This Week in Science

Science  09 Mar 2018:
Vol. 359, Issue 6380, pp. 1114
  1. Quantum Electronics

    Coupling light to single spins

    1. Ian S. Osborne

    Stylized illustration of coupled electron spin and light

    CREDIT: N. SAMKHARADZE ET AL.

    To help develop quantum circuits, much effort has been directed toward achieving the strong-coupling regime by using gate-defined semiconductor quantum dots. Potentially, the magnetic dipole, or spin, of a single electron for use as a qubit has advantages over charge-photon coupling owing to its longer lifetime. Samkharadze et al. hybridized the electron spin with the electron charge in a double silicon quantum dot. This approach yielded strong coupling between the single electron spin and a single microwave photon, providing a route to scalable quantum circuits with spin qubits.

    Science, this issue p. 1123

  2. Climate Change

    Starving ocean productivity

    1. H. Jesse Smith

    Projected increases in greenhouse gas emissions could suppress marine biological productivity for a thousand years or more. As the climate warms, westerly winds in the Southern Hemisphere will strengthen and shift poleward, surface waters will warm, and sea ice will disappear. Moore et al. suggest that one effect of these changes will be a dramatic decrease in marine biological productivity (see the Perspective by Laufkötter and Gruber). This decrease will result from a global-scale redistribution of nutrients, with a net transfer to the deep ocean. By 2300, this could drive declines in fisheries yields by more than 20% globally and by nearly 60% in the North Atlantic.

    Science, this issue p. 1139; see also p. 1103

  3. Microbiota

    Microbial modulation of diabetes

    1. Caroline Ash

    Short-chain fatty acids (SCFAs) are produced by various human gut microbes. SCFAs act as an energy source to the colonic epithelium and are also sensed by host signaling pathways that modulate appetite and inflammation. Deficiency of gut SCFAs is associated with type 2 diabetes. Zhao et al. found that adopting a high-fiber diet promoted the growth of SCFA-producing organisms in diabetic humans. The high-fiber diet induced changes in the entire gut microbe community and correlated with elevated levels of glucagon-like peptide-1, a decline in acetylated hemoglobin levels, and improved blood-glucose regulation.

    Science, this issue p. 1151

  4. Applied Ecology

    Unscientific hunt management plans

    1. Aaron Clauset

    Governments often claim, and society often believes, that science guides policy for natural resource management, including hunting policies across the United States and Canada. But no standard exists for what science-based management entails. Artelle et al. identified four fundamental hallmarks of science for natural resource management. Fewer than half were present in most hunt management plans surveyed across U.S. states and Canadian provinces and territories. Broader application of a science-based framework could improve policies and mitigate risks.

    Sci. Adv. 10.1126/sciadv.aao0167 (2018).

  5. Molecular Biology

    Hemimethylation drives chromatin assembly

    1. Steve Mao

    Cytosine DNA methylation is a heritable and essential epigenetic mark. During DNA replication, cytosines on mother strands remain methylated, but those on daughter strands are initially unmethylated. These hemimethylated sites are rapidly methylated to maintain faithful methylation patterns. Xu and Corces mapped genome-wide strand-specific DNA methylation sites on nascent chromatin, confirming such maintenance in the vast majority of the DNA methylome (see the Perspective by Sharif and Koseki). However, they also identified a small fraction of sites that were stably hemimethylated and showed their inheritance at CTCF (CCCTC-binding factor)/cohesin binding sites. These inherited hemimethylation sites were required for CTCF and cohesin to establish proper chromatin interactions.

    Science, this issue p. 1166; see also p. 1102

  6. Malaria

    Malaria relief, one amino acid at a time

    1. Yevgeniya Nusinovich

    Malaria-infected pregnant women in Malawi lack l-arginine.

    CREDIT: PAUL JEFFREY/ALAMY STOCK PHOTO

    Malaria infection during pregnancy can disrupt placental vasculature and cause complications. Nitric oxide plays a key role in placental vascular function, and its synthesis requires l-arginine. l-arginine and nitric oxide are both depleted during malaria-induced hemolysis, and many people in malaria-endemic areas lack sufficient l-arginine in their diets. McDonald et al. examined the effects of dietary l-arginine supplementation. In a cohort of pregnant women in Malawi, the blood of patients with malaria had less l-arginine, and this was associated with worse pregnancy outcomes. Conversely, l-arginine supplementation in a mouse model of malaria in pregnancy improved fetal weight and viability.

    Sci. Transl. Med. 10, eaan6007 (2018).

