This Week in Science

Science  29 Aug 2014:
Vol. 345, Issue 6200, pp. 1016
  1. Conservation Economics

    Cost-effective conservation on private land

    1. Andrew M. Sugden

    A Brazilian opossum in the Atlantic Forest


    How affordable is biodiversity conservation in a fragmented landscape? Banks-Leite et al. asked this question for the biodiversity hotspot of the Brazilian Atlantic Forest. An annual investment of <10% of Brazil's agricultural subsidies could support effective ecological restoration on private lands. This would increase biodiversity in set-aside land to the same level observed in protected areas. The cost-effectiveness of this scheme suggests a path forward for conservation strategies in other similarly mixed landscapes, too.

    Science, this issue p. 1041

  2. Human Microbiota

    Signature microbes follow you from house to house

    1. Caroline Ash

    Householders share more than habitation; they also share inhabitants. In a diverse sample of U.S. homes, Lax et al. found that people and animals sharing homes shared their microbial communities (microbiota) too, probably because of skin shedding and hand and foot contamination. When families moved, their microbiological “aura” followed. If one person left the home even for a few days, their contribution to the microbiome diminished. These findings have implications not only for household identity and composition, but also for indicators of the members' health and well-being.

    Science, this issue p. 1048

  3. Stellar Distances

    Distance score settled for Seven Sisters

    1. Margaret M. Moerchen

    Most of us have seen the Pleiades star cluster in the night sky, one of the few groups of physically related stars that are separately visible to the naked eye. In spite of its proximity to us, its distance has been disputed. Melis et al. settle the controversy with astrometric measurements from radio interferometry that reveal a distance of 136.2 parsecs (see the Perspective by Girardi). Other methods yielded similar values, but the trusted astrometry satellite Hipparcos measured only 120.2 parsecs. The new result alleviates the concern that astronomers would need to adjust their stellar evolution models to align with the Hipparcos distance.

    Science, this issue p. 1029; see also p. 1001

  4. Earthquake Dynamics

    Strong yet creeping megathrust faults

    1. Brent Grocholski

    Powerful faults in subduction zones, called “megathrust faults,” produce the largest earthquakes on Earth. Gao and Wang use heat flow data to show that when the faults subduct jagged sea floor, they generate tamer earthquakes than do faults that subduct smooth sea floor. The rugged sea floor brings irregularities into the fault that cause it to deform slowly over time, which results in a comparatively higher fault strength and lower seismicity. The finding has a direct impact on assessing regional earthquake and tsunami hazards.

    Science, this issue p. 1038

  5. Evolutionary Genomics

    Rabbits softly swept to domestication

    1. Laura M. Zahn

    When people domesticate animals, they select for tameness and tolerance of humans. What else do they look for? To identify the selective pressures that led to rabbit domestication, Carneiro et al. sequenced a domestic rabbit genome and compared it to that of its wild brethren (see the Perspective by Lohmueller). Domestication did not involve a single gene changing, but rather many gene alleles changing in frequency between tame and domestic rabbits, known as a soft selective sweep. Many of these alleles have changes that may affect brain development, supporting the idea that tameness involves changes at multiple loci.

    Science, this issue p. 1074; see also p. 1000

  6. Immunology

    Cutting out a kinase for T cell survival

    1. John F. Foley

    Sufficient numbers of T cells are required in the body to fight pathogens. To survive, T cells need to receive signals through both the T cell receptor and the interleukin-7 receptor. However, constant interleukin-7 receptor activation causes T cells to die, so the T cell receptor intermittently blocks the activity of the interleukin-7 receptor. Signaling through the interleukin-7 receptor requires the kinase Jak1. Katz et al. found that T cells contained very little Jak1 protein and that it was unstable. When researchers activated the T cell receptor, they generated increased amounts of microRNA. The microRNA prevented the T cells from producing new Jak1 protein and interfered with the ability of the interleukin-7 receptor to signal.

    Sci. Signal. 7, ra83 (2014).

