This Week in Science

Science  11 Sep 2015:
Vol. 349, Issue 6253, pp. 1178
  1. Neuroscience

    How crickets communicate by sound

    1. Philip Yeagle

    Female crickets need only five neurons to recognize male songs

    CREDIT: © LIFE ON WHITE / ALAMY STOCK PHOTO

    Sound patterns present a computational challenge in all animals that communicate by sound. Schöneich unraveled the processing of male calling songs by female crickets. A local network of only five neurons in the brains of the females forms an auditory feature detector circuit, with a response tuning that matches the selectivity of the female behavioral responses to the calls.

    Sci. Adv. 10.1126/ sciadv.1500325 (2015).

  2. Critical Phenomena

    Vortices in a superconducting egg crate

    1. Jelena Stajic

    Near equilibrium phase transitions, physical systems that bear no resemblance to one another can behave in a very similar way. For example, thermodynamic functions follow the same scaling behavior in a magnetic transition as in the seemingly unrelated gas-liquid transition. Does such universality exist in nonequilibrium phase transitions? Poccia et al. fabricated a square array of superconducting islands on a metallic surface. They applied a magnetic field, which caused vortices to form in between the islands, and induced a transition from a state in which vortices were stuck to their positions to one where they were able to move. They observed the same scaling behavior that applies to some equilibrium transitions.

    Three-dimensional image of the dynamic resistance as a function of the driving current and the applied magnetic field

    CREDIT; POCCIA ET AL,

    Science, this issue p. 1202

  3. Structural Biology

    Structure and function of the spliceosome

    1. Valda Vinson

    When RNA is transcribed from DNA in the eukaryotic cell nucleus, the initial transcript includes noncoding introns that must be spliced out. This splicing is done by a complex macromolecular machine, the spliceosome, which comprises five small nuclear RNAs and more than 100 associated proteins. Now, two papers reveal insights into the structure and function of the yeast spliceosome. Yan et al. describe a high-resolution structure determined by electron microscopy of a spliceosome complex comprising four RNAs and 37 proteins. Hang et al. focus on the catalytic site and show how protein components anchor the transcribed RNA and allow sufficient flexibility to deliver RNA components involved in catalyzing the splicing reaction.

    Science, this issue pp. 1182 and 1191

  4. Plant Science

    Transplanting the wisdom of the mayapple

    1. Pamela J. Hines

    Etoposide, a topoisomerase inhibitor, is used to treat various cancers. However, etoposide isn't that easy to get. Its precursor comes from the very slow-growing mayapple plant. Lau and Sattely used bioinformatics, heterologous enzyme expression, and kinetic characterization, to work out the pathway that makes the precursor in mayapple (see the Perspective by O'Connor). They then successfully transplanted the full biosynthetic pathway into tobacco plants.

    Science, this issue p. 1224; see also p. 1167

  5. Global Carbon Cycle

    Uptake uptick

    1. H. Jesse Smith

    Has global warming slowed the uptake of atmospheric CO2 by the Southern Ocean? Landschützer et al. say no (see the Perspective by Fletcher). Previous work suggested that the strength of the Southern Ocean carbon sink fell during the 1990s. This raised concerns that such a decline would exacerbate the rise of atmospheric CO2 and thereby increase global surface air temperatures and ocean acidity. The newer data show that the Southern Ocean carbon sink strengthened again over the past decade, which illustrates the dynamic nature of the process and alleviates some of the anxiety about its earlier weakening trend.

    Science, this issue p. 1221; see also p. 1165

  6. Electrochemistry

    Improving cobalt catalysts

    1. Jake Yeston

    Tethering molecular catalysts together is a tried and trusted method for making them easier to purify and reuse. Lin et al. now show that the assembly of a covalent organic framework (COF) structure can also improve fundamental catalytic performance. They used cobalt porphyrin complexes as building blocks for a COF. The resulting material showed greatly enhanced activity for the aqueous electrochemical reduction of CO2 to CO.

    Science, this issue p. 1208

  7. Neuronal Identity

    Changing properties of interneurons

    1. Peter Stern

    Neuronal identity is determined early during development. It is assumed that once a neuron has adopted its identity, this remains stable throughout life. However, Dehorter et al. investigated the mechanisms controlling the specification of fast-spiking interneurons. They found that the transcription factor Er81 is crucial for the normal specification of these cells by regulating the expression of a potassium channel subunit.

    Science, this issue p. 1216

  8. Antiviral Immunity

    Viruses pack antiviral mediators

    1. Kristen L. Mueller

    Viruses often hijack host proteins for their own use, turning host cells into virion-spewing machines. However, Bridgeman et al. and Gentili et al. now report a sneaky way that the host can fight back (see the Perspective by Schoggins). Host cells that expressed the enzyme cGAS, an innate immune receptor that senses cytoplasmic DNA, packaged the cGAS-generated second messenger cGAMP into virions. Virions could then transfer cGAMP to neighboring cells, triggering an antiviral gene program in these newly infected cells. Such transfer of an antiviral mediator may help to speed up the immune response to put the brakes on viral spread.

