This Week in Science

Science  18 Mar 2016:
Vol. 351, Issue 6279, pp. 1276
  1. Feeding Behavior

    When enough isn't enough

    1. Peter Stern

    Mice lacking OGT in certain neurons become obese

    CREDIT: AMILOTORRES/ISTOCK PHOTO

    Overeating and obesity are rapidly becoming worldwide problems. Normally, mice do not overeat—they balance their caloric intake with their caloric needs. Lagerlöf et al. deleted an enzyme called O-GlcNAc transferase (OGT) from a subset of neurons in the mouse hypothalamus (see the Perspective by Schwartz). After the loss of OGT, the animals began to overeat and rapidly gained weight. The animals ate more at meal times, rather than eating more often. Thus, OGT seems to regulate satiety and helps to couple caloric intake to caloric need.

    Science, this issue p. 1293; see also p. 1268

  2. Superconductivity

    Peeking into a diamond pressure cell

    1. Jelena Stajic

    A defining characteristic of a superconductor is that it expels an external magnetic field. Demonstrating this effect can be tricky when the sample is under enormous pressures in a diamond anvil cell. Troyan et al. placed a tinfoil sensor inside a sample of H2S under pressure. They then bombarded it with synchrotron radiation and watched how the scattering of photons of tin nuclei changed over time. When H2S was in the normal state, an external magnetic field reached the sensor through the sample, causing the nuclear levels of tin to split. In the superconducting state, however, no splitting was observed because H2S expelled the field before it could reach the sensor.

    Science, this issue p. 1303

  3. Vascular Biology

    Reelin in leukocytes for atherosclerosis

    1. Wei Wong

    Atherosclerotic plaques can buid up within arteries

    CREDIT: DING ET AL.

    In the circulation, the secreted protein Reelin acts to stem bleeding after injury. Receptors for Reelin are found on the endothelial cells that line blood vessels. Ding et al. asked whether Reelin contributes to atherosclerosis: plaque buildup in arteries. Mice that lacked Reelin in the circulation were protected from diet-induced atherosclerosis. Reelin deficiency prevented leukocytes from sticking to endothelial cells, a critical first step in the inflammatory response that promotes atherosclerosis.

    Sci. Signal. 9, ra29 (2015).

  4. Microbiota

    Mom's bugs shape offspring immunity

    1. Kristen L. Mueller

    In utero, babies are relatively microbe-free but are quickly colonized at birth. These early microbial residents help to shape our immune systems. Gomez de Agüero et al. wondered whether the maternal microbiome also affects the offsprings' immune system during gestation. To do this, they transiently colonized otherwise microbe-free pregnant mice. Compared to those born to microbe-free moms, pups born to colonized moms had increased numbers of certain innate immune cells and different patterns of gene expression in their guts.

    Science, this issue p. 1296

  5. Hydrogen Bonding

    Gear-like rotation by a wobbly water duo

    1. Jake Yeston

    The molecules in liquid water move about constantly, but on average they cling to each other through hydrogen bonds, like dancers who keep switching partners. Richardson et al. uncovered a fresh twist in this molecular dance (see the Perspective by Clary). Studying clusters of six molecules each—essentially the smallest three-dimensional water droplets—they observed coupled motion of two different molecules in the cluster. The process breaks two different hydrogen bonds concurrently in a pattern akin to rotating gears.

    Science, this issue p. 1310; see also p. 1267

  6. Gas Infrastructure

    The magnitude of a major methane leak

    1. Nicholas S. Wigginton

    The Aliso Canyon underground gas storage facility outside Los Angeles, CA, houses enormous natural gas reserves. One well at the site experienced a blowout in late October 2015 and began leaking gas until it was sealed in February 2016. Over the course of 13 flights in the region, Conley et al. sampled the air column and determined daily release rates of methane (a powerful greenhouse gas) and ethane throughout the leak. The methane release rates were nearly double that of the entire Los Angeles region combined. Thus, single vulnerabilities can have major implications for state and federal climate policy.

    Science, this issue p. 1317

  7. Ebola Virus

    Antibodies block Ebola virus entry

    1. Kristen L. Mueller

    The recent Ebola virus outbreak in West Africa illustrates the need for both an effective vaccine and therapies to treat infected individuals. Corti et al. isolated two monoclonal antibodies from a survivor of the 1995 Kikwit outbreak and demonstrated their therapeutic efficacy in Ebola virus–infected macaques. In fact, one antibody protected macaques when it was given up to 5 days after infection. Misasi et al. solved the crystal structures of fragments of the two antibodies bound to the Ebola virus glycoprotein (GP), which mediates viral cell entry. The two antibodies targeted different regions of GP, but in both cases blocked steps required for viral entry.

