This Week in Science

Science  23 Sep 2016:
Vol. 353, Issue 6306, pp. 1377
  1. Carbon Cycle

    Less storage sinks soil models

    1. H. Jesse Smith
    Figure

    Soils may be a smaller carbon sink than previously assumed and might provide less relief from future global warming than expected. Soils contain more carbon than any other terrestrial reservoir and thus can have large impacts on climate, depending how much atmospheric carbon dioxide they sequester. He et al. use soil radiocarbon measurements to show that models tend to overestimate how much carbon soils will store by the year 2100, mostly because they underestimate the turnover time of soil carbon. Consequently, model projections of carbon storage by the end of the century may be too high by a factor of 2.

    Science, this issue p. 1419

  2. Structural Biology

    Keeping the spliceosome in check

    1. Valda Vinson

    In eukaryotes, RNA is transcribed as precursor mRNA. Noncoding sequences must be spliced out before proteins are made. Mechanistic insight into the splicing process has come from determining the structures of distinct spliceosome complexes at different steps of the reaction. Rauhut et al. describe the structure of the activated spliceosome (Bact) in Saccharomyces cerivisiae at 5.8 Å resolution. The complex is held in a state that is inactive but ready to be remodeled into a catalytically active machine.

    Science, this issue p. 1399

  3. Forest Ecology

    Diversity in neotropical dry forests

    1. Andrew M. Sugden

    Dry forests in the American tropics are not as extensive as rain forests and are more severely threatened by human activity. The DRYFLOR network compiled a floristic inventory of the entire neotropical dry forest biome and used this database of nearly 5000 woody species to analyze the geographical distribution of plant diversity that it hosts. Large variation in floristic composition between different sites and regions implies that effective conservation of dry forest plant diversity will require the protection of numerous priority areas across neotropical nations.

    Science, this issue p. 1383

  4. Evolution

    G proteins diverge and conquer

    1. Annalisa VanHook

    In plants, signaling through G (heterotrimeric GTP-binding) proteins involves either canonical Gα proteins, which are structurally and functionally similar to animal Gα proteins, or extra-large Gα (XLG) proteins. Urano et al. found that plant canonical Gα proteins evolved slowly, like their animal counterparts, and were involved in developmental processes. In contrast, XLG proteins rapidly diversified early in the land plant lineage and mediated stress responses. Thus, diversification of plant XLG proteins coincided with the colonization of land and may have helped plants to withstand the new stresses encountered in this environment.

    Sci. Signal. 9, ra93 (2016).

  5. Geophysics

    Catching earthquakes from the sky

    1. Brent Grocholski

    Wastewater injection appears to be driving the sharp increase in earthquakes in the central United States. Shirzaei et al. use satellites to show that wastewater injection caused surface deformation before the 2012 magnitude-4.8 Timpson earthquake in eastern Texas. Changes in subsurface pore pressure link injection to the surface deformation. Using satellites to track the impact of wastewater injection may improve earthquake forecasting in regions that are prone to induced seismicity.

    Figure

    Science, this issue p. 1416

  6. Host Tolerance

    Microbes teach tolerance in the gut

    1. Kristen L. Mueller

    The trillions of microbes inhabiting and interacting in our gut can greatly influence how we respond to infection. Rangan et al. find that worms and mice harboring Enterococcus faecium in their guts can better tolerate Salmonella infections. Tolerance requires E. faecium to express the enzyme SagA, which can also exert a probiotic effect when expressed by other bacteria. SagA protects worms by cleaving bacterial peptide fragments so that they stimulate the tol-1 protein. In contrast, Pedicord et al. find that SagA protects mice against Salmonella and Clostridium difficile infections in a manner dependent on antimicrobial peptides and multiple innate immune receptors.

    Science, this issue p. 1434; Sci. Immunol. 1, eaai7732 (2016).

