This Week in Science

Science  09 Nov 2018:
Vol. 362, Issue 6415, pp. 651
  1. Neonicotinoids

    Trouble at the hive

    1. Sacha Vignieri

    Bumblebee (Bombus impatiens) worker foraging outdoors, fitted with a tracking device

    PHOTO: JAMES CRALL

    Neonicotinoid pesticides cause mortality and decline in insect pollinators. One repeatedly noted effect is a reduction in bee colony size. However, the mechanism behind this reduction is unclear. Crall et al. performed complex real-time monitoring of bumblebee behavior within their nests (see the Perspective by Raine). Neonicotinoid exposure reduced nurse and caretaking behaviors, which affected productivity and harmed colony thermoregulation. These changes in behavior acted together to decrease colony viability, even when exposure was nonlethal.

    Science, this issue p. 683; see also p. 643

  2. Quantum Optics

    Inducing interactions between quantum emitters

    1. Ian S. Osborne

    The development of scalable quantum systems will require the ability to control the interactions between the individual quantum building blocks of the system. Evans et al. used a pair of silicon vacancy centers embedded in a diamond nanocavity to show that interactions between the quantum emitters can be mediated optically (see the Perspective by Lodahl). Such optical control provides a speed advantage as well as the potential to develop an integrated platform for future quantum communication and quantum networking.

    Science, this issue p. 662; see also p. 646

  3. Neuroscience

    Theta rhythm protects sleep replay

    1. Peter Stern

    Hippocampal replay of place cell sequences during sleep is critical for memory consolidation in target cortical areas. How is the sequential organization of place cell assemblies maintained across different time scales? Drieu et al. compared periods when a rat either sat passively on a moving train or ran actively on a treadmill on the same train. During the passive movement, the slow behavioral sequence of place cells was still present, but the rapid generation of theta sequences was lost. Active running on the treadmill, however, maintained the theta rhythm. After passive transport, sequence replay during sleep was destroyed, whereas active running protected replay.

    Science, this issue p. 675

  4. Organic Chemistry

    The staying power of electron-poor ligands

    1. Jake Yeston

    The venerable Suzuki coupling reaction originally used palladium to pair up unsaturated carbon centers. The protocol has been widely extended to chiral saturated alkyl carbons, but control over product stereochemistry is a pressing challenge. Zhao et al. systematically studied how the properties of the phosphine ligands that are coordinated to the catalyst influence the stereochemical outcome. Certain electron-withdrawing phosphines favored retention of the initial configuration in chiral alkyltrifluoroborate reactants. Conversely, bulky electron-rich phosphines lead to inverted configurations in the products.

    Science, this issue p. 670

  5. Genetic Privacy

    Detecting familial matches

    1. Laura M. Zahn

    Recent advances in DNA technology and companies that provide array-based testing have led to services that collect, share, and analyze volunteered genomic information. Privacy concerns have been raised, especially in light of the use of these services by law enforcement to identify suspects in criminal cases. Testing models of relatedness, Erlich et al. show that many individuals of European ancestry in the United States—even those that have not undergone genetic testing—can be identified on the basis of available genetic information. These results indicate a need for procedures to help maintain genetic privacy for individuals.

    Science, this issue p. 690

  6. Batteries

    Oil when not in use

    1. Marc S. Lavine

    Photo of aluminum-air prototype battery

    PHOTO: BRANDON J. HOPKINS

    For primary or nonrechargeable batteries, the overall energy density will be limited by any discharge or open-circuit corrosion that occurs during storage. For batteries based on aluminum and air, this longstanding problem has prevented their widespread use and has been challenging to overcome. Hopkins et al. used commercially available components to construct aluminum-air batteries. During standby periods, the electrolyte in the batteries was replaced with oil to protect the electrodes from corrosion, thus preventing energy loss.

    Science, this issue p. 658

  7. Osteoporosis

    Building and rebuilding bone

    1. Caitlin Czajka

    WNT signaling is important for proper embryonic development, shaping cell fate and migration, stem cell renewal, and organ and tissue formation. Luther et al. investigated the role of WNT1 in osteoporosis. Patients with early-onset osteoporosis and mutations in the WNT1 gene had low bone turnover and high fracture rates, and loss of WNT1 activity caused fracture and osteoporosis in mice. Inducing WNT1 in bone-forming cells increased bone mass in aged mice, and this process did not require LRP5, a co-receptor involved in WNT signaling. Thus, WNT1 acts as an anabolic (bone building) factor and might represent a therapeutic target for osteoporosis.