    Science, this issue pp. 1339 & 1343

  8. Inflammation

    A prostaglandin barrier to inflammation

    1. Kristen L. Mueller

    Blood-borne bacterial infections and severe trauma can send the immune system into overdrive, causing it to pump out inflammatory mediators, sometimes at lethal doses. Duffin et al. now report on a role for prostaglandins in keeping systemic inflammation in check. Systemic inflammation correlates with decreased production of the prostaglandin E2 (PGE2). Blocking PGE2 signaling in mice led to severe inflammation associated with the translocation of gut bacteria. PGE2 acts on innate lymphoid cells, which produce interleukin-22, a secreted protein that helps promote intestinal integrity.

    Science, this issue p. 1333

  9. Surface Science

    Durable coatings that repel ice

    1. Zakya H. Kafafi

    Preventing ice buildup on surfaces is crucial for ensuring the proper operation and safety of airplanes, ships, communication towers, and wind turbines. Golovin et al. studied the mechanisms that control how ice detaches from surfaces. They developed durable coatings with extremely low ice adhesion, from which ice simply falls off under its own weight. These high-performing icephobic coatings could be spun, dipped, sprayed, or painted onto any underlying substrate. The coatings functioned well outdoors over winter or after extreme abrasion or exposure to harsh chemicals.

    Sci. Adv. 2, 10.1126.sciadv.01496 (2016).

  10. Chemistry

    Temporarily caught in a bind

    1. Marc S. Lavine

    When an atom or molecular fragment is covalently bonded, its release is controlled by the rate of degradation of the bond or by the rate of degradation of the matrix or shell material that keeps it trapped. When molecules are held by noncovalent interactions, the affinity of the molecule to its binding site can be tuned by a number of parameters, such as changing pH, temperature, or salt concentration. This makes it possible to finely tune the release profile. Pakulska et al. review our increased understanding of these interactions as found in nature, and their increased use for the delivery of molecular agents and therapeutics.

    Science, this issue p. 10.1126/science.aac4750

  11. Planetary Science

    New Horizons unveils the Pluto system

    1. Keith T. Smith

    In July 2015, the New Horizons spacecraft flew through the Pluto system at high speed, humanity's first close look at this enigmatic system on the outskirts of our solar system. In a series of papers, the New Horizons team present their analysis of the encounter data downloaded so far: Moore et al. present the complex surface features and geology of Pluto and its large moon Charon, including evidence of tectonics, glacial flow, and possible cryovolcanoes. Grundy et al. analyzed the colors and chemical compositions of their surfaces, with ices of H2O, CH4, CO, N2, and NH3 and a reddish material which may be tholins. Gladstone et al. investigated the atmosphere of Pluto, which is colder and more compact than expected and hosts numerous extensive layers of haze. Weaver et al. examined the small moons Styx, Nix, Kerberos, and Hydra, which are irregularly shaped, fast-rotating, and have bright surfaces. Bagenal et al. report how Pluto modifies its space environment, including interactions with the solar wind and a lack of dust in the system. Together, these findings massively increase our understanding of the bodies in the outer solar system. They will underpin the analysis of New Horizons data, which will continue for years to come.

    Science, this issue pp. 1284, 10.1126/science.aad9189, 10.1126/science.aad8866, 10.1126/science.aae0030, & 10.1126/science.aad9045

  12. Nanomaterials

    Creating semiconductor nanocages

    1. Phil Szuromi

    The surface area of nanomaterials can be increased by creating open cage structures. Now it seems that the shape of nanocrystals can be used as a tool to manipulate crystal structure in nanocrystals. Wu et al. show how single nanocrystals of copper oxide are converted through anion exchange reactions to multiply twinned open cages of a copper sulfide in a process that changes the crystal lattice symmetries. These structures were then converted into cadmium sulfide nanocages through cation exchange.

