Editors' Choice

Science  16 Aug 2019:
Vol. 365, Issue 6454, pp. 653
  1. Galaxies

    Dust declines after a starburst

    1. Keith T. Smith

    The mass of dust in galaxies decreases exponentially with time since the end of their star formation phase.

    PHOTO: NASA GODDARD

    Post-starburst (PSB) galaxies recently experienced a short episode of vigorous star formation, which has now ceased. Li et al. have studied 58 PSB galaxies whose starbursts ended 100 million to 800 million years ago. By combining data from the ultraviolet to the far infrared, they measure the mass of dust in PSB galaxies and find that it declines approximately exponentially with time since the starburst. The decline is too fast to be the result of the residual star formation, so it may reflect dust destruction by an active galactic nucleus. The dust and gas levels would evolve to typical levels for early-type galaxies about a billion years after the starburst.

    Astrophys. J. 879, 131 (2019).

  2. Neuroscience

    Social isolation biases rodent data

    1. Peter Stern

    Rodents are social animals, and social isolation and barren environments are stressful for them. However, experimental protocols sometimes insist on single housing to obtain accurate measurements of biological parameters or to avoid damage to monitoring apparatus, such as severing of EEG wires, or to prevent aggressive behavior from others. Manouze et al. investigated the consequences of animal housing conditions on stress response and epilepsy severity in rats and mice. Isolated healthy individuals showed higher stress and anxiety levels compared with socially housed animals. Epileptic rats and mice also had more severe seizures when they were isolated. Hence, materials and methods should systematically report housing conditions and all efforts should be made to maintain social interaction during experimentation whenever possible.

    eNeuro 6, ENEURO.0179-18.2019 (2019).

  3. Agricultural Ecology

    Benefits of diversity

    1. Caroline Ash

    Smaller fields and diverse crops improve the biodiversity and resilience of farmed landscapes.

    PHOTO: BLOM/GETTY IMAGES

    Increasingly, our planet's landscapes are becoming homogenized into large areas of monoculture of very few species. This renders food security vulnerable to pests, disease, and natural disasters. Increasing biodiversity by encouraging seminatural patches in a landscape improves crop resilience by harboring natural predators and pollinators. By sampling a variety of agricultural landscapes across North America and Europe, Sirami et al. show that making fields smaller and crops more diverse has an even stronger effect on resilience than just leaving seminatural areas between crops. This is because crop diversity provides multiple refuges for predatory animals. Policies to increase crop heterogeneity may improve biodiversity in agricultural landscapes without taking land out of production.

    Proc. Natl. Acad. Sci. U.S.A. 10.1073/pnas.1906419116 (2019).

  4. Ovarian Dysfunction

    Microbiota and polycystic ovaries

    1. Priscilla N. Kelly

    Polycystic ovary syndrome (PCOS) is a common hormonal disorder that mainly affects women of reproductive age. It results in small ovarian cysts that can affect fertility, as well as metabolic conditions such as insulin resistance and obesity. Finding an increased presence of the bacterium Bacteroides vulgatus in PCOS patients, Qi et al. report a link between the gut microbiome and PCOS. Enhanced abundance of B. vulgatus was associated with alterations in gut bile acid metabolites, which up-regulated interleukin-22 (IL-22) expression via TGR5-GATA3 signaling. Therapeutic administration of IL-22 perturbed browning of adipose tissue and improved insulin sensitivity and ovarian function in mouse models.

    Nat. Med. 25, 1225 (2019).

  5. Immunology

    Class (II) warfare

    1. Seth Thomas Scanlon

    Natural killer (NK) cells are cytotoxic lymphocytes that recognize virus-infected, stressed cells and tumor cells with both activating and inhibitory receptors. Many NK cell receptors bind human leukocyte antigen (HLA) class I, which presents self-peptides but which is often lost within tumors and during infection. Whether and how NK cells might then bind HLA class II molecules, which are required for adaptive immunity, remains unclear. Niehrs et al. report a direct functional interaction between the NK cell receptor NKp44 and a subset of commonly expressed HLA-DP molecules, including HLA-DP401. Intriguingly, the strength of NK cell binding and activation was both peptide- and HLA allotype–dependent. This work may help explain previously reported associations between certain HLA allotypes and some autoimmune, viral, and graft-versus-host disease outcomes.

    Nat. Immunol. 10.1038/s41590-019-0448-4 (2019).

  6. Organic Chemistry

    An E-Z resolution

    1. Jake Yeston

    Compounds with carbon-carbon double bonds can adopt two distinct geometries, designated E or Z on the basis of whether the largest substituents on each carbon are across from or adjacent to each other. Majhi et al. report a method to transform a mixture of E and Z reactants into a single E-configured alkylated product. This dynamic kinetic resolution process relies on deprotonating the carbon next to the double bond to facilitate the rotation. Modeling highlights a coordinative role of the base's sodium counter-ion after deprotonation.

    J. Am. Chem. Soc. 141, 11770 (2019).

  7. Psychology

    Training to reduce cognitive biases

    1. Tage S. Rai

    Human beings are susceptible to cognitive biases, such as the tendency to seek out information that confirms their prior beliefs. Sellier et al. examined whether a single debiasing training intervention could reduce confirmation bias outside of the training setting. Students assigned to solve a business case exercise were less likely to choose the inferior confirmatory solution when they had previously undergone the debiasing intervention. These results stand in contrast to prior work, which had failed to find evidence that debiasing training could transfer to other settings and have implications for improving decision-making.

    Psychol. Sci. 10.1177/0956797619861429 (2019).