Editors' Choice

Science  20 Feb 2015:
Vol. 347, Issue 6224, pp. 837
  1. Materials Science

    Microporous mechanics

    1. Phil Szuromi

    Truncated rhombic dodecahedral ZIF-8 crystals

    PHOTO: SU ET AL. JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 137, 5 (29 JANUARY 2015) © 2015 AMERICAN CHEMICAL SOCIETY

    Metal-organic framework (MOF) materials, in which metal ions or inorganic clusters are linked together by organic ligands to form cages, are highly porous and potentially useful for gas storage. However, repeated cycles of adsorption and desorption mechanically stress these materials and reduce their functionality. With transmission electron microscopy, Su et al. examined the effects of compression on individual micrometer- and submicrometer-scale crystals of a zinc zeolitic-imidazolate framework compound. The presence of methanol in the pores made the crystals much more rigid; they shattered when similar forces would have caused only plastic deformation of the empty framework.

    J. Am. Chem. Soc. 10.1021/ja5113436 (2015).

  2. T Cell Metabolism

    Flexibility lets activated T cells thrive

    1. Kristen L. Mueller

    For T cells, fighting infections is demanding work. They must proliferate many times over and quickly produce a myriad of antimicrobial factors. T cells do this by switching from mitochondrial to glycolytic metabolism, but what happens when nutrients are scarce, such as in infected tissues or tumors? Blagih et al. examined this question by starving mouse T cells of glucose. They found that T cells are highly adaptable—they pulled back on protein translation, used glutamine as an energy source, and relied more on mitochondrial metabolism. The enzyme AMPK, an evolutionarily conserved energy sensor, facilitated these changes.

    Immunity 42, 41 (2015).

  3. Genomics

    What are the genomic requirements for life?

    1. L. Bryan Ray

    To promote identification and understanding of the minimal set of genomic elements required for life, Lluch-Senar et al. studied M. pneumonia. This small bacterium has an 816-kb genome with about 700 open reading frames; about a third of the genome appeared to be essential. Small open reading frames, of less than 100 residues, made up slightly more than half of the essential components, and they appeared to encode components of larger protein, DNA, or RNA complexes. Protein domains, rather than complete proteins, were often the essential elements of larger proteins, whereas regulatory elements—5′ untranslated regions and noncoding RNAs—were also fundamental components.

    Mol. Syst. Biol. 10.15252/msb.20145558 (2015).

  4. Crowd Science

    Wisdom of the crowd, waning

    1. Brad Wible

    Many researchers, agencies, and companies are turning to “the crowd” for help with data collection and analysis, but we lack systematic understanding of who those volunteers are and how they perform. Such insights might help expand and improve crowd sourcing for research. Sauermann and Franzoni draw on over 12 million daily observations of more than 100,000 users across seven projects on the Zooniverse platform. They estimate that the average project received volunteer labor worth roughly $220,000 during the first 180 days. But 79% of the effort, on average, was provided by the most productive 10% of users. Roughly 75% of users failed to participate in a project after their first session, and even those who returned multiple times did so with increasingly long breaks between visits. Significant effort is expended by new users who join over time, but this does not offset the loss of effort from original users.

    Proc. Natl. Acad. Sci. U.S.A. 10.1073/pnas.1408907112 (2014).

  5. Neurodevelopment

    Growth cones carve a path through tissues

    1. Pamela J. Hines

    Neural growth cones use invadopodia-like fingers to push through tissues

    PHOTO: TIMOTHY GOMEZ

    A growth cone leading a neuron's development needs more than muscle to push its way through tissues and across boundaries. Santiago-Medina et al. found features on neuronal growth cones that are like the invadosomes of immune and metastatic cancer cells, which themselves have a knack for squeezing through existing tissues. These invadosomes, fingers that poke out into the surrounding tissue, are packed with cytoskeleton and exude proteases that degrade the extracellular matrix. The invadosomes were key for Xenopus motoneurons trying to find a path out of the spinal cord and into the developing musculature.

    Development 10.1242/dev.108266 (2015).

  6. Planetary Science

    Why the “Y” in the Venusian sky?

    1. Brent Grocholski

    Venus has its own version of Jupiter's Great Red Spot, an enormous Y-shaped feature which comes and goes on a monthly cycle. The origin and stability of the atmospheric feature, visible only in ultraviolet photographs, have perplexed observers for decades. Peralta et al. take a fresh look at this persistent structure with an updated analytic atmospheric model. A wind-distorted equatorial wave reproduces the morphology, darkness, and time evolution of the “Y.” The model should be applicable to the atmospheres of other slowly rotating bodies, in our solar system and beyond.

    Geophys. Res. Lett. 10.1002/2014GL062280 (2014).

  7. Evolutionary Biology

    Finch genomes and human face shapes

    1. Sarah C.P. Williams

    The beak shapes of 15 Galápagos finch species, each optimized for its island's most ample food source, helped shape Charles Darwin's ideas on evolution. Now, scientists have a genetic link: Lamichhaney et al. sequenced the genomes of 120 individual birds and found a gene, ALX1, which varies between species with large or small, pointy or dull beaks. In humans, mutations in this gene are linked to frontonasal dysplasia, a birth defect ranging in severity from a cleft palate to skull malformations. Smaller variations in ALX1 could be behind the diversity of our face shapes.

    Nature 10.1038/nature14181 (2015).

  8. Origin of Life

    Solving the “tyranny of the short”

    1. Guy Riddihough

    Early self-replication may have started deep within rocks, like these white smokers

    PHOTO: NOAA

    At an unknown but momentous point in the origin of life on Earth, nucleic acids became the dominant self-replicating molecules. There's a problem, however, because normally, shorter nucleic acid polymers replicate faster than longer ones and outcompete them, with a subsequent loss of genetic information. Kreysing et al. studied DNA replication in a tiny pore with a thermal gradient across its width and a steady fluid flow along its length. In this confined space, perhaps similar to a pore within a rock, the longer nucleic acid chains outcompete their smaller brethren, which are diluted out of the pore.

    Nat. Chem. 10.1038/nchem.2155 (2015).