This Week in Science

Science  28 Feb 2014:
Vol. 343, Issue 6174, pp. 947
  1. Deciphering Language

    CREDIT: XAVIER STUDIO

    Consonants and vowels represent basic building blocks of human language. How their characteristics are extracted from acoustic speech input is not well understood. Directly recording from the superior temporal gyrus of patients as part of their clinical evaluation for epilepsy surgery, Mesgarani et al. (p. 1006, published online 30 January; see the Perspective by Grodzinsky and Nelken) investigated neural responses while the subjects listened to continuous speech. The findings reveal how both vowels and consonants of different phonetic categories are encoded.

  2. Ordering Cosmic Rays

    Earth and other planets are constantly bombarded by cosmic rays (charged particles from the cosmos). The flux of very-high-energy cosmic rays varies according to where we look in the sky. Schwadron et al. (p. 988, published online 13 February) show that recent measurements of the local interstellar parameters by NASA's Interstellar Boundary Explorer satellite are consistent with observed cosmic ray anisotropies at tera–electron volt energies, implying that local interstellar conditions play a role in ordering very-high-energy cosmic rays in our cosmic vicinity.

  3. Polymer Film Behavior

    An ongoing debate in the understanding of the behavior of thin-film glassy polymers is whether there is nanoconfinement of large molecules or enhanced mobility near a free surface. Chai et al. (p. 994; see the Perspective by Chen et al.) prepared polymer films with a sharp step in the profile by depositing broken film fragments onto a uniform underlay. Atomic force microscopy revealed changes to the overall film profile with time at various temperatures. A transition was observed from localized motions to relaxation of the entire film at a temperature close to that of the bulk glass transition temperature.

  4. Once in a While

    Many regions at the edge of the Antarctic Ice Sheet have rapidly increased the rates at which they are sliding into the sea and thinning, raising concerns that global warming might cause the sudden collapse of some sections. Johnson et al. (p. 999, published online 20 February) present data from Pine Island Glacier, which has been thinning and retreating rapidly over the past two decades. The glacier experienced another rapid thinning around 8000 years ago, which occurred about as quickly as is happening now, and which lasted for 25 to 100 years.

  5. A Boost for Bismuth Vanadate

    CREDIT: KIM AND CHOI

    In theory, given its light-absorption spectrum, bismuth vanadate should be an effective photoanode for solar water-splitting. However, in prior studies, few of the “holes” generated upon photoexcitation have persisted long enough to strip electrons from water. Kim and Choi (p. 990, published online 13 February) now show that the use of a hydrophobic vanadium source in the semiconductor's synthesis results in a high-surface-area morphology with substantially enhanced hole lifetimes. Deposition of two successive catalyst layers enhanced the proportion of holes that reacted with water at the surface, thereby raising the efficiency of the oxygen evolution reaction.

  6. Oncogenic Suspect Exposed

    It can be difficult logistically to study the genomics of rare variants of common cancers. Nevertheless, Honeyman et al. (p. 1010) studied fibrolamellar hepatocellular carcinoma (FL-HCC), a rare and poorly understood liver tumor that affects adolescents and young adults and for which there is no effective treatment. FL-HCCs from 15 patients all expressed a chimeric RNA transcript and protein containing sequences from a molecular chaperone fused in frame with sequences from the catalytic domain of protein kinase A. The chimeric protein retained kinase activity in vitro. Such recurrent gene fusions in cancer may signal a role in pathogenesis and provide an opportunity for therapeutic intervention.

  7. Allergen Affinity

    Allergic responses are initiated by interaction of allergens with immunoglobulin E (IgE) antibodies, which in turn bind to IgE receptors on the surface of mast cells. Suzuki et al. (p. 1021, published online 6 February; see the Perspective by Daëron) explored how the signaling properties of such receptor complexes differ, depending on the affinity of the IgE antibody for the antigen leading to different allergic responses.

