Editors' Choice

Science  29 Apr 2016:
Vol. 352, Issue 6285, pp. 547
  1. Interstellar Medium

    Under pressure in the Magellanic Clouds

    1. Keith T. Smith

    The tip of the “wing” of the Small Magellanic Cloud

    PHOTO: NASA/CXC/JPL-CALTECH/STSCI

    The Large and Small Magellanic Clouds (LMC and SMC) are small nearby galaxies and a familiar sight in the Southern Hemisphere sky, easily visible to the naked eye. Welty et al. have combined ultraviolet and optical spectroscopy to measure the pressure of the gas in the interstellar medium of the LMC and SMC. They find a generally higher pressure than in our own Milky Way galaxy, which is consistent with the higher ultraviolet radiation field and lower abundance of heavy elements in the Magellanic Clouds. These results will aid astronomers seeking to extrapolate our understanding of the Milky Way to conditions found in other galaxies.

    Astrophys. J., in press; http://arxiv.org/abs/1603.03801 (2016).

  2. Cancer Treatment

    Breaking down a barrier to tumor therapy

    1. Paula A. Kiberstis

    Medulloblastoma is a childhood brain tumor whose response to chemotherapy varies dramatically depending on the tumor's genomic profile. So-called “WNT-medulloblastomas” are curable, but “SHH-medulloblastomas” are more refractory to treatment. Studying mouse models, Phoenix et al. find that differences in tumor vasculature integrity, a property controlled by the tumor, regulate differences in chemosensitivity. WNT-medulloblastomas secrete molecules that antagonize the WNT signaling pathway in endothelial cells, which results in leaky vessels and better diffusion of chemotherapeutic drugs into the tumor. In contrast, SHH-medulloblastomas display an intact blood-brain barrier, which is relatively impermeable by therapeutics. Treatment of SHH-medulloblastomas with WNT inhibitors could potentially enhance their response to chemotherapy.

    Cancer Cell 29, 508 (2016).

  3. Biotechnology

    Cyanobacteria put to work as chemists

    1. Jake Yeston

    Chemists continue to make great strides in raising the efficiency of inorganic catalysts that split water into hydrogen and oxygen. Of course, cyanobacteria have been busily carrying out more or less that same reaction for billions of years. Köninger et al. enlist their help in order to cleanly source hydrogen equivalents (protons and electrons) for the reduction of carbon-carbon double bonds in enones. The authors introduce an enoate reductase enzyme to catalyze the formal hydrogenation with high enantioselectivity and photosynthetically derived oxygen as the sole by-product.

    Angew. Chem. Int. Ed. 10.1002/anie.201601200 (2016).

  4. Heart Development

    A chromatin modifier for the developing heart

    1. Beverly A. Purnell

    The alteration of chromatin structure enables differential gene expressions necessary for organ development. For example, the specific histone modifier protein KMT2D regulates transcription during heart development. Methylation of histone H3 at lysine 4 by KMT2D correlates with gene activation, and mutation of KMT2D is associated with congenital heart defects. Ang et al. now show that deleting the gene that encodes KMT2D in mice disrupts embryonic heart development. Defects result from altered expression of genes involved in directing the development of mesodermal precursors and cardiomyocytes as well as genes controlling the cell cycle and ion transport for calcium signaling. This work elucidates a cardiac transcriptional program for heart development as controlled by a chromatin modifier.

    Development 143, 810 (2016).

  5. Microbiology

    Metagenomes yield archaeal metabolisms

    1. Nicholas S. Wigginton

    Archaea play crucial roles in many environments on Earth and have done so for billions of years. However, they are notoriously difficult to isolate and culture. Two studies show the power of metagenomics in reconstructing the metabolisms and life history of these abundant yet enigmatic microbes. He et al. demonstrate that members of the phylum Bathyarchaeota from subseafloor sediments can perform acetogenesis—a versatile lifestyle previously confined to the bacterial domain. Sousa et al. reveal that a member of the phylum Lokiarchaeota is a strict anaerobe and contains a complete Wood-Ljungdahl pathway, consistent with a hypothesis that the original host of mitochondria was an autotrophic hydrogen-dependent archaeon.

    Nat. Microbiol. 1, 16034, 16035 (2016).

  6. Climate Change

    How accurate are emission estimates?

    1. Julia Fahrenkamp-Uppenbrink

    According to estimates by the International Energy Authority, global carbon dioxide emissions fell by 0.2% in 2014, largely because of a 2.9% drop in Chinese coal consumption. But do these estimates hold up? Korsbakken et al. show that coal consumption estimates are less reliable as predictors of carbon dioxide emissions than is coal-derived energy use. Using data from the Chinese National Bureau of statistics, together with mean emission rates and oxidation rates from different uses of this coal in the Chinese economy, the authors estimate that Chinese fossil fuel emissions grew by 0.8% and that global emissions rose by about 0.5% in 2014.

    Nat. Clim. Change 10.1038/NCLIMATE2963 (2016).

  7. Plant Ecology

    Dabbling ducks disperse seeds

    1. Andrew M. Sugden

    Dabbling ducks like this northern pintail, are important seed dispersers.

    PHOTO: © MANJEET & YOGRAJ JADEJA / ALAMY STOCK PHOTO

    Omnivorous dabbling ducks (Anas spp.) number in the millions worldwide, are highly mobile, and migrate long distances, which suggests that they may disperse seeds from a wide variety of plants. To find out, Soon et al. collated data on seeds ingested by seven species of dabbling ducks, recording more than 400 plant species. Surprisingly, more than half of the seeds came from plants that were not previously known to be animal-dispersed, and many grew in habitats other than the wetlands that dabblers normally prefer. The data suggest that in Europe alone, and depending on the season, dabbling ducks may disperse up to 5 billion seeds daily—many, many more than previously suspected.

    J. Ecol. 104, 443 (2016).

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