This Week in Science

Science  11 Aug 2017:
Vol. 357, Issue 6351, pp. 560
  1. Neuroscience

    I've seen this face before

    1. Peter Stern

    Brain areas for recognizing specific familiar faces have been identified.

    PHOTO: FIONA ROGERS/GETTY IMAGES

    We have known for some time that there is a network of brain regions for face recognition. However, how and where face familiarity is encoded has been elusive for decades. Landi and Freiwald performed brain imaging in macaques and identified two areas specifically involved in recognizing familiar faces. These two areas showed a nonlinear response as blurred faces gradually became visible, rapidly becoming active when the faces of familiar monkeys became recognizable.

    Science, this issue p. 591

  2. Organic Chemistry

    A charged approach to forming C–N bonds

    1. Jake Yeston

    Adjacent carbon-nitrogen bonds often appear in chemical compounds of pharmaceutical interest. Fu et al. developed a versatile method to form these bonds by pairing manganese catalysis with electrochemical azide oxidation in the presence of olefins. A major advantage of the electrochemical approach is the tunable precision of its oxidizing power, which leaves other sensitive substituents such as alcohols and aldehydes intact. The reaction proceeded over several hours at room temperature, forming hydrogen at the counter electrode as a benign by-product.

    Science, this issue p. 575

  3. Geophysics

    A coherent depth for continental plates

    1. Brent Grocholski

    The thickness of the continental portion of Earth's cold and rigid surface plates is a source of debate. Tharimena et al. analyzed a specific type of seismic signal called SS precursors to provide a robust estimate of plate thickness under the continents (see the Perspective by Savage). The values range from 130 to 190 km, which lines up well with the depth where diamonds are stable—an independent line of evidence for the depth of continents.

    Science, this issue p. 580; see also p. 549

  4. Cancer

    Rock-a-bye bone marrow

    1. Yevgeniya Nusinovich

    Chemotherapy saves the lives of many cancer patients. However, it is a difficult treatment that induces many major side effects, with one of the most common being myelosuppression—depletion of bone marrow cells. The consequences of myelosuppression include anemia, thrombocytopenia, and neutropenia, all of which can cause severe complications and delay subsequent courses of chemotherapy. Taylor et al. discovered that quizartinib, a tyrosine kinase inhibitor, can decrease the risk of myelosuppression during cancer treatment by transiently suppressing the proliferation of bone marrow progenitor cells. In mice with leukemia, cancer cells continued to proliferate during treatment, making them a target for chemotherapy even when the bone marrow was protected.

    Sci. Transl. Med. 9, eaam8060 (2017).

  5. Biomaterials

    Squid lenses beat spherical aberration

    1. Marc S. Lavine

    When light rays pass through a curved lens, greater refraction at the edges can distort the resulting image. This problem can be overcome if the refractive index of the lens is varied according to the curvature. Cai et al. show that the lenses of squid eyes have an internal structure containing a set of globular proteins that form a gradient of colloidal particles to counter spherical aberration (see the Perspective by Madl). Thus, the evolutionary process has used the principles of patchy colloid theory to construct a self-assembling, complex optical device.

    Science, this issue p. 564; see also p. 546

  6. Flooding

    Flooding along the river

    1. H. Jesse Smith

    Will a warming climate affect river floods? The prevailing sentiment is yes, but a consistent signal in flood magnitudes has not been found. Blöschl et al. analyzed the timing of river floods in Europe over the past 50 years and found clear patterns of changes in flood timing that can be ascribed to climate effects (see the Perspective by Slater and Wilby). These variations include earlier spring snowmelt floods in northeastern Europe, later winter floods around the North Sea and parts of the Mediterranean coast owing to delayed winter storms, and earlier winter floods in western Europe caused by earlier soil moisture maxima.

    Science, this issue p. 588; see also p. 552

  7. Neural Epigenomics

    Methylation and the single neuronal cell

    1. Laura M. Zahn

    The presence or absence of methylation on chromosomal DNA can drive or repress gene expression. Now, a comprehensive map of methylation variation in neuronal cell populations, including a between-species comparison, illustrates how epigenetic diversity plays important roles in neuronal development. Luo et al. examined how DNA methylation is both similar and different within neurons at the single-nucleus level in humans and mice. They identified 16 mouse and 21 human neuronal clusters, with greater complexity of excitatory neurons in deep brain layers than in superficial layers.

    Science, this issue p. 600

  8. Research Impact

    Picking up a patent

    1. Barbara R. Jasny

    What is the relationship between patents and scientific advances? Ahmadpoor and Jones devised a metric for the “distance” between patentable inventions and prior research to study this question. They analyzed the relationship between 4.8 million U.S. patents and 32 million research articles. Universities tended to cite their own research directly in their patents (in other words, a distance of 1), but the distance was greater for companies, suggesting that companies may rely on outsiders for their foundational research. The distance varied by discipline, with nanotechnology and computer science having the shortest distances between published research and patents.