  7. Cell Migration in 3D

    Push me, pull you, that's the way to move

    1. Stella M. Hurtley

    Primary cells, derived directly from human tissue, exhibit different behaviors in shape and signaling within three-dimensional (3D) or 2D spaces. When the pressure within the cell increases, cells display limb-like bumps, which they use to move through their 3D environment. Petrie et al. now show that when the complex of actin and myosin contracts, it controls the pressure within cells and therefore the shape of those protruding structures (see the Perspective by DeSimone and Horwitz). The authors measured internal pressures in migrating mammalian cells. In the 3D matrix, those cells have higher pressure that differs between the front and back of the cell, which creates a piston effect.

    Science, this issue p. 1062; see also p. 1002

  8. Pain

    An enzyme offers a new path to pain control

    1. Katrina L. Kelner
    Aldehyde levels influence pain response ILLUSTRATION: V. ALTOUNIAN/SCIENCE

    Many people suffer from uncontrolled pain, and new drugs are needed. Zambelli et al. build on the fact that aldehydes—molecules that occur naturally in the body—can cause pain directly. Specifically, an enzyme that degrades aldehydes is a key regulator of pain. Mice with genetically inactive versions of the enzyme are extra sensitive to a painful stimulus. Conversely, revving up the enzyme with a drug reverses this effect. New drugs that modulate aldehyde levels could benefit patients, possibly without risk of addiction. These results may also explain the greater pain sensitivity in East Asians, many of whom carry a relevant mutation.

    Sci. Transl. Med. 6, 251ra119 (2014).

  9. Circumstellar Disks

    A cosmic dust storm that came and went

    1. Margaret M. Moerchen

    Unseen planets may still kick up a lot of dust. While rocky exoplanets finish their growth, destructive collisions among them throw off clouds of fine debris that shine bright in the infrared. Meng et al. monitored the star ID8 with the Spitzer Space Telescope and observed a rapid thermal flareup and fadeout within only 2 years. This modulation is consistent with recent collisions among its orbiting protoplanets. Such dynamic variations in presumed planet-forming systems encourage more studies that exploit the real-time changes.

    Science, this issue p. 1032

  10. Superfluidity

    Making a superfluid lithium mixture

    1. Jelena Stajic

    At some of the coldest temperatures achieved in the laboratory, researchers can coax dilute gases of atoms into becoming a superfluid, with the whole gas behaving as one entity. Bosonic atoms, which like to congregate in one state, achieve this willingly. Fermions, which effectively repel each other, require more persuasion. Ferrier-Barbut et al. made a superfluid mixture of two gases, one made up of bosons and one of fermions. They used two isotopes of lithium, fermionic 6Li and bosonic 7Li. When they made the mixture oscillate, the two components took turns feeding energy into each other.

    Science, this issue p. 1035

  11. Glass Structure

    Catching changing boron coordination

    1. Brent Grocholski

    Laboratory glassware and kitchen cookware alike are made of glass that contains different cations, including boron, sodium, and aluminum. Properties of glass depend on the number and location of oxygen atoms surrounding each cation. Edwards et al. combine nuclear magnetic resonance measurements with theoretical calculations to understand structural transformations in borosilicate glass (see the Perspective by Youngman). Boron atoms in planar threefold coordination move out of plane with increasing pressure to form trigonal pyramids. Identification of this type of transition state connects structural evolution with stress-induced processes in amorphous materials. In borosilicate glass, the transition leads to the formation of tetrahedral fourfold-coordinated boron that tunes glass properties for use in numerous applications.

    Science, this issue p. 1027; see also p. 998

  12. Human Genetics

    Arctic genetics comes in from the cold

    1. Laura M. Zahn

    Despite a well-characterized archaeological record, the genetics of the people who inhabit the Arctic have been unexplored. Raghavan et al. sequenced ancient and modern genomes of individuals from the North American Arctic (see the Perspective by Park). Analyses of these genomes indicate that the Arctic was colonized 6000 years ago by a migration separate from the one that gave rise to other Native American populations. Furthermore, the original paleo-inhabitants of the Arctic appear to have been completely replaced approximately 700 years ago.

