Science news

• Here's How Many Americans Actually Sleep 7 Hours

  18-02-2016 23:58
  The Centers for Disease Control and Prevention, which conducted the study, recommends that adults ages 18 to 60 get at least 7 hours of sleep per night. Too little sleep increases the risk for a number of health conditions, including obesity, diabetes, high blood pressure, heart disease, stroke and frequent mental distress, the CDC said. The new findings suggest "an ongoing need for public awareness and public education about sleep health," the report said.
  
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• Missing gut microbes linked to childhood malnutrition

  18-02-2016 23:39
  
  The right mix of gut microbes could prevent kids from succumbing to malnutrition.
  
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• Mercury Splatters the Central U.S.

  18-02-2016 22:40 via rss.sciam.com
  
  Rainfall in the Rocky Mountains shows a surprisingly high amount of mercury, worrying scientists about what’s to come
  -- Read more on ScientificAmerican.com
  
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• Google appeal of worldwide injunction headed to Supreme Court

  18-02-2016 22:08 via cbc.ca
  
  The Supreme Court of Canada has agreed to hear Google's appeal of an international injunction which critics warn could turn B.C. into a destination for 'censorship tourism'.
  
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• [Working Life] Room for a new generation

  18-02-2016 21:35
  Author: Roc Ordman
  
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• [This Week in Science] Sensing single proteins with diamonds

  18-02-2016 21:35
  Author: Ian S. Osborne
  
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• [This Week in Science] Keeping immune cells quiet on a diet

  18-02-2016 21:35
  Author: Kristen L. Mueller
  
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• [This Week in Science] Dynamic DNA clustering of nanoparticles

  18-02-2016 21:35
  Author: Marc S. Lavine
  
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• [This Week in Science] CRISPR Cas9 molecular scissors

  18-02-2016 21:35
  Author: Guy Riddihough
  
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• [This Week in Science] A route to nitrile that bypasses cyanide

  18-02-2016 21:35
  Author: Jake Yeston
  
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• [Report] Structures of a CRISPR-Cas9 R-loop complex primed for DNA cleavage

  18-02-2016 21:35
  Bacterial adaptive immunity and genome engineering involving the CRISPR (clustered regularly interspaced short palindromic repeats)–associated (Cas) protein Cas9 begin with RNA-guided DNA unwinding to form an RNA-DNA hybrid and a displaced DNA strand inside the protein. The role of this R-loop structure in positioning each DNA strand for cleavage by the two Cas9 nuclease domains is unknown. We determine molecular structures of the catalytically active Streptococcus pyogenes Cas9 R-loop that sh
  
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• [Report] Structural basis of lipoprotein signal peptidase II action and inhibition by the antibiotic globomycin

  18-02-2016 21:35
  With functions that range from cell envelope structure to signal transduction and transport, lipoproteins constitute 2 to 3% of bacterial genomes and play critical roles in bacterial physiology, pathogenicity, and antibiotic resistance. Lipoproteins are synthesized with a signal peptide securing them to the cytoplasmic membrane with the lipoprotein domain in the periplasm or outside the cell. Posttranslational processing requires a signal peptidase II (LspA) that removes the signal peptide. Here
  
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• [Report] Neurons diversify astrocytes in the adult brain through sonic hedgehog signaling

  18-02-2016 21:35
  Astrocytes are specialized and heterogeneous cells that contribute to central nervous system function and homeostasis. However, the mechanisms that create and maintain differences among astrocytes and allow them to fulfill particular physiological roles remain poorly defined. We reveal that neurons actively determine the features of astrocytes in the healthy adult brain and define a role for neuron-derived sonic hedgehog (Shh) in regulating the molecular and functional profile of astrocytes. Thu
  
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• [Report] DNA-controlled dynamic colloidal nanoparticle systems for mediating cellular interaction

  18-02-2016 21:35
  Precise control of biosystems requires development of materials that can dynamically change physicochemical properties. Inspired by the ability of proteins to alter their conformation to mediate function, we explored the use of DNA as molecular keys to assemble and transform colloidal nanoparticle systems. The systems consist of a core nanoparticle surrounded by small satellites, the conformation of which can be transformed in response to DNA via a toe-hold displacement mechanism. The conformati
  
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• [Report] Dietary antigens limit mucosal immunity by inducing regulatory T cells in the small intestine

  18-02-2016 21:35
  Dietary antigens are normally rendered nonimmunogenic through a poorly understood “oral tolerance” mechanism that involves immunosuppressive regulatory T (Treg) cells, especially Treg cells induced from conventional T cells in the periphery (pTreg cells). Although orally introducing nominal protein antigens is known to induce such pTreg cells, whether a typical diet induces a population of pTreg cells under normal conditions thus far has been unknown. By using germ-free mice raised and bred
  
