This Week in Science

Science  16 Jan 2015:
Vol. 347, Issue 6219, pp. 244
  1. Genetic Medicine

    What happens when titins are trimmed?

    1. Katrina L. Kelner

    Colorized scanning electron micrograph of cardiac muscle tissue

    CREDIT: ASA THORESEN/SCIENCE SOURCE

    The most common form of heart failure, dilated cardiomyopathy, is often caused by mutations in a mammoth heart protein, called titin. Roberts et al. asked which titin mutations cause disease and why. They sequenced the titin gene in over 5200 people—some healthy and some with heart failure—and measured the corresponding RNA and protein levels. Many of the mutations truncated titin, causing short nonfunctional versions of the RNA or protein. These defects produced cardiomyopathy when they occurred closer to the protein's carboxyl terminus and in abundantly transcribed exons. The titin-truncating mutations that occurred in the healthy people did not have these characteristics and were usually benign.

    Sci. Transl. Med. 7, 270ra6 (2015).

  2. Norovirus

    Turning viral persistence on and off

    1. Kristen L. Mueller

    Norovirus causes >90% of the world's gastroenteritis. Norovirus can establish persistent infections, which may contribute to its spread. How does norovirus establish itself as a permanentw resident of the gut and how can such persistent infections be cured (see the Perspective by Wilks and Golovkina)? Baldridge et al. studied mice persistently infected with norovirus and found that viral persistence required the gut microbiota: resident bacteria in the gastrointestinal tract. Antibiotics prevented persistent mouse norovirus infection in a way that depended on the secreted antiviral protein interferon λ (IFN-λ). Nice et al. report that IFN-λ can cure mice persistently infected with norovirus, independent of the adaptive immune system.

    Science, this issue p. 266, p. 269; see also p. 233

  3. Asian Archeology

    Colonizing the roof of the world

    1. Andrew M. Sugden

    Humans only settled permanently on the Tibetan plateau about 3600 years ago. Chen et al. examined archaeological crop remains unearthed in northeastern Tibet, which elucidate the timing of agricultural settlement. Although much earlier traces of humans in Tibet have been dated to 20,000 years ago, year-round presence at the highest altitudes appears to have been impossible until the advent of suitable crops, such as barley. Surprisingly, these prehistoric farming communities expanded onto the plateau at the same time as climate was cooling.

    Science, this issue p. 248

  4. Telomeres in Cancer

    Cancer's alternative means to an end

    1. Paula A. Kiberstis

    ALT-positive cells: DNA white; microtubules red.

    CREDIT: NEIL J. GANEM AND RACHEL L. FLYNN

    To stay alive and proliferating, tumor cells must maintain their telomeres: the DNA sequences at the ends of chromosomes. The majority accomplish this by activating the enzyme telomerase. However, certain tumor types favor a different mechanism called alternative lengthening of telomeres (ALT), which involves DNA recombination. Flynn et al. delineated the molecular events that occur at the telomeres of ALT-proficient tumor cells by studying the function of a protein that is altered by mutation in these tumors. The analysis revealed a specific protein kinase that is essential for ALT, which could in principle be targeted to halt tumor growth.

    Science, this issue p. 273

  5. Animal Physiology

    Geese need to hug the land to fly high

    1. Sacha Vignieri

    Animal migrations provide numerous examples of astonishing feats. Impressive even among these is the migration of bar-headed geese across the Himalayan Mountains, which reach heights of thousands of meters. Bishop et al. remotely monitored birds' heart rates, movement, and body temperature during migration. The geese “hug” the landforms, taking advantage of drafting and wind patterns. This unexpected strategy conserves energy, even though it means the geese repeatedly lose, and must then regain, altitude.

    Science, this issue p. 250

  6. Paleoceanography

    A new tilt on predicting future ENSO variability

    1. H. Jesse Smith

    A new finding should improve the ability of climate models to predict the behavior of the El Niño–Southern Oscillation (ENSO) in a warmer future. Ford et al. looked at the distribution of surface and subsurface temperatures in the eastern and western equatorial Pacific 19,000 years ago and between 3000 and 6000 years ago. Temperatures fluctuated over a greater range during the older period. ENSO thus depended more on the tilt of the equatorial Pacific thermocline than on the east-to-west temperature gradient, as previously thought.

    Science, this issue p. 255

  7. Women in Science

    Women's participation and attitudes to talent

    1. Pamela J. Hines

    Some scientific disciplines have lower percentages of women in academia than others. Leslie et al. hypothesized that general attitudes about the discipline would reflect the representation of women in those fields (see the Perspective by Penner). Surveys revealed that some fields are believed to require attributes such as brilliance and genius, whereas other fields are believed to require more empathy or hard work. In fields where people thought that raw talent was required, academic departments had lower percentages of women.

    Science, this issue p. 262; see also p. 234

  8. Applied Physics

    Tunnel through and emit coherently

    1. Ian S. Osborne

    The generation of coherent light (lasers and masers) forms the basis of a large optics industry. Liu et al. demonstrate a type of laser that is driven by the tunneling of single electrons in semiconductor double-quantum dots. Distinct from other existing semiconductor lasers, the emission mechanism is driven by tunneling of single charges between discrete energy levels that are electrically tunable. The ability to tune the levels by single-electron charging would allow their laser (or maser) to be turned on and off rapidly.

    Science, this issue p. 285

  9. Topological Matter

    Nailing down the topology of a semimetal

    1. Jelena Stajic

    Topological insulators are exotic materials that have a conducting surface state that can withstand certain types of material imperfection. Theoreticians have predicted a different kind of surface state in related three-dimensional topological Dirac semimetals, which do not have an energy gap in the band structure of the bulk. Xu et al. used photoemission spectroscopy to map out the band structure of the material Na3Bi and detected the predicted surface state. Their results may lead to further insights into the physics of topological matter.

