This Week in Science

Science  06 Mar 2015:
Vol. 347, Issue 6226, pp. 1109
  1. Freshwater Ecology

    Carbon kicked out by nutrients

    1. Nicholas S. Wigginton

    Forest-derived leaves and wood support stream functions but are lost with nutrient pollution

    IMAGE: PHILLIP M. BUMPERS

    Excess nutrients added to streams result in net carbon loss from aquatic ecosystems. Nitrogen and phosphorus are known to fuel increases in algal carbon. Now, Rosemond et al. show that nutrients stimulate losses of terrestrially derived carbon (e.g., from twigs and leaves). The authors monitored several multiyear experiments on headwater forest streams in the United States. Some of these streams had extra nitrogen and phosphorus added at levels that are now common in many streams and lakes. To successfully manage river ecosystems, we need to take into account nutrient pollution effects on multiple carbon pathways.

    Science, this issue p. 1142

  2. Structural Biology

    Molecular “go” signals reveal their secrets

    1. Kristen L. Mueller

    Chemokines are proteins that direct how cells move within the body. For instance, chemokines help immune cells locate invading pathogens and ensure that cells position themselves correctly within a developing organ. Cells detect chemokines through G protein–coupled receptors on their surface; however, the molecular details of how these proteins interact remain unclear (see the Perspective by Standfuss). Qin et al. solved the crystal structure of the chemokine receptor CXCR4 bound to the viral chemokine vMIP-II. Burg et al. solved the crystal structure of a viral chemokine receptor bound to the chemokine domain of CX3CL1. Given the role of chemokines in a number of diseases, these results may help in future drug design.

    Science, this issue p. 1117, p. 1113; see also p. 1071

  3. Brain Structure

    Cellular diversity in the brain revealed

    1. Pamela J. Hines

    The mammalian brain has an extraordinarily large number of cells. Although there are quite a few different cell types, many cells in any one category tend to look alike. Zeisel et al. analyzed the transcriptomes of mouse brain cells to reveal more than meets the eye. Interneurons of similar type were found in dissimilar regions of the brain. Oligodendrocytes that seemed to be all of one class were differentiated by their molecular signatures into a half-dozen classes. Microglia associated with blood vessels were distinguished from look-alike perivascular macrophages. Thus, the complex microanatomy of the brain can be revealed by the RNAs expressed in its cells.

    Science, this issue p. 1138

  4. Quantum Electronics

    Listen to the quantum art of noise

    1. Ian S. Osborne

    Electrons in metals are subject to thermally induced noise that can generate tiny magnetic fields. For quantum electronic applications, the noise and magnetic fields can be damaging. Kolkowitz et al. show that the spin properties of single defects in diamond can be used to probe the noise. The findings provide insight into how the noise is generated, which could help to mitigate its damaging effects in sensitive quantum electronic circuits.

    Science, this issue p. 1129

  5. Evolutionary Genomics

    Of mice, men, and macaque brains

    1. Laura M. Zahn

    The human brain represents a unique evolutionary trajectory. To better understand how the human brain came to be, Reilly et al. sought to identify changes in gene expression between mice, macaques, and humans. They compared epigenetic marks in the embryonic cortex, which revealed changes in gene regulation in biological pathways associated with cortical development.

    Science, this issue p. 1155

  6. Astrophysics

    Finding four for the light of one

    1. Margaret M. Moerchen

    Seeing double may cause concern for some, but seeing quadruple? It's just what astronomers have been hoping for. Kelly et al. have now detected four images of the same distant supernova with the sharp eye of a space telescope. The supernova shines brightly from the arm of a spiral galaxy that lies far beyond another galaxy between it and us. This intervening galaxy is massive enough to bend the light from the supernova and its host galaxy into multiple images. This behavior relies on the curvature of spacetime and will provide insight into the luminous and dark matter in the lensing galaxy.

    Science, this issue p. 1123

  7. Repellent Materials

    A robust paintlike repellent coating

    1. Marc S. Lavine

    Superhydrophobic materials often depend on a particular surface patterning or an applied coating. However, these surfaces can be damaged by wear or fouled by oily materials. Lu et al. devised a suspension of coated titanium dioxide nanoparticles that can be spray-painted or dipcoated onto a range of hard and soft surfaces, including paper, cloth, and glass. The coatings resisted rubbing, scratching, and surface contamination.

    Superhydrophobic painting corrals water

    PHOTO: YAO LU

    Science, this issue p. 1132

  8. Political Economy

    Political preferences provide economic capital

    1. Gilbert Chin

    Longer periods of democratic government favor economic growth, which in turn stabilizes democracy. But is this relationship a given? Fuchs-Schundeln and Schundeln collected individual-level data from more than 100 countries over two decades. Support for democracy did indeed increase as the length of time lived in a democratic system increased.

    Science, this issue p. 1145

  9. Inflammation

    Interpreting immune signals in the CNS

    1. John F. Foley

    Mice with experimental autoimmune encephalomyelitis (EAE) provide a model of multiple sclerosis. In these mice, a subset of T helper cells that secrete the proinflammatory cytokine interleukin-17 (IL-17) are among the first immune cells to infiltrate the central nervous system (CNS). Huang et al. found that the kinase p38α mediated IL-17–dependent signaling in mice with EAE (see the Focus by Gaffen and McGeachy). Disease symptoms were reduced in mice lacking p38α in CNS cells such as astrocytes but were exacerbated in mice deficient in a phosphatase that inhibits p38α.

    Sci. Signal. 8, ra24; see also fs5 (2015).