    Science, this issue p. 583

  9. CRISPR Biology

    Bacterial defense amplification

    1. Steve Mao

    Prokaryotic type III CRISPR systems use the effector complex and additional proteins such as Csm6 to destroy both the genome and the transcripts of invaders. However, how the effector complex and Csm6 coordinate CRISPR activity remains a mystery. Kazlauskiene et al. found that a cyclic oligonucleotide–based signaling pathway can regulate the defense response (see the Perspective by Amitai and Sorek). Upon target recognition, the Cas10 subunit of the effector complex synthesizes cyclic oligoadenylates, which act as second messengers to initiate and amplify the nuclease activity of Csm6.

    Science, this issue p. 605; see also p. 550

  10. Microbial Genomics

    Archaeal diversity and evolution

    1. Laura M. Zahn

    Archaea are prokaryotes that make up a third branch of the tree of life. Knowledge of archaeal biological diversity and their role in evolution has rapidly expanded in the past decade. Despite the discovery of previously unknown groups and lineages, few lineages have been well studied. Spang et al. review the diversity of Archaea and their genomes, metabolomes, and history, which clarifies the biology and placement of recently discovered archaeal lineages.

    Science, this issue p. eaaf3883

  11. Chromosome Structure

    Origin of DNA compaction

    1. Steve Mao

    As a repeating unit in eukaryotic chromatin, a nucleosome wraps DNA in superhelical turns around a histone octamer. Mattiroli et al. present the crystal structure of an archaeal histone-DNA complex in which the histone-mediated DNA geometry is exactly the same as that in the nucleosome. Comparing features of archaeal and eukaryotic chromatin structures offers important insights into the evolution of eukaryotic nucleosomes.

    Science, this issue p. 609

  12. Education

    High schoolers' interest in STEM is contagious

    1. Robert E. Megginson

    When asked what is influential in pointing students toward science, technology, engineering, and mathematics (STEM) careers, many would name science teachers and parents as obvious candidates. Hazari et al. offer evidence for another important group: classmates in high school science courses. They hypothesized that students who perceive that their classmates are highly interested in the course material are themselves more likely to enter STEM careers, and this hypothesis was supported by information collected from a national survey. The effect remained strong after controlling for differences between students such as prior interest in STEM careers, family support for pursuing such a career, and academic achievement, and after controlling for differences in teaching quality.

    Sci. Adv. 10.1126/sciadv.1700046 (2017).

  13. Metabolism

    Antiviral and anti–fatty liver

    1. Wei Wong

    In myeloid cells, the Toll-like receptor signaling adaptor TRIF promotes inflammation to fight infection. Chen et al. found that TRIF also has a metabolic role in the liver. TRIF activation decreased the levels of SCD1, a key lipogenic enzyme. TRIF activation reduced lipid accumulation in hepatocytes exposed to palmitic acid, a saturated fatty acid that is abundant in high-fat diets and in the livers of mice with diet-induced obesity. Because the hepatitis C virus co-opts host lipogenesis to ensure its replication, this TRIF-dependent pathway may restrict viral infection of hepatocytes.

    Sci. Signal. 10, eaal3336 (2017).

  14. Neuroscience

    Neural mechanisms for hallucinations

    1. Peter Stern

    Pairing a stimulus in one modality (vision) with a stimulus in another (sound) can lead to task-induced hallucinations in healthy individuals. After many trials, people eventually report perceiving a nonexistent stimulus contingent on the presence of the previously paired stimulus. Powers et al. investigated how different groups of volunteers and patients respond to this conditioning paradigm. They used behavior, neuroimaging, and computational modeling to dissect the effect of perceptual priors versus sensory evidence on such induced hallucinations. People who are more prone to hear voices were more susceptible to the induced auditory hallucinations. The network of brain regions that was active during the conditioned hallucinations resembled the network observed during clinical symptom capture in individuals who hallucinate while in a brain scanner.

    Science, this issue p. 596

  15. Microbiota

    Healthy guts exclude oxygen

    1. Caroline Ash

    Normally, the lumen of the colon lacks oxygen. Fastidiously anaerobic butyrate-producing bacteria thrive in the colon; by ablating these organisms, antibiotic treatment removes butyrate. Byndloss et al. discovered that loss of butyrate deranges metabolic signaling in gut cells (see the Perspective by Cani). This induces nitric oxidase to generate nitrate in the lumen and disables β-oxidation in epithelial cells that would otherwise mop up stray oxygen before it enters the colon. Simultaneously, regulatory T cells retreat, and inflammation is unchecked, which contributes yet more oxygen species to the colon. Then, facultative aerobic pathogens, such as Escherichia coli and Salmonella enterica, can take advantage of the altered environment and outgrow any antibiotic-crippled and benign anaerobes.

    Science, this issue p. 570; see also p. 548