  7. Geochemistry

    Encapsulating Earth's deep water filter

    1. Brent Grocholski

    Small inclusions in diamonds brought up from the mantle provide valuable clues to the mineralogy and chemistry of parts of Earth that we cannot otherwise sample. Tschauner et al. found inclusions of the high-pressure form of water called ice-VII in diamonds sourced from between 410 and 660 km depth, the part of the mantle known as the transition zone. The transition zone is a region where the stable minerals have high water storage capacity. The inclusions suggest that local aqueous pockets form at the transition zone boundary owing to the release of chemically bound water as rock cycles in and out of this region.

    Science, this issue p. 1136

  8. Social Science

    Lies spread faster than the truth

    1. Barbara R. Jasny

    There is worldwide concern over false news and the possibility that it can influence political, economic, and social well-being. To understand how false news spreads, Vosoughi et al. used a data set of rumor cascades on Twitter from 2006 to 2017. About 126,000 rumors were spread by ∼3 million people. False news reached more people than the truth; the top 1% of false news cascades diffused to between 1000 and 100,000 people, whereas the truth rarely diffused to more than 1000 people. Falsehood also diffused faster than the truth. The degree of novelty and the emotional reactions of recipients may be responsible for the differences observed.

    Science, this issue p. 1146

  9. Chemical Biology

    Regulating molecule proximity

    1. Beverly A. Purnell

    The physical distance, or proximity, between molecules often directs biological events. The development of membrane-permeable small molecules that reversibly regulate proximity has enabled advances in fields such as synthetic biology, signal transduction, transcription, protein degradation, epigenetic memory, and chromatin dynamics. This “induced proximity” can also be applied to the development of new therapeutics. Stanton et al. review the wide range of advances and speculate on future applications of this fundamental approach.

    Science, this issue p. eaao5902

  10. Stem Cells

    Fibroblasts as lung stem cell niche

    1. Beverly A. Purnell

    Each breath that we take provides oxygen to the bloodstream via tiny sacs in the lung called alveoli. AT1 cells line the alveoli and mediate gas exchange, whereas AT2 cells secrete lung surfactant. A subset of AT2s also serve as stem cells that slowly generate new alveolar cells throughout adult life. Nabhan et al. show that the rare AT2 stem cells have a special niche next to a fibroblast secreting Wnts. This Wnt activity is needed to select and maintain the stem cells. Injury expands the stem cell pool by transiently inducing autocrine Wnts in other surfactant-secreting alveolar cells. This simple but expandable niche sustains oxygen delivery, and it is co-opted in lung cancer.

    Science, this issue p. 1118

  11. Nanomaterials

    Coherent strained superlattices

    1. Phil Szuromi

    Two-dimensional superlattices represent the atomic-thickness limit of heterostructures that enable technologies such as strain-engineered multiferroics and quantum-cascade lasers. Xie et al. were able to produce monolayer superlattices of transition metal dichalcogenides (WS2 and WSe2) with full lattice coherence, despite a 4% lattice mismatch. They used a modulated metal-organic chemical vapor deposition process that precisely controlled each precursor. Furthermore, the authors could strain-engineer the optical properties of the superlattices to observe out-of-plane rippling.

    Science, this issue p. 1131

  12. Water Structure

    Unmasking supercooled water transitions

    1. Phil Szuromi

    The unusual thermodynamic properties of water suggest that when supercooled, a second critical point should exist between two liquid phases that differ in density. Pure water crystallizes before such conditions can be reached. Woutersen et al. studied hydrazinium trifluoroacetate solutions that have similar hydrogen bonding to that of water. They observed a liquid-liquid transition near 190 K by using infrared spectroscopy and calorimetry. The liquid states were analogous to the predicted high- and low-density amorphous phases of water.

    Science, this issue p. 1127

  13. Microbiota

    Bacterial involvement in autoimmunity

    1. Caroline Ash

    The composition of the commensal microbiota is known to influence autoimmune disease development and persistence. Manfredo Vieira et al. identified a gut microbe, Enterococcus gallinarum, that translocates from the gut into the organs of mice with a genetic predisposition to lupus-like autoimmunity (see the Perspective by Citi). Molecular signatures of gut barrier disintegration and pathogenic T helper cells were evident in the gut, liver, and lymphoid organs during colonization with the pathobiont. The ensuing pathology could be reversed by vancomycin treatment and by vaccination against E. gallinarum. The same bug was also found in liver biopsies of autoimmune patients, but not in healthy controls.

