This Week in Science

Science  16 Nov 2018:
Vol. 362, Issue 6416, pp. 788
  1. Tropical Storms

    Warm water and big winds

    1. H. Jesse Smith

    Tropical storm Nate caused extensive damage in Costa Rica in October 2017.

    CREDIT: JEFFREY ARGUEDAS/EPA-EFE/SHUTTERSTOCK

    The 2017 North Atlantic hurricane season was highly active, with six major storms—nearly two standard deviations above the normal number. Three of those storms made landfall over the Gulf Coast and the Caribbean, causing terrible damage and loss. Why was the season so fierce? Murakami et al. used a suite of high-resolution model experiments to show that the main cause was pronounced warm sea surface conditions in the tropical North Atlantic. This effect was distinct from La Niña conditions in the Pacific Ocean that were involved in other years. It remains unclear how important anthropogenic forcing may be in causing such increased hurricane activity.

    Science, this issue p. 794

  2. Network Science

    The science of art advancement

    1. Barbara R. Jasny

    Art appreciation is highly subjective. Fraiberger et al. used an extensive record of exhibition and auction data to study and model the career trajectory of individual artists relative to a network of galleries and museums. They observed a lock-in effect among highly reputed artists who started their career in high-prestige institutions and a long struggle for access to elite institutions among those who started their career at the network periphery.

    Science, this issue p. 825

  3. Mass Spectrometry

    Innovating to be nondisruptive

    1. Valda Vinson

    Insights into the architecture and stoichiometry of membrane complexes have grown with advances in cryo–electron microscopy and native mass spectroscopy. However, most of these studies are not in the context of native membrane. Chorev et al. released intact membrane complexes directly from native lipid membrane vesicles into a mass spectrometer. They analyzed components of the Escherichia coli inner and outer membranes and the bovine mitochondrial inner membrane. For several identified complexes, they found a stoichiometry that differs from published results and, in some cases, confirmed interactions that could not be characterized structurally.

    Science, this issue p. 829

  4. Biotechnology

    A programmable type of CRISPR system

    1. Steve Mao

    CRISPR-Cas9 systems have been causing a revolution in biology. Harrington et al. describe the discovery and technological implementation of an additional type of CRISPR system based on an extracompact effector protein, Cas14. Metagenomics data, particularly from uncultivated samples, uncovered the CRISPR-Cas14 systems containing all the components necessary for adaptive immunity in prokaryotes. At half the size of class 2 CRISPR effectors, Cas14 appears to target single-stranded DNA without class 2 sequence restrictions. By leveraging this activity, a fast and high-fidelity nucleic acid detection system enabled detection of single-nucleotide polymorphisms.

    Science, this issue p. 839

  5. Polymers

    Patterned fiber formation

    1. Marc S. Lavine

    The ability of liquid crystalline materials to order spontaneously has driven many innovations, from display technologies to extremely tough polymer fibers. Cheng et al. exploited this preponderance toward long-range ordering to direct the growth of nonliquid crystalline polymers into sheets of highly ordered fibers. Small changes to the processing conditions could be used to tweak the arrangement of the liquid crystals to generate a wide range of polymer mats or sheets for potential use in sensing or filtration applications.

    Science, this issue p. 804

  6. Inflammation

    DNA binding as an anti-inflammatory

    1. Seth Thomas Scanlon

    Mice that lack the gene encoding 8-oxoguanine DNA glycosylase 1 (OGG1) show resistance to inflammation. This enzyme binds to sites of oxidative DNA damage and initiates DNA base excision repair. Visnes et al. developed a small-molecule drug that acts as a potent and selective active-site inhibitor that stops OGG1 from recognizing its DNA substrate (see the Perspective by Samson). The drug inhibited DNA repair and modified OGG1 chromatin dynamics, which resulted in the inhibition of proinflammatory pathway genes. The drug was well tolerated by mice and suppressed lipopolysaccharide- and tumor necrosis factor–α–mediated neutrophilic inflammation in the lungs.

    Science, this issue p. 834; see also p. 748

  7. Dynamic Materials

    Chemically reversible hydrogels

    1. Phil Szuromi

    Illustration of triggered superstructure changes

    CREDIT: MARK SENIW, SIMPSON QUERREY INSTITUTE, NORTHWESTERN UNIVERSITY

    The dynamic reorganization of some cellular biopolymers in response to signals has inspired efforts to create artificial materials with similar properties. Freeman et al. created hydrogels based on peptide amphiphiles that can bear DNA strands that assemble into superstructures and that disassemble in response to chemical triggers. The addition of DNA conjugates induced transitions from micelles to fibers and bundles of fibers. The resulting hydrogels were used as an extracellular matrix mimic for cultured cells. Switching the hydrogel between states also switched astrocytes between their reactive and naïve phenotypes.