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• [This Week in Science] Unleashing natural killer cells

  18-02-2016 21:35
  Author: John F. Foley
  
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• [This Week in Science] The yin and yang of proteasomal regulation

  18-02-2016 21:35
  Author: Stella M. Hurtley
  
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• [This Week in Science] The real cause of cancer in Fanconi anemia

  18-02-2016 21:35
  Author: Guy Riddihough
  
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• [This Week in Science] Preparing for the next epidemic

  18-02-2016 21:35
  Author: Julia Fahrenkamp-Uppenbrink
  
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• [This Week in Science] Microbiota and infant development

  18-02-2016 21:35
  Author: Caroline Ash
  
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• [This Week in Science] Killing cancer with a soft touch

  18-02-2016 21:35
  Author: Yevgeniya Nusinovich
  
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• [This Week in Science] Insight into a bacterial membrane protease

  18-02-2016 21:35
  Author: Valda Vinson
  
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• [This Week in Science] Glial cell properties dictated by neurons

  18-02-2016 21:35
  Author: L. Bryan Ray
  
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• [This Week in Science] Crowdsourcing earthquake early warnings

  18-02-2016 21:35
  Author: Kip Hodges
  
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• [This Week in Science] Calcium channels deliver a one-two punch

  18-02-2016 21:35
  Author: Stella M. Hurtley
  
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• [This Week in Science] AAA ATPase conformational high jinks

  18-02-2016 21:35
  Author: Valda Vinson
  
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• [Technical Response] Response to Comments on “Cortical folding scales universally with surface area and thickness, not number of neurons”

  18-02-2016 21:35
  De Lussanet claims that our model that accounts for the degree of folding of the cerebral cortex based on the product of cortical surface area and the square root of cortical thickness is better reduced to the product of gray-matter proportion and folding index. Lewitus et al., in turn, claim that the assumptions of our model are in conflict with experimental data; that the model does not accurately fit the data; and that the ancestral mammalian brain was gyrencephalic. Here, we show that both c
  
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• [Technical Response] Response to Comment on “Global assessment of arbuscular mycorrhizal fungus diversity reveals very low endemism”

  18-02-2016 21:35
  Bruns and Taylor argue that our finding of widespread distribution among Glomeromycota “virtual taxa” is undermined by the species definition applied. Although identifying appropriate species concepts and accessing taxonomically informative traits are challenges for microorganism biogeography, the virtual taxa represent a pragmatic classification that corresponds approximately to the species rank of classical Glomeromycota taxonomy, yet is applicable to environmental DNA.
  Authors: Maarja Öp
  
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• [Technical Comment] Comment on “Global assessment of arbuscular mycorrhizal fungus diversity reveals very low endemism”

  18-02-2016 21:35
  Davison et al. (Reports, 28 August 2015, p. 970) claim that virtual taxa of Glomeromycota show little endemism and that endemism that exists is similar to the levels seen in plant families. We show that this is likely due to the conservative species definition rather than to any ecological pattern.
  Authors: Thomas D. Bruns, John W. Taylor
  
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• [Technical Comment] Comment on “Cortical folding scales universally with surface area and thickness, not number of neurons”

  18-02-2016 21:35
  The cerebrum of large mammals is convoluted, whereas that of small mammals is smooth. Mota and Herculano-Houzel (Reports, 3 July 2015, p. 74) inspired a model on an old theory that proposed a fractal geometry. I show that their model reduces to the product of gray-matter proportion times the folding index. This proportional relation describes the available data even better than the fractal model.
  Author: Marc H. E. de Lussanet
  
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• [Research Article] Rpn1 provides adjacent receptor sites for substrate binding and deubiquitination by the proteasome

  18-02-2016 21:35
  Hundreds of pathways for degradation converge at ubiquitin recognition by a proteasome. Here, we found that the five known proteasomal ubiquitin receptors in yeast are collectively nonessential for ubiquitin recognition and identified a sixth receptor, Rpn1. A site (T1) in the Rpn1 toroid recognized ubiquitin and ubiquitin-like (UBL) domains of substrate shuttling factors. T1 structures with monoubiquitin or lysine 48 diubiquitin show three neighboring outer helices engaging two ubiquitins. T1 c
  
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• [Research Article] Gut bacteria that prevent growth impairments transmitted by microbiota from malnourished children

