This Week in Science

Science  18 Aug 2017:
Vol. 357, Issue 6352, pp. 656
  1. Surface Science

    When you don't want things to stick

    1. Marc S. Lavine

    Mussels are opportunistic macrofouling organisms that can attach to most immersed solid surfaces.

    CREDITS: AMINI ET AL.

    During marine fouling, surfaces are encrusted with scale or biological organisms, which can be expensive to remove. Amini et al. used polymers infused with organic lubricants to prevent mussels from adhering to a submerged surface. The infused polymer presents a relatively soft surface to the mussel. This means that when the mussel probes the surface with its feet, it is less likely to release adhesive threads, which reduces its adhesion. The antifouling properties of the treatment were observed in both a laboratory setting and field testing.

    Science, this issue p. 668

  2. Neuroscience

    The circuits of itching and scratching

    1. Peter Stern

    Itch is a major clinical problem with poor treatment options. In the past few years, much progress has been made in identifying itch-selective molecules and neurons. However, we know very little about the brain circuits underlying itch processing. Mu et al. found that a subpopulation of itch-processing neurons in the spinal cord directly excite other neurons that project to a brain stem structure called the parabrachial nucleus. Inhibition of this spino-parabrachial pathway reduced itching and scratching in mice.

    Science, this issue p. 695

  3. Single-Cell Genomics

    Sequencing each cell of the nematode

    1. Laura M. Zahn

    Single-cell sequencing is challenging owing to the limited biological material available in an individual cell and the high cost of sequencing across multiple cells. Cao et al. developed a two-step combinatorial barcoding method to profile both single-cell and single-nucleus transcriptomes without requiring physical isolation of each cell. The authors profiled almost 50,000 single cells from an individual Caenorhabditis elegans larval stage and were able to identify and recover information from different, even rare, cell types.

    Science, this issue p. 661

  4. Stellar Astrophysics

    Unusual star may be supernova debris

    1. Keith T. Smith

    Type Ia supernovae occur when a white dwarf star is completely destroyed in a thermonuclear explosion. Recently, another class of supernova has been found, dubbed type Iax; these look like type Ia but are much fainter and may be the result of only partial destruction of a white dwarf. In support of this notion, Vennes et al. found a white dwarf star in our Galaxy that is low-mass, is moving quickly, and has an unusual composition. These properties suggest that it could be the predicted leftover remains from a type Iax supernova.

    Science, this issue p. 680

  5. Type 6 Secretion

    Identification of a new injection system

    1. Stella M. Hurtley

    To interact with other cells, bacteria use contractile machines that function similarly to membrane-puncturing bacteriophages. The so-called type 6 secretion system (T6SS) functions from inside a bacterial cell. Böck et al. used modern electron microscopy methods and functional assays to resolve the structure and function of a T6SS in the cellular context. They identified three modules and showed large-scale structural changes upon firing. T6SSs are organized in multibarrel gun-like arrays and may contribute to the survival of bacteria inside their host.

    Science, this issue p. 713

  6. Neurodegeneration

    A new therapeutic target in view?

    1. Orla M. Smith

    The genetics, pathology, and clinical manifestations of neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS) are heterogeneous, which makes the development and testing of candidate therapeutics difficult. Le Pichon et al. identified dual leucine zipper kinase (DLK) as a common regulator of neuronal degeneration in mouse models of ALS and Alzheimer's disease and in postmortem brain tissue from human patients. In several mouse models of neurodegenerative disease, deletion of DLK or treatment with a DLK inhibitor protected neurons and slowed disease progression. Thus, DLK may represent a therapeutic target for a number of neurodegenerative diseases.

    Sci. Transl. Med. 9, eaag0394 (2017).

  7. Pregnancy

    Modeling a pregnancy disorder

    1. Priscilla N. Kelly

    Preeclampsia in pregnancy is dangerous for mother and child.

    PHOTO: BY MIKUMISTOCK/SHUTTERSTOCK

    Preeclampsia, a dangerous pregnancy disorder marked by high blood pressure, can lead to premature birth and be life-threatening to the mother and baby. Research leading to effective treatments has been hampered by a lack of informative animal models. Ho et al. identified ELABELA as a hormone produced by the placenta whose levels are lower in preeclampsia (see the Perspective by Wirka and Quertermous). ELABELA-deficient pregnant mice showed clinical signs of preeclampsia, including high blood pressure and elevated urine protein. A proportion of embryos lacking ELABELA displayed defective heart development, and full-term pups had low birth weights.

