Editors' Choice

Science  12 Apr 2019:
Vol. 364, Issue 6436, pp. 142
  1. Ecology

    Drought in tropical forests

    1. Andrew M. Sugden

    Signs of climate change causing drought in a rain forest


    In the context of a changing global climate, ecologists are examining the effects of drought on ecosystems. Drought has increased in several of the world's forested zones, including tropical West Africa, where Aguirre-Gutiérrez et al. have studied the multidecadal consequences of climate drying on forest composition and plant traits. In the Ghanaian study sites, drought has become more prevalent since the 1970s, and the authors were able to compare the responses of wetter and drier forests along a precipitation gradient. The drier forests were more able to adapt to further drought than were wetter forests and shifted toward a greater proportion of deciduous trees—a change that may enhance the resilience of the drier forest to further climatic change.

    Ecol. Lett. 22, 855 (2019).

  2. Astrobiology

    Habitability impacts of molecular clouds

    1. Keith T. Smith

    The Sun is currently located in a low-density region of interstellar space, but conditions would be very different if it were inside a giant molecular cloud (GMC). These vast assemblages of relatively dense gas and dust are concentrated within the Milky Way's spiral arms. Passing through a GMC would block visible light from other stars, owing to dust absorption, and reduce the habitability of Earth by scattering comets onto impact orbits. Kokaia and Davies calculated the expected encounter rate between the Sun and GMCs: 1.6 ± 1.3 per billion years, lasting a few million years each time. Fortunately for life on Earth, these disruptive encounters are rare.

    Mon. Not. R. Astron. Soc., in press, arXiv:1903.08026 (2019).

  3. Neuroscience

    Remyelinating axons

    1. Claudia Pama

    The search for therapeutic targets to support remyelination in demyelinating diseases such as multiple sclerosis is challenging. Existing oligodendrocytes in the brain do not remyelinate demyelinated axons. Selective estrogen receptor modulators have been suggested to make oligodendrocyte precursor cells (OPCs) differentiate into functional, myelinating cells. In the search for myelinization-promoting agents, Rankin et al. selected bazedoxifene from a high-throughput screen and tested it in vitro and in vivo. This drug increased the differentiation of OPCs into functional oligodendrocytes (both in murine and human cells) and did so when axons were demyelinated after an induced lesion. A genetic knockout experiment revealed that the mechanism of action is independent of its presumed target, the estrogen receptor. Bazedoxifene is already approved by the Food and Drug Administration (as it is regularly prescribed for vasomotor menopausal symptoms in women) and is known for having relatively few side effects, which makes it a promising therapeutic drug for multiple sclerosis.

    J. Neurosci. 39, 2184 (2019).

  4. Soil Microbes

    Stinky molecules undermine competitors

    1. Michael A. Funk

    Wild-type and mutant Streptomyces venezuelae cultures growing on an agar medium

    CREDIT: S. JONES ET AL., MBIO 10, E00171-19 (2019)

    Soil bacteria produce several earthy and unpleasant-smelling compounds, but for what reason? The filamentous bacterium Streptomyces venezuelae is known to both produce and respond to fishy trimethylamine as a volatile signaling molecule. Jones et al. found that airborne trimethylamine from S. venezuelae reduced growth and survival of other microbes growing nearby. This effect was reversed by iron supplementation, suggesting a role for trimethylamine in making iron less available to competing bacteria, likely by increasing the local pH. S. venezuelae may compensate for the unhospitable environment it has created by secreting iron-chelating compounds to recover recalcitrant iron.

    mBio 10, e00171-19 (2019).

  5. Parkinson's Disease

    Passing the sniff test

    1. Priscilla N. Kelly

    Parkinson's disease (PD) is a chronic progressive neurological disorder that largely affects movement. There is currently no diagnostic test. Trivedi et al. collected sebum samples from PD patients and unaffected volunteers to identify volatile metabolites that may serve as PD biomarkers. The research team included a woman with a sensitive sense of smell who reported to be able to detect PD by odor. In blinded studies, she identified the “musky” samples that belonged to the PD patients with high accuracy, which guided mass spectrometry to identify the volatile compounds that constituted a signature PD scent. These studies may pave the way for development of the first PD-specific diagnostic test.

    ACS Cent. Sci. 10.1021/acscentsci.8b00879 (2019).

  6. Electrochemistry

    Tin and silver make a rough combination

    1. Jake Yeston

    There's a wide-ranging effort to find an efficient means of using electricity to transform carbon dioxide into value-added compounds. One persistent challenge in this context is identification of inexpensive catalysts that avoid competing production of hydrogen at the cathode. Choi et al. found that pretreating silver with an oxygen plasma initially favored carbon dioxide reduction, but hydrogen concentration rose over time. Depositing a tin oxide layer kept the hydrogen production at bay for at least 20 hours. X-ray spectroscopy suggested that the selectivity ensues from enduring surface roughness.

    J. Am. Chem. Soc. 141, 5261 (2019).

  7. Research Ethics

    Research on wildlife

    1. Sacha Vignieri

    The use of animals in research has gained increasing attention and regulation, with the use of animals in laboratories now monitored by institutions and journals. Although there is still room for improvement for laboratory animals, monitoring of the welfare of animals studied in the wild has received much less attention. Field et al. investigated the legal and institutional oversight of animals studied in the field and found that legal guidelines are often unclear or absent and that institutional oversight, even when present, can be side-stepped. Furthermore, they found that journal requirements for publication collectively lack safeguards for the protection of wildlife during research, with only a third including any policy statement at all.

    PLOS Biol. 10.1371/journal.pbio.3000193 (2019).