This Week in Science

Science  24 Nov 2017:
Vol. 358, Issue 6366, pp. 1015
  1. Light Pollution

    Brightening nights across the globe

    1. Kip Hodges

    Satellites reveal the artificial brightening of night skies.

    CREDIT: ROBERT SIMMON/NASA EARTH OBSERVATORY

    The degradation of nighttime darkness by artificial illumination has well-documented ecological and sociological consequences. Excessive outdoor lighting also compromises the quality of light-telescope astronomical observations from Earth. Satellite sensor technologies have now improved to the point that repeat observations reveal how outdoor lighting is changing worldwide, and Kyba et al. document a worsening problem. The areas of Earth with artificial outdoor lighting, as well as the brightness of outdoor lighting in areas already lit, are increasing by more than 2% per year.

    Sci. Adv. 10.1126/sciadv.1701528 (2017).

  2. Neurodevelopment

    The makings of the primate brain

    1. Pamela J. Hines

    Although nonhuman primate brains are similar to our own, the disparity between their and our cognitive abilities tells us that surface similarity is not the whole story. Sousa et al. overlaid transcriptome and histological analyses to see what makes human brains different from those of nonhuman primates. Various differentially expressed genes, such as those encoding transcription factors, could alter transcriptional programs. Others were associated with neuromodulatory systems. Furthermore, the dopaminergic interneurons found in the human neocortex were absent from the neocortex of nonhuman African apes. Such differences in neuronal transcriptional programs may underlie a variety of neurodevelopmental disorders.

    Science, this issue p. 1027

  3. Biotechnology

    Precise transcriptome engineering

    1. Steve Mao

    Efficient and precise RNA editing to correct disease-relevant transcripts holds great promise for treating genetic disease. Cox et al. took advantage of the ability of Cas13b, an effector from a type VI CRISPR-Cas system, to target specific RNAs directly (see the Perspective by Yang and Chen). They fused Cas13b with the ADAR2 adenosine deaminase domain and used rational protein engineering to improve the resultant enzyme. These approaches yielded an RNA knockdown and editing platform that allowed efficient and specific RNA depletion and correction in mammalian cells.

    Science, this issue p. 1019; see also p. 996

  4. Glassy Materials

    Behavioral universality across size scales

    1. Marc S. Lavine

    Glassy materials are characterized by a lack of long-range order, whether at the atomic level or at much larger length scales. But to what extent is their commonality in the behavior retained at these different scales? Cubuk et al. used experiments and simulations to show universality across seven orders of magnitude in length. Particle rearrangements in such systems are mediated by defects that are on the order of a few particle diameters. These rearrangements correlate with the material's softness and yielding behavior.

    Science, this issue p. 1033

  5. Nuclear Physics

    Nailing down the proton magnetic moment

    1. Jelena Stajic

    Fundamental physical laws are believed to remain the same if subjected to three simultaneous transformations: flipping the sign of electric charge, taking a mirror image, and running time backward. To test this charge, parity, and time-reversal (CPT) symmetry, it is desirable to know the fundamental properties of particles such as the proton to high precision. Schneider et al. used a double ion trap to determine the magnetic moment of a single trapped proton to a precision of 0.3 parts per billion. Comparatively precise measurements of the same quantity in the antiproton are now needed for a rigorous test of CPT symmetry.

    Science, this issue p. 1081

  6. Network Science

    In network science, change is good

    1. Barbara R. Jasny

    Historically, network science focused on static networks, in which nodes are connected by permanent links. However, in networked systems ranging from protein-protein interactions to social networks, links change. Although it might seem that permanent links would make it easier to control a system, Li et al. demonstrate that temporality has advantages in real and simulated networks. Temporal networks can be controlled more efficiently and require less energy than their static counterparts.

    Science, this issue p. 1042

  7. Immunology

    Two snapshots of the TAPBPR-MHC I complex

    1. Seth Thomas Scanlon

    Cytotoxic CD8+ T cells recognize infected and cancerous cells by scrutinizing the antigenic peptides presented by the major histocompatibility complex class I (MHC I). Peptide binding and exchange occurs in the endoplasmic reticulum in a sequence of events mediated by the chaperones tapasin and TAPBPR (see the Perspective by Cresswell). Thomas and Tampé resolved the crystal structure of the TAPBPR–MHC I editing complex by using a photocleavable high-affinity peptide to stabilize the MHC molecule. Jiang et al. crystalized MHC I molecules inhabited by truncated disulfide-linked peptides that still permit TAPBPR to bind. These complimentary snapshots elucidate the dynamic process by which chaperones stabilize the groove of peptide-free MHC I molecules. This helps MHC I sample peptide candidates and facilitates the generation of peptide repertoires enriched with high-affinity antigenic peptides.