    Science, this issue p. 707; see also p. 643

  8. Cancer Therapy

    Treating a tumor to metastasize

    1. Leslie K. Ferrarelli

    The standard treatment for prostate cancer, androgen deprivation therapy, is associated with increased transforming growth factor-β (TGFβ) signaling, which can promote metastasis. Working in mice, Chen et al. found that androgen receptor activation induced a transcriptional repressor of the TGFβ pathway. However, androgen deprivation therapy decreased the levels of this transcriptional repressor, leading to increased TGFβ signaling and prostate tumor metastasis. Thus, the standard treatment for prostate cancer may prevent growth in the primary tumor but could inadvertently promote metastasis.

    Sci. Signal. 10, eaam6826 (2017).

  9. Human Genetics

    Sharing data, protecting privacy

    1. Barbara R. Jasny

    Although data-sharing is crucial for making the best use of genetic data in diagnosing disease, many individuals who might donate data are concerned about privacy. Jagadeesh et al. describe a solution that combines a protocol from modern cryptography with frequency-based clinical genetics used to diagnose causal disease mutations in patients with monogenic disorders. This framework correctly identified the causal gene in cases involving actual patients, while protecting more than 99% of individual participants' most private variants.

    Science, this issue p. 692

  10. Environment

    Collaborative governance

    1. Andrew M. Sugden

    By its nature, environmental governance requires collaboration. However, studies have shown that various types of stakeholders often lack the willingness to deliberate and contribute to jointly negotiated solutions to common environmental problems. Bodin reviews studies and cases that elucidate when, if, and how collaboration can be effective and what kind of environmental problems are most fruitfully addressed in this way. The piece provides general conclusions about the benefits and constraints of collaborative approaches to environmental management and governance and points out that there remain substantial knowledge gaps and key areas where more research is needed.

    Science, this issue p. eaan1114

  11. Developmental Biology

    The makings of the reproductive tract

    1. Beverly A. Purnell

    Every embryo, regardless of its sex, contains both male and female primitive reproductive tracts before sexual differentiation. To establish a sex-specific reproductive system, female embryos need to remove the components of male tracts. The general consensus contends that removal of the male tracts occurs by default, a passive outcome owing to a lack of testis-derived androgens. Working in mice, Zhao et al. discovered that this process instead was actively promoted by the transcription factor COUP-TFII (see the Perspective by Swain). Without the action of this factor, embryos retained male reproductive tracts, independently of androgen action. These findings unveil unexpected mechanisms underlying the sexually dimorphic establishment of reproductive tracts.

    Science, this issue p. 717; see also p. 648

  12. Autoimmunity

    Suppressing Sjögren syndrome

    1. Angela Colmone

    T follicular regulatory (Tfr) cells regulate antibody production in the germinal center. Individuals with the autoimmune disease Sjögren syndrome have increased numbers of circulating Tfr cells. Fonseca et al. found that blood and tissue Tfr cells were phenotypically distinct. Blood Tfr cells did not preferentially suppress humoral responses and had a naïve-like phenotype. These cells were generated during germinal center responses, exiting the tissue to enter the blood. These data explain why the increased number of blood Tfr cells does not correlate with increased suppression potential and suggest that, instead, increased numbers of blood Tfr cells indicate ongoing humoral activity.

    Sci. Immunol. 2, eaan1487 (2017).

  13. Neuroscience

    Faulty remembrance of objects past

    1. Peter Stern

    The primate brain analyzes visual input along the ventral processing stream to extract the identity of an object. The final stage of this stream, the perirhinal cortex, plays a crucial role in object recognition. Tamura et al. systematically biased the judgments of monkeys in an old-new object recognition task by using either optogenetic or electrical stimulation. The monkeys judged an encountered object as familiar when the stimulation site was in a hotspot where memory neurons were clustered. However, at the hotspot's fringe region, where neurons lost selective responses to the learned objects, electrical microstimulation led the monkeys to mistakenly judge an object as never seen before.

