Editors' Choice

Science  16 Dec 2016:
Vol. 354, Issue 6318, pp. 1388
  1. Stellar Astrometry

    A star passing close to the solar system

    1. Keith T. Smith

    Many new comets could be produced by the passage of the small star Gliese 710 through the Oort Cloud.

    PHOTO: WILLIAM ATTARD MCCARTHY/ALAMY STOCK PHOTO

    The Gaia astrometry satellite has greatly improved measurements of the position and motion of nearby stars. Berski and Dybczyński searched the Gaia data for the star that will pass closest to the Sun. They found that Gliese 710, a small faint star, will pass within 13,000 ± 6,000 astronomical units (one astronomical unit is roughly the distance from Earth to the Sun). That will be well within the Oort Cloud, a collection of small bodies on the outskirts of our solar system. Some of those bodies will be knocked inward, generating large numbers of new comets. Earth is safe for now, though; the encounter will happen in 1.3 million years.

    Astron. Astrophys. 595, L10 (2016).

  2. Cell Biology

    Crawling cells need to explore

    1. Sarah Harrison

    As it crawls, a cell explores the space in front of it by extending protrusions. These are formed by the branching of actin filaments in the cytoskeleton at the leading edge that push the cell membrane outward. Leithner et al. disrupted actin branching in crawling leukocytes and observed profound changes in cell shape. The cells were able to move but were unable to change direction or navigate, whereas wild-type cells oriented in response to chemical gradients and navigated obstacles. Thus, although actin filament branching is not required to move a crawling cell forward, it is essential for generating the protrusions necessary to explore and navigate a complex three-dimensional environment.

    Actin filaments allow cells to explore.

    PHOTO: A. LEITHNER ET AL., NATURE CELL BIOLOGY 18, 1253 (24 OCTOBER 2016) © 2016 MACMILLAN PUBLISHERS LIMITED

    Nat. Cell Biol. 18, 1253 (2016).

  3. Cancer Etiology

    Poor clock management and cancer

    1. Paula A. Kiberstis

    For most people, sleeping and waking on a regular schedule is an aspiration rather than a reality. Unfortunately, it is becoming clear that chronic disruption of the circadian clock, or “social jet lag,” can pose health risks. Kettner et al. studied mice to explore how jet lag affects liver function experimentally by varying the times at which lights were switched on and off each week. Despite a healthy diet, the jet-lagged mice gained weight and developed fatty liver disease, which progressed to fibrosis and in some cases to hepatocellular carcinoma, a form of liver cancer. The livers of these mice showed marked dysregulation of metabolic pathways controlled by two specific nuclear receptors, FXR and CAR.

    Cancer Cell 30, 1 (2016).

  4. Microbiology

    Crowd-sourced CRISPR-Cas responses

    1. Caroline Ash

    Bacterial populations can coordinate their responses to environmental change by quorum sensing. Bacteria also possess protective combinations of clustered regularly interspaced short palindromic repeats and associated proteins (CRISPR-Cas) to defend themselves against viral predation and attack by mobile elements. Patterson et al. have discovered that Serratia species do not rely on one CRISPR-Cas setup but rather have two backups to modulate responses to foreign nucleic acid sequences. Moreover, these CRISPR-Cas combinations are triggered by quorum sensing, which kicks in when a bacterial population reaches a density high enough that it becomes apparent and vulnerable to predators, competitors, and other threats.

    Molec. Cell 64, 1 (2016).

  5. Cardiac Muscle

    Inhibitor reduces heart muscle calcification

    1. Beverly A. Purnell

    Electrical impulses propagate through the heart for proper cardiac function. Heart muscle calcification, which can occur with aging, disease, or injury, blocks electrical conduction, resulting in cardiac pump dysfunction and arrhythmias. By tracing cell lineage, Pillai et al. show that cardiac fibroblasts induce this mineralization and take on an osteoblast cell–like fate. Calcification was reduced in mice by administering a small molecule inhibitor that effectively blocks the bone mineralization enzyme ENPP1. Hence, calcification associated with disease or injury may be prevented by targeting ENPP1 to restore cardiac muscle function.

    Blocking the mineralization enzyme ENPP1 prevents muscle calcification.

    PHOTO: I. C. L. PILLAI ET AL., CELL STEM CELL 20 (2 FEBRUARY 2017) © 2016 ELSEVIER INC.

    Cell Stem Cell 10.1016/j.stem.2016.10.005 (2016).

  6. Education

    Expanding access to gifted education

    1. Brad Wible

    Universal screening using a nonverbal test of cognitive ability increased representation of minorities and economically disadvantaged students in school programs for gifted and talented children. Card and Giuliano show that in years before and after this screening process, when students had to be referred by teachers or parents for testing into gifted programs, the programs were disproportionately populated by students who were white and from higher-income neighborhoods. These results suggest that teachers and parents commonly fail to recognize potential among minorities, the poor, or those who have limited proficiency with the English language.

    Proc. Natl. Acad. Sci. U.S.A. 10.1073/pnas.1605043113 (2016).

  7. Quantum Simulation

    An ultrafast peek into the ultracold

    1. Jelena Stajic

    Gases of Rydberg atoms—exotic atoms in which one of the electrons is orbiting the nucleus at a large distance—can simulate the effects of long-range interactions in many-body systems. Commonly, such experiments are conducted in a low-density regime where the Rydberg atoms are few and far apart. Takei et al. created a cold, high-density gas of 87Rb Rydberg atoms and studied its ultrafast dynamics. The low-temperature gas was effectively “frozen,” and the dynamics were caused solely by many-body interactions. The researchers found that they had to go beyond the standard mean-field description to account for their data.

    Nat. Commun. 10.1038/ncomms13449 (2016).

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