This Week in Science

Science  14 Nov 2014:
Vol. 346, Issue 6211, pp. 822
  1. Sexual Conflict

    Why some male animals kill infants

    1. Sacha Vignieri
    PHOTO: © GEORGESANKER.COM/ALAMY

    One of the most unpleasant aspects of social life in some animal species is killing of the young by adult males. Lukas and Huchard looked at mammalian groups with a variety of social systems—from mice to mongoose and from bats to bears. Infanticidal behavior in males appeared to be a result of sexual conflict in social species with nonseasonal breeding. Killing of a female's young by a new male will speed her return to a reproductive state and allow him to raise his own young. Evolutionarily, the only successful defense in females appears to be polyandry: Females that mate with multiple males make it hard for any one male to know that he is, or is not, the father of her offspring.

    Science, this issue p. 841

  2. Viral Infection

    Flagellin gives rotavirus a one-two punch

    1. Kristen L. Mueller

    Rotavirus causes gastroenteritis, which can be especially severe in infants and young children. The bacterial protein flagellin activates the innate immune system and protects mice against a variety of infectious and inflammatory agents. Zhang et al. now report that flagellin both prevented rotavirus infection in mice and cured mice chronically infected with rotavirus. It did so by activating two distinct innate immune signaling pathways, which led to cells in the infected mice producing the cytokines interleukin 22 and interleukin 18. Similar to flagellin, treating mice with both of these cytokines prevented or cured rotavirus infection.

    Science, this issue p. 861

  3. Climate Change

    Striking when hot, and more when hotter

    1. H. Jesse Smith

    Lightning occurs more frequently when it is hotter than when it is colder, but how much more lightning should we expect as global temperatures increase? Currently there are around 25 million lightning strikes per year. Romps et al. constructed a proxy based on the energy available to make air rise in the atmosphere and on precipitation rates to model the frequency of lightning strikes across the continental United States. They predict that the number of lightning strikes will increase by about 12% for every degree of rise in global average air temperature.

    Science, this issue p. 851

  4. Circadian Rhythm

    The Sun rises (and sets) on hamster memories

    1. Melissa McCartney

    Internal circadian clocks set a rhythm to which biological systems beat. In addition to regulating sleep and wake cycles, the circadian system influences learning and memory. Using Siberian hamsters as a model, Fernandez et al. evaluated the role of the part of the brain that regulates the circadian cycle, the suprachiasmatic nucleus (SCN), in altered memory processing when circadian rhythms are disrupted. As expected, animals with disrupted rhythms had recognition and spatial memory impairments. However, when the animals' SCN was disconnected, these memory deficits were reversed. Thus, memory impairment resulting from circadian dysfunction is dependent on preserving SCN circuit connections.

    Science, this issue p. 854

  5. Exoplanet Atmosphere

    Sunny side hot for tidally locked world

    1. Margaret M. Moerchen

    Most planets in our solar system spread their heat evenly across their surfaces in the course of a day. They accomplish this with relatively fast rotations and a generous distance from the Sun. Some exoplanets, however, aren't so well balanced. Stevenson et al. show that planets like the Jupiter-sized WASP-43b whirl closely around their star in less than 24 hours, which leaves them tidally locked with little chance for heat redistribution.

    Science, this issue p. 838

  6. Cilia and Flagella

    Molecular ruler rules cilia and flagella length

    1. Stella M. Hurtley

    Cilia and flagella contain within their ultrastructure repeating structures at regularly spaced intervals. How does the cell measure length with nanometer precision? Oda et al. identify a flagella protein complex in Chlamydomonas that appears to act as a sort of molecula ruler to define repeat length. Genetic changes that would change the length of this protein led to corresponding changes in the length of repeats within the resulting flagella.

    Science, this issue p. 857

    PHOTO: ANDREW SYRED/SCIENCE SOURCE
  7. Nanophotonics

    Gold nanoparticles form potential plasmons

    1. Ian S. Osborne

    Plasmons—the collective light-induced electronic excitations that occur at the surface of a metal—may form the basis for a new technology for harvesting solar energy. Currently, solar energy is converted into useful energy either by solar-thermal and photovoltaic conversion systems seen on rooftops, or, in some niche applications, by thermoelectric devices. Sheldon et al. observed electric potentials induced in gold nanospheres by optical irradiation. The effect may be useful in the design of a new generation of energy conversion devices based on plasmonics.

    Science, this issue p. 828

  8. Immunology

    A step toward better vaccine adjuvants

    1. John F. Foley

    The receptor TLR4 stimulates immune signaling pathways. It can do so through two adaptor proteins: MyD88, which can trigger undesirable inflammatory responses; and TRIF, which stimulates immune responses. Currently, adjuvants to boost immune responses to vaccines are developed with the idea that their structure determines the adaptor protein that TLR4 will use. However, Kolb et al. suggest that TLR4 signaling is inherently biased toward the TRIF-dependent pathway, particularly in the context of type I interferon signaling. The findings may help in the development of more effective vaccine adjuvants that enhance immune responses without triggering potentially harmful inflammatory reactions.

