylococcus aureus that encodes the different functions required for the biosynthesis and trafficking of a broad-spectrum metallophore related to plant nicotianamine (here called staphylopine). The biosynthesis of staphylopine reveals the association of three enzyme activities: a histidine
  
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• [Report] An ice age recorded in the polar deposits of Mars

  26-05-2016 21:39
  Layered ice deposits at the poles of Mars record a detailed history of accumulation and erosion related to climate processes. Radar investigations measure these layers and provide evidence for climate changes such as ice advance and retreat. We present a detailed analysis of observational data showing that ~87,000 cubic kilometers of ice have accumulated at the poles since the end of the last ice age ~370,000 years ago; this volume is equivalent to a global layer of ~60 centimeters. The majority
  
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• [Report] A Schrödinger cat living in two boxes

  26-05-2016 21:39
  Quantum superpositions of distinct coherent states in a single-mode harmonic oscillator, known as “cat states,” have been an elegant demonstration of Schrödinger’s famous cat paradox. Here, we realize a two-mode cat state of electromagnetic fields in two microwave cavities bridged by a superconducting artificial atom, which can also be viewed as an entangled pair of single-cavity cat states. We present full quantum state tomography of this complex cat state over a Hilbert space exceeding
  
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• [Report] A force-generating machinery maintains the spindle at the cell center during mitosis

  26-05-2016 21:39
  The position and orientation of the mitotic spindle is precisely regulated to ensure the accurate partition of the cytoplasm between daughter cells and the correct localization of the daughters within growing tissue. Using magnetic tweezers to perturb the position of the spindle in intact cells, we discovered a force-generating machinery that maintains the spindle at the cell center during metaphase and anaphase in one- and two-cell Caenorhabditis elegans embryos. The forces increase with the nu
  
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• [Policy Forum] Paying for future success in gene therapy

  26-05-2016 21:39
  Imagine a young man with hemophilia A who no longer has to self-administer factor VIII replacement; an individual with sickle cell disease who is free of chronic pain and intermittent crises; a girl functionally blind since the age of 5 who can now see; or a baby rescued from a fatal, inherited neurodegenerative disease. For decades, gene therapy has tantalized us with such futuristic scenarios. However, these goals are now coming into focus, and it is the time to consider some of the consequenc
  
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• [Perspective] Unwinding inducible gene expression

  26-05-2016 21:39
  The inflammatory response is coordinated by hundreds of genes that promote host defense against infection and injury. Inducible expression of these genes is mediated by distinct mechanisms, including transcriptional elongation, histone modifications, and nucleosome remodeling. On page 1074 of this issue, Rialdi et al. (1) report that a subset of the genes activated by viral infections depends on topoisomerase 1 (Top1) for induced expression. Pharmacological targeting of specific gene subsets has
  
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• [Perspective] The cancer predisposition revolution

  26-05-2016 21:39
  Studies of rare cancer predisposition syndromes often lead to the identification of genes critical to carcinogenesis. In 1969, Li and Fraumeni described a constellation of various cancers in the family members of four unrelated children who were diagnosed with soft tissue sarcomas (1). They posited that the cancers best fit an autosomal dominant pattern of inheritance, attributable to a genetic defect. At that time, cancer was not generally thought of as a genetic disease. Their hypothesis set t
  
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• [Perspective] Organic photocatalysts for cleaner polymer synthesis

  26-05-2016 21:39
  The material properties of synthetic polymers can be tuned by changing their chain length and branching and the way in which monomer units repeat. For example, high-density polyethylene, which has little chain branching, is a stiff polymer used for food containers and drain pipes, whereas low-density polyethylene, which has more chain branching, is flexible and used to make grocery bags and bottles for chemicals. Polymers are usually made through thermal polymerization, but recent efforts focusi
  
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• [Perspective] Matching markets in the digital age

  26-05-2016 21:39
  Recent advances in information technology are enabling new markets and revolutionizing many existing markets. For example, taxicabs used to find passengers through chance drive-bys or slow central dispatching (see the photo). Location tracking, computer navigation, and dynamic pricing now enable ride-sharing services such as Uber to offer low and consistent delay times of only a few minutes. In a recent study, Cramer and Krueger (1) show that ride-sharing has dramatically increased the usage of
  
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• [Perspective] How to break down crystalline cellulose

