Editors' Choice

Science  30 Jun 2017:
Vol. 356, Issue 6345, pp. 1347
  1. Plant Evolution

    Genomics trace plant gene evolution

    1. Laura M. Zahn

    Spatial separation of hormones across cells facilitates temperature-mediated initiation of seed germination.

    PHOTO: JEREMY BURGESS/SCIENCE SOURCE

    MADS-box genes have essential functions in plant development and morphology. However, in plants, as a result of multiple rounds of whole-genome duplications combined with specific gene gains and losses, the relationships and evolution of this gene family have been difficult to trace. Zhao et al. applied a network-based phylogenetic analysis examining synteny—the location of genes and their relative position within the genome—across all identified MADS-box genes from 51 plant species. Through this analysis, the relationships, approximate timing, gains and losses, and specific movements of these genes within the genome could be traced. This allows for a better understanding of how evolution has acted on a key regulatory gene family in the plant kingdom.

    Plant Cell 10.1105/tpc.17.00312 (2017).

  2. Physiology

    Characterizing a 12-hour biological clock

    1. L. Bryan Ray

    A mathematical analysis of changes in gene expression in mouse liver, designed to detect oscillations of various frequencies, showed more than 3500 genes whose expression cycled with a 12-hour period. This is distinct from circadian gene expression, which is coupled to the 24-hour light cycle, and has been noted before in marine animals, perhaps because of a need to synch with 12-hour tidal changes. Zhu et al. found that gene products associated with 12-hour cycles are particularly related to metabolic function, endoplasmic reticulum stress, and the unfolded protein response. The 12-hour clock appears to be distinct from the well-known circadian oscillator and was evident in nematodes and crustaceans, as well as mammals.

    Cell Metab. 10.1016/j.cmet.2017.05.004 (2017).

  3. Education

    Social activity: A new dimension in STEM

    1. Melissa McCartney

    As active learning continues to replace traditional lectures, a new dimension of learning needs to be measured: social activity. Specifically, how are students interacting with and learning from their peers? Wiggins et al. developed and validated a 16-item survey to measure multiple facets of student experience in active-learning classrooms. The Assessing Student Perspective of Engagement in Class Tool (ASPECT) was designed to be widely applicable for different types of active learning and allows for the comparison of relative student engagement levels across various active-learning strategies. As researchers begin to investigate what makes active learning effective, tools such as ASPECT will provide insight into potential barriers presented by active learning, as well as strategies that increase engagement of all students.

    CBE Life Sci. Educ. 10.1187/cbe.16-08-0244 (2017).

  4. Plant Biology

    Temperature signals in seed germination

    1. Catherine Griffin

    The switch between seed dormancy and germination in Arabidopsis thaliana is regulated by the balance between the hormones abscisic acid (ABA) and gibberellin (GA). Low temperatures are known to cause an increase in GA synthesis and receptor abundance, thereby increasing the probability of germination. Topham et al. studied the integration of temperature signals and determined that the embryo radicle is enriched for factors involved in hormone signaling, synthesis, and degradation. A clear spatial pattern emerged whereby ABA and GA pathway components were broadly separated into different cell types. This spatial separation and control over transport of hormones between cells facilitates processing of fluctuating temperature inputs and increases their propensity to break seed dormancy, compared with signals from continuous cold exposure. This is hypothesized to ensure accurate timing of seedling establishment through recognition of environmental temperature oscillations.

    Proc. Natl. Acad. Sci. U.S.A. 10.1073/pnas.1704745114 (2017).

  5. Stratospheric Ozone

    Great American ozone loss

    1. H. Jesse Smith

    Strong atmospheric convection over the badlands of South Dakota

    PHOTO: MIKE HOLLINGSHEAD/SCIENCE SOURCE

    The central United States is a region particularly vulnerable to stratospheric ozone loss in summer, in part because of the severe storms that occur over the Great Plains. Anderson et al. present measurements of the convective penetration of water into the stratosphere over the United States in summer caused by these storms, along with relevant accompanying physical and chemical effects, to better understand the mechanisms of stratospheric ozone loss and to facilitate decadal forecasting in our changing environment. Their findings imply that there exists an increased risk of ozone loss over the Great Plains in summer as the climate warms.

    Proc. Natl. Acad. Sci. U.S.A. 10.1073/pnas.1619318114 (2017).

  6. Drug Addiction

    A vaccine for heroin addiction?

    1. Priscilla N. Kelly

    Addiction to opiate drugs has become a worldwide public health epidemic. Bremer et al. sought to test whether a vaccination approach might be a way to combat heroin addiction. They designed a vaccine that contained part of the heroin molecule, which trained the immune system in monkeys to produce antibodies against heroin. The vaccine was able to neutralize heroin and prevent the heroin high feeling for up to 8 months. Antiheroin immunity continued to improve over time with the administration of booster shots. The researchers next aim to test the vaccine in human trials.

    J. Am. Chem. Soc. 10.1021/jacs.7b03334 (2017).

  7. Electrochemistry

    Pairing up copper and tin to reduce CO2

    1. Jake Yeston

    Copper could be a cost-effective catalyst for solar-powered reduction of CO2 to fuels and chemicals, but it tends to produce a variety of different products. Building on recent observations, Schreier et al. now show that coating copper oxide nanowires with tin oxide by atomic layer deposition confers high selectivity for CO production in CO2 electrolysis. Moreover, these nanowires proved effective in catalyzing the anodic oxidation of water to oxygen as well. The authors took advantage of a bipolar membrane to carry out the cathodic and anodic reactions at neutral and basic pH, respectively, reaching a solar-to-CO2 conversion efficiency of 13.4% with a three-junction solar cell to power the process.

    Nat. Energy 2, 17087 (2017).