    Sci. Transl. Med. 10, eaau7137 (2018).

  8. Skin Biology

    A basic way to tan

    1. Wei Wong

    Darker-skinned individuals have more melanin in their skin and a lower risk for skin cancers. The production of melanin in organelles called melanosomes is pH sensitive. Zhou et al. found that the enzymatic activity of soluble adenylyl cyclase (sAC) resulted in decreases in both melanosome pH and melanin synthesis. sAC deficiency or inhibitors increased melanosome pH and pigmentation in mice. This mechanism for rapidly regulating melanin synthesis could potentially be exploited to reduce skin cancer risk for fair-skinned individuals.

    Sci. Signal. 11, eaau7987 (2018).

  9. Predation

    No longer a safe haven

    1. Sacha Vignieri

    Many biological patterns have a latitudinal component. One long-recognized pattern is that predation rates are higher at lower latitudes. This may explain why many migratory birds travel thousands of miles from the tropics to the poles to breed. Looking across thousands of records, Kubelka et al. found that climate change seems to have altered this fundamental pattern. In shorebirds, at least, predation rates on nests are now higher in the Arctic than in the tropics.

    Science, this issue p. 680

  10. Neuroscience

    A framework for cognitive spaces

    1. Peter Stern

    Ever since Tolman's proposal of cognitive maps in the 1940s, the question of how spatial representations support flexible behavior has been a contentious topic. Bellmund et al. review and combine concepts from cognitive science and philosophy with findings from neurophysiology of spatial navigation in rodents to propose a framework for cognitive neuroscience. They argue that spatial-processing principles in the hippocampalentorhinal region provide a geometric code to map information domains of cognitive spaces for high-level cognition and discuss recent evidence for this proposal.

    Science, this issue p. eaat6766

  11. Evolution

    Replaying the tape of life

    1. Sacha Vignieri

    The evolutionary biologist Stephen Jay Gould once dreamed about replaying the tape of life in order to identify whether evolution is more subject to deterministic or contingent forces. Greater influence of determinism would mean that outcomes are more repeatable and less subject to variations of history. Contingency, on the other hand, suggests that outcomes are contingent on specific events, making them less repeatable. Blount et al. review the numerous studies that have been done since Gould put forward this question, both experimental and observational, and find that many patterns of adaptation are convergent. Nevertheless, there is still much variation with regard to the mechanisms and forms that converge.

    Science, this issue p. eaam5979

  12. Immunology

    Dendritic cells give mast cells a nudge

    1. Seth Thomas Scanlon

    Anaphylaxis is a life-threatening allergic reaction triggered after antigen-specific immunoglobulin E (IgE) antibodies bind to target allergens. These antibodies then cross-link IgE-specific Fc receptors on the surface of mast cells. The mast cells rapidly release inflammatory mediators, including histamine, resulting in smooth muscle contraction, vasodilation, and blood vessel leakage. Because mast cells are usually found in the perivascular abluminal surface of blood vessels, it has been unclear how blood-borne allergens can interact with them. Choi et al. used live intravital imaging of the mouse vasculature to show that a specialized subset of dendritic cells sample blood-borne antigens and relay them to mast cells on the surface of microvesicles (see the Perspective by Levi-Schaffer and Scheffel). IgE-bound mast cells then vigorously degranulate after contact with these microvesicles.

    Science, this issue p. eaao0666; see also p. 640

  13. Structural Biology

    Structures of eukaryotic ribonuclease P

    1. Steve Mao

    Ribonuclease P (RNase P) is a ribozyme that processes transfer RNA (tRNA) precursors and is found in all three kingdoms of life. Now, Lan et al. report the structures of yeast RNase P (see the Perspective by Scott and Nagai). The aporibozyme structure reveals how the protein components stabilize the RNA and explains how the structural roles of bacterial RNA elements have been delegated to the protein components in RNase P of higher organisms during evolution. The structure of yeast RNase P in complex with its natural substrate, a tRNA precursor, demonstrates the structural basis for substrate recognition and provides insights into its catalytic mechanism.

    Science, this issue p. eaat6678; see also p. 644

  14. Nanomaterials

    Cleaving with a metal handle

    1. Phil Szuromi

    Using adhesive tape to pull off monolayers of two-dimensional (2D) materials is now a well-established approach. However, the flakes tend to be micrometer scale, and the creation of multilayer stacks for device application can be challenging and time consuming. Shim et al. show that monolayers of a variety of 2D materials, including molybdenum disulfide and hexagonal boron nitride, can be cleaved from multilayers grown as 5-centimeter-diameter wafers. The multilayer is capped with a nickel layer, which can be used to pull off the entire grown stack. The bottom of the stack is again capped with nickel, and a second round of cleaving leaves the monolayer on the bottom nickel layer. The monolayers could be transferred to other surfaces, which allowed the authors to make field-effect transistors with high charge-carrier mobilities.

