Editors' Choice

Science  10 Jun 2016:
Vol. 352, Issue 6291, pp. 1289
  1. Toxicology

    Triclosan restructures gut communities

    1. Nicholas S. Wigginton

    Ingesting organic compounds can modify the gut microbial communities in zebrafish.

    PHOTO: KAZAKOV MAKSIM/SHUTTERSTOCK

    Trace organic compounds can have a range of unintended consequences for environmental ecosystems and exposed animals. The adverse health effects of the antimicrobial compound triclosan and its degradation by-products, for example, have led to bans of its use in some consumer products. Gaulke et al. show how triclosan modifies gut microbial communities after ingestion. In zebrafish fed triclosan-laced diets, gut community composition dramatically shifted over short time intervals. Some community members were highly susceptible to triclosan exposure, whereas others, including members of the genus Pseudomonas and the family Rhodobacteraceae, were more resistant. Overall, triclosan exposure altered ecological dynamics and interaction networks, demonstrating how such trace compounds can have a profound impact on the gut microbiome.

    PLOS ONE 10.1371/journal.pone.0154632 (2016).

  2. DNA Recombination

    An up-close view of DNA cut and paste

    1. Valda Vinson

    DNA recombination, which involves the exchange of DNA between chromosomes, is fundamental to evolution. One of the best-characterized recombination reactions is between bacteriophage λ and the bacteria Escherichia coli: The bacteriophage DNA can be integrated into or excised from the bacterial DNA. Laxmikanthan et al. trapped an intermediate in the excision reaction and determined its structure at 11 A resolution. This structure, along with fitting known component structures into the electron density, revealed that the DNA forms a structure known as a Holliday junction that is bound by four enzymes and seven accessory proteins. The accessory proteins help position the DNA for the enzymatic reactions. The excision structure also provided insights into how the integrative complex probably functions.

    eLife 5, e14313 (2016).

  3. Immunology

    Infection history matters

    1. Kristen L. Mueller

    Previous infections may influence vaccine responses.

    PHOTO: © BSIP SA/ALAMY STOCK PHOTO

    People's responses to infections vary; for instance, seasonal influenza viruses kill only a fraction of the people they infect. Environmental factors such as age, health status, and even one's microbiota can influence outcomes, and now Reese et al. report that infection history may matter too. The authors found that both basal and vaccine-induced immune responses differed between barrier-raised mice, which are largely protected from infections, and mice sequentially infected with viruses that cause chronic infections, influenza virus, and a parasitic worm. Moreover, the gene signatures of these sequentially infected mice more closely resembled those of pet store–raised mice as compared to laboratory-raised mice and of adult blood as compared to fetal cord blood. Sequential microbial exposures of laboratory mice may therefore better model the complexity of human immunity.

    Cell Host Microbe 19, 713 (2016).

  4. Cancer Genetics

    Genotyping to identify cancer risk

    1. Laura M. Zahn

    Certain genetic variants can increase a person's risk of developing cancer. For breast cancer, the link between BRCA1/2 variants and increased cancer risk is well established; however, the risk conferred by other breast cancer–associated genetic variants is not as well understood. To gain more insight, Li et al. combined family history with 24 previously identified cancer-associated single-nucleotide variants (excluding the BRCA1/2 genes) to develop a breast cancer risk score. Applying these risk scores prospectively to 2599 women revealed that this method was more accurate than familial history alone in determining the risk of developing breast cancer.

    Genet. Med. 10.1038/gim.2016.43 (2016).

  5. Cell Biology

    Remodeling DNA by phases

    1. Guy Riddihough

    The cell contains a number of organelles that lack membranes. Their interiors, composed of the disordered regions of proteins, probably form a mesh-like hydrogel, which behaves as a distinct solvent phase inside the cell. Nott et al. created model membraneless organelles in culture. These organelles destabilized double-stranded nucleic acids and preferentially bound single-stranded (ss) DNA and RNA, especially structured ssDNA or ssRNA, favoring compact oligonucleotide structures over extended ones. The interiors of membraneless organelles thus provide the cell with solvent properties that can modulate the behavior of the molecules they absorb.

    Nat. Chem. 10.1038/NCHEM.2519 (2016).

  6. Quantum Photonics

    Interchip quantum connectivity

    1. Ian S. Osborne

    Optical circuits based on the fabrication of waveguides in silica have the proven capacity to transport single photons from one part of an optical chip to another. Quantum-enhanced sensing and communication applications will require the single photons and the generated quantum states of several interacting single photons to be transported between separate chips. However, the delicate nature of the quantum states has made such interconnectivity difficult to achieve. Using grating couplers on each chip and connecting them with a single-mode fiber, Wang et al. demonstrate the ability to generate an entangled state on one chip and transfer it to another. Such a coupling and transfer of quantum states will be crucial for developing advanced quantum-based technologies.

    Optica 3, 407 (2016).

  7. Geophysics

    Managing metal the core left behind

    1. Brent Grocholski

    At the very base of Earth's rocky mantle lie two distinct regions called large low shear wave velocity provinces (LLSVPs). Zhang et al. suggest a very old origin for the LLSVPs by tying their formation to Earth's 4.5 billion years ago. Tiny amounts of metallic melt trapped at the base of the mantle during this process could explain the enigmatic properties of LLSVPs. Their model also provides a way for large-scale mantle heterogeneities to persist for billions of years.

    Geophys. Rev. Lett. 10.1002/2016GL068560 (2016).

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