Editors' Choice

Science  03 Nov 2017:
Vol. 358, Issue 6363, pp. 605
  1. Plant Genomics

    An olive branch for sequencing

    1. Laura M. Zahn

    Ancient gene duplications differentiate olives from their relative sesame.

    PHOTO: JOANNATKACZUK/SHUTTERSTOCK.COM

    Olives are a major component of the Mediterranean diet, especially consumed as olive oil, which may provide health benefits. Unver et al. investigated the composition of the genome of the oleaster (wild olive) tree, the ancestor of cultivated olive trees, and characterized its transcriptome. Evolutionary analyses indicate that the oleaster genome contains multiple signatures of ancestral genome duplication events (paleopolyploidy) after divergence from its close relative, sesame, another oil-producing plant. Comparison of genes in the oil-biosynthetic pathways of oleaster and sesame revealed differences in gene expression resulting from the genome and gene duplications. These differences appear to explain the occurrence of oleic acid in olive and linoleic acid in sesame.

    Proc. Natl. Acad. Sci. U.S.A. 10.1073/pnas.1708621114 (2017).

  2. Cancer Biology

    Soaking up tumor suppression

    1. Gemma Alderton

    MicroRNAs (miRNAs) regulate gene expression by inducing mRNA decay. But miRNAs can be regulated through other RNAs and DNA that bind and sequester them without inducing any mRNA decay; these are known as miRNA sponges. Gilot et al. show that tyrosinase-related protein 1 (TYRP1) mRNA confers a growth advantage to metastatic melanoma cells by functioning as a sponge for miR-16, a tumor-suppressor miRNA. Blocking miR-16 binding to TYRP1 mRNA induced melanoma cell death and reduced the growth of human-derived tumor cells in mice. Thus, understanding the complex interplay and competition between RNAs in gene expression is an important consideration for drug development.

    Nat. Cell Biol. 10.1038/ncb3623 (2017).

  3. Synthetic Biology

    Growing pressure sensors from bacteria

    1. L. Bryan Ray

    Mimicking the way that biological organisms combine organic and inorganic materials with microscopic structural properties, Cao et al. show that pattern-forming bacteria can be engineered to support construction of miniature pressure sensors. Bacteria modified with a genetic regulatory circuit produced patterns of excreted inorganic matrix materials. These materials interacted with metal particles to make patterns that depended on the properties of a membrane on which the bacteria were grown. Gold nanoparticles could thus be layered to make domelike structures that, when opposed to one another, formed pressure sensors. They could even be combined into circuits to allow noise filtering or signal amplification.

    Nat. Biotechnol. 10.1038/nbt.3978 (2017).

  4. Evolutionary Cognition

    They can smell your fear

    1. Sacha Vignieri

    Dogs can detect human emotion from smell alone.

    PHOTO: LATTEDA/FLICKR

    It is often said that dogs can “smell fear,” but the majority of research into communication between dogs and humans has focused on gestures, words, and facial expressions. Olfaction has tended to be overlooked, despite dogs' well-known olfactory capabilities. To explore smell discrimination in more detail, D'Aniello et al. tested pet dogs by exposing them to underarm secretions from humans who had experienced happy or fearful stimuli. Dogs exposed to fearful secretions were less likely to approach an unknown human and displayed elevated heart rates. In contrast, dogs exposed to happy secretions were more exploratory, approaching the stranger, and had heart rates similar to those shown in control conditions. The results indicate that the dogs are detecting emotion by smell and support the conclusion that communication between humans and dogs has an olfactory component.

    Anim. Cogn. 10.1007/s10071-017-1139-x (2017).

  5. RNA Folding

    Watching SAM flip the switch

    1. Michael A. Funk

    Riboswitches change their structure upon binding to a ligand, thereby altering downstream gene expression. Manz et al. report a map of the free-energy landscape of the S-adenosylmethionine (SAM)–binding SAM-I riboswitch derived from observing conformations of single molecules over many seconds. Changes in the free-energy landscape upon SAM binding shift the equilibrium toward the off state of the riboswitch, halting transcription. SAM binding also accelerates switching between on and off states, thus releasing switches kinetically trapped during transcription.

    Nat. Chem. Biol. 10.1038/nchembio.2476 (2017).

  6. Chirality

    Charging through the looking glass

    1. Jake Yeston

    Like left and right shoes, chiral molecules can manifest two mirror-image enantiomers. In some cases, hindered rotation is the only barrier to sending one such molecule through the looking glass, but more often the chirality is intrinsic to the bonding framework. As such, it is necessary to break and then remake bonds in order to interconvert the enantiomers. Kim et al. report a striking exception to this paradigm. They prepared a compound in which a monoalkylated carbon atom bridges a quinone ring and a hydroquinone ring. Swapping the oxidation levels of these rings inverts the configuration without carbon bond scission or group migration.

    J. Am. Chem. Soc. 10.1021/jacs.7b09176 (2017).

  7. Galaxy Structure

    Elliptical galaxies spinning on end

    1. Keith T. Smith

    Most elliptical galaxies have a flattened shape and rotate around their shortest axis, like a wheel. However, some galaxies, known as prolate rotators, are elongated and spin around their longest axis, like a spindle. Tsatsi et al. searched a large survey of galaxy kinematics to discover eight previously unknown examples. They estimate that around 10% of elliptical galaxies are prolate rotators, but the fraction is higher at higher masses. They use simulations to show that prolate rotators can form if two massive spiral galaxies merge in a polar orientation, potentially explaining the evolutionary history of these systems.

    Astron. Astrophys. 606, A62 (2017).