    Science, this issue p. 808

  8. Geology

    Impact crater under ice

    1. Philippa J. Benson

    Ancient meteorite impact craters have been found across the surface of Earth. Kjær et al. performed an ice-penetrating radar analysis of the Hiawatha Glacier in northwest Greenland and discovered an impact crater under Earth's ice sheets. The oldest ice in this crater is debris-ridden or heavily disturbed, suggesting that the impact postdates initiation of the ice sheet. Sediments carried by a river draining out of the Hiawatha Glacier included grains that were physically shocked in an impact by a relatively rare iron meteorite. Models suggest that the meteorite must have been on the scale of a kilometer wide. The crater may have formed relatively recently during the Pleistocene.

    Sci. Adv. 10.1126/sciadv.aar8173 (2018).

  9. Cancer

    Lung cancer search and destroy

    1. Yevgeniya Nusinovich

    Like many cancer types, lung cancer is easier to treat when it is detected in its early stages. Scafoglio et al. discovered that a glucose transporter called sodium-dependent glucose transporter 2 is specifically found in early-stage lung tumors. They used a receptor-specific, radiolabeled tracer to perform positron emission tomography to identify early tumors. Furthermore, a class of diabetes drugs called gliflozins, which target the same receptor, effectively targeted these lung tumors in mouse models.

    Sci. Transl. Med. 10, eaat5933 (2018).

  10. Cell Metabolism

    Mitochondrial serine transporter identified

    1. Steve Mao

    One-carbon (1C) metabolism is a universal metabolic process that is required for purine synthesis and supports the high levels of proliferation in cancer cells. The transport of serine into mitochondria supplies most of the 1C units needed for biosynthesis. Kory et al. used a genetic screen to identify the long-sought-after mitochondrial serine transporter. Elucidating the key step of serine transport is important for our understanding of metabolism and has potential implications for cancer treatment.

    Science, this issue p. eaat9528

  11. Neurogenomics

    Mapping the brain, one neuron at a time

    1. Laura M. Zahn

    Spatial transcriptomics can link molecularly described cell types to their anatomical positions and functional roles. Moffitt et al. used a combination of single-cell RNA-sequencing and MERFISH (multiplexed error-robust fluorescence in situ hybridization) to map the identity and location of specific cell types within the mouse preoptic hypothalamus and surrounding areas of the brain (see the Perspective by Tasic and Nicovich). They related these cell types to specific behaviors via gene activity. The approach provides an unbiased description of cell types of the preoptic area, which are important for sleep, thermoregulation, thirst, and social behavior.

    Science, this issue p. eaau5324; see also p. 749

  12. Neurodevelopment

    Development of human brain neurons

    1. Pamela J. Hines

    The earliest stages of human brain development are very difficult to monitor, but using induced pluripotent stem cells (iPSCs) can help to elucidate the process. Real et al. transplanted neural progenitors derived from human iPSCs into the brains of adult mice. They used intravital imaging to visualize how resulting neurons grew and connected. The human cells produced neurons that integrated and developed synaptic networks with oscillatory activity. Dendritic pruning was observed and involved a process of branch retraction, not degeneration. Cells derived from individuals with Down syndrome, upon transplantation into the mouse brain, produced neurons that grew normally but showed reduced dendritic spine turnover and less network activity.

    Science, this issue p. eaau1810

  13. Organic Chemistry

    Heterocycles meet and marry on phosphorus

    1. Jake Yeston

    Metals such as palladium are routinely used to link together carbon rings in pharmaceutical synthesis. However, the presence of nitrogen in both rings can trip up this process. Hilton et al. report a versatile alternative process in which phosphorus takes the place of the metal. The phosphorus binds successively to both rings at the sites opposite the nitrogen, and treatment with acidic ethanol then pushes them off, bound to each other. Theory implicates a five-coordinate phosphorus intermediate that kinetically favors coupling of the two nitrogen-bearing rings over reactions of the other all-carbon substituents.

