Editors' Choice

Science  10 Aug 2018:
Vol. 361, Issue 6402, pp. 565
  1. Ice Sheets

    A responsive past

    1. H. Jesse Smith

    A melt river on Petermann Glacier in northwestern Greenland

    CREDIT: DAVE WALSH/VWPICS/ALAMY STOCK PHOTO

    One of the ways that we might develop more accurate projections of the Greenland Ice Sheet's response to global warming is to investigate analogous periods in the past and use them to establish constraints for its future behavior. Reusche et al. investigated the history of two large outlet glaciers in the northwestern sector of the ice sheet across the Holocene by measuring surface-exposure ages of associated moraines. Their data shed light on the competing effects of generally warming surface air temperatures and discrete climate cooling events. These results help show how quickly the ice sheet can respond to both positive and negative centennial atmospheric temperature fluctuations.

    Geophys. Res. Lett. 10.1029/2018GL078266 (2018).

  2. Microbiota

    Establishing bad host relations

    1. Gemma Alderton

    The human microbiota is a mixture of microorganisms that are maintained in symbiosis with the host. However, sometimes this symbiosis goes awry, causing pathogen outgrowth and disease. For example, periodically, Staphylococcus aureus emerges from the skin-resident microbiome as a disease-causing pathogen. Boldock et al. show that such irruptions can be mediated by particulate peptidoglycan (PTG) expressed from the cell walls of nonpathogenic (commensal) skin bacteria. PTG promotes S. aureus survival in innate immune cells such as macrophages and neutrophils, and this facilitates systemic infection. This phenomenon is not mediated by established receptor pathways such as Nod1, Nod2, Myd88, or the NLPR3 inflammasome.

    Nat. Microbiol. 3, 881 (2018).

  3. Neurodevelopment

    Malaria challenges learning

    1. Pamela J. Hines

    A malaria-free childhood improves educational outcomes in Tanzania.

    PHOTO: JAKE LYELL/ALAMY STOCK PHOTO

    Owing to interventions, the prevalence of malaria has declined in Tanzania. Klejnstrup et al. analyzed 15 years' worth of data on malaria rates, along with school achievement data for more than 200,000 children. They found that children born in periods with higher prevalences of malaria struggled more with numeracy and English literacy than counterparts at less risk of malaria. The effect of a malaria-free childhood on educational outcomes rivaled the effects of smaller class sizes and better-trained teachers.

    PLOS ONE 10.1371/journal.pone.0199542 (2018).

  4. Metabolism

    High fat promotes overeating

    1. L. Bryan Ray

    Disagreement abounds over what constitutes a healthy diet and which components might provoke overeating and obesity in human populations. Hu et al. took a systematic approach to the latter question by feeding mice diets that differed in their proportion of fat (from 8 to 80%), protein (from 5 to 30%), carbohydrate (from 10 to 80%), or sucrose (from 5 to 30%). The only mice that ate more than they needed and became overweight were those eating a diet high in fat content. Furthermore, high-fat diets stimulated hedonic or reward pathways in the brain, as measured by gene expression. Because an equivalent comparison in humans would require a decade of study, we are unlikely to know how closely the results would be replicated in people.

    Cell Metab. 10.1016/j.cmet.2018.06.010 (2018).

  5. Plant Genomics

    Decoding parasitic plant genomes

    1. Laura M. Zahn

    Parasitism has evolved multiple times in plants and resulted in some major agricultural pests, including relatives of the morning glory family called dodder or strangleweed. To examine the effects of parasitism on the genome, Vogel et al. and Sun et al. respectively sequenced the genomes of field dodder (Cuscuta campestris) and Australian dodder (Cuscuta australis). Both studies identified major gene losses, likely facilitating the transformation into leafless, rootless plants unable to photosynthesize. Vogel et al. documented more than 50 examples of gene transfer into field dodder from their hosts. Sun et al. examined transcriptomes of the haustoria, which are specialized organs that allow dodder to extract water and nutrients from host plants.

    Nat. Commun. 10.1038/s41467-018-04344-z, 10.1038/s41467-018-04721-8 (2018).

  6. Geophysics

    Gravity tracking of a great earthquake

    1. Brent Grocholski

    Changes in local gravity are connected to changes in subsurface mass. Panet et al. used GRACE (Gravity Recovery and Climate Experiment) satellite data to track large-scale deformation before and after the magnitude-9 Tohoku-Oki earthquake in Japan. Their analysis of the gravity data indicates that deformation occurred deep in the subducting slab starting several months before the earthquake. After the earthquake, mass transferred to the Pacific and Philippine Sea plate interiors. The large-scale and long-time-period gravity observations provide a distinctive perspective on this devastating and well-studied earthquake.

    Nat. Geosci. 10.1038/s41561-018-0099-3 (2018).

  7. Optics

    Lighting the path to AI

    1. Ian S. Osborne

    Artificial intelligence (AI) explores different architectures that strive to exploit the powerful information-processing capability of the brain. Artificial neural networks use connected artificial components (mimicking the function of neurons and synapses) to process information and perform complex tasks such as written and spoken language and image recognition from vast datasets. All the networks require training, however, which usually has been done by computer, and the process can be very time-consuming. Hughes et al. developed an optical method in which the training process is done with laser light propagating through a complex network of paths patterned into an optical chip. The results bring the prospect of an optical chip–based AI platform operating at the speed of light a step closer.

    Optica 5, 864 (2018).