Editors' Choice

Science  21 Nov 2014:
Vol. 346, Issue 6212, pp. 961
  1. Microbiology

    Mycoplasma doubles the cost of an STD

    1. Caroline Ash

    Scanning electron micrograph of Trichomonas vaginalis

    CREDIT: DAVID PHILLIPS/VISUALS UNLIMITED, INC.

    It's cruel enough to acquire one sexually transmitted infection, but gaining two for one is harsh. Trichomoniasis is a very common protozoal infection of the vagina that causes symptoms ranging from urogenital inflammation to pregnancy complications. Fettweis et al. analyzed the microbiomes from vaginal samples collected from more than 1300 women and now report that a previously unknown mycoplasma (a type of bacteria) tightly associates with trichomonas organisms. The genome of the new mycoplasma (called candidatus Mycoplasma girerdi) encodes proteins similar to known virulence factors, which suggests that the mycoplasma might be contributing to trichomoniasis disease.

    PLOS One 9, e110943 (2014).

  2. Biotechnology

    Disorder enhances binding cooperativity

    1. Michael D. Crabtree

    Some natural proteins, such as hemoglobin, bind their ligands in a cooperative manner, whereby the binding of the first ligand alters the structure of the protein, favoring binding of subsequent ligands. Taking inspiration from this mechanism, Simon et al. created unstructured receptors from DNA. Upon binding their ligand, the disordered receptors become structured, forming sites for further ligands to bind. Because ligands bind more favorably to these sites than to the unstructured receptor, the binding of subsequent ligands is enhanced. Relatively small changes in ligand concentration can therefore lead to an all-or-none binding response, a feature that could prove useful for artificial biotechnologies.

    Proc. Natl. Acad. Sci. U.S.A. 10.1073/pnas.1410796111 (2014).

  3. Materials Science

    Climbing up the walls like a gecko

    1. Jake Yeston
    PHOTO: HAWKES ET AL.

    The Tokay gecko scurries across ceilings with the help of tiny hair on its feet, which generate weak intermolecular forces that add up to a secure foothold. Scientists have recreated dry gecko-like adhesion using silicones, plastics, carbon nanotubes, and other materials, but they've run into a scaling problem: The stickiness drops rapidly with increasing surface area. Hawkes et al. offer a solution: an adhesive consisting of 24 tiles that distribute loads evenly among themselves, offering the same adhesive strength for sizes from a square millimeter to the area of a human hand. The adhesive works even if one tile fails to stick. Wearing hand-sized adhesives, a 70-kilogram human can climb a vertical glass wall, the team showed.

    J. R. Soc. Interface, 10.1098/rsif.2014.0675.

  4. Quantum Communication

    Symmetric photons make good communicators

    1. Ian S. Osborne

    Future communication networks will be based on quantum mechanics and will rely on the ability to store quantum information in quantum nodes and transfer that information between them. Photons offer the ability to transfer information over long distances, but that requires that single photons be emitted and detected reliably at each end of the communication channel—a feat that requires the photons to be symmetric. Using a superconducting-based quantum circuit, Pechal et al. demonstrate how to generate the symmetric microwave photons that will be necessary to carry quantum information successfully.

    Phys. Rev. X 4, 041010 (2014).

  5. Cosmology

    Dark matter may yield x-ray glow nearby

    1. Margaret M. Moerchen
    PHOTO: NASA/SDO

    Dark matter often has been observed to influence the dynamics of galaxies. Still, astrophysicists have great difficulty demonstrating the presence of dark matter with some type of direct detection. Now, observations made by the European XMM-Newton satellite of what should be blank sky instead show a variable background x-ray signal that could result from axions, a proposed component of dark matter. Fraser et al. explain that these candidate particles—a billionth the mass of an electron—could be produced by the Sun and then converted into x-rays by Earth's magnetic field. This step toward understanding dark matter still may be supported or refuted by further x-ray measurements with other observatories.

    Mon. Not. Roy. Astron. Soc. 10.1093/mnras/stu1865 (2014).

  6. AAA+ Atpases

    Redox regulation of Lon protease

    1. Stella M. Hurtley

    Bacteria and other organisms use so-called AAA+ proteases to degrade cytosolic proteins. The Lon protease is the main protease used by bacteria to degrade damaged or misfolded cytosolic proteins, which can be toxic to the cell. Both too much and too little Lon protease activity is bad for survival. Nishii et al. asked how cells keep Lon activity levels just right. By examining the crystal structure of Lon from Escherichia coli they identified conserved cysteine residues that acted as a redox switch. The exit pore changed in size depending on whether the bacteria were growing in the presence or absence of oxygen: Reducing its size decreased products from passing through the pore and therefore the activity of the enzyme.

    Nat. Chem. Biol. 10.1038/nchembio.1688 (2014).

  7. Education

    Follow scientists, not the lab notebook

    1. Melissa McCartney

    Scientific experiments rarely go as planned. Despite following the scientific method, experiments often double back, repeat a step, or move in a new direction. Why then, do classroom laboratory exercises present students with a linear set of tasks resulting in a known outcome? To create a more authentic experience, Alaimo et al. redesigned four undergraduate organic chemistry labs to allow students to generate reliable data through repeating experiments, participate in authentic data analysis, and receive instruction in data-driven decision-making. These changes shifted the lab from an exercise in following directions to an exercise of learning the iterative process of a scientific study.

    J. Chem. Educ. 10.1021/ed400510b (2014).

  8. Human Immunology

    A (w)holistic approach to track T cells

    1. Kristen L. Mueller

    Immunologists know a lot about mouse T cells: how they develop, respond to infection, form memory cells, and where they reside. But whether this knowledge h olds true for human T cells is still a black box because of the difficulty in obtaining samples from anywhere other than the blood. To gain more insight into human T cell biology, Thome et al. performed multidimensional, quantitative analyses on T cells obtained from the blood, lymph nodes, spleen, and mucosal tissues of 56 individual organ donors aged 3 to 73 years. They find that the distribution and maintenance of different T cell subsets depends on the differentiation state of the T cell and its location within the body.

    Cell 159, 814 (2014).

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