  18-02-2016 21:35
  Undernourished children exhibit impaired development of their gut microbiota. Transplanting microbiota from 6- and 18-month-old healthy or undernourished Malawian donors into young germ-free mice that were fed a Malawian diet revealed that immature microbiota from undernourished infants and children transmit impaired growth phenotypes. The representation of several age-discriminatory taxa in recipient animals correlated with lean body mass gain; liver, muscle, and brain metabolism; and bone morp
  
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• [Report] Ubiquitinated Fancd2 recruits Fan1 to stalled replication forks to prevent genome instability

  18-02-2016 21:35
  Mono-ubiquitination of Fancd2 is essential for repairing DNA interstrand cross-links (ICLs), but the underlying mechanisms are unclear. The Fan1 nuclease, also required for ICL repair, is recruited to ICLs by ubiquitinated (Ub) Fancd2. This could in principle explain how Ub-Fancd2 promotes ICL repair, but we show that recruitment of Fan1 by Ub-Fancd2 is dispensable for ICL repair. Instead, Fan1 recruitment—and activity—restrains DNA replication fork progression and prevents chromosome abnorm
  
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• [Report] Sequential ionic and conformational signaling by calcium channels drives neuronal gene expression

  18-02-2016 21:35
  Voltage-gated CaV1.2 channels (L-type calcium channel α1C subunits) are critical mediators of transcription-dependent neural plasticity. Whether these channels signal via the influx of calcium ion (Ca2+), voltage-dependent conformational change (VΔC), or a combination of the two has thus far been equivocal. We fused CaV1.2 to a ligand-gated Ca2+-permeable channel, enabling independent control of localized Ca2+ and VΔC signals. This revealed an unexpected dual requirement: Ca2+ must first mobi
  
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• [Report] Nuclear magnetic resonance detection and spectroscopy of single proteins using quantum logic

  18-02-2016 21:35
  Nuclear magnetic resonance spectroscopy is a powerful tool for the structural analysis of organic compounds and biomolecules but typically requires macroscopic sample quantities. We use a sensor, which consists of two quantum bits corresponding to an electronic spin and an ancillary nuclear spin, to demonstrate room temperature magnetic resonance detection and spectroscopy of multiple nuclear species within individual ubiquitin proteins attached to the diamond surface. Using quantum logic to imp
  
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• [Report] Lactobacillus plantarum strain maintains growth of infant mice during chronic undernutrition

  18-02-2016 21:35
  In most animal species, juvenile growth is marked by an exponential gain in body weight and size. Here we show that the microbiota of infant mice sustains both weight gain and longitudinal growth when mice are fed a standard laboratory mouse diet or a nutritionally depleted diet. We found that the intestinal microbiota interacts with the somatotropic hormone axis to drive systemic growth. Using monocolonized mouse models, we showed that selected lactobacilli promoted juvenile growth in a strain-
  
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• [Report] Catalytic reversible alkene-nitrile interconversion through controllable transfer hydrocyanation

  18-02-2016 21:35
  Nitriles and alkenes are important synthetic intermediates with complementary reactivity that play a central role in the preparation of materials, pharmaceuticals, cosmetics, and agrochemicals. Here, we report a nickel-catalyzed transfer hydrocyanation reaction between a wide range (60 examples) of alkyl nitriles and alkenes. This strategy not only overcomes the toxicity challenge posed by the use of HCN in traditional approaches, but also encompasses distinct chemical advances, including retro-
  
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• [Report] 2.3 Å resolution cryo-EM structure of human p97 and mechanism of allosteric inhibition

  18-02-2016 21:35
  p97 is a hexameric AAA+ adenosine triphosphatase (ATPase) that is an attractive target for cancer drug development. We report cryo–electron microscopy (cryo-EM) structures for adenosine diphosphate (ADP)–bound, full-length, hexameric wild-type p97 in the presence and absence of an allosteric inhibitor at resolutions of 2.3 and 2.4 angstroms, respectively. We also report cryo-EM structures (at resolutions of ~3.3, 3.2, and 3.3 angstroms, respectively) for three distinct, coexisting functional
  
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• [Policy Forum] Complexity theory and financial regulation

  18-02-2016 21:35
  Traditional economic theory could not explain, much less predict, the near collapse of the financial system and its long-lasting effects on the global economy. Since the 2008 crisis, there has been increasing interest in using ideas from complexity theory to make sense of economic and financial markets. Concepts, such as tipping points, networks, contagion, feedback, and resilience have entered the financial and regulatory lexicon, but actual use of complexity models and results remains at an ea
  
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• [Perspective] How does the immune system tolerate food?