    Science, this issue p. 1060, p. 1064; see also p. 992

  8. Cognitive Development

    Ranking valuations on the basis of observed choices

    1. Gilbert Chin

    Obliged to make a choice between two goals, we evaluate the benefits of achieving the goals compared with the costs of the actions required before deciding what to do. This seems perfectly straightforward, and it is unsurprising to learn that we can also apply this reasoning to others; that is, someone that we see choosing a goal that requires a more costly action must value that goal more highly. What is remarkable, as Liu et al. report, is that preverbal children can reason in this same fashion.

    Science, this issue p. 1038

  9. Cancer

    A tale of two receptors

    1. Lindsey Pujanandez

    Despite the explosion of research on chimeric antigen receptor (CAR) T cell therapy, most preclinical studies use transduced human T cells in immunodeficient mice. To determine how CAR activity is affected by T cell receptor (TCR) engagement, Yang et al. used a CAR targeting CD19 and transgenic T cells in immunocompetent mice. Exposure of CD8+ CAR T cells to the TCR antigen led to T cell exhaustion, apoptosis, and reduced therapeutic efficacy; this phenomenon was not observed for CD4+ CAR T cells. Thus, considering T cell biology could further improve CAR T cell therapy.

    Sci. Transl. Med. 9, eaag1209 (2017).

  10. Structural Biology

    The inner workings of an optogenetic tool

    1. Valda Vinson

    Channelrhodopsins are membrane channel proteins whose gating is controlled by light. In their native setting, they allow green algae to move in response to light. Their expression in neurons allows precise control of neural activity, an approach known as optogenetics. Volkov et al. describe the high-resolution structure of channelrhodopsin 2, the most widely used optogenetics tool, as well as the structure of a mutant with a longer open-state lifetime (see the Perspective by Gerwert). Light activation perturbs an intricate hydrogen-bonding network to open the channel. The structures provide a basis for designing better optogenetic tools.

    Science, this issue p. 10.1126/science.aan8862; see also p. 1000

  11. Solid-State Physics

    Tuning diamagnetism with current

    1. Jelena Stajic

    Properties of materials can be tuned by various means, such as chemical doping, magnetic field, or pressure. Sow et al. used electrical currents of modest density to turn the Mott insulator Ca2RuO4 into a semimetal. Concurrently, its diamagnetic response—the ability to counter an externally applied magnetic field—rose to levels higher than in any other nonsuperconducting material. The use of electrical current as a powerful experimental knob may be applicable to other similar materials.

    Science, this issue p. 1084

  12. Molecular Separation

    Purifying ethylene with flexible zeolites

    1. Phil Szuromi

    Ethylene is a key feedstock for many chemicals and polymers, but its production requires cryogenic separation from ethane, an energy-consuming step. In theory, pure silica zeolites are well suited to separate olefins from paraffins. Bereciartua et al. synthesized a pure silica zeolite with very small pores, which, if static, would not adsorb either of these hydrocarbons. However, molecular dynamics suggested that the pores should be flexible. Indeed, in competitive adsorption experiments, the zeolite preferentially adsorbed ethylene from a mixed stream of ethylene and ethane.

    Science, this issue p. 1068

  13. Topology

    Fluid waves with topological origins

    1. Brent Grocholski

    Topological effects that arise from material boundaries are well known in solid-state physics and form the basis for topological insulators. Delplace et al. describe atmospheric and ocean waves that appear to have a similar topological origin (see the Perspective by Biello and Dimofte). The waves exist because of the symmetry-breaking nature of Earth's rotation, which allows certain fixed topological constraints on the system. These findings may be useful for understanding a wide variety of geophysical and astrophysical flows.

    Science, this issue p. 1075; see also p. 990

  14. Metamaterials

    Getting twisted with metamaterials

    1. Brent Grocholski

    In the classical picture of solid mechanics, deformation in response to stress is constrained owing to limitations on the degrees of freedom. For instance, when you push on a material, you do not expect it to twist in response. Frenzel et al. designed a mechanical metamaterial with a pronounced twist to the left or right when pushed (see the Perspective by Coulais). Designing this type of chirality for a macroscopic material is unexpected, but it points to a more general strategy for developing materials with unusual deformation behavior.

    Science, this issue p. 1072; see also p. 994

  15. Atomic Physics

    Packing rubidium into quantum degeneracy

    1. Jelena Stajic

    When atomic gases, such as those of alkali elements, are cooled to very low temperatures, they can reach a state of quantum degeneracy, where their quantum nature comes to the fore. In this process, the very last step is evaporative cooling, in which the hottest atoms are coaxed into leaving the gas. Hu et al. devised a protocol that evades the evaporative cooling step, is faster, and suffers less atom loss. The method rests on iteratively manipulating the laser beams of an optical lattice in which a gas of 87Rb atoms is held so that the gas becomes progressively denser. The method should be widely applicable to other atomic species.

