Editors' Choice

Science  08 Jan 2016:
Vol. 351, Issue 6269, pp. 135
  1. Biogeochemistry

    A global census of lake nutrients

    1. Nicholas S. Wigginton

    Lake Powell, seen from Alstrom Point in Arizona, USA.

    PHOTO: JOHN SHAW/SCIENCE SOURCE

    Lakes of all sizes are sensitive to local water and pollution management strategies. Excess nutrients in lakes can induce a series of unexpected consequences for water quality or greenhouse gas emissions. Based on previously collected data from over 8000 lakes across six continents, Chen et al. compiled a global estimate of carbon, nitrogen, and phosphorus in lakes. These trace nutrients have intertwined fates in lakes, often related to morphological and climatic factors that change over time. Perturbations of climate or land use by humans will therefore have wide-ranging effects on biogeochemical cycling of nutrients within lakes across the globe.

    Sci. Rep. 10.1038/srep15043 (2015).

  2. Immunogenomics

    Following the bloodline downstream

    1. Laura M. Zahn

    Seven progenitor cells lead to a variety of blood cells

    PHOTO: ANDREW SYRED/SCIENCE SOURCE

    There are many different types of blood cells that originate from a single progenitor cell, but their developmental pathways are not well understood. Applying single-cell sequencing to mouse bone marrow cell populations, Paul et al. identify seven myeloid progenitor states indicating developmental heterogeneity among these cells. Characterizing cellular in vivo functions, they find clusters of cells that express previously well-characterized transcriptional profiles in both rare and common cell types, as well as novel profiles helping demarcate different cellular lineages.

    Cell 163, 1663 (2015).

  3. Geophysics

    Setting the table for a new plate

    1. Brent Grocholski

    A new and surprising discovery on the floor of the Indian Ocean could help determine the age of the Himalayan Mountains. Matthews et al. suggest that the India-Eurasia collision responsible for the great mountain range also explains an unexpected extinct tectonic plate. The formation of a previously unknown “Mammericx Microplate” was created at the beginning of plate convergence. The microplate is about 50 million years old, providing an independent estimate for the continent-continent collision.

    Earth Planet. Sci. Lett. 10.1016/j.epsl.2015.10.040 (2015).

  4. DNA Repair

    Breaking DNA for gene expression

    1. Guy Riddihough

    DNA breaks are potentially highly mutagenic, and the cell has an array of DNA damage response systems to rapidly repair such damage. Curiously, DNA repair factors have been found associated with transcriptionally paused, inducible genes. Bunch et al. show that the activation of paused and inducible genes in human tissue culture cells triggers DNA breaks at the RNA polymerase pause site. The subsequent recruitment and signaling activity of DNA repair factors is critical for DNA repair, release of the RNA polymerase, and the transition to the transcription elongation phase of gene expression.

    Nat. Commun. 6, 10191 (2015).

  5. Graphene Electronics

    Tuning graphene at a stretch

    1. Ian S. Osborne

    Graphene is often described as the superlative material, collectively possessing electronic, thermal, and mechanical properties that exceed those of most other materials. The ability to tune these properties is, however, challenging. Stretching graphene alters the lattice structure, causing a change in the electronic properties as if there was a large magnetic field locally applied to the electrons. Zhu et al. exploit this electromechanical property to demonstrate that, by patterning the geometry of the graphene layer in just the right way, they can design-in the desired strain that then gives rise to uniform pseudomagnetic fields. The engineered stretching technique should offer a route toward enhanced and tunable functionality of graphene.

    Testing cell circuits like an engineer

    PHOTO: KRYSTIAN NAWROCKI/ISTOCK PHOTO

    Phys. Rev. Lett. 115, 245501 (2015).

  6. Signal Transduction

    Testing a cell signaling circuit

    1. L. Bryan Ray

    It remains a challenge to understand how a limited number of signaling mechanisms encode a broad range of cellular responses. Ryu et al. explored signaling by the mitogen-activated protein kinase pathway activated by various growth factors in single PC-12 rat pheochromocytoma cells. As Blüthgen explains in a commentary, the authors tested the circuit much as an electrical engineer might test an electrical circuit. They compared effects of pulses or sustained doses of growth factor. Sustained growth factor stimulus caused a heterogeneous response of single cells—some transiently and some sustaining pathway activation. Mathematical modeling and evaluation of pulsed growth factor stimulation in cells showed that different frequencies of stimulation enabled the same growth factor to cause different cell fate decisions.

    Mol. Syst. Biol. 10.15252/msb.20156458 (2015).

    Mol. Syst. Biol. 10.15252/msb.20156642 (2015).

  7. Drug Delivery

    A protein assist for brain border crossings

    1. Kristen L. Mueller

    Getting therapies into the brain represents a major challenge to drug developers. A layer of brain endothelial cells (BECs) acts as a barrier by preventing large molecules in the blood from accessing the brain. One promising way to overcome this is by using protein receptors on BECs to transfer large molecules like antibodies across the barrier. Zuchero et al. used proteomics to identify candidate proteins expressed highly on mouse BECs. They found that BECs expressed high amounts of CD98hc and then created antibodies to target it. These antibodies could access the brain after systemic dosing of mice and showed substantial pharmacodynamic activity after being engineered so that one antibody arm recognized a potential drug target for Alzheimer's disease.

    Neuron 10.1016/j.neuron.2015.11.024 (2016).