    Sci. Signal. 7, ra108 (2014).

  9. Paleoceanography

    Leading a wintry march from a distance

    1. H. Jesse Smith

    When the Antarctic ice sheet began to expand around 3 million years ago, it caused changes in deep ocean circulation, hastening the pace of glaciation in the Northern Hemisphere. Woodard et al. analyzed marine sediments from the northwest Pacific Ocean. A substantial fraction of the sea level fall actually occurred before the Northern Hemispheric ice sheets began to grow rapidly, probably because of continental ice growth in Antarctica. Thus, Antarctic glaciers appear to be more dynamic than anticipated, which has implications for the stability of the Antarctic ice sheet in a warming world.

    Science, this issue p. 847

  10. Synthetic Biology

    Record your memories with a DNA recorder

    1. Barbara R. Jasny

    DNA-based memory devices are not optimal for recording analog information, such as the magnitude of inputs over time. Farzadfard and Lu converted genomic DNA into a “tape recorder” within living bacterial populations (see the Perspective by Ausländer and Fussenegger). Specific DNAs were used to introduce precise mutations into genomic DNA. The stored information could be read out via reporter genes, functional assays, and DNA sequencing. This approach allowed the memorization of multiple inputs at the population level. The record could also be erased when required.

    Science, this issue 10.1126/science.1256272 see also p. 813

  11. Mesenchymal Cells

    How lung mesenchymal cells behave

    1. Beverly A. Purnell

    Despite the variety of organ systems, there is a common theme: Stromal tissues support and maintain most vertebrate organs. These stromal tissues form from mesenchymal stem cells. Kumar et al. used clonal cell labeling in mice to identify and characterize stromal progenitors in the developing mouse lung at single-cell resolution (see the Perspective by Lee and Kim). Progenitor populations occupied different locations and displayed a variety of movements and lineage boundaries. Airway smooth muscle progenitors are located just ahead of budding branches in the bronchial tree and are organized into carefully controlled domains.

    Science, this issue 10.1126/science.1258810; see also p. 810

  12. DNA Recombination

    Mapping recombination in individual human males

    1. Guy Riddihough

    Sperm and eggs form from diploid cells that contain two copies of our genomic DNA. The haploid germ cells must undergo a special cell division, meiosis, which halves their DNA content. Meiosis involves a DNA recombination step between parental chromosomes. Recombination is initiated by a DNA double-strand break, which can exchange DNA between the chromosomes, a process that drives human genetic variation. Pratto et al. mapped meiotic recombination sites in individual human males (see the Perspective by de Massy). Recombination hotspots were influenced by variants of the histone-lysine N-methyltransferase protein, PRDM9, as well as by other factors. The recombination sites also influence genome evolution and the incidence of genetic disease.

    Science, this issue 10.1126/science.1256442; see also p. 808

  13. Interfacial Water

    Dissecting the electrical double layer

    1. Phil Szuromi

    The structure of water within a nanometer of an electrode surface is known as the electrical double layer. This layer creates a strong electrical field that can affect electrochemical reactions. Velasco-Velez et al. explored the structure of the electrical double layer at a bare gold electrode. With no applied potential and at positive potentials, the layer is highly structured (resembling ice) with few dangling hydrogen bonds. However, at negative potentials, the layer was more like bulk water, and half of the water molecules lie flat on the surface.

    Science, this issue p. 831

  14. Strong Bases

    Bring your own template for deprotonation

    1. Jake Yeston

    When manufacturing pharmaceuticals and agrochemicals, chemists need to add substituents to specific carbon sites in hexagonal benzene rings. If there's already a substituent on the ring, it can often direct a base to deprotonate the site next to it. But what if you want the base to attack the site two carbons away? Martínez-Martínez et al. devised a method to do this by taking advantage of the sodium and magnesium counterions associated with their base. These ions form a template that orients the base to attack the more distant site.

    Science, this issue p. 834

  15. Landscape Hydrology

    Impacts of deforestation on wetlands

    1. Andrew M. Sugden

    Deforestation worldwide may be causing an increase in the extent of wetlands. Using a combination of different approaches, Woodward et al. show that ancient and more recent deforestation has resulted in major changes in global wetland hydrology. For example, in Australia and New Zealand, deforestation has created new wetlands or increased the water level in existing wetlands. Recognition of this effect has implications for landscape management: Reforestation programs in wetland catchments may have unintended consequences for vulnerable wetlands.

    Science, this issue p. 844

  16. Antibiotic Resistance

    It takes two antibiotics—but which two?

    1. Kelly LaMarco

    Treatment with multiple antibiotics reduces the development of antibiotic-resistant bacteria, but not all combinations are created equal. Predictive models are needed to design therapeutic regimens that avoid resistance. Munck et al. used adaptive evolution and genomics to unravel resistance responses of bacteria to single and pairs of antibiotics. The authors pinpointed mutations that lead to different levels of drug resistance. The findings can be exploited to design better drug combinations that limit the acquisition of antibiotic resistance.

    Sci. Transl. Med. 6, 262ra156 (2014).

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