    Science, this issue p. 1156; see also p. 1097

  14. Neuroscience

    The mechanisms behind grid cell changes

    1. Peter Stern

    When grid cells were first discovered in the brain, the grids were considered to have rigid coordinates beyond the borders of the testing environments. However, recent findings suggest that the grid cell pattern can be altered easily by changing the space of the enclosure. But how? Krupic et al. discovered that local changes in the geometry of the environment shifted individual neighboring grid fields, while more distant fields remained unchanged. Thus, changes to the grid structure are localized. Stable landmarks continue to exert an effect on most grid cells, whereas the ones close to changed borders are modified.

    Science, this issue p. 1143

  15. Colitis

    Overcoming a barrier to IBD

    1. Priscilla N. Kelly

    Inflammatory bowel disease (IBD) is a group of disorders linked to inflammation of the gastrointestinal tract. Colitis is a type of IBD that affects the inner lining of the colon and has been linked to a gene known as C1orf106. Mohanan et al. found that C1orf106 encodes a protein that stabilizes the integrity of epithelial junctions and enhances barrier defense (see the Perspective by Citi). IBD-associated mutations in C1orf106 lead to greater cytohesin-1 protein levels, changes in E-cadherin localization, and enhanced susceptibility to intestinal pathogens. Modulation of C1orf106 may thus hold promise for treating colitis and other IBDs.

    Science, this issue p. 1161; see also p. 1097

  16. Heart Development

    Committing the heart

    1. Beverly A. Purnell

    The heart is a complex organ composed of multiple cell types such as cardiomyocytes and endothelial cells. Cardiovascular cells arise from Mesp1-expressing progenitor cells. Lescroart et al. performed single-cell RNA-sequencing analysis of mouse wild-type and Mesp1-deficient cardiovascular progenitor cells at early gastrulation (see the Perspective by Kelly and Sperling). When Mesp1 was eliminated, embryonic cells remained pluripotent and could not differentiate into cardiovascular progenitors. During gastrulation, the different Mesp1 progenitors rapidly became committed to a particular cell fate and heart region. Notch1 expression marked the earliest step of cardiovascular lineage segregation.

    Science, this issue p. 1177; see also p. 1098

  17. Protein Folding

    Taking the heat together

    1. Valda Vinson

    Many of the processes in living cells are mediated by protein complexes that dynamically assemble and dissociate depending on cellular needs. Tan et al. developed a method called thermal proximity coaggregation (TPCA) to monitor the dynamics of native protein complexes inside cells (see the Perspective by Li et al.). The method is based on the idea that proteins within a complex will coaggregate upon heat denaturation. It uses a previously described cellular shift assay to determine melting curves for thousands of proteins and assigns a TPCA signature on the basis of similarity between the curves. The method was validated by detection of many known protein complexes. It identified cell-specific interactions in six cell lines, highlighting the potential for identifying protein complexes that are modulated by disease.

    Science, this issue p. 1170; see also p. 1105

  18. Skin Inflammation

    Curbing ILC2 enthusiasm

    1. Anand Balasubramani

    Atopic dermatitis is an allergic disease driven by type 2 immune responses in the skin. Malhotra et al. studied mouse models of dermatitis. They identified the TNF (tumor necrosis factor) family cytokine TL1A (TNF ligand–related molecule 1) and its receptor DR3 (death receptor 3) as being critical in regulating cross-talk between skin-resident T regulatory cells (Tregs) and type 2 innate lymphoid cells (ILC2s) that drive skin inflammation. RORα (retinoid-related orphan receptor α) drove expression of DR3 in Tregs. Upon deletion of RORα, skin-resident Tregs were unable to sequester TL1A, which drives effector functions of ILC2s. Thus, targeting the TL1A-DR3 axis may provide a route to treating dermatitis and other skin allergies.

    Sci. Immunol. 3, eaao6923 (2018).

  19. Rheumatoid Arthritis

    Kinase networks in inflammation

    1. Leslie K. Ferrarelli

    Although inflammation in rheumatoid arthritis is driven by the increased activity of p38, inhibitors of this kinase are ineffective in patients. Using synovial fibroblasts and fluid from rheumatoid arthritis patients, Jones et al. found that p38 mediated negative cross-talk to the related kinase JNK. Thus, inhibiting p38 facilitated JNK activity and the perpetuation of inflammatory cytokine production. Inhibitors of the upstream kinase TAK1 curbed the activity of both the p38 and JNK pathways in synovial fibroblasts cells. Such inhibitors might thus be effective in treating rheumatoid arthritis.

    Sci. Signal. 11, eaal1601 (2018).