Editors' Choice

Science  29 Aug 2014:
Vol. 345, Issue 6200, pp. 1017
  1. Proteostasis

    Need proteasomes? Make some!

    1. Stella M. Hurtley

    Adc17 modifies proteasomes levels

    ILLUSTRATION: BRYCE SMALL/STANFORD UNIVERSITY

    Cells need to clear out damaged proteins, or they age and become unhealthy. To do this, cells use tiny protein-destroying machines called proteasomes. Building these proteasomes is a complex process, and it's not clear how stressed cells can make sure the proteasome supply meets demand. Working with yeast cells, Hanssum et al. discovered a protein that helps cells assemble just enough proteasomes to fit their needs. In a process called chaperoning, the protein, which they called Adc17, helps pair two proteasomal proteins, Rpt6 and Rpt3, during proteasome assembly.

    Mol. Cell 10.1016/j.molcel.2014.06.017 (2014).

  2. Human Behavior

    Incentives work on economists, too!

    1. Gilbert Chin

    Editors treasure prompt and informative referees. Chetty et al. show that modest psychological and economic nudges can speed up how rapidly referees return their reviews without degrading their quality. In a randomized experiment involving 1500 referees at the Journal of Public Economics, they offered some referees $100 for turning in their reviews by the 4-week deadline, whereas they told others, who had agreed to a 6-week deadline, that their delivery dates would be posted publicly. From a comparison across these groups and the non-incentivized controls, they conclude that 4 weeks is enough and that both social pressure and money work.

    J. Econ. Perspect. 28, 169 (2014).

  3. Physics

    Eliminating the effects of the pesky bulk

    1. Jelena Stajic

    A material's imperfections can greatly influence how well it conducts electricity. Theoretical physicists have, however, come up with the concept of topological insulators (TIs): materials that conduct only at their surface in a way that makes them “immune” to certain kinds of disorder. The compounds that have been identified as TIs, such as Bi2Se3, fall short of this ideal because they conduct electricity both through the “immune” surface states and the bulk of the material, which is still affected by disorder. Brahlek et al. made thin samples of Bi2Se3, adding copper atoms in precise quantities. When the samples were thick enough and had just the right concentrations of copper, the authors found that the samples were conducting only at their surfaces. This work is a step forward toward making useful TI devices.

    Phys. Rev. Lett. 113, 026801 (2014).

  4. Geophysics

    Making mantle melt analogs more accurate

    1. Brent Grocholski
    Hot-compressed glass structure CREDIT: D. B. GHOSH ET AL. AMERICAN MINERALOGIST 99 (JULY 2014) © MINERALOGICAL SOCIETY OF AMERICA

    Glasses, which can be thought of as “frozen” liquids, often are used as a proxy to study the properties of silicate melts in Earth's mantle. Glasses can be studied at temperatures and pressures lower than those found deep underground, which are impossible to achieve in the lab. Ghosh et al. conduct computational analyses to show that temperature is important in determining the properties of glass. Glass compressed at high temperature can change its structure and become denser than glass compressed at room temperature, making it a better analog for liquid melts generated deep in the mantle.

    Am. Mineral. 10.2138/am.2014.4631 (2014).

  5. Innate Immunity

    Cleaving RNA dials down inflammation

    1. Kristen L. Mueller

    The immune system detects viruses when viral nucleic acids bind protein receptors in immune cells. But what keeps these receptors from reacting to the host cells' own nucleic acids in the cytoplasm and causing unwanted inflammation? Eckard et al. examined the case of RIG-I–like receptors (RLRs), which bind to viral RNA. Th ey found that host RNAs generated during cellular stress could induce an RLR-dependent inflammatory response. In normal cells, the protein SKIV2L, which is part of a large protein complex that chews up RNA, prevented such inflammation by degrading the RNAs. The authors observed an inflammatory response in two patients who had mutated versions of SKIV2L, suggesting that SKIV2L keeps inflammation in check in human cells, too.

    Nat. Immunol. 10.1038/ni.2948 (2014).

  6. Social Science

    Moving from one novelty to the next

    1. Barbara R. Jasny

    Life would be boring if things were always the same. Tria and colleagues explore whether novelties—discoveries of things new to us—are independent of each other or whether one novelty leads to another. They analyzed selected text, online music, Wikipedia, and a social tagging site and measured how the number of different elements grew with time. Although two of the data sets contained innovations (items new to everyone) and two contained novelties (items new to individual users), they all showed the same kinetics and probability distributions. Modeling analyses suggested that novelties are not independent of each other. As the authors state, each novelty “comes with a cloud of other potentially new ideas that are thematically adjacent to it and hence can be triggered by it.”

    Sci. Rep. 10.1038/srep05890 (2014).

  7. Infectious Disease

    Seals infected early Americans with TB

    1. EP

    The South American fur seal may have helped spread TB

    CREDIT: © INCAMERASTOCK/ALAMY

    How did Mycobacterium tuberculosis, which causes tuberculosis (TB), first infect humans? Microbial DNA from 1000-year-old Peruvian mummies suggests that seals may have spread the disease to South American humans long before European settlers arrived. Bos et al. used DNA sequencing to solve the mystery. After finding the TB bacteria's DNA in three of the mummies, the team determined that the bacterial genomes were closest in sequence to a TB strain that infects marine mammals, suggesting that the ancient humans got TB from eating seal or sea lion meat, the researchers say.

    Nature 10.1038/nature13591 (2014).

  8. Catalysis

    Interior design with nanoparticles

    1. Phil Szuromi

    Catalysts made from metal nanoparticles (NPs) absorbed on oxide surfaces often are used in many industrial reactions and in automotive catalysts. These usually work best at high temperatures. High temperatures, however, promote surface diffusion and the subsequent formation of larger particles with less surface area, which become less active over time. Qiao et al. synthesized thermally stable NPs of palladium (Pd) and platinum within a hollow shell of microporous silica that allowed small molecules to enter and leave the interior. Polymer nanodots synthesized with the shell-bound metal ions formed NPs with average sizes under 2 nm and high thermal stability upon reduction and heating. The micropores also controlled catalytic product formation. Oxidative reduction of cyclohexene with trapped Pd NPs yielded almost pure benzene, versus a host of larger oxygenated rings for exposed Pd NPs.

    J. Am. Chem. Soc. 10.1021/ja505903r (2014).

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