This Week in Science

Science  30 May 2014:
Vol. 344, Issue 6187, pp. 984
  1. Conservation Ecology

    Conservation vs. eradication

    1. Andrew M. Sugden
    PHOTO: © LIFE ON WHITE/ALAMY

    Endangered California clapper rail.

    PHOTO: ROBERT CLARK

    What's an ecologist to do when an endangered bird lives in an invasive grass? Ecosystems are complicated networks, with one species relying on another, and managing one species in isolation may damage other members of a community. Lampert et al. (see the Perspective by Buckley and Han) looked at the conflict between eradicating a damaging invasive grass species and protecting an endangered bird species that uses the grass as its home. The most effective management and restoration approach focused not on eradicating the invasive grass as quickly as possible but on making changes slowly enough that the birds could adapt. This approach may prove useful in other situations in which active restoration conflicts with other conservation goals.

    Science, this issue p. 1028; see also p. 975

  2. Childhood Development

    Help as hungry children helps young adults

    1. Gilbert Chin

    Supporters of early childhood interventions follow the rule “better early than late,” but so far there's been limited evidence that the rule applies to disadvantaged children in developing countries. Gertler et al. looked at the earnings of young adults in Jamaica, 20 years after, as toddlers, they were given 2 years of help from community health workers. The earnings of the treatment group caught up to those of a comparison group of well-fed children, but the control group of undernourished children that did not receive the health worker visits has lagged behind.

    Science, this issue p. 998

  3. Cancer

    Fighting cancer needs more of the right T cells

    1. Angela Colmone

    In immunotherapy that helps the body's fight against cancer, antibodies that block the cell surface protein CTLA-4 (cytotoxic T lymphocyte–associated antigen-4) entice the immune system to enter the ring. Cha et al. used next-generation sequencing to show that blocking CTLA-4 in cancer sufferers drives change among T cells, so that the population becomes active against a different collection of targets. However, increasing T cell diversity is not the whole story—after treatment, the patients with more favorable clinical outcomes were able to maintain certain preexisting abundant T cells, whereas poorly responding patients lost these cells. Thus, although CTLA-4 blockade induces T cell repertoire diversification, it may actually be the maintenance of particular vigorous T cell clones that helps the antitumor immune response.

    Sci. Transl. Med. 6, 238ra70 (2014).

  4. Water Splitting

    Keeping semiconductors safe from harm

    1. Phil Szuromi

    Solar cells harvest the energy of sunlight to create electricity, but electricity is hard to store. Solar cells could also be used to make hydrogen from water, which can be stored as a fuel. Separating water into hydrogen and oxygen, however, presents challenges, especially if this is done directly by illuminating the anode that oxides water. Under the acidic or alkaline conditions needed for practical devices, semiconducting anode materials corrode during operation. Hu et al. now show that amorphous titanium dioxide coatings can protect semiconductors from alkaline corrosion while still allowing light through.

    Science, this issue p. 1005

  5. Interferon Signaling

    A way to build a better interferon?

    1. John F. Foley

    Type I interferons stimulate an antiviral response during infections, but they also prevent immune cells from proliferating. This effect complicates the use of interferons in patients, because the body needs greater numbers of immune cells to fight viruses effectively. Interferons activate two distinct sets of genes: one for the antiviral response and the other to block immune cells from proliferating. Levin et al. engineered an interferon called IFN-1ant that prevented other forms of interferon from binding to the interferon receptor. At certain doses, IFN-1ant activated the genes required for antiviral immunity without activating the genes that keep immune cells from proliferating.

    Sci. Signal. 7, ra50 (2014).

  6. Subsurface Microbes

    How bacteria manage to breathe on rust

    1. Nicholas S. Wigginton

    The detoxifying bug Shewanella oneidensis (green) growing on crystals of hematite (brown).

    PHOTO: EMSL/FLICKR

    In the absence of oxygen, anaerobic bacteria turn to other chemical compounds during respiration. This can be helpful in detoxifying heavy-metal pollution. Flynn et al. (see the Perspective by Friedrich and Finster) found that alkaline conditions prevent a detoxifying bug—Shewanella oneidensis—from using enzymes to reduce rust-like minerals. Instead, the bacteria reduce elemental sulfur compounds, generating hydrogen sulfide that reduces the iron indirectly. This interplay between anoxic biogeochemical cycles may explain why some anaerobic bacteria contain the genetic machinery necessary to reduce multiple compounds besides oxygen.

    Science, this issue p. 1039; see also p. 974

  7. Synapses

    High-definition view of the synapse

    1. Stella M. Hurtley

    Individual neurons communicate with one another via their synapses, so to understand the nervous system, we need to understand in detail how the synapses are organized. Wilhelm et al. present a quantitative molecular-scale image of the “average” synapse populated with realistic renditions of each of the protein components that contribute to the inner workings of neurons.

    Science, this issue p. 1023

  8. Molecular Magnetism

    Maximizing atomic magnetic memory

    1. Phil Szuromi

    A study of the magnetic response of cobalt atoms adsorbed on oxide surfaces may lead to much denser storage of data. In hard drives, data are stored as magnetic bits; the magnetic field pointing up or down corresponds to storing a zero or a one. The smallest bit possible would be a single atom, but the magnetism of a single atom —its spin—has to be stabilized by interactions with heavy elements or surfaces through an effect called spin-orbit coupling. Rau et al. (see the Perspective by Khajetoorians and Wiebe) built a model system in pursuit of single-atom bits—cobalt atoms adsorbed on magnesium oxide. At temperatures approaching absolute zero, the stabilization of the spin's magnetic direction reached the maximum that is theoretically possible.