    Science, this issue p. 799

  14. Biohybrid Microbes

    Light-powered cell factories

    1. Michael A. Funk

    Bacteria and fungi are used industrially to produce commodity fine chemicals at vast scale. Sugars are an economical feedstock, but many of the desired products require enzymatic reduction, meaning that some of the sugar must be diverted to regenerate the cellular reductant NADPH (reduced form of nicotinamide adenine dinucleotide phosphate). Guo et al. show that electrons from light-sensitive nanoparticles can drive reduction of cellular NADPH in yeast, which can then be used for reductive biosynthetic reactions. This system can reduce diversion of carbon to NADPH regeneration and should be compatible with many existing engineered strains of yeast.

    Science, this issue p. 813

  15. Nanomaterials

    Wafer-scale hBN crystalline films

    1. Phil Szuromi

    Although wafer-scale polycrystalline films of insulating hexagonal boron nitride (hBN) can be grown, the grain boundaries can cause both scattering or pinning of charge carriers in adjacent conducting layers that impair device performance. Lee et al. grew wafer-scale single-crystal films of hBN by feeding the precursors into molten gold films on tungsten substrates. The low solubility of boron and nitrogen in gold caused micrometer-scale grains of hBN to form that coalesced into single crystals. These films in turn supported the growth of epitaxial wafer-scale films of graphene and tungsten disulfide.

    Science, this issue p. 817

  16. Ultrafast Dynamics

    Physics and chemistry in concert

    1. Jelena Stajic

    Shining a short, intense light pulse on a material can cause a transition in both its atomic and electronic structures. The dynamics of the electronic structure in such transitions can be monitored using, for example, time-resolved photoemission spectroscopy. Nicholson et al. observed a photoinduced metal-insulator transition in indium nanowires on a silicon surface. They monitored both the physics and the chemistry of the system after the initial photoexcitation and correlated the closing of the electronic bandgap with the rearrangement of chemical bonds. The results showcase the wealth of information that time-resolved tools can reveal about the dynamics of complex systems.

    Science, this issue p. 821

  17. Cell Biology

    Cell transitions in pathology

    1. Gemma Alderton

    Endothelial cells line the vasculature. These plastic cells can undergo a cell fate transition to produce mesenchymal cells, known as the endothelial-to-mesenchymal transition (EndMT). This transition is important in embryonic heart development and has also been observed in vascular pathologies, such as atherosclerosis. In a Perspective, Dejana and Lampugnani discuss the debate surrounding how EndMT contributes to disease and whether it can be targeted to treat various pathologies associated with vascular and extracellular matrix dysfunction.

    Science, this issue p. 746

  18. Conservation

    Impacts of outdoor artificial light

    1. Julia Fahrenkamp-Uppenbrink

    The use of artificial light at night is increasing around the world, causing both direct emissions, mostly in the vicinity of the light, and a brightening of the night sky called skyglow. In a Perspective, Gaston explains that this light is changing the activity patterns of many animal species and can even affect the timing of budburst in temperate trees. Outdoor artificial light at night may also affect human sleep patterns and human health. The ongoing shift to light-emitting diode (LED) lamps with a broader and colder light spectrum is exacerbating these problems.

    Science, this issue p. 744

  19. Cardiac Dysfunction

    Breaking mitochondria and hearts

    1. Wei Wong

    Blocking the excessive mitochondrial fission mediated by dynamin-related protein 1 (Drp1) that occurs after myocardial infarction prevents cardiac dysfunction from developing. Nishimura et al. found that the cytoskeletal regulator filamin increased Drp1 activity after myocardial infarction and that the filamin-Drp1 interaction was inhibited by the U.S. Food and Drug Administration–approved drug cilnidipine (see the Focus by Boyer and Eguchi). Administering cilnidipine to mice after myocardial infarction reduced mitochondrial fission and cardiac dysfunction, suggesting that this drug could be repurposed to reduce heart attack–induced damage.

    Sci. Signal. 11, eaat5185, eaav3267 (2018).

  20. Immunogenetics

    Fine-tuning CD8+ T cell responses

    1. Ifor Williams

    Human cytotoxic CD8+ T cells are important for defense against viral infections. Boelen et al. investigated whether inhibitory killer cell immunoglobulin-like receptors (iKIRs) carried by patients with chronic viral infections affected the efficacy of their CD8+ T cell responses. Possession of an iKIR gene along with a gene encoding a KIR ligand enhanced protective and detrimental human leukocyte antigen (HLA) class I associations for HIV-1, hepatitis C virus, and human T cell leukemia virus type 1. Analysis of virus dynamics, in vitro survival assays, and mathematical modeling suggested that iKIR ligation enhances HLA associations by increasing T cell survival. In contrast to many reported iKIR-disease associations, these observations applied to all iKIRs and the three viral infections studied.

    Sci. Immunol. 3, eaao2892 (2018).