Editors' Choice

Science  09 Dec 2016:
Vol. 354, Issue 6317, pp. 1246
  1. Metallurgy

    Steel goes for the quick draw

    1. Brent Grocholski

    Strong steel is important for infrastructure such as the Golden Gate Bridge.

    PHOTO: DUBLIN; RANDYANDY101/ISTOCKPHOTO

    Steel is an important engineering material with properties that change with different processing techniques. Djaziri et al. found a new route for strengthening steel by using severe mechanical deformation. The improved strength comes from regions of Fe-C martensite, a known strengthening phase that normally requires quenching from high temperature. Extremely quick drawing of steel wires seems to have a similar effect without requiring high-temperature processing.

    Adv. Mater. 10.1002/adma.201601526 (2016).

  2. DNA Events

    mRNA quality control

    1. Guy Riddihough

    DNA is packaged into chromatin, and it must be actively unpacked, or remodeled, for genes to be transcribed into mRNA. That mRNA, synthesized in the nucleus, is also packed onto proteins, forming mRNA ribonucleoparticles (mRNPs). mRNPs are then shunted into the cytoplasm. Babour et al. show that one of the chromatin remodeling machines, the enzyme complex ISW1, has a second role in checking that mRNPs are properly packaged and competent to be exported to the cytoplasm. The ISW1 complex binds directly to the premature mRNPs, retaining them in proximity to their transcription sites.

    Cell 167, 1201 (2016).

  3. Cancer Immunotherapy

    Blocking PI3Kγ makes cold tumors hot

    1. Kristen L. Mueller

    Immunotherapy has changed the face of cancer treatment. However, despite some success, most individuals do not respond to this type of treatment. One potential reason is the presence of immunosuppressive macrophages in the tumor microenvironment. Kaneda et al. and De Henau et al. now show in mice that inhibiting the lipid kinase phosphoinositide 3-kinase γ (PI3Kγ), or deleting the gene that encodes it, turns immunosuppressive macrophages into immunostimulatory ones in a cell-intrinsic manner. Inhibiting PI3Kγ in tumor-bearing mice led to greater T cell activation within tumors and, when combined with clinically available immunotherapies, to reduced tumor growth and improved overall survival. Clinical trials testing whether this strategy will also work in people are ongoing.

    Nature 539, 437, 443 (2016).

  4. Cancer Immunotherapy

    How fiber feeds a healthy gut

    1. L. Bryan Ray

    Starving bacteria in the gut may turn a beneficial microbial community into one that enhances disease susceptibility. Desai et al. explored the effects of eating adequate dietary fiber in a model in which 14 well-characterized strains of human gut bacteria were inoculated into germfree mice. A diet deficient in fiber increased the abundance of bacteria that digest the polysaccharides in the mucin layer that lines the gut. Thus, instead of helping digest the polysaccharides in dietary fiber, the microbiota attacked the protective layer of the intestinal wall. This allowed an introduced bacterial pathogen to grow and cause lethal colitis. The results may help establish the amounts and types of fiber that best maintain the protective mucin layer in the colon.

    Cell 167, 1339 (2016).

  5. Biodiversity

    Housemates

    1. Sacha Vignieri

    Genetic screening of dust allows us to identify the arthropods that share our homes.

    PHOTO: ANNE A. MADDEN, WITH THE ASSISTANCE FROM ROBERT MCGUGAN/UNIVERSITY OF COLORADO, BOULDER NANOMATERIALS CHARACTERIZATION FACILITY, FALSE-COLORING DONE BY ROBIN HACKER-CARY

    Whether we recognize it or not, we share our homes with a remarkable diversity of arthropods. Classifying the species that share our space is a challenging task. Madden et al. identified over 600 of these species by genotyping house dust collected by citizen scientists from over 700 homes across the United States, revealing the presence of both expected species, such as cockroaches, and unexpected species, such as parasitic wasps. The characteristics of the home or the home occupants were more important for predicting occurrence than were climatic or regional factors, suggesting that home arthropod distributions cannot reliably be predicted from outdoor arthropod predictions but may represent groups of species that are well adapted to human environments.

    Mol. Ecol. 10.1111/mec.13900 (2016).

  6. Metrology

    An on-chip cold-atom gravimeter

    1. Ian S. Osborne

    Gravimeters sense tiny changes in the local gravitational field and are used in geological studies, mineral exploration, and civil engineering to detect underground voids. Typically the size and weight of a small microwave oven, their operation is mechanical: A test mass pulls on a sensitive spring, and any difference in extension is compared with a reference point. Cold atoms cooled to their quantum ground state offer a quantum mechanical approach for detecting gravity. Abend et al. have developed an onchip cold-atom interferometer in which the active part of the sensor, including atom cooling and interference, takes up less than a cubic centimeter. The on-chip approach offers the prospect of compact and sensitive gravimeters for field deployment.

    Phys. Rev. Lett. 117, 203003 (2016).

  7. Materials Chemistry

    Forcing iron to bond to bismuth

    1. Phil Szuromi

    Iron-bismuth compounds are of interest for extending the series of superconducting iron-pnictide materials, but the Fe-Bi bond has been elusive. One problem is the immiscibility of Bi in Fe. Walsh et al. report that the formation of FeBi2 can be observed under extreme pressure conditions created with diamond anvils. Previous work was unsuccessful with the lower-pressure (body-centered cubic) phase of iron, so pressures sufficient to create its face-centered cubic phase were needed. At pressures above 30 GPa and temperatures of ∼1500°C, a phase was observed in x-ray diffraction in which each iron atom coordinated to eight Bi atoms, along with stabilizing Bi-Bi interactions. Once formed, the material was stable down to 2.9 GPa.

    ACS Central Sci. 10.1021/acscentsci.6b00287 (2016).

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