    Science, this issue pp. 1228 and 1232; see also p. 1166

  9. Cancer

    Shutting off cancer's motor

    1. Yevgeniya Nusinovich

    Glioblastoma is a difficult-to-treat common and aggressive brain tumor. Two mechanisms that contribute to its lethality are proliferation of the tumor cells and their invasion into normal brain tissue. Although these two processes are usually believed to be independent, Venere et al. show that a molecular motor, KIF11, plays a role in both. Inhibiting KIF11 with a small molecule blocked the proliferation and invasion of glioblastoma cells and prolonged survival in mouse models of the disease. These findings, together with the availability of a KIF11 inhibitor that is safe for human use, suggest KIF11 as a viable therapeutic target for treating glioblastoma.

    Sci. Transl. Med. 7, 304ra143 (2015).

  10. Human Genomics

    Duplications and deletions in the human genome

    1. Laura M. Zahn

    Duplications and deletions can lead to variation in copy number for genes and genomic loci among humans. Such variants can reveal evolutionary patterns and have implications for human health. Sudmant et al. examined copy-number variation across 236 individual genomes from 125 human populations. Deletions were under more selection, whereas duplications showed more population-specific structure. Interestingly, Oceanic populations retain large duplications postulated to have originated in an ancient Denisovan lineage.

    Science, this issue 10.1126/science.aab3761

  11. Mesoscopic Physics

    Making and manipulating a weak-link qubit

    1. Jelena Stajic

    In superconductors, single particles cannot have energies smaller than the superconducting gap. Yet when two superconductors are separated by a thin nonsuperconducting bridge (the “weak link”), quasi-particles can occupy states that are inside the gap, the so-called Andreev bound states (ABSs). Janvier et al. fabricated such a structure out of superconducting aluminum and manipulated the occupation of a pair of ABSs. They observed oscillations in population between two of the energy levels, forming a type of qubit, which they dubbed the Andreev qubit. The results may lead to applications in quantum information processing.

    Science, this issue p. 1199

  12. Geophysics

    Faults well oriented for failure

    1. Brent Grocholski

    A deck of cards will remain motionless while pressed on from above, but easily separates when sheared. Similarly, the ease by which geological faults rupture depends on the geometry of the fault relative to the size and direction of stress. Hardebeck finds that faults are well oriented for failure in subduction zones worldwide, suggesting a low-stress environment (see the Perspective by Bürgmann). Subduction zone faults unleash powerful earthquakes. These estimates on the state of stress constrain potential generation mechanisms of destructive subduction zone earthquakes.

    Science, this issue p. 1213; see also p. 1162

  13. Chromosomes

    A misstep in the chromosomes' dance

    1. Guy Riddihough

    The chromosomes of most cancer cells are unstable, suffering breaks and rearrangements. These aberrations perturb normal gene-regulatory programs and contribute to cancer progression. Tanno et al. studied several human cell lines that show chromosome instability. Homologous chromosomes did not pair very well with each other during cell division. These chromosomes had lost a specific chromatin covalent modification, methylation of histone H3 lysine 9, and/or the protein “glue” cohesin at the chromosomes' centromeres. Either of these losses interfered with the binding of the shugoshin 1 protein, which is required for proper chromosome pairing and segregation.

    Science, this issue p. 1237

  14. Cancer

    RNF43 halts Wnt at the nucleus

    1. Leslie K. Ferrarelli

    Wnt signaling, which triggers the transcriptional activity of β-catenin, is critical during development and is often reactivated in cancer. Loregger et al. found that RNF43 inhibited Wnt–β-catenin signaling by sequestering TCF4, a β-catenin partner and transcription factor, at the nuclear membrane. Wnt signaling was increased in frog embryos that expressed forms of RNF43 with mutations such as those found in human gastrointestinal tumors. Furthermore, coexpression of wild-type RNF43 suppressed Wnt signaling even in cells with a constitutively active mutant of β-catenin.

    Sci. Signal. 8, ra90 (2015).

  15. Evolution

    Symbioses between single-celled organisms

    1. Julia Fahrenkamp-Uppenbrink

    Examples abound of long-term mutually beneficial relationships between microorganisms and plants or animals. In contrast, only a few examples of such symbioses between unicellular partners are known. In a Perspective, Zehr highlights recent reports of unicellular symbioses in marine and fresh-water systems. In both cases, the cyanobacterial partner in the symbiosis has a much reduced genome and must thus always carry their symbiont. These systems resemble organelle evolution and may help to understand the evolutionary events that led to organelle formation in eukaryotic cells.

    Science, this issue p. 1163

  16. Quantum Mechanics

    Interfering with time

    1. Ian S. Osborne

    The interference pattern arising from light or particles passing through a double slit is a simple experiment that belies the subtleties of interpretation when attempting to describe and understand the effect. For example, determining “which path” the light or particles travel can result in the interference pattern disappearing. Margalit et al. present a new take on interferometry using time (see the Perspective by Arndt and Brand). A clock—i.e., the internal state of a cold atom condensate—was coherently split and brought back together to interfere. Making one-half of the clock tick at a different rate resulted in a change in the interference pattern, possibly as a consequence of the time being a “which path” witness.

    Science, this issue p. 1205; see also p. 1168

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