Editors' Choice

Science  25 Mar 2016:
Vol. 351, Issue 6280, pp. 1412
  1. Geophysics

    Balancing the Himalayan strain budget

    1. Brent Grocholski

    Nepal, 1st May 2015 — A man standing on the ruins of what used to be his home in Bhaktapur, near Kathmandu

    CREDIT: © OTO ŽAN/DEMOTIX/CORBIS

    Subduction zones are known to occasionally unleash huge earthquakes with magnitudes of 9 or larger. It is unclear whether continental thrusts can produce quakes that large, even though they share some common features with subduction zones. Stevens and Avouac address this question by comparing geodetic strain with the historic earthquake record of the Main Himalayan Thrust. Closing the strain budget seems to require magnitude 9 or larger earthquakes every 800 years on average. This finding underscores the high level of seismic hazard along the Himalayas.

    Geophys. Res. Lett. 10.1002/2015GL067336 (2016).

  2. Structural Biology

    A domain swap makes motor rings

    1. Guy Riddihough

    Cells are packed with protein complexes. Cells must appropriately assemble these complexes while ensuring that component proteins do not aggregate prematurely. Baker et al. show that the FliG protein, part of the bacterial flagellar motor complex, can polymerize to forms rings by “domain swapping.” Domains within a single FliG can interact with each other or “swap” with neighboring FliG proteins to form the same interaction—a molecular form of linking arms. The flexibility of the peptides that tether these domains ensures that FliG remains a monomer in the cytoplasm. FliG binding to a scaffolding ring promotes motor assembly by increasing the local concentration of FliG and promoting domain swapping.

    Nat. Struct. Mol. Biol. 197, 23 (2016).

  3. Genetics

    When Mom or Dad's inheritance counts

    1. Laura M. Zahn

    Retinoblastoma (Rb), a largely inherited form of pediatric eye cancer, arises when patients carry two utant copies of the RB1 tumor suppressor gene. However, not all individuals carrying two mutant copies of RB1 go on to develop cancer. Eloy et al. investigated why, focusing on one specific mutation of RB1, and found differences depending on whether the mutant gene was maternally or paternally inherited. Maternal inheritance led to higher Rb protein expression, and because the particular mutation allowed for some residual protein function, this probably protected some individuals from developing cancer. Thus, in some cases, parent-of-origin effects can explain why genetic carriers may not always go on to develop disease.

    PLOS Genet. 12, e1005888 (2016).

  4. Optics

    Improving the measure of optical rulers

    1. Ian S. Osborne

    Rulers are familiar tools used to measure short distances and separations, but for separations smaller than those that can be resolved by optical microscopes, more advanced methods must be used. For example, fluorescent centers change their optical properties when placed in close proximity to a metal or semiconducting surface, and modeling that change can determine the distance between them. Such optical rulers are typically limited to distances exceeding 20 nm, but by replacing that surface by a transparent conducting oxide, Moerland and Hoogenboom show that they can determine separations well below 10 nm. Measuring such small distances with subnanometer sensitivity could prove useful in imaging live cells and in the precision placement of active optical centers for nanophotonic applications.

    Optica 3, 112 (2016).

  5. Neuroinflammation

    Controlling T cell access to the brain

    1. Kristen L. Mueller

    Mouse brain section showing virus (red)

    PHOTO: J. CUPOVIC ET AL., IMMUNITY 44, 3 (23 FEBRUARY 2016) © 2016 ELSEVIER INC.

    Although immune cells fight infections, given their potential to cause damage, the brain must carefully regulate their entry. Cupovic et al. sought to better understand this process in mice infected with a neurotrophic coronavirus. They found that in response to infection, pockets of stromal cells in the brain rapidly expressed high amounts of the chemokines CCL19 and CCL21, secreted proteins that can attract virus-fighting T cells. Disrupting this important molecular circuitry increased the susceptibility of mice to the virus, and for the few T cells that could enter the brain, reduced their antiviral capabilities. Viral clearance led to reduced chemokine expression by stromal cells, indicating that the brain quickly rebuilds its barriers once an infection runs its course.

    Immunity 10.1016/j.immuni.2015.12.022 (2016).

  6. Protein Delivery

    Assembling proteins for delivery

    1. Valda Vinson

    One of the challenges facing scientists who wish to one day use genome editing to treat disease is how to efficiently deliver proteins into cells. Wang et al. report one new strategy in which they combine positively charged synthetic lipids with negatively charged proteins to drive the self-assembly of nanoparticles that can efficiently enter cells. The hydrophobic tails of the lipids include a disulphide bond. The reductive environment inside the cell causes this bond to break, which enhances protein release from the nanoparticles. Delivering supercharged Cre recombinase enzyme or anionic Cas9:single-guide RNA resulted in efficient gene recombination and genome editing in cultured human cells and mouse brains, suggesting the promise of this technique.

    Proc. Natl. Acad. Sci. U.S.A. 10.1073/pnas.1520244113 (2016).

  7. Chemistry

    Engineering open structures using DNA

    1. Marc S. Lavine

    In DNA origami, designed libraries of single strands assemble into complex structure in two and three dimensions. However, these tend to be block or solid structures, which is often an inefficient use of material. In the engineering world, structures based on triangles allow for open frames or hollow structures that still show strong resistance to shearing forces. Matthies et al. developed a program to search for continuous, flat, triangular structures, which were used as the inputs for the DNA sequence design program. With the addition of connector strands, the flat structures become three-dimensional, with tetrahedral, octahedral, or irregular dodecahedral trusses.

    Nano Lett. 10.1021/acs.nanolett.6b00381 (2016).

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