    Science, this issue p. 665

  15. Antibiotic Resistance

    Efflux pumps and mutation

    1. Caroline Ash

    Antibiotic resistance is an alarming and growing challenge. Bacteria show great heterogeneity in growth and mutation rates. Such variability allows some cells to persist during transient antibiotic exposure. During this persistent phase, mutations accumulate, which can result in selection for full-blown antibiotic resistance. El Meouche and Dunlop found that increased expression of efflux pumps on some cells affords them some relief from antibiotic toxicity. But up-regulating efflux pumps is costly for the bacteria, reducing growth rate and expression of MutS, a protein involved in DNA mismatch repair. These changes thus lift the lid on increased levels of bacterial mutation.

    Science, this issue p. 686

  16. Immunology

    An IgG1 SNP enhances autoimmunity

    1. Seth Thomas Scanlon

    One common feature of autoimmune diseases like systemic lupus erythematosus (SLE) is the presence of high titers of self-reactive antibodies. These result in immune complexes, inflammation, and tissue pathology. Consequently, the checkpoints that normally keep immunoglobulin G (IgG)–positive autoreactive B cells in check are of intense interest. Chen et al. report the presence of a common IgG1 single-nucleotide polymorphism (SNP) in East Asian populations (hIgG1-G396R). This SNP was enriched in SLE patients and associated with increased disease severity. Humans with this SNP, as well as knockin mice, showed enhanced plasma cell accumulation and antibody production. This SNP enhanced IgG1 immunoglobulin tail tyrosine motif phosphorylation, triggering longer adaptor protein Grb2 dwell times in immunological synapses and hyper–Grb2–Bruton's tyrosine kinase signaling after antigen binding.

    Science, this issue p. 700

  17. Protein Design

    Built to be reversible

    1. Valda Vinson

    There has been some success in designing stable peptide filaments; however, mimicking the reversible assembly of many natural protein filaments is challenging. Dynamic filaments usually comprise independently folded and asymmetric proteins and using such building blocks requires the design of multiple intermonomer interfaces. Shen et al. report the design of self-assembling helical filaments based on previously designed stable repeat proteins. The filaments are micron scale, and their diameter can be tuned by varying the number of repeats in the monomer. Anchor and capping units, built from monomers that lack an interaction interface, can be used to control assembly and disassembly.

    Science, this issue p. 705

  18. Immunology

    Adding to the cross-presentation family

    1. Priscilla N. Kelly

    Immune responses to viral or tumor antigens are typically initiated by the process of cross-presentation. Cross-presentation is believed to be the major way that innate immune cells, such as the classical dendritic cell 1 (cDC1) subset, activate and prime immunological T cells. Theisen et al. used CRISPR-based screening to identify regulators of cross-presentation by cDC1s (see the Perspective by Barbet and Blander). One such regulator that was identified, WDFY4 (WD repeat- and FYVE domain–containing protein 4), was required for cross-presentation of cell- and bacterial-associated antigens. WDFY4 played a critical role in cDC1-mediated viral and tumor immunity yet did not seem necessary for major histocompatibility complex class II presentation or for cross-presentation by monocyte-derived DCs.

    Science, this issue p. 694; see also p. 641

  19. Cancer Immunology

    Tandem immunotherapy achieves synergy

    1. Ifor Williams

    Immune checkpoint–inhibitor therapies bolster the antitumor activity of CD8+ T lymphocytes. Wang et al. performed single-cell analysis of tumor-infiltrating lymphocytes in mouse cancer models in which inhibitory anti–PD-1 (programmed cell death protein 1) and stimulatory anti–GITR (glucocorticoid-induced tumor necrosis factor receptor–related protein) antibodies together enhanced tumor control. This combination immunotherapy led to a synergistic increase in tumor antigen–specific memory precursor effector T cells dependent on the CD226 costimulatory pathway. Biochemical studies in liposomes identified CD226 as an additional target of dephosphorylation mediated by the PD-1–SHP2 (Src homology region 2) complex. Thus, further clinical trials could usefully test the efficacy of combined anti-GITR and anti–PD-1 immunotherapy in human cancer.

    Sci. Immunol. 3, eaat7061 (2018).

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