  26-05-2016 21:39
  Biomass-degrading microorganisms use lytic polysaccharide monooxygenase (LPMO) enzymes to help digest cellulose, chitin, and starch. By cleaving otherwise inaccessible crystalline cellulose chains, these enzymes provide access to hydrolytic enzymes. LPMOs are of interest to biotechnology because efficient depolymerization of cellulose is a major bottleneck for the production of biologically based chemicals and fuels. On page 1098 of this issue, Kracher et al. (1) compare LPMO-reducing substrates
  
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• [Perspective] A metal shuttle keeps pathogens well fed

  26-05-2016 21:39
  Staphylococcus aureus is a Gram-positive bacterium that is a leading cause of life-threatening infections in humans. Knowledge of how this pathogen colonizes the human host and causes disease is crucial for the development of strategies to prevent and treat S. aureus infections (see the image, next page). On page 1105 of this issue, Ghssein et al. report the discovery, isolation, and functional evaluation of staphylopine (see the figure), a compound biosynthesized by S. aureus that captures meta
  
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• [Letter] Public participation in China's project plans

  26-05-2016 21:39
  Authors: Guoyou Qi, Yanhong Jia, Saixing Zeng, Jonathan J. Shi
  
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• [Letter] Infection and the first eukaryotes—Response

  26-05-2016 21:39
  Authors: Steven G. Ball, Debashish Bhattacharya, Andreas P. M. Weber
  
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• [Letter] Infection and the first eukaryotes

  26-05-2016 21:39
  Author: Sven B. Gould
  
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• [In Depth] Shooting for a star

  26-05-2016 21:39
  Last month, Russian internet billionaire Yuri Milner announced plans to send thousands of tiny spacecraft to visit Alpha Centauri, the closest star system to Earth. In order to cover the vast distance—41 trillion kilometres—in a reasonable time, the proposed spacecraft will each weigh less than a gram and will unfurl lightweight sails to catch laser beams shot from Earth, accelerating them to one-fifth the speed of light. But the proposal has polarized opinion: Some are enthused by its ambit
  
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• [In Depth] Near miss at Fukushima is a warning for U.S

  26-05-2016 21:39
  Japan's chief cabinet secretary called it “the devil's scenario.” Two weeks after the 11 March 2011 earthquake and tsunami devastated the Fukushima Daiichi Nuclear Power Plant, causing three nuclear reactors to melt down and release radioactive plumes, officials were bracing for even worse. They feared that spent fuel stored in pools in the reactor halls would catch fire and might send radioactive smoke across a much wider swath of eastern Japan, including Tokyo. Thanks to a lucky break deta
  
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• [In Depth] India nears putting GM mustard on the table

  26-05-2016 21:39
  Six years after it backed down from approving cultivation of a transgenic food crop, India's government is trying again. But it is encountering stiff headwinds as it mulls whether to approve what would be India's first such crop, a genetically modified (GM) mustard. Environmentalists argue that the mustard, grown for its edible leaves and for cooking oil, could harm local varieties and that the toxicity tests being carried out to evaluate GM mustard's safety as a food are inadequate. Heightening
  
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• [In Depth] Government ‘nudges’ prove their worth

  26-05-2016 21:39
  Over the past 5 years, on behalf of state governments, nearly 100,000 Americans were gently manipulated by a team of social scientists. In 15 randomized, controlled trials, people in need of social services either encountered the standard application process or received a psychological nudge, in which the information was presented slightly differently—a postcard reminded them of deadlines, for example, or one choice was made easier than another. In 11 of the trials, the nudge modestly increase
  
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• [In Depth] Brazilian crisis threatens science and environment

  26-05-2016 21:39
  In the midst of Brazil's political turmoil, scientists and environmentalists are wondering whether they have an enemy in Interim President Michel Temer, who came to power after Dilma Rousseff was removed on 12 May. Days after Temer assumed office, the government merged the science ministry with the communications ministry, leaving researchers fearing for what's left of their already diminished budgets. Meanwhile, pro-development forces are moving ahead on a constitutional amendment that could sp
  
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• [Feature] The battery builder

  26-05-2016 21:39
  Yi Cui, a materials scientist at Stanford University in Palo Alto, California, is trying to take lithium-ion batteries to the next level. He's not alone: Massive corporations are also attempting to make batteries smaller, lighter, and more powerful. But unlike others who focus on tweaking the chemical composition of a battery's electrodes or its charge-conducting electrolyte, Cui—and his startup, Amprius—are marrying battery chemistry with nanotechnology. He is building intricately structure
  
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