    Science, this issue p. 687

  14. Cancer

    Modeling the cancer transcriptome

    1. Priscilla N. Kelly

    Recent initiatives such as The Cancer Genome Atlas have mapped the genome-wide effect of individual genes on tumor growth. By unraveling genomic alterations in tumors, molecular subtypes of cancers have been identified, which is improving patient diagnostics and treatment. Uhlen et al. developed a computer-based modeling approach to examine different cancer types in nearly 8000 patients. They provide an open-access resource for exploring how the expression of specific genes influences patient survival in 17 different types of cancer. More than 900,000 patient survival profiles are available, including for tumors of colon, prostate, lung, and breast origin. This interactive data set can also be used to generate personalized patient models to predict how metabolic changes can influence tumor growth.

    Science, this issue p. eaan2507

  15. Brown Dwarfs

    Beating bands in substellar atmospheres

    1. Keith T. Smith

    Brown dwarfs are objects with masses that are between those of large planets and small stars. They share many features with gas giant planets, particularly conditions in their atmospheres. Apai et al. analyzed how the infrared brightness of three brown dwarfs changes over time. Several perplexing features can be explained if bands of clouds rotating within their atmospheres generate beat patterns. Such bands are seen in optical images of Jupiter but best match infrared images of Neptune. The results shed light on the atmospheric physics of brown dwarfs and gas giant planets around the Sun and other stars.

    Science, this issue p. 683

  16. Molecular Frameworks

    Conjugated covalent networks

    1. Phil Szuromi

    Although graphene and related materials are two-dimensional (2D) fully conjugated networks, similar covalent organic frameworks (COFs) could offer tailored electronic and magnetic properties. Jin et al. synthesized a fully π-conjugated COF through condensation reactions of tetrakis(4-formylphenyl)pyrene and 1,4-phenylenediacetonitrile. The reactions were reversible, which provides the self-healing needed to form a crystalline material of stacked, π-bonded 2D sheets. Chemical oxidation of this semiconductor with iodine greatly enhanced its conductivity, and the radicals formed on the pyrene centers imparted a high spin density and paramagnetism.

    Science, this issue p. 673

  17. Structural Biology

    Methanogenic archaea metabolism

    1. Valda Vinson

    Most of the methane on Earth is produced by the metabolism of methanogenic archaea. The final step involves a reaction between methyl-coenzyme M and coenzyme B to give CoM-S-S-CoB and methane. Wagner et al. report a high-resolution structure of the methanogenic heterodisulfide reductase (HdtABC)-[NiFe]-hydrogenase, the enzyme that reduces the disulfide and couples this to the reduction of ferredoxin in an energy-conserving process known as flavin-based electron bifurcation (FBEB) (see the Perspective by Dobbek). The reduced ferredoxin, in turn, drives the first step of methanogenesis. The structure shows how two noncubane [4Fe-4S] clusters perform disulfide cleavage and gives insight into the mechanism of FBEB.

    Science, this issue p. 699; see also p. 642

  18. Device Technology

    A spin-valve solar cell

    1. Phil Szuromi

    Electronic spin currents can be measured with a spin valve—a device that injects charge carriers from one ferromagnetic electrode to another through a semiconductor layer. Some organic semiconductors can have long spin-carrier lifetimes and can also generate charge carriers through the photovoltaic effect. Sun et al. fabricated a spin valve based on C60 and showed that the spin current could be modulated by the photocurrent. At certain light intensities, the sign of the photocurrent could be changed using an applied magnetic field, an effect that could potentially be harnessed for sensing applications.

    Science, this issue p. 677

  19. Cytoskeleton

    Making the right catch

    1. Stella M. Hurtley

    Tension reveals cryptic vinculin-binding sites on α-catenin and talin at cadherin-based cell-cell and integrin-based cell-matrix adhesions, respectively. The enrichment of vinculin at cellular adhesions is thus an indicator of load-induced reinforcement of the cytoskeletal linkage. Huang et al. used a single-molecule optical trap assay to measure the binding lifetimes of vinculin to single actin filaments under load. The vinculin-F-actin interaction formed a directional catch bond—one that is very weak at low force but that greatly increases in lifetime with increasing force. This explains vinculin's role as a reinforcing linker at both cell-cell and cell-matrix adhesions.

    Science, this issue p. 703