This Week in Science

Science  23 Mar 2018:
Vol. 359, Issue 6382, pp. 1373
  1. Geophysics

    Building better early warning systems

    1. Kip Hodges

    Collapsed houses and damaged cars, 1 month after a series of earthquakes struck Kumamoto, Japan, in April 2016.

    CREDIT: KAREL PICHA/CTK/AP IMAGES

    Earthquake early warning systems are designed to alert the public in time to seek shelter before a devastating seismic event. Typically, they are triggered when a minimum threshold of earthquake-related ground motion is sensed. However, the time required for this motion to reach the sensors depends on their distance from the earthquake source. Minson et al. found that triggering such systems at low levels of ground motion provided substantially faster warning than waiting until strong ground motion was sensed. These results offer a foundation for better responses to earthquake hazards in high-risk regions.

    Sci. Adv. 10.1126/sciadv.aaq0504 (2018).

  2. Plant Science

    Keeping the channels open

    1. Pamela J. Hines

    When the rice blast fungus enters a rice cell, the plasma membrane stays intact, so the rice cell remains viable. The fungus then moves to adjacent cells via plasmodesmata, the plant's intercellular channels. Sakulkoo et al. used a chemical genetic approach to selectively inhibit a single MAP (mitogen-activated protein) kinase, Pmk1, in the blast fungus. Inhibition of Pmk1 trapped the fungus within a rice cell. Pmk1 regulated the expression of a suite of effector genes involved in suppression of host immunity, allowing the fungus to manipulate plasmodesmal conductance. At the same time, Pmk1 regulated the fungus's hyphal constriction, which allows movement into new host cells.

    Science, this issue p. 1399

  3. Infection

    Metabolic syndrome, leaky guts, and infection

    1. Caroline Ash

    Metabolic syndrome often accompanies obesity and hyperglycemia and is associated with a breakdown in the integrity of the intestinal barrier and increased risk of systemic infection. Thaiss et al. found that mice with systemic infection of a Salmonella analog, Citrobacter rodentium, also exhibited hyperglycemia. Deletion of the glucose transporter GLUT2 altered sensitivity to chemically induced epithelial permeability and protected mice from pathogen invasion. The authors also found a correlation in humans between glycated hemoglobin (an indicator of hyperglycemia) and serum levels of pathogen recognition receptor ligands.

    Science, this issue p. 1376

  4. Neurodevelopment

    Genomic plasticity during brain development

    1. Pamela J. Hines

    Mice genomes contain many mobile retrotransposons. Bedrosian et al. analyzed DNA from the mouse hippocampus during development (see the Perspective by Song and Gleeson). They found that the amount of maternal care in the first few weeks of a mouse pup's life affected the number of copies of the L1 retrotransposon. The experience of maternal care was thus “recorded” in the DNA of these mice pups during a time when the brain was still actively developing.

    Science, this issue p. 1395; see also p. 1330

  5. Conducting Polymers

    Moving charges with radicals

    1. Phil Szuromi

    Conducting polymers usually contain backbones with multiple bonds. After chemical doping to remove some of the electrons, charge carriers can move freely. These conjugated backbones can also make the polymers rigid and hard to process. Joo et al. synthesized a redox-active, nonconjugated radical polymer that exhibited high conductivity (see the Perspective by Lutkenhaus). The polymer has a low glass transition temperature, allowing it to form intermolecular percolation networks for electrons.

    Science, this issue p. 1391; see also p. 1334

  6. Cell Biology

    Local control of localized protein synthesis

    1. Stella M. Hurtley

    Localized protein synthesis provides spatiotemporal precision for injury responses and growth decisions at remote positions in nerve axons. Terenzio et al. show that this process is controlled by local translation of preexisting axonal mRNA encoding the master regulator mTOR (see the Perspective by Riccio). mTOR controls both its own synthesis and that of most newly synthesized proteins at axonal injury sites, thereby determining the subsequent survival and growth of the injured neuron.

    Science, this issue p. 1416; see also p. 1331

  7. Materials Science

    More than just simple folding

    1. Marc S. Lavine

    The foldaway wings of an earwig inspire materials design.

    PHOTO: JAKOB FABER/ETH ZÜRICH

    Origami involves folding two-dimensional sheets into complex three-dimensional objects. However, some shapes cannot be created using standard folds. Faber et al. studied the wing of an earwig, which can fold in ways not possible using origami and can alter its shape for flight. The authors replicated this ability by using a membrane that allows for deformations and variable stiffness. Prestretching generated energetically bistable origami patterns that exhibited passive self-folding behavior.