    Science, this issue p. 1078

  16. Carbon Cycle

    Dissolved inorganic carbon fixers revealed

    1. Caroline Ash

    Most of the ocean is dark. Yet it is in this darkness, away from photosynthesizing sunlight, that most planetary carbon cycling occurs. Pachiadaki et al. show that nitrite-oxidizing bacteria in one phylum are the predominant fixers of dissolved inorganic carbon in the mesopelagic ocean. The authors sequenced thousands of single amplified genomes of marine prokaryotes. They identified more than 30 nitrite-oxidizing obligate chemoautotrophic bacteria that were unable to transport carbohydrate and that expressed nitrite oxidoreductase. This enzyme provides electrons to drive a reverse tricarboxylic acid cycle that fixes the carbon. Many of the genomes also suggest organisms that have the capacity to produce ammonium and other substrates, possibly to feed nitrite-producing metabolic partners.

    Science, this issue p. 1046

  17. Structural Biology

    Structural basis for mRNA 3′-end processing

    1. Steve Mao

    The eukaryotic mRNA 3′-end processing machinery interacts with the transcription machinery and adds the polyadenylation tail on the mRNA substrate. Casañal et al. used cryo–electron microscopy, mass spectrometry, and biochemical reconstitutions to show that the mRNA 3′-end processing machinery is organized into nuclease, polymerase, and phosphatase modules. The polymerase module of the complex acts as a hub to bring the RNA substrate and the accessory factors together to achieve efficient and controlled polyadenylation coordinated with transcription.

    Science, this issue p. 1056

  18. Infectious Diseases

    Control the vector, beat the disease

    1. Julia Fahrenkamp-Uppenbrink

    Infectious diseases such as malaria, leishmaniasis, and dengue are transmitted by insect vectors. In a Perspective, Hemingway highlights the often underestimated role of insecticides in bringing these vector-borne diseases under control. The emergence of insects that are resistant to commonly used insecticides is harming disease-control efforts, but developers of new insecticides are encountering many hurdles when trying to bring them to market. This problem is particularly acute for insecticide-treated bed nets. Introducing new insecticides in combinations will reduce the likelihood of resistance development. A streamlined process for World Health Organization guidance and recommendations would help to speed up the introduction of such interventions.

    Science, this issue p. 998

  19. Viral Immunity

    Host RNA helps promote viral replication

    1. Steve Mao

    Viruses exploit host metabolic networks for survival. Wang et al. identified a long noncoding RNA (lncRNA) that enhances replication of multiple viruses in both mouse and human cells (see the Perspective by Kotzin et al). The expression of this cytoplasmic lncRNA was induced by viruses and independent of type I interferon. The lncRNA directly bound to and stimulated the metabolic enzyme glutamic-oxaloacetic transaminase. This viral strategy may have relevance for clinical diseases involving metabolic dysfunction and viral infection.

    Science, this issue p. 1051; see also p. 993

  20. Fibrosis

    A nuclear off-switch for fibrosis

    1. Annalisa M. VanHook

    CD44 is a receptor for the extracellular matrix component hyaluronan. The standard isoform of CD44 enhances the differentiation of myofibroblasts that drive fibrosis. In contrast, prevention or reversal of myofibroblast differentiation depends on an alternatively spliced isoform, CD44v7/8. Midgley et al. found that hyaluronidase 2 (HYAL2), a hyaluronan-degrading enzyme, had a nonenzymatic role in determining CD44 splicing. In human lung fibroblasts exposed to an antidifferentiation factor, HYAL2 displaced components of the splicing machinery on CD44 precursor mRNA to promote the production of CD44v7/8 mRNA.

    Sci. Signal. 10, eaao1822 (2017).

  21. Tumor Immunology

    Tumor immunity flounders without FIP200

    1. Christiana N. Fogg

    The tumor microenvironment impairs the function of effector and memory T cells, but its effect on naïve T cells is not well understood. Xia et al. show that the autophagy component FIP200 is critical to promoting antitumor responses mediated by T cells. Ovarian cancer patients and mouse tumor models had higher rates of apoptosis and impaired autophagy in naïve T cells. This was associated with the selective loss of FIP200, which disrupted the balance of pro- and anti-apoptotic factors. Tumor-derived lactate suppressed FIP200 expression, thus causing enhanced apoptosis and attenuated antitumor responses.

    Sci. Immunol. 2, eaan4631 (2017).