Editors' Choice

Science  13 Oct 2017:
Vol. 358, Issue 6360, pp. 184
  1. Ecology

    Coffee plants benefit from ant dung

    1. Emily Morris

    Weaver ants earn their keep on coffee plants by providing extra fertilization.

    PHOTO: NNPHOTOS/SHUTTERSTOCK

    Ants and the plants on which they live have evolved to benefit from their close relationship. Plants provide nesting space and food for the ants, which in turn defend the plant against herbivory. In coffee plants, Pinkalski et al. show a previously undescribed aboveground uptake of nutrients provided by weaver ants. Nitrogen in the ants' food was traced using isotopic labeling, allowing the authors to observe that nitrogen in the ants' excretion was absorbed through leaves and translocated throughout the plant. Leaves from plants that hosted ants contained more nitrogen than those that did not. It is not yet known how widespread this phenomenon is, but it may be that canopy fertilization, as well as protection from herbivory, earns ants their keep in relationships with plants.

    J. Ecol. 10.1111/1365-2745.12841 (2017).

  2. Health Disparities

    For diabetes screening, race matters

    1. Paula A. Kiberstis

    Type 2 diabetes is diagnosed and monitored by a blood test for HbA1c, a modified form of hemoglobin produced when blood glucose is high. HbA1c levels can be influenced by genetic variants unrelated to glucose homeostasis. To examine whether such variants affect the reliability of the HbA1c test, Wheeler et al. studied 60 genetic variants in nearly 160,000 people of different ancestries. They identified a specific variant that, by shortening the lifespan of red blood cells, reduced HbA1c levels irrespective of blood glucose. This variant occurs almost exclusively in individuals of African ancestry. The results suggest that about 650,000 African Americans with type 2 diabetes may be misdiagnosed as healthy if they are screened solely by the HbA1c test.

    PLOS Med. 10.1371/journal.pmed.1002383 (2017).

  3. Cancer

    Blood test for early-stage cancer

    1. Priscilla N. Kelly

    Cancer cells release circulating tumor DNA into the bloodstream, which can sometimes be used to measure tumor progression and treatment response. Chan et al. sought to address whether so-called “liquid biopsies” could be used to diagnose cancer before an individual had symptoms. They used nasopharyngeal cancer as a model, which is known to be associated with Epstein-Barr virus (EBV) infection. By screening EBV DNA in the plasma from more than 20,000 Chinese men, the researchers were able to accurately detect early-stage nasopharyngeal cancer in this high-risk population. In a 3-year study, the blood test increased the patient survival rate to 97%, compared with around 70% in a historical cohort.

    N. Engl. J. Med. 10.1056/NEJMoa1701717 (2017).

  4. Evolutionary Genomics

    Not missing the origins of lncRNAs

    1. Laura M. Zahn

    Long noncoding RNAs (lncRNAs) are RNA transcripts within the human genome that do not encode proteins. Some lncRNAs have important regulatory functions, such as in silencing the extra X chromosome in females. However, little is known about the origin and maintenance of lncRNAs that are conserved across many mammalian lineages. Hezroni et al. used computational methods to determine that less than 5% of lncRNAs originated from RNA transcripts that once could be translated into proteins. Although they make up a relatively small amount of the genome, these lncRNAs show persistence: Some appear to have lost their protein-coding function more than 200 million years ago but are still maintained as conserved transcripts within mammalian genomes.

    Genome Biol. 18, 62 (2017).

  5. Education

    More undergraduates, more publications

    1. Melissa McCartney

    The benefits to students of undergraduate research experience have been well documented, but what are the benefits for the faculty mentors? One possibility is faculty-student publications, an important outcome both for students' scientific development and for faculty promotion. Morales et al. examined predictors of faculty-student publications, including measures of faculty-student collaboration, faculty commitment to undergraduate students, and faculty characteristics. Results show that faculty who were productive in publishing with undergraduates worked with students for more than 1 year, enjoyed teaching students about research, had mentored black students, and had received more grant funding. Results from this study can be used promote faculty awareness that undergraduates can be successful participants in their laboratories.

    CBE Life Sci. Educ. 10.1187/cbe.16-11-0326 (2017).

  6. Nanomaterials

    Subtleties of growing iron sulfides

    1. Marc S. Lavine

    Pyrrhotite (Fe7S8) prepared from the precursor phenyl disulfide

    PHOTO: J. M. RHODES ET AL., CHEM. MATER. 10.1021/ACS.CHEMMATER.7B03550 (2017) © 2017 AMERICAN CHEMICAL SOCIETY

    Many recipes for growing colloidal nanoparticles exist, but achieving full control over the final products can be challenging, even for well-studied systems. This is particularly true for iron sulfides, for which there exist numerous phase variations with only small differences in stoichiometry. Rhodes et al. found that the formation of sulfur-rich phases correlated with lower C-S bond strength in the organosulfur precursors. However, phases also were affected by the decomposition pathway of the precursor, which could be influenced by using oleylamine as a solvent, because it can also act as a coordinating ligand and a reducing agent. FeS2 or pyrite only formed when using the weakest precursor, diallyl disulfide, and it formed directly, without requiring a FeS intermediate.

    Chem. Mater. 10.1021/acs.chemmater.7b03550 (2017).

  7. Photoswitches

    Aqueous azobenzene switching

    1. Phil Szuromi

    Photoswitching molecules can enable targeted delivery of drugs in the body, but the body is best penetrated by near-infrared radiation (wavelengths between 700 and 900 nanometers). Most photoswitching processes in molecules require shorter wavelengths, and high light intensities are needed to trigger two-photon processes. Dong et al. extensively substituted azobenzene molecules so that they were soluble in water and could photoswitch from the trans isomer after single-photon irradiation at 720 nanometers. The half-life of the resulting cis isomer was 1 second. The benzene rings were substituted with methoxy and pyrrolidine groups, as well as a fused dioxane ring, so that the molecule remained protonated at physiological pH while exhibiting good stability in water.

    J. Am. Chem. Soc. 10.1021/jacs.7b06471 (2017).