Editors' Choice

Science  12 Aug 2016:
Vol. 353, Issue 6300, pp. 661
  1. Symbiosis

    Fungi help trees hunt for food

    1. Caroline Ash

    Symbiotic root fungi help trees access nutrient “patches” in soil

    PHOTO: EYE OF SCIENCE/SCIENCE SOURCE

    Trees face a difficult paradox: how to access nutrients that are not uniformly spread throughout the soil while remaining stationary. Nearly all plant roots associate with symbiotic soil-dwelling fungi (either intracellular arbuscular mycorrhizal or extracellular ectomycorrhizal fungi), which aid in nutrient uptake. Chen et al. now report that mycorrhizae help trees forage. Tree species with finer roots that associate with arbuscular mycorrhizal fungi produce more roots when they encounter a nutrient patch, and those that associate with ectomycorrhizal fungi produce more fungal hyphae. Moreover, trees in mixed woodlands probably have complementary foraging strategies by virtue of their differing symbionts, likely contributing to tree diversity in temperate forests.

    Proc. Natl. Acad. Sci. U.S.A. 10.1073/pnas.1601006113 (2016).

  2. Psychology

    The persuasiveness of reductionism

    1. Gilbert Chin

    A decade ago, it seemed as though every other neuroscience paper in high-profile journals featured multiple multicolored images of brain scans. In some cases, readers—many of whom were psychologists who had written papers on the same topic—pointed out that the pictographic scans added little explanatory power. Hopkins et al. have extended an earlier study of the relative impact of psychology and neuroscience to encompass both more reductive disciplines, such as physics, chemistry, and biology, and less reductive disciplines, such as social science. They find that study subjects judge scientific explanations to be of higher quality when they contain information from the neighboring more reductive field, even when that information is irrelevant.

    Cognition 155, 67 (2016).

  3. Near-Field Cosmology

    Is the Local Group useful for cosmology?

    1. Keith T. Smith

    A nighttime view from Earth of our Milky Way Galaxy

    PHOTO: BABAK TAFRESHI/NATIONAL GEOGRAPHIC CREATIVE

    Our Milky Way Galaxy is the second largest member of the Local Group, a gravitationally bound assemblage of several dozen galaxies. Researchers in near-field cosmology use detailed studies of the Local Group to understand how galaxies form and evolve over cosmic time but have never been sure how well the Local Group represents the wider universe. Boylan-Kolchin et al. used cosmological simulations to demonstrate that the Local Group occupies a sufficiently large volume at high redshift to make it a representative sample, at least for the dwarf galaxies. They show that Local Group studies can complement deep observations of high-redshift galaxies, which are sensitive to different mass ranges.

    Mon. Not. R. Astron. Soc. 462, L51 (2016).

  4. Magnetism

    Measuring the elusive interaction

    1. Jelena Stajic

    When two spins interact, the part of the interaction that changes sign when the spins are exchanged is called the Dzyaloshinsky-Moriya (DM) interaction. The DM interaction favors nonparallel spins and can play an important role in the formation of skyrmions (miniature whirlpools of spins) and in the magnetoelectric effect in multiferroics. However, measuring both the size and the direction of this interaction is tricky. Laplane et al. conceived a general method that they demonstrated on a pair of Nd3+ ions embedded as dopants in a YVO4 crystal. Working at low temperatures where the Nd3+ ions behaved as effective ½ spins, they extracted the details of the interaction by using the electron spin resonance technique combined with optical detection.

    Phys. Rev. Lett. 117, 037203 (2016).

  5. Ecophysiology

    Staying away for the long haul

    1. Sacha Vignieri

    Frigatebirds can fly long distances with little need for sleep.

    PHOTO: BOB GIBBONS/ALAMY STOCK PHOTO

    Frigatebirds can fly without stopping for months. Such long flights, however, present considerable challenges to some physiological processes, notably sleep. Scientists think that birds undergoing long flights use hemispheric sleep, where half of the brain sleeps at a time. To find out whether this is indeed the case, Rattenborg et al. placed mobile electroencephalogram recorders on flying frigatebirds and found that although they do use hemispheric sleep, especially when riding updrafts, they actually sleep remarkably little during their long flights. Though the birds may be able to catch up on their sleep when on land, it seems that they can mostly avoid the sleep deprivation effects that plague most vertebrates, an ability that is probably shaped by strong selection for wakefulness during flight.

    Nat. Comm. 10.1038/ncomms12468 (2016).

  6. Climate Warming

    Warming our world

    1. H. Jesse Smith

    How much will human emissions of carbon dioxide cause global temperatures to rise? The magnitude of that warming depends a great deal on the response of clouds: If clouds reflect more sunlight back into space, warming will be reduced, but if they reflect less, warming will be greater. Brient and Schneider use satellite data to show that low clouds over tropical oceans will reflect less shortwave radiation as surface waters warm, supporting estimates of climate sensitivity to atmospheric carbon dioxide concentrations on the higher end of the existing range, and that this behavior will make it unlikely that global temperature rise can be capped at less than the common target of 2.0°C.

    J. Clim. 10.1175/JCLI-D-15-0897.1 (2016).

  7. RNA Stability

    Codon optimality at genome transition

    1. Beverly A. Purnell

    Nucleotide triplets, or codons, designate specific amino acids for protein synthesis. However, that is not their only job. In yeast and bacteria, codons contribute to RNA stability, with “optimal” codons stabilizing RNAs and “suboptimal” codons destabilizing RNAs. This is possible because multiple codons can encode the same amino acid. Bazzini et al. now demonstrate that codon usage in zebrafish, frogs, mice, and flies can affect transcript degradation and polyadenylation at the critical stage in development when transcription switches from the maternal to the zygotic genome. Furthermore, enriching genes with nonoptimal codons can reduce translation efficiency.

    EMBO J. 10.15252/embj.201694699 (2016).

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