  8. Know Your Enemy

    Fire ants accidentally introduced to North America from their native range in Argentina have been hugely invasive and difficult to eradicate and caused both environmental and economic damage. Recently, another accidentally introduced Argentine ant, the tawny crazy ant, appears to be displacing the fire ants. How? LeBrun et al. (p. 1014, published online 13 February; see the Perspective by Kaspari and Weiser) show that tawny crazy ants have a chemical and behavioral response to the toxic bite of fire ants that vastly reduces their mortality during confrontations and that allows the tawny crazy ants to outcompete their rivals.

  9. Neandertal Shadows in Us

    Non-African modern humans carry a remnant of Neandertal DNA from interbreeding events that have been postulated to have occurred as humans migrated out of Africa. While the total amount of Neandertal sequence is estimated to be less than 3% of the modern genome, the specific retained sequences vary among individuals. Analyzing the genomes of more than 600 Europeans and East Asians, Vernot and Akey (p. 1017, published online 29 January) identified Neandertal sequences within modern humans that taken together span approximately 20% of the Neandertal genome. Some Neandertal-derived sequences appear to be under positive selection in humans, including several genes associated with skin phenotypes.

  10. Synthesis in the Spotlight

    Most organic molecules absorb little or no visible light. Consequently, conventional organic photochemistry has relied on excitation in the ultraviolet regime, with the drawback that the high energy involved can lead to undesirable by-products. Over the past several years, an alternative strategy has emerged involving the visible excitation of metal complexes (primarily ruthenium and iridium) that can then engage in electron or energy transfer with organic compounds. The ensuing reactivity patterns complement thermally accessible outcomes without introducing detrimental quantities of excess energy. Schultz and Yoon (10.1126/science.1239176) review developments in this rapidly advancing area of photoredox catalysis.

  11. ESCRT Your Wound Away

    The ESCRT (endosomal sorting complex required for transport) protein complex plays a role in budding into multivesicular bodies, in cytokinesis, and in HIV budding. Now, Jimenez et al. (10.1126/science.1247136, published online 30 January) propose a role for ESCRT proteins in wound repair at the plasma membrane. In vivo imaging, modeling, and electron microscopy were used to reveal how the ESCRTs participate in a rapid energy-independent, calcium-dependent, membrane-shedding process at the plasma membrane that reseals small wounds caused by toxins or laser treatment.

  12. Metabolic Heterogeneity

    We commonly think of genetic or epigenetic sources of variation in cells and individuals. However, biochemical regulatory pathways can potentially also exist in multiple stable states and confer variable phenotypes on cells in a population. Van Heerden et al. (10.1126/science.1245114, published online 16 January) demonstrate such a phenomenon in yeast cells. Two distinct types of cell were observed that differed in the state of glycolysis, the central pathway in energy metabolism for these cells. This allowed some members of a population of cells to survive changes in glucose concentrations, whereas most cells did not.

  13. Repeat Silencing

    Fragile X syndrome, a genetic cause of many cases of autism and mental retardation, involves expansion of a trinucleotide repeat in the fragile X mental retardation 1 (FMR1) gene. Working with human embryonic stem cells, Colak et al. (p. 1002) found that the expanded repeat region was transcribed into the untranslated region of FMR1 messenger RNA, which then bound to the DNA repeat region in the FMR1 gene, inactivating the gene. The findings explain how the trinucleotide repeat expansion causes RNA-directed gene silencing during development in fragile X syndrome.

  14. A Different Route

    CREDIT: XU ET AL.

    The plant hormone auxin regulates a variety of developmental processes and responses to environmental inputs, often via changes in gene transcription. Xu et al. (p. 1025) analyzed a signaling pathway involving ABP1 (auxin-binding protein 1) that affects the cytoskeleton and endocytosis in Arabidopsis without changing gene transcription. Instead, ABP1 functions at the cell surface to bind auxin and a family of membrane kinases, thereby activating intracellular guanosine triphosphatases to initiate important developmental changes in cell shape.

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