    Science, this issue p. 1306

  13. Ionic Materials

    Transporting the hydrogen anion

    1. Marc S. Lavine

    Hydrogen cation (H+) transport is common in both biological systems and engineered ones such as fuel cells. In contrast, the transport of hydrogen anions (H) is far less common and is usually coupled with or compromised by the parallel transport of electrons. Kobayashi et al. examined the transport of H in a series of rare-earth lithium oxyhydrides (see the Perspective by Yamaguchi). They prevented electronic conduction by using Li+ as a countercation. In an electrochemical cell, the oxyhydride material acted as a solid-state electrolyte for H, which suggests an alternative avenue for developing energy storage devices.

    Science, this issue p. 1314; see also p. 1262

  14. Biochemistry

    A radical carboxyl migration

    1. Nicholas S. Wigginton

    The antibiotic nosiheptide, produced by Streptomyces actuosus, has high activity against multidrug-resistant pathogens. The enzymes involved in its biosynthesis include NosL, which cannibalizes tryptophan and forms a methylindolic acid precursor. Although NosL is included in a growing family of remarkable radical SAM enzymes, the mechanism by which it functions has been difficult to identify. Using spectroscopic and theoretical approaches, Sicoli et al. show that an unexpected radical intermediate forms during the course of the reaction (see the Perspective by Bridwell-Rabb and Drennan). Unlike similar known enzymes, NosL cleaves a Cα-C bond, which results in the migration of tryptophan's carboxyl group to its side-chain indole.

    Science, this issue p. 1320; see also p. 1266

  15. Neuroinflammation

    Linking neurodegeneration and immune cells

    1. Stella M. Hurtley

    The expansion of a repetitive DNA sequence in the C9orf72 gene is the major genetic cause of amyotrophic lateral sclerosis and frontotemporal dementia. Although the expansion decreases C9orf72 expression, most research has focused on the toxic RNA and protein products it creates in neurons. O'Rourke et al. found that C9orf72 unexpectedly plays a key role in innate immune cells. Loss of C9orf72 in mice led to macrophage and microglial dysfunction and age-related neuroinflammation. This raises the possibility of a “dual-effect” disease mechanism, in which toxic byproducts in neurons are combined with microglial dysfunction from decreased C9orf72 expression, together promoting neurodegeneration.

    Science, this issue p. 1324

  16. Mucosal Immunity

    Tuft cells help contain parasites

    1. Kristen L. Mueller

    Trillions of microbes inhabit our guts, including worms and other parasites. Epithelial cells that line the gut orchestrate parasite-targeted immune responses. Howitt et al. now identify a key cellular player in immunity to parasites: tuft cells (see the Perspective by Harris). Tuft cells make up a small fraction of gut epithelial cells but expand when parasites colonize or infect the gut. Parasites cause tuft cells to secrete large amounts of interleukin-25, a key cytokine for parasite clearance that also indirectly feeds back on tuft cells to expand their numbers. Tuft cells express chemosensory signaling machinery: disrupting this blocked parasite-triggered tuft cell expansion and weakened the ability of mice to control a parasitic infection.

    Science, this issue p. 1329; see also p. 1264

  17. Antibiotic Resistance

    The spectre of untreatable infections

    1. Julia Fahrenkamp-Uppenbrink

    Antimicrobial resistance is on the rise around the world, in some cases leaving few treatment options. Recent evidence for antimicrobial resistance against a treatment of last resort, colistin, is therefore particularly troubling. In a Perspective, Sprenger and Fukuda describe recent evidence for resistance against this antibiotic and explain how this resistance can be transmitted between different bacteria. Colistin has severe side effects but is increasingly used against Gram-negative pathogens that are resistant to other antimicrobial treatments. Colistin-resistant bacteria may therefore result in untreatable infections.

    Science, this issue p. 1263

  18. Infectious Disease

    Dengue model rises to the challenge

    1. Angela Colmone

    Human efficacy testing remains a major hurdle in bringing new vaccine candidates to the clinic. Without accepted correlates of protection, rounds of safety trials must be performed before efficacy can be tested in a large population in an endemic area. Kirkpatrick et al. developed a controlled human challenge model for dengue virus to assess the protective efficacy of the most clinically advanced dengue vaccine candidate. TV003, a live attenuated dengue vaccine that induces antibodies against all four dengue virus serotypes, protected against infection by an attenuated virus in 21 recipients when compared with 20 nonvaccinated controls. This model may serve as an early check for dengue vaccine candidates, limiting the risk of conducting large unsuccessful trials.

    Sci. Transl. Med. 8, 330ra36 (2016).

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