    Science, this issue p. 294

  10. Cancer

    Visualizing active signaling in cancer

    1. Jason D. Berndt

    The receptor tyrosine kinase epidermal growth factor receptor (EGFR) can be aberrantly activated in diverse cancers. The ability to identify tumors with increased EGFR activity should improve the personalization of therapies. However, genetic analysis fails to identify such tumors if the increase in activity is not due to mutations in EGFR-encoding genes. Smith et al. developed an assay to detect the interaction between EGFR and the adaptor protein GRB2 as a marker for EGFR signaling. This assay detected active EGFR signaling in tumors with normal EGFR, which would have been undetectable by genetic analysis. Moreover, using this assay, the researchers could predict therapeutic response to EGFR inhibitors in both mice and humans.

    Sci. Signal. 8, ra4 (2015).

  11. T Cell Vaccines

    For vaccines, CD4+ T cells can spell trouble

    1. Kristen L. Mueller

    The ideal vaccine elicits immune memory—either antibodies or memory T cells—to protect the host from subsequent infections. T cell–mediated immunity requires both helper CD4+ T cells and cytotoxic CD8+ T cells to kill virus-infected cells. But what happens when a vaccine only elicits CD4+ memory T cells? Penaloza-MacMaster et al. probed this question by giving mice a vaccine that generated only memory CD4+ T cells against lymphocytic choriomeningitis virus (LCMV). Instead of protecting mice against chronic LCMV, vaccinated mice developed massive inflammation and died. Virus-specific CD8+ T cells or antibodies protected mice from the pathology. These results may have implications for vaccines against chronic viruses such as HIV.

    Science, this issue p. 278

  12. Superconductivity

    Finding order in exotic superconductors

    1. Jelena Stajic

    Physicists can coax some copper-oxide compounds into becoming superconducting by chemically adding extra charge carriers: holes or electrons. Concentrating on hole-doped materials, researchers have found a host of different phases in the neighborhood of or co-existing with superconductivity. One such phase is a modulation in charge density [a charge density wave (CDW)] that appears to be ubiquitous in hole-doped families. Da Silva Neto et al. now show that a similar phase exists in the electron-doped material Nd2-xCexCuO4. As they cooled the material, the authors first detected the CDW at temperatures considerably higher than in the hole-doped copper-oxides.

    Science, this issue p. 282

  13. Quantum Gases

    Nailing down graphene's topology

    1. Jelena Stajic

    An electron traveling along a closed path in the momentum space of the graphene crystal lattice may not end up exactly the way it started. If its path happens to include one of the special points in momentum space, it will acquire a phase shift. Physicists can detect the signatures of this process by studying the transport properties of graphene. Duca et al. used interferometry to directly measure this so-called Berry flux in a hexagonal optical lattice, where intersecting laser beams simulate the environment that electrons experience in graphene (see the Perspective by Lamacraft). The high-precision technique may be useful in characterizing other topological structures.

    Science, this issue p. 288; see also p. 232

  14. Interfacial Solvents

    Structured solvents near nanoparticles

    1. Phil Szuromi

    The physical properties and reactivity of nanoparticles in solution depend not only on their surface termination but also on changes in solvent ordering caused by the presence of the interface created by the nanoparticle. Zobel et al. used x-ray scattering to study solvent ordering for a variety of metal and metal-oxide nanoparticles in a variety of polar solvents (alcohols) and a nonpolar solvent (n-hexane). They observed layers of enhanced ordering near the nanoparticle surface relative to the bulk solvent. These trends were largely independent of surface chemistry, such as changing the surface groups from hydroxyls to carboxylates.

    Science, this issue p. 292

  15. Geology

    Current impacts of the first geological map made

    1. Julia Fahrenkamp-Uppenbrink

    In the late 18th century, William Smith, an English canal surveyor, noticed that two canal branches in adjacent valleys passed through the same sequence of rock strata and that each bed of rock contained a distinctive set of fossils. These insights were central to his geological map of England, Wales, and part of Scotland, published in 1815. The map was the first of its kind, depicting stratigraphic order from oldest rocks to youngest in a way that gives an impression of three dimensions. In a Perspective, Sharpe explains how the principles used to create the map remain in use today, for example in the identification of fossil fuel deposits and sites rich in mineral resources.

    Science, this issue p. 230

  16. Marine Conservation

    Marine animals are disappearing, too

    1. Sacha Vignieri

    The loss of animal species in terrestrial environments has been well documented and is continuing. Loss of species in marine environments has been slower than in terrestrial systems, but appears to be increasing rapidly. McCauley et al. review the recent patterns of species decline and loss in marine environments. Though they note many worrying declines, they also highlight approaches that might allow us to prevent the type of massive defaunation that has occurred on land.

    Science, this issue 10.1126/science.1255641

  17. Paleoecology

    Fluctuations revealed in fossil forests

    1. Andrew M. Sugden

    The reconstruction of past vegetation unlocks the door to understanding ecological changes associated with climatic change. But it is also difficult. Dunn et al. developed a method for assessing changes in vegetation openness based on epidermal cell morphology from conserved plant tissue. Applying this method to fossil assemblages from Patagonia, they show how vegetation structure changed over the Cenozoic era (49 to 11 million years ago). These changes map onto the known climate changes over this period and can also be used to track how the evolution of herbivorous mammals responded to vegetation structure.

    Science, this issue p. 258