  18-02-2016 21:35
  The gastrointestinal immune system (gut-associated lymphoid tissue) has the unique capacity to discriminate between harmless and potentially dangerous material. It can raise a protective response against pathogenic microbes and toxins while tolerating food antigens and commensal microbes. This is a challenge given the vast number of foreign antigens, mainly derived from food (>100 g of protein per day), and commensal microbes colonizing the gut (an estimated 100 trillion, 10 times the number
  
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• [Perspective] Differences among astrocytes

  18-02-2016 21:35
  Astrocytes are diverse in morphology and molecular makeup (1, 2), potentially enabling them to provide for the varying needs of their diverse neuronal counterparts (3). What accounts for and maintains astrocyte heterogeneity are only beginning to be explored. One possibility is that the signals specifying astrocyte subpopulations might operate only during the critical phases of development, after which the cell is hardwired. Alternatively, these signals might be operational at all times. On page
  
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• [Perspective] Controlled interaction of nanoparticles with cells

  18-02-2016 21:35
  For many medical applications, controlled interaction of cells with surfaces is desirable. For example, in the already clinically applied cell-sheet technology, cells detach from a polymer surface upon cooling, which causes the polymer to swell and become nonadhesive (1). On page 841 of this issue, Ohta et al. applied the same idea to the surface of colloidal nanoparticles (NPs) (2). In the adhesive state, in which ligands on the NP surface are accessible, the NPs specifically adhere to the surf
  
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• [Perspective] Cas9, poised for DNA cleavage

  18-02-2016 21:35
  Over the past 3 years, the technique known as CRISPR—clustered regularly interspaced short palindromic repeats—has revolutionized the field of genome editing (1). A single enzyme called CRISPR-associated protein 9 (Cas9) can be programmed with CRISPR-derived RNAs (crRNAs) to introduce double-stranded DNA (dsDNA) breaks at specific sites in the genome. On page 867 of this issue, Jiang et al. (2) describe structures of Streptococcus pyogenes Cas9 captured in a state poised for DNA cleavage. Th
  
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• [Perspective] Beyond Ebola

  18-02-2016 21:35
  On 14 January 2016, Liberia was declared Ebola-free. A new case was identified shortly after the announcement, but it is nevertheless clear that the West African epidemic has moved on to a more hopeful phase. What lessons can be drawn from the Ebola crisis to help the international community to prepare for and respond to the next global epidemic? This question is particularly pertinent given the recent declaration of the Zika virus as a public health emergency.
  Authors: Janet Currie, Bryan Grenf
  
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• [Perspective] A molecular shuttle for hydrogen cyanide

  18-02-2016 21:35
  In recent decades, transition-metal catalysis has become an indispensable tool in organic synthesis. Nevertheless, there remains a need for practical, safe, and efficient protocols for some transformations. A challenging example is nickelcatalyzed hydrocyanation (1), in which nonactivated olefins (alkenes) are converted to branched or linear nitriles through addition of hydrogen cyanide (HCN) (see the figure, panel A). This transformation is used industrially on a very large scale to produce adi
  
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• [Letter] Teaching trust with art

  18-02-2016 21:35
  Author: Prashant Sood
  
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• [Letter] Protect the Tasmanian wilderness

  18-02-2016 21:35
  Author: Xiaojiang Yu
  
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• [Letter] Plant scientists: GM technology is safe

  18-02-2016 21:35
  Authors: Noah Fahlgren, Rebecca Bart, Luis Herrera-Estrella, Rubén Rellán-Álvarez, Daniel H. Chitwood, José R. Dinneny
  
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• [In Depth] The scientist who spotted the fateful signal—and let the cat out of the bag

  18-02-2016 21:35
  The first scientist to see the long-awaited sign of gravitational waves was a soft-spoken Italian postdoc. Marco Drago, 33, works at the Max Planck Institute for Gravitational Physics in Hanover, Germany, overseeing one of four automatic "pipelines" that comb the raw data from LIGO's twin detectors, thousands of kilometers away. On 14 September 2015, the pipeline flagged a possible detection. Drago thought the event had to be a test—it was too sharp and clear to be true, and the rece
  
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• [In Depth] The right gut microbes help infants grow

  18-02-2016 21:35
  Almost 180 million children across the globe are stunted, a severe, disabling consequence of malnutrition, repeated childhood infections, and sometimes irreversible damage. Now, new studies suggest the gut microbiome plays a critical role in infant growth—sometimes promoting it even in the absence of sufficient calories—providing tantalizing, if preliminary, clues about possible new interventions. They show that microbial communities change as an infant ages, and when they don't poor nutriti
  
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