Editors' Choice

Science  10 Jan 2020:
Vol. 367, Issue 6474, pp. 159
  1. Microbiota

    Up in the clouds with the fungi

    1. Caroline Ash

    The aerial microbiota above Singapore show diurnal patterns of occurrence.

    PHOTO: ADEL NEWMAN/SHUTTERSTOCK

    Airborne transport of microorganisms is assumed to occur over vast global scales, but we know little about it. Gusareva et al. undertook a year-long metagenomic study of atmospheric organisms above Singapore. Daily patterns were seen in more than 700 taxa, dominated by eukaryotes. At night, spores of basidiomycete fungi formed the greatest airborne biomass. Ascomycete fungal spores prevailed during daytime and correlated with rainfall. The richness of the bacterial groups Firmicutes and Proteobacteria peaked at noon, whereas Cyanobacteria and Actinobacteria abundances stayed uniform over 24 hours. The chief variable was the shift between temperatures at night (26°C) and day (35°C at noon), which presumably drives lift-off.

    Proc. Natl. Acad. Sci. U.S.A. 116, 23299 (2019).

  2. Molecular Biology

    Coincidence detection stalls ribosome

    1. Steve Mao

    Translation of aberrant messenger RNAs that lack in-frame stop codons leads to malfunctioning proteins. To prevent this deleterious effect, cells have quality control processes to monitor translation into polyadenylated regions, including ribosome stalling. Using a combination of biochemistry and structural biology approaches, Chandrasekaran et al. show how ribosomes stall selectively on polyadenylated regions. Polylysine peptide (the codon AAA is decoded as lysine) in the exit channel of a ribosome slows translation, whereas a stabilized polyadenylated RNA helix in a ribosome decoding center blocks incoming transfer RNAs. Therefore, coincidence detection of both polylysine and polyadenylate allows polyadenylated regions, but not polylysine, within normal coding regions to halt translation.

    Nat. Struct. Mol. Biol. 26, 1132 (2019).

  3. Astrophysics

    Interior properties of a neutron star

    1. Keith T. Smith

    The NICER instrument mounted on the International Space Station

    PHOTO: NASA

    Neutron star interiors are composed of exotic neutron-rich matter that cannot be produced in laboratories, and its properties are of interest to both astronomers and nuclear physicists. The Neutron Star Interior Composition Explorer (NICER) instrument performs precise timing of x-ray emission from fast-spinning neutron stars. Riley et al. and Miller et al. report independent blind analyses of the same NICER dataset for a single neutron star. The resulting models have some differences but lead to mass and radius measurements that are consistent within their uncertainties. Companion papers show how the NICER measurements constrain the properties of exotic neutron-rich matter.

    Astrophys. J. Lett. 887, L21, L24 (2019).

  4. Gene Expression

    Sensing amino acid starvation

    1. Valda Vinson

    Most Gram-positive bacteria have genetic switches that regulate the expression of genes involved in amino acid synthesis. These switches are sequences called T-boxes that occur before the coding sequence in the relevant messenger RNAs. They bind to specific transfer RNA (tRNA) and, if it is charged with amino acid, suppress expression of the messenger RNA. Three papers—by Li et al., Battaglia et al., and Suddala and Zhang, with an overview provided by Weaver and Serganov—describe the structures of different classes of T-boxes bound to tRNA. The structures show differences in anticodon recognition that ensure specific binding. The papers differ in their interpretations of how expression is inhibited when the tRNA is charged with amino acid.

    Nat. Struct. Mol Biol. 26, 1094, 1106, 1114, 1081 (2019).

  5. Immunology

    Infection rewires liver metabolism

    1. Seth Thomas Scanlon

    The liver serves as an important hub for metabolism and host-pathogen interactions. However, the link between these two functions is poorly understood. To study this link, Lercher et al. infected mice with chronic lymphocytic choriomeningitis virus (LCMV). Infection caused pronounced transcriptional changes to the liver's metabolic wiring, which in turn altered the host's systemic metabolism. These effects were driven by reprogramming of the hepatocyte urea cycle by type I interferon signaling. The resulting reduction in the ratio of arginine to ornithine in the circulation suppressed antiviral CD8+ T cell responses. Notably, treatment of mice with recombinant pegylated human arginase 1 (used to inhibit hepatocellular carcinoma proliferation) lessened LCMV-induced hepatitis. Thus, the liver can control T cell–mediated tissue pathology by tweaking the metabolites it releases into the circulation.

    Immunity 51, 1074 (2019).

  6. Biomaterial

    A recruitment center for biorepair

    1. Marc S. Lavine

    Although it is possible to incorporate tissue-specific cells into a biomaterial for tissue repair, it requires cell isolation and expansion and a way to constrain the cells after implantation. An alternative option would be a biomaterial that harnesses and accelerates the body's own capabilities for repair. Adenosine is found throughout the body, but its concentration will temporarily and locally spike after a tissue injury because it acts as an extracellular signaling molecular to encourage repair. Because boronate molecules bond to and sequester adenosine, Zeng et al. developed a polymeric material that incorporates 3-(acrylamido) phenylboronic acid. When implanted as a patch at the site of a bone injury, the polymer maintained an increased level of adenosine, thus promoting osteoblastogenesis and angiogenesis.

    Adv. Mat. 10.1002/adma.201906022 (2019).

  7. Gender Bias

    A higher standard for women

    1. Brad Wible

    Despite the absence of explicit gender bias among journal editors and reviewers, female economists were held to a higher standard in order to publish their work. Four leading economics journals shared data on nearly 30,000 manuscripts with Card et al., who found that author gender did not influence key aspects of the evaluation process. However, when looking at future citations as a proxy for the quality of the research, female-authored papers received 25% more citations than similarly evaluated male-authored papers, suggesting that women needed to produce higher quality work than men in order for referees to recommend publication.

    Quart. J. Econ. 135, 269 (2020).

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