Editors' Choice

Science  03 Aug 2018:
Vol. 361, Issue 6401, pp. 464
  1. Education

    No gender differences in early math cognition

    1. Tage S. Rai

    Young girls and boys perform equally well in tests of intrinsic mathematical ability.

    PHOTO: THOMAS KOEHLER/CONTRIBUTOR/GETTY IMAGES

    Men are overrepresented in STEM (science, technology, engineering, and mathematics) fields. One proposed reason is that men hold an intrinsic advantage over women in mathematical cognition. If such an intrinsic difference exists, it should be present early in child development. To address this question, Kersey et al. examined data from more than 500 children ranging in age from 6 months to 8 years across several tests of numerosity, counting, and elementary mathematics concepts. The authors found no differences in mathematical performance between boys and girls in any of the ages tested. These data provide some of the strongest evidence yet that differences in STEM representation are unlikely to be due to intrinsic differences in cognitive ability.

    NPJ Sci. Learn. 10.1038/s41539-018-0028-7 (2018).

  2. Cancer

    Predicting esophageal cancer

    1. Ming Yang

    Barrett's esophagus (BE) is an abnormal change in the lining of the lower esophagus caused by stomach acid reflux injury. This is the biggest risk factor for esophageal cancer, although fewer than 1% of BE patients will develop cancer. Stachler et al. analyzed genomic changes in biopsy samples from almost 100 patients with BE and monitored them for esophageal cancer for 5 years. Patients who progressed to cancer showed more mutations than nonprogressors, particularly in the tumor suppressor gene TP53. Mutations were detected frequently before the onset of dysplasia in 46% of the progressors, but only in 5% of the nonprogressors. TP53 mutations in BE lesions increased the risk of developing esophageal cancer by almost 14-fold.

    Gastroenterology 10.1053/j.gastro.2018.03.047 (2018).

  3. Dengue

    Transit time inside a mosquito

    1. Caroline Ash

    Dengue virus genetic variation and ambient temperature influence the rate of transmission by mosquitoes and thus the risk and magnitude of an outbreak. Virus in a blood meal within the vector mosquito's gut takes several days—roughly a quarter of the short life of an Aedes mosquito—to transition from the gut to the salivary gland, ready for inoculation into the next host. So, 1 day's difference can mean success or failure for ongoing transmission. Fontaine et al. found that eight strains of recently circulating dengue virus have different gut–salivary gland transit times. In an agent-based model, this parameter translated into a roughly 20% difference in the probability of a subsequent human infection, with a Haitian strain being the slowest, resulting in smaller outbreaks.

    PLOS Pathog. 10.1371/journal.ppat.1007187 (2018).

  4. Social Science

    Differences promote spreading

    1. Barbara R. Jasny

    Infecting a human population with ideas or viruses depends on interpersonal contact. However, patterns of interactions can vary. For example, in the workplace, some people will regularly have their doors open in the afternoon, whereas others open their doors frequently for short periods throughout the day. Although it might seem that there would be one “optimal” pattern for diffusing information or spreading contagious disease within a population, Akbarpour and Jackson show, through simulations with random and real-world networks, that heterogenous patterns can favor spread. A combination of people who rarely alternate from being available or susceptible to being unavailable or recovered with people who frequently alternate between the two states maximized diffusion in a simple model.

    Proc. Natl. Acad. Sci. U.S.A. 10.1073/pnas.1722089115 (2018).

  5. Ecology

    Fruitfulness of forest drought

    1. Andrew M. Sugden

    Prolonged forest stress, such as drought, affects litterfall.

    PHOTO: NASA/JPL-CALTECH

    Drought resulting from climate change is becoming pervasive. Increasing research effort is being focused on the ecological effects of drought on the world's tropical forested regions. Rowland et al. measured the multiyear effects of drought on the litterfall of leaves, flowers and fruits, and twigs in a Brazilian forest. Drought was simulated by covering a 1-hectare experimental plot with plastic panels 1 to 2 meters above the ground. Litterfall over 14 years was compared with that on an uncovered neighboring plot. Litterfall of flowers and fruits decreased by more than half during the first 4 years. After 10 years, where trees survived, the fall of reproductive parts recovered to levels that exceeded those in the control plot. It appears that prolonged stress can lead to restabilization of forest function.

    J. Ecol. 106, 1673 (2018).

  6. Neuroimmunology

    Hauling away injured neurons

    1. Priscilla N. Kelly

    Microglia are specialized immune cells of the central nervous system that recognize and help remove defunct neurons during development. Norris et al. asked whether microglia can curb injury after brain damage. Using a mouse model of optic nerve crush injury, they find that microglia produce complement proteins to help identify destroyed tissue. Activated microglia cleared debris and prevented damage from spreading to neighboring neurons. This newly identified mechanism may have implications for limiting brain and spinal cord injuries.

    J. Exp. Med. 10.1084/jem.20172244 (2018).

  7. Protein Assembly

    Artificial β-barrel pores

    1. Phil Szuromi

    The de novo construction of proteins from peptide fragments that assemble into β-barrel structures, as opposed to α-helix or α/β folds, is challenging. Yamagami et al. show that six octapeptides, terminated with pyridyl groups, assemble into an antiparallel β-barrel structure when coordinated with ZnI2 linkers. The peptides contain a phenylalanine-valine-phenylalanine-valine sequence with a high propensity for forming β-sheets linked to a proline-glycine-proline sequence that forms a loop. The crystal structure reveals the formation of a pore lined with the hydrophobic isopropyl side chains of the valine residues.

    J. Am. Chem. Soc. 10.1021/jacs.8b04284 (2018).