Editors' Choice

Science  05 Feb 2016:
Vol. 351, Issue 6273, pp. 572
  1. Conservation Ecology

    Ecological legacy of a civil war

    1. Andrew M. Sugden

    Decline of large mammals due to Mozambique's civil war has led to an increase in tree cover in Gorongosa National Park

    PHOTO: © ARIADNE VAN ZANDBERGEN/ALAMY STOCK PHOTO

    The Mozambique civil war (1977–1992) changed the trajectory of ecological succession in the 3620-km2 Gorongosa National Park. During the civil war, the large mammalian herbivores characteristic of East African savannas were largely extirpated from the park, and this in turn has led to substantial changes in the park's vegetation. Using a combination of aerial and satellite imagery, coupled with limited ground-truthing, Daskin et al. show that tree cover in the park has increased by 34% over a 35-year period, most likely as a result of release from herbivore pressure rather than any changes in the physical environment. The recovery of herbivore populations may proceed more slowly in the presence of increased tree cover.

    J. Ecol. 104, 19 (2016).

  2. Quantum Optics

    To catch a photon nondestructively

    1. Ian S. Osborne

    With several techniques now available for generating single photons, coupled with their relative robustness and ability to be transmitted long distances, photons are ideal carriers of quantum information. However, determining the best methodol-ogy for detecting a single propagating photon without absorbing it (and destroying it) remains a work in progress. Xia et al. propose a cavity-free approach based on an induced nonlinear interaction. By co-propagating a weak probe beam with the signal beam containing the single photon in a nonlinear medium, they show theoretically that the phase of the probe beam should be shifted, conditional on the presence of the single photon. The proposed technique could offer a simpler route for implementing such quantum non-demolition detection strategies necessary for successful quantum information processing.

    Phys. Rev. Lett. 116, 023601 (2016).

  3. Drug Screening

    Imaging to improve drug target mapping

    1. L. Bryan Ray

    Finding effective new drugs, or combinations thereof, that are free of toxicity and off-target effects is a big challenge—one that may only be solved with large amounts of data. Breinig et al. present a screening method that includes automated quantitative high-throughput imaging to track not only cell viability and proliferation, but also other features such as DNA texture, nuclear and cell shape, and cytoskeletal properties. Screening over 1200 pharmacological agents in 12 isogenic cell lines allowed the mapping of quantitative “footprints” or signatures of phenotypic responses to a drug (the data with over 300,000 drug-gene-phenotype interactions are available at an interactive webpage: http://dedomena.embl.de/PGPC/). The authors found interactions between inhibitors of MEK protein kinases and an antialcoholism drug and between a receptor tyrosine kinase inhibitor and the proteasome.

    Mol. Syst. Biol. 10.15252/msb.20156400 (2015).

  4. DNA Methylation

    Methylation for making a placenta

    1. Guy Riddihough

    The trophoblast cells of a developing embryo give rise to extra-embryonic tissues that support embryonic growth, such as the placenta. The epigenetic modification DNA methylation is critical for the regulation of embryonic development. Branco et al. show that maternal DNA methylation also plays a role in trophoblast development. DAN methylation is required for the regulation of genes involved in cell adhesion and migration, processes required for proper placental formation that are perturbed in placental disorders such as pre-eclampsia.

    Dev. Cell 10.1016/j.devcel.2015.12.027 (2015).

  5. Biofilms

    Cationic biofilm inhibitors

    1. Phil Szuromi

    Antibiotics are far more effective if the bacteria they target have not formed a biofilm, a structure held together by an extracellular matrix composed of a variety of polysaccharides, proteins, and other biomolecules, through weak interactions such as hydrogen bonds, van der Waals interactions, and ionic contacts. Joseph et al. show that the formation of biofilms by several Gram-positive bacteria is inhibited by cationic pillarenes, small ring compounds that link five or six aryl groups. The ring interior could interact with hydrophobic contacts, and substituted quaternary ammonium groups on the exterior faces could disrupt ionic contacts. Because these molecules are not antimicrobial, they should not inhibit beneficial gut bacteria.

    J. Am. Chem. Soc. 10.1021/jacs.5b11834 (2016).

  6. Antibodies

    Unusual antibodies target malaria

    1. Kristen L. Mueller

    An unusual gene insertion allows antibodies to detect red blood cells infected with the malaria parasite Plasmodium falciparum

    PHOTO: GARY D. GAUGLER/SCIENCE SOURCE

    B cells make antibodies through a process of somatic recombination. This gives rise to a diverse repertoire of antibodies able to target many pathogens, such as the malaria-causing parasite Plasmodium falciparum. Tan et al. screened the plasma of P. falciparum—in infected individuals to look for antibodies that kill infected red blood cells (RBCs). They isolated several monoclonal antibodies from multiple individuals that showed broad reactivity for infected RBCs. To their surprise, these antibodies all contained a genomic insertion that encoded a collagen-binding protein called LAIR1, and it was this insert, rather than the antibody-encoding gene segments themselves, which recognized the infected RBCs. Whether such insertions exist in other antibodies remains to be determined.

    Nature 529, 105 (2016).

  7. Geophysics

    A shallow explanation for tsunamis

    1. Brent Grocholski

    The Mw 8.3 Illapel, Chile, earthquake generated violent shaking and triggered a large tsunami that required the evacuation of 1 million people. Melgar et al. found that the ground shaking was primarily driven by deep fault rupture, whereas the tsunami was generated by fault rupture near the surface. Their modeling suggests that strain accumulates at different rates in the deep and shallow portions of the Chilean subduction zone. This means that shallow rupture is less frequent and could explain the lack of historic tsunamis in the region.

    Geophys. Res. Lett. 10.1002/2015GL067369 (2015).

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