  7. Infectious Disease

    Cultured guts combat gastroenteritis

    1. Caroline Ash

    Human noroviruses are highly contagious. They cause explosive outbreaks of gastrointestinal disease, which can be dangerous to the very young, the elderly, and the immunocompromised. Ettayebi et al. succeeded in growing several strains of noroviruses in human gut stem cell cultures and found that the addition of bile substantially increased viral infectivity. This culture system will allow evaluation of new methods to inactivate human noroviruses for vaccine development and to determine the effectiveness of disinfectants and novel control measures.

    Figure

    Science, this issue p. 1387

  8. Nanomaterials

    Rapidly reducing graphene oxide

    1. Phil Szuromi

    The reduction of exfoliated graphene oxide platelets can produce graphene for applications in materials, energy storage, and catalysis. However, reduction methods often leave a substantial fraction of oxygenated functional groups in graphene, lowering its electrical conductivity. Voiry et al. report that brief microwave pulses (1 to 2 s) resulted in the near-complete reduction of graphene oxide. The resultant high-quality graphene, with high carrier mobility, served as a catalyst support with low overpotential for the oxygen reduction reaction.

    Science, this issue p. 1413

  9. Convergent Evolution

    Genetic convergence to the extreme

    1. Laura M. Zahn

    Species in the same habitat may be only distantly related but yet share the need to adapt to environmental extremes. Yeaman et al. examined the underlying genetics of local environmental adaptation in lodgepole pine and interior spruce, which diverged over 140 million years ago (see the Perspective by Hancock). A suite of duplicated genes, which exhibited the hallmark of selection, were associated with cold tolerance in both species. Adaptations to climate may therefore be genetically constrained, even among distantly related species.

    Science, this issue p. 1431; see also p. 1362

  10. Materials Science

    Seeing the disorder in the ordered

    1. Marc S. Lavine

    The ordered nature of crystalline materials makes it relatively straightforward to calculate their bulk structures from partial information. In contrast, it can be much harder to describe the local structure of defects in a crystal, such as grain boundaries, vacancies, or stacking faults. Miao et al. review the advances in atomic electron tomography that make it possible, at least in some materials, to determine the three-dimensional coordinates for partially disordered systems.

    Science, this issue p. 1380

  11. Yeast Genetics

    A global genetic interaction network

    1. Laura M. Zahn

    Studies of genetic interactions help identify networks and pathways that may not be easily apparent through observations of single mutations. Constanzo et al. mapped the global network of genetic interactions, both positive and negative, for essential and nonessential genes in yeast. From this, they were able to map a hierarchy of gene and cellular function, as well as connectivity between networks, and identify the function of previously uncharacterized genes. The interactions identified in this study may even be extended to generate predictions for human genetic interactions.

    Science, this issue p. 1381

  12. RNA Structure

    Unfolded in vivo

    1. Guy Riddihough

    RNA can form a diverse array of folded structures. The four-stranded RNA G-quadraplex is a potentially very stable structure that has been implicated in both gene regulation and disease. Guo and Bartel show that many eukaryotic RNA sequences have the potential to form G-quadraplexes, yet most of them are unfolded in eukaryotic cells. Because there are very few RNA G-quadraplex structures in prokaryotic RNA, despite also being stable in vivo, G-quadraplexes may have been actively eliminated from the genome.

    Science, this issue p. 1382

  13. Solar Cells

    Protective liquid motions

    1. Phil Szuromi

    Hybrid organic-inorganic perovskites used in solar cells exhibit long carrier lifetimes compared with all-inorganic perovskites. This is in spite of the higher amount of disorder in the former that would normally increase unproductive carrier recombination. Zhu et al. used time-resolved photoluminescence and optical Kerr effect spectroscopies to compare the hybrid organic-inorganic perovskites CH3NH3PbBr3 and CH(NH2)2PbBr3 and the all-inorganic perovskite CsPbBr3 (see the Perspective by Ziffer and Ginger). The hybrid materials exhibited hot fluorescence indicative of liquid-like organic cation motion, which may protect charge carriers through solvation or formation of large polarons.