    Science, this issue p. 988; see also p. 976

  9. Biodiversity Status

    Maintaining biodiversity: From here to eternity?

    1. Andrew M. Sugden

    There has been substantial recent progress in determining the distributions and identity of vulnerable species, and in understanding how (and where) human activity is leading to extinctions. Pimm et al. review the current state of knowledge and ask what the future rates of species extinction will be, how well protected areas will slow extinction rates, and how the remaining gaps in knowledge might be filled.

    Science, this issue 10.1126/science.1246752

  10. Solar Cells

    Pull, pull, pulling electrons along

    1. Jake Yeston

    Organic photovoltaics operate by transferring charge from a light-absorbing donor material to a nearby acceptor. Falke et al. show that molecular vibrations smooth the way for this charge transfer to proceed. A combination of ultrafast spectroscopy and theoretical simulations revealed an oscillatory signal in a model donor/acceptor blend that implicates carbon-carbon bond stretching in concert with the electronic transition. This vibrational/electronic, or vibronic, process maintains a quantum-mechanical phase relationship that guides the charge more rapidly and directly than an incoherent migration from donor to acceptor.

    Science, this issue p. 1001

  11. Water Structure

    Blackjack water cluster detected

    1. Jake Yeston

    Spectroscopy of protonated water clusters has played a pivotal role in elucidating the molecular arrangement of acid solutions. Whereas bulk liquids manifest broad spectral features, the cluster bands tend to be sharper. The 21-membered water cluster has for decades inspired particular interest on account of its stability and its place in the transition from two-dimensional to three-dimensional hydrogen-bonding network motifs, but the spectral signature of its bound proton has proved elusive. Fournier et al. have now detected this long-sought vibrational feature by applying an innovative ion cooling technique.

    Science, this issue p. 1009

  12. Imaging Techniques

    A close-up view of carbon-bromide bonds

    1. Marc S. Lavine

    Polarizing filters are widely used in optical microscopy to highlight a range of material properties that cause optical path boundaries or birefringence in a material. Palmer et al. (see the Perspective by Lidin) developed an analog method for x-ray microscopy using linearly polarized x-ray beams and an area detector inside a synchrotron. The technique revealed the orientation of the C-Br bonds within crystalline materials.

    Science, this issue p. 1013; see also p. 969

  13. Marine Biogeography

    Ancient reefs provided fishy refuges

    1. Sacha Vignieri

    Climate fluctuations have occurred repeatedly in Earth's history, and so there is much to be learned from examining the responses of past systems. Pellessier et al. reconstructed paleoenvironments over the past 3 million years from sediment cores collected across coral reef systems to explore the impacts of past conditions on reef fish diversity. Coral reefs survived in the Indo-Australian regions during times of otherwise extensive habitat loss. These robust reefs can explain much of the diversity found in present-day reef fish species.

    Science, this issue p. 1016

  14. Neural Development

    Making and breaking neuronal synapses

    1. Pamela J. Hines

    As the brain develops, early synapse formation is exuberant and haphazard. But as development progresses, connections are refined into functional networks. In that process, many synapses get eliminated. Uesaka et al. now show that molecules already known for axon guidance are functional later on when they regulate the synaptic pruning needed to refine the circuits connected during axon guidance.

    Science, this issue p. 1020

  15. Cellular Dynamics

    Motors stirring within the living cell

    1. Valda Vinson

    Cytoskeletal dynamics is key to cellular function. At very short time scales, thermal motions probably dominate, whereas on time scales from minutes to hours, motor-protein-12–based directed transport is dominant. But what about the times in between? Fakhri et al. tracked kinesin molecules labeled with carbon nanotubes and monitored their motion in living cells for milliseconds to hours. The kinesins motored along microtubule tracks, but sometimes moved more randomly as the tracks themselves were moved by active, larger-scale cell movements. This active “stirring” of the cytoplasm may play a role in nonspecific transport.

    Science, this issue p. 1031

  16. Structural Biology

    How to recruit membrane trafficking machinery

    1. Stella M. Hurtley

    PI4KIIIβ is a lipid kinase that underlies Golgi function and is enlisted in biological responses that require rapid delivery of membrane vesicles, such as during the extensive membrane remodeling that occurs at the end of cell division. Burke et al. determined the structure of PI4KIIIβ in a complex with the membrane trafficking GTPase Rab11a. The way in which the proteins interact gives PI4KIIIβ the ability to simultaneously recruit Rab11a and its effectors on specific membranes.

    Science, this issue p. 1035

  17. Transcription

    Transcription takes a pause to consider

    1. Guy Riddihough

    A short sequence in DNA causes RNA polymerase (RNAP) to pause at thousands of previously undocumented locations in the genome. Larson et al. mapped these pause sites at single-nucleotide resolution in vivo in actively growing bacteria. Transcriptional pausing can be critical for the regulation of gene expression, by allowing RNA folding events and in the recruitment of other transcription factors.

    Science, this issue p. 1042

  18. Ion Channel Structure

    Intact NMDA receptor structure revealed

    1. Valda Vinson

    For brains to develop and form memories, a signal must be transmitted from one neuron to the next. Glutamate is an important neurotransmitter that excites the receiving nerve cell by binding to an ion channel called an N-Methyl-d-Aspartate (NMDA) receptor. This activates the NMDA receptors, causing calcium ions to flood in, triggering signal transduction. Either under- or overactivation can result in a variety of neurological disorders and diseases. Karakas and Furukawa describe the crystal structure of an intact NMDA receptor composed of four separate subunits.

    Science, this issue p. 992

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