    Science, this issue 10.1126/science.1255832; see also p. 1004

  13. Ion Channel Structure

    Activating a receptor to excite a neuron

    1. Valda Vinson

    Transmitting signals between nerve cells, occuring at structures known as synapses, is critical to processes such as learning and memory. Fast transmission occurs when glutamate is released from a presynaptic neuron and binds to ionotropic glutamate receptors (iGluRs) in the cell membrane of a postsynaptic neuron. The iGluR contains an ion channel that is transiently opened, to activate the postsynaptic neuron, but then closes rapidly. Chen et al. and Yelshanskaya et al. report crystal structures in a range of conformations that together provide insight into how glutamate binding causes the channel to open and how other molecules that bind to the receptor modulate this. The information could aid in the design of drugs to treat cognitive impairment or seizure disorders

    Science, this issue p. 1021 and p. 1070

  14. Memory Enhancement

    Brain stimulation to improve human memory

    1. Peter Stern

    The hippocampus is a crucial brain area for certain types of memory. Working with humans, Wang et al. found that a specific type of non-invasive brain stimulation improved memory tests and enhanced information flow between the hippocampus and a number of other brain regions. This increased connectivity was highly specific for the individual target areas selected for each participant.

    Science, this issue p. 1054

  15. Chromatin Regulation

    Chromatin mutations disrupt development

    1. Guy Riddihough

    Histone proteins form the core packaging material for our genomic DNA, and covalent modifications to amino acid residues in their structure play an important role in the epigenetic control of gene expression. Herz et al. show that specific mutations in the residues that are normally modified to regulate expression cause severe disruption of normal development in the fruit fly. Similar mutations are known to be involved in a subtype of aggressive pediatric brain cancers. Insights into the epigenetic regulatory pathways disrupted by these mutations in Drosophila may suggest possible treatments for human cancers.

    Science, this issue p. 1065

  16. Germinal Centers

    T and B cells' intricate molecular dance

    1. KM

    Generating high-affinity antibodies to fight infection is no easy task. To do so requires multiple steps, including T cells interacting with antibody-producing B cells in lymph nodes. These interactions select B cells expressing high-affinity antibodies for further proliferation, ensuring that the immune response generates high-affinity antibodies in large quantities. Shulman et al. use fluorescent live-cell imaging in mice to determine the molecular details of these interactions. They find that T cells engage B cells in short-lived mobile contacts during selection. These contacts cause T cells to flux calcium and produce proteins called cytokines, which probably drive B cells to proliferate and produce high-affinity antibodies.

    Science, this issue p. 1058

  17. Microbial Metabolism

    Oxidizing hydrogen in place of nitrite

    1. Nicholas S. Wigginton

    Microorganisms are important drivers of Earth's nitrogen cycle. Many of the organisms responsible for mediating the reactions of one phase of nitrogen to another are thought to be ecologic specialists. Using a combination of genomic and experimental analyses, Koch et al. show that Nitrospira moscoviensis, a member of a widely distributed genus of nitrite-oxidizing bacteria, can oxidize hydrogen instead of nitrite to support growth when oxygen is present. Not only does this ecologic flexibility suggest a broader distribution of these organisms in natural settings, but they may be important in engineered environments as well.

    Science, this issue p. 1052

  18. Paleoceanography

    El Niño shifted between the center and the East

    1. H. Jesse Smith

    El Niño has changed quite a bit over the past 10,000 years. During some periods it was less variable than now, and during others it shifted from its current locale toward the central Pacific. Carré et al. analyzed the shells of mollusks from Peru to construct a record of the El Niño–Southern Oscillation (ENSO) in the eastern Pacific over the Holocene period. They compared this record with other records from the rest of the Pacific to reveal how much the strength and frequency of El Niños changed and how their positions varied.

    Science, this issue p. 1045

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