Editors' Choice

Science  28 Jun 2019:
Vol. 364, Issue 6447, pp. 1248
  1. Sensory Perception

    A measured sniffer

    1. Sacha Vignieri

    The Asian elephant's long trunk supports a keen sense of smell.

    CREDIT: SMILEUS IMAGES/ALAMY STOCK PHOTO

    We humans see the world through a primate-centric viewpoint that has influenced how we test for traits in other animals, most of whom experience the world in very different ways. One area where this bias has been apparent is in tests of animal cognition and perception, where vision is often the focal sense. Plotnik et al. branched out beyond the bounds of sight to test whether elephants, who have a well-known and impressive nose, could differentiate relative amounts of food based entirely on scent. Controlling for alternative interpretations, they found that, indeed, Asian elephants could identify buckets that had more sunflower seeds solely using olfaction. The elephants did struggle to select among the buckets when the amounts of seeds in them differed only slightly, however, this is also the case in most animals tested for visual discrimination, including humans.

    Proc. Natl. Acad. Sci. U.S.A. 116, 12566 (2019).

  2. Virology

    Matchmaking between virus and host

    1. Valda Vinson

    Coronaviruses not only include the deadly respiratory viruses, such as SARS and MERS, but also viruses that usually cause mild respiratory tract infections. However, mild coronavirus infections can cause severe complications in immunocompromised people. To infect cells, trimers of the coronaviruses' transmembrane spike glycoprotein bind to host receptors. Tortorici et al. determined the cryo–electron microscopy structures of the trimeric spike from human coronavirus HCoV-OC43 in isolation and in complex with a 9-O-acetylated sialic acid—a modification found on glycoproteins at the host cell surface. The ligand binds in a surface-exposed groove that is conserved in all coronaviruses.

    Nat. Struct. Mol. Biol. 26, 481 (2019).

  3. Molecular Biology

    Noisy transcription

    1. Steve Mao

    Transcription factors (TFs) bind to a promoter, a DNA region next to a gene. TFs recruit cofactors and RNA polymerase (RNAP) to initiate gene transcription in bursts. In single cells, RNAP bursting at a certain gene is stochastic. Using a single-molecule imaging approach, Donovan et al. visualized TF dynamics and RNAP bursting kinetics simultaneously at a single gene in budding yeast cells. The binding affinity of the TF for its binding site dictates its dwell time on the promoter. Dwell time determines bursting duration of RNAP, and the frequency of bursting within each duration depends on the effective concentration of TF on the promoter.

    EMBO J. 38, e100809 (2019).

  4. Food Policy

    Unaffordable oasis in a food desert

    1. Brad Wible

    To address disparities in healthful eating, policy-makers have promoted development of new supermarkets in “food deserts” in poorer neighborhoods, making it easier to find healthy groceries locally instead of having to travel to wealthier neighborhoods. Combining data including household grocery purchases and relocations, and locations of new supermarkets, Allcott et al. conclude that exposing poorer people to healthier food typical of wealthier neighborhoods would increase demand for healthy food by only 10%. They calculate that a subsidy to help poorer people afford healthier food would be much more effective.

    Quart. J. Econ. 10.1093/qje/qjz015 (2019).

  5. Granular Materials

    Mimicking millions of earthquakes

    1. Brent Grocholski

    Earthquakes are simulated in many different ways in the lab, but these simulations tend to produce a limited number of “labquakes.” Lherminier et al. solve this problem by using continuously sheared cylinders filled with photoelastic disks, generating millions of small ruptures in the lab. Their labquakes reproduce size distributions found in regions with lots of earthquakes, along with the foreshock and aftershock behaviors. The experimental approach provides a unique way of simulating and tracking force networks responsible for rupture in the lab and on real-world faults.

    Phys. Rev. Lett. 122, 218501 (2019).

  6. Tree Demography

    Slow-growing trees sequester more carbon

    1. Andrew M. Sugden

    Tree rings mark yearly growth.

    PHOTO: DEA/G. CIGOLINI/GETTY IMAGES

    Dendrochronology—the study of tree growth patterns through the analysis of annual growth rings—is a powerful tool for studying the past but may also help to inform the future. Through tree-ring analysis of living and dead conifers from highland ecosystems in Spain and Russia, Büntgen et al. show that longest-lived individuals are those with the slowest juvenile growth rates. This means that higher levels of carbon accumulation are achieved in communities of slow-growing species, which indicates potential limits to the effectiveness of policies for carbon sequestration that rely on fast-growing tree plantations to mitigate the effects of global warming.

    Nat. Commun. 10, 2171 (2019).

  7. Quantum Computing

    Coding fault-tolerant quantum computing

    1. Ian S. Osborne

    Recent advances in creating quantum processors comprising several tens of qubits bring the era of quantum advantage tantalizingly close. Reaching that point, however, will require quantum processors that are scalable and fault tolerant. With the underlying architectures of these processors based on superconducting qubits laid out in a two-dimensional array, so-called surface codes are being developed that enable a robust error-correction capability due to the collective behavior of several qubits. Li et al. describe compass codes, a generalized version of surface codes, that can deal various kinds of noise affecting the processor. A compass code can be engineered to correct for specific types of noise and thus provides a general route to fault-tolerant quantum processors.

    Phys. Rev. X 9, 021041 (2019).