    Science, this issue p. 1386

  8. Cancer

    For cancer, think globally, act locally

    1. Yevgeniya Nusinovich

    Systemic immunotherapy in cancer treatment can have major side effects because it stimulates the entire immune system and is not necessarily tumor-specific. Surgery, a classic mainstay of cancer treatment, has the drawback of temporarily suppressing the immune response at the site of tumor resection. To address both concerns, Park et al. designed hydrogel scaffolds to gradually release agonists of innate immunity. They implanted these scaffolds into mice at the sites of tumor resection. This approach was safe and more effective than systemic or even locally injected immunotherapy.

    Sci. Transl. Med. 10, eaar1916 (2018).

  9. Cancer

    An alternate route for metastatic cells

    1. Paula A. Kiberstis

    Metastatic tumor cells are thought to reach distant organs by traveling through the blood circulation or the lymphatic system. Two studies of mouse models now suggest a hybrid route for tumor cell dissemination. Pereira et al. and Brown et al. used distinct methodologies to monitor the fate of tumor cells in lymph nodes. They found that tumor cells could invade local blood vessels within a node, exit the node by entering the blood circulation, then go on to colonize the lung. Whether this dissemination route occurs in cancer patients is unknown; the answer could potentially change the way that affected lymph nodes are treated in cancer.

    Science, this issue p. 1403, p. 1408

  10. Inorganic Chemistry

    Silicon clears a wet path to phosphines

    1. Jake Yeston

    Phosphoric acid is produced on a massive scale for fertilizer by treating phosphate rock with sulfuric acid. In contrast, preparation of more elaborate phosphorus compounds used in chemical catalysis, pharmaceutical, and battery applications requires laborious generation and chlorination of elemental phosphorus. Geeson and Cummins now show that phosphoric acid may also be a practical source of such compounds (see the Perspective by Protasiewicz). They isolated and characterized a phosphide salt derived from treatment of dehydrated phosphoric acid with trichlorosilane, a compound already used at the commercial scale to produce high-purity silicon. The salt proved to be a versatile precursor for a range of alkylated and fluorinated phosphorus compounds.

    Science, this issue p. 1383; see also p. 1333

  11. Biochemistry

    Using iron to generate a copper ligand

    1. Valda Vinson

    Many microbial enzymes are metal-dependent, and the microbe must acquire scarce metals from the environment. Microbes that use methane as a carbon source have a copper-dependent enzyme that oxidizes the methane. Peptides known as methanobactins (Mbns) acquire copper by using a pair of ligands comprising a nitrogen-containing ring and an adjacent thioamide. Kenney et al. describe the biosynthetic machinery that adds the copper-binding groups to a precursor peptide. This involves a complex of two homologs: MbnB, a member of a functionally uncharacterized protein family that includes a diiron cluster, and MbnC, which is even less well characterized. The iron cofactor is required for ligand synthesis. MbnB and MbnC homologs are encoded in many genomes, suggesting that they may have roles beyond Mbn biosynthesis.

    Science, this issue p. 1411

  12. Neurodegeneration

    Pinpointing amyloid's toxicity

    1. Leslie K. Ferrarelli

    Alzheimer's disease patients have decreased activity of the peptidyl-prolyl cis-trans isomerase Pin1, an enzyme that structurally alters phosphorylated proteins and reduces amyloid-β (Aβ) production. Using mouse models of Alzheimer's disease, Stallings et al. found that Pin1 was dephosphorylated and inactivated by the phosphatase calcineurin, which is stimulated by Aβ-induced changes in Ca2+ signaling. Aβ-induced dendritic spine loss, which underlies the synaptic dysfunction in Alzheimer's disease, was prevented by treating mice with the calcineurin inhibitor FK506, an immunosuppressant that reduces organ transplant rejection.

    Sci. Signal. 11, eaap8734 (2018).

  13. Climate

    How green is burning wood?

    1. Julia Fahrenkamp-Uppenbrink

    To fulfill its renewable energy pledges, the European Union is increasingly using wood rather than coal to fuel power stations. In a Perspective, Schlesinger cautions that this policy is having unintended consequences. This is particularly so in the southeastern United States, from which millions of tons of wood pellets are shipped to Europe each year. Wood is only a carbon-neutral fuel if the areas from which it is harvested can fully regrow. Offsetting the carbon used in production and transport requires additional biomass to accumulate on the land after harvest. Furthermore, carbon emissions from wood burning enter the atmosphere now, whereas forest growth removes carbon from the atmosphere over the course of several decades.

    Science, this issue p. 1328

  14. Metabolism

    An emerging target for vascular diseases

    1. Gemma Alderton

    Various pathologies, including cancer and ocular diseases, are associated with hypervascularization—a localized increase in blood vessels. Recent studies have revealed the importance of metabolism in driving endothelial cell activity to form new blood vessels (angiogenesis). In a Perspective, Li and Carmeliet discuss the therapeutic opportunities to target metabolic pathways in endothelial cells to disrupt or promote vascularization in a range of different pathological conditions.

    Science, this issue p. 1335