    Science, this issue p. 1409; see also p. 1365

  14. Atmospheric Oxygen

    Oxygen deficit

    1. H. Jesse Smith

    The partial pressure of atmospheric O2 has declined by 0.7% over the past 800,000 years, according to data from air trapped in polar ice cores. Stolper et al. compiled existing records of O2/N2 to determine this loss. O2 sinks must have been about 2% larger than sources over that time interval, possibly because of increasing rates of global erosion or decreasing rates of marine organic carbon burial. Declining O2 requires a CO2-dependent feedback such as silicate weathering to help stabilize atmospheric CO2 concentrations on geological time scales.

    Science, this issue p. 1427

  15. Neuroscience

    How brain neurons turn down the heat

    1. L. Bryan Ray

    The preoptic area of the hypothalamus serves as the brain's thermostat. Song et al. found that a particular set of neurons mediate this function and identified the molecular heat sensor that they use (see the Perspective by Bartfai). Neurons in cultures of mouse brain that were activated in response to warming expressed temperature-sensitive TRPM2 ion channels. In mice lacking these channels, body temperature increased more in response to an induced fever than it did in control animals. In mice engineered to allow specific control of the TRPM2-containing neurons, the activity of the neurons was shown to modulate core body temperature.

    Science, this issue p. 1393; see also p. 1363

  16. Climate Change

    Services for successful adaptation

    1. Julia Fahrenkamp-Uppenbrink

    Nations around the world are seeking the help of climate services to adapt to climate change. In a Perspective, Goddard explains that for climate services to be successful, they must be based on a clear understanding of the place of climate considerations in the decision-making process. Also, climate services must be built on the best-available observational data sets and must consider climatic patterns at time scales from seasonal to decadal. Because each region will experience climate change in different ways, successful adaptation will depend on close cooperation between climate services and national agencies.

    Science, this issue p. 1366

  17. Infectious Disease

    Stemming MRSA-induced pneumonia

    1. Orla M. Smith

    Controversies persist about the use of human intravenous immunoglobulin (IVIG) as an adjunct treatment for severe pneumonia caused by Staphylococcus aureus infections. Diep et al. show that in rabbits, only two specific antibodies contained in IVIG are necessary and sufficient to confer protection against necrotizing pneumonia caused by methicillin-resistant S. aureus (MRSA) strains. These antibodies neutralize the toxic effects of α-toxin and Panton-Valentine leukocidin. Preexposure prophylaxis with IVIG, or postexposure treatment with IVIG in combination with either vancomycin or linezolid, improved survival outcomes.

    Sci. Transl. Med. 8, 357ra124 (2016).

  18. Geophysics

    Finding the weak spots of subduction

    1. Brent Grocholski

    The asthenosphere is a weak layer in the Earth that allows the rigid plates of Earth's crust to move over geologic time. Hawley et al. found an unexpectedly large accumulation of a weak material just beneath the rigid Juan de Fuca slab in the Cascadia subduction zone, located along the northwestern coast of the United States. Seismically imaging this “roll” of weak material required the use of both onshore and offshore seismometers. The roll appears to be positioned underneath where the Juan de Fuca plate bends and plunges into the mantle, providing potential explanations for several puzzling features of this and other subduction zones.

    Science, this issue p. 1406

  19. Atmospheric Science

    A change in the wind

    1. H. Jesse Smith

    The quasi-biennial oscillation (QBO), one of the most dependable features of atmospheric circulation, was unexpectedly disrupted in 2016. Normally, the winds in the equatorial stratosphere between the altitudes of ∼16 and 50 km alternate between eastward and westward motion at intervals between 22 and 36 months. In February 2016, however, Osprey et al. show that an easterly jet formed within the westerly phase that occupied the lower stratosphere—an occurrence that existing models of the QBO did not predict. Some climate projections suggest that this behavior may become more frequent in the future as climate warms, which could affect winter storminess and rainfall over northern Europe in particular.

    Science, this issue p. 1424

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