  10. Immunogenetics

    How the immune system readies for battle

    1. Laura M. Zahn

    Although gene expression is tightly controlled at both the RNA and protein levels, the quantitative contribution of each step, especially during dynamic responses, remains largely unknown. Indeed, there has been much debate whether changes in RNA level contribute substantially to protein-level regulation. Jovanovic et al. built a genome-scale model of the temporal dynamics of differential protein expression during the stimulation of immunological dendritic cells (see the Perspective by Li and Biggin). Newly stimulated functions involved the up-regulation of specific RNAs and concomitant increases in the levels of the proteins they encode, whereas housekeeping functions were regulated posttranscriptionally at the protein level.

    Science, this issue 10.1126/science.1259038; see also p. 1066

  11. Stellar Dynamics

    Stars that blow up and bug out

    1. Margaret M. Moerchen

    When stars move at speeds that will launch them out of our Galaxy, eyes often turn to our core supermassive black hole as the slingshot responsible. For at least one hypervelocity star, however, the galactic center remains innocent. Geier et al. traced back the trajectory of a compact helium star, US 708, and deduced a different origin in a binary. In this scenario, US 708 acted as the mass donor in a type Ia supernova pair, which spun US708 to the point of ejection. By knowing this star's exotic past, we learn both about its specific history and about the nature of all type Ia supernovae.

    Science, this issue p. 1126

  12. Protein Imaging

    Single-protein spectroscopy

    1. Phil Szuromi

    The spin of a single nitrogen-vacancy (NV) center in diamond is a highly sensitive magnetic-field sensor. Shi et al. used the NV center to detect a nitroxidelabeled protein through electron spin resonance under ambient conditions (see the Perspective by Hemmer and Gomes). The strength of the interaction and the details of the hyperfine interaction between the electron and nitrogen spin revealed the position and orientation of the spin label relative to the NV center. The findings also elucidate the dynamical motions of the protein on the diamond surface.

    Science, this issue p. 1135; see also p. 1072

  13. Protein Targeting

    How to GET to the right membrane

    1. Stella M. Hurtley

    Membrane proteins with a hydrophobic transmembrane domain (TMD) play critical roles in virtually all aspects of cell physiology. After it has been synthesized in the cytosol, this TMD must be targeted to and inserted into the correct membrane. The GET pathway is one of two targeting pathways to the endoplasmic reticulum conserved across all eukaryotes. It is not clear how the central targeting factor, Get3, recognizes a TMD to shield it from aggregation until it is successfully inserted into the membrane. Now, Mateja et al. show that the functional targeting complex comprises a Get3 dimer bound to a single TMD. The helical hydrophobic TMD binds deep within a large hydrophobic groove in the Get3 dimer. This groove closes slightly upon TMD binding, forming a dynamic “lid” over the mouth of the groove.

    Science, this issue p. 1152

  14. Exoplanets

    The search for signatures of life on exoplanets

    1. Kip Hodges

    A “terracentric” view of the likely chemical signatures of life on planets outside our solar system may be naive. Now that we are in the early stages of characterizing exoplanets, rather than just identifying them, the question arises of how best to search for tangible evidence of life on these faraway worlds. Seager and Bains review present theory and future opportunities in the search for biosignatures in planetary atmospheres. They argue that searching for a broader range of small-molecule volatiles than those that are characteristic of biological activity on Earth may prove to be a better way forward.

    Sci. Adv. 10.1126/sciadv.15 00047 (2015).

  15. Nuclear Pores

    A closeup view of the nuclear pore's coat

    1. Stella M. Hurtley

    The precise molecular architecture of the nuclear pore complex (NPC), which mediates traffic between the cytoplasm and the nucleus, has been difficult to ascertain owing to the size and complexity of this subcellular structure. Now, Stuwe et al. describe the crystal structure of the intact ~400-kD coat nucleoporin complex (CNC) of Saccharomyces cerevisiae in the presence of an engineered antibody fragment. Docking the crystal structure into an electron tomography reconstruction of the human NPC established the presence of 32 copies of the CNC arranged in four stacked rings and revealed the details of higher-order CNC oligomerization at the near-atomic level.

    Science, this issue p. 1148

  16. Heart Failure

    Taking antidepressants to heart

    1. Angela Colmone

    Drug repurposing—using drugs already approved by the Food and Drug Administration for new diseases—can save money and time. The antidepressant paroxetine, a selective serotonin reuptake inhibitor (SSRI), also inhibits GRK2, an enzyme that contributes to heart failure. Now Schumacher et al. report that paroxetine can block, or even reverse, the heart damage seen after myocardial infarction in mice. These effects are distinct from its SSRI action and are enhanced by β-adrenergic receptor blockers, already often used to treat heart failure.

    Sci. Transl. Med. 7, 277ra31 (2015).

  17. Infectious Diseases

    Countering antibiotic resistance

    1. Julia Fahrenkamp-Uppenbrink

    Many disease-causing bacteria are resistant to one or more antibiotics, making them difficult to treat. Yet few new antibiotics are being approved for use as medicines. In a Perspective, Perros argues that better understanding of the fundamental characteristics of Gram-negative bacteria is particularly important for the development of new antibiotics. Advances in rapid diagnostics will help to treat patients with the right medication, and also help in the development of highly targeted antibiotics. In a second Perspective, Baker chronicles how antibiotic resistance has become a daily reality in lower-income countries. Drug resistance in the bacterium causing typhoid fever, for example, is so widespread that conditions may return to those of the pre-antibiotic era. New drugs may help, but without large-scale changes in antibiotic use, their impact is likely to be short-lived.

    Science, this issue p. 1062, p. 1064

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