This Week in Science

Science  17 Oct 2014:
Vol. 346, Issue 6207, pp. 310
  1. Climate Change

    Tornadoes clustering in greater numbers

    1. H. Jesse Smith

    Tornado traveling across a plain


    Will global warming cause more tornadoes? If so, that has not happened yet. Brooks et al. compiled data on the occurrence of tornadoes in the United States between 1954 and 2013 to determine if and how tornado numbers have changed. Although the authors saw no clear trend in the annual number of tornadoes, they did see more clusters of tornadoes since the 1970s. In other words, there has been a decrease in the number of days per year with tornadoes but an increase in the number of days with multiple tornadoes. Why this clustering effect has occurred is not clear.

    Science, this issue p. 349

  2. Planetary Geology

    What's inside Saturn's tiniest moon?

    1. Margaret M. Moerchen

    The icy body Mimas is the smallest of Saturn's main moons, only slightly wider than Switzerland. Like our own Moon, Mimas is tidally locked in its orbit and shows nearly the same face to Saturn at all times. The rotational and orbital periods continually overtake each other slightly, however, so that the moon would appear to rock back and forth as viewed from Saturn. Tajeddine et al. measured these movements with the Cassini spacecraft to see what they reveal about the moon's interior. Surprisingly, the data are consistent with models for a subsurface ocean or an elongated core.

    Science, this issue p. 322

  3. Nanomedicine

    Detoxing drug overdoses with nanoparticles

    1. Megan Frisk

    Quick action can save lives from drug overdoses. But what if the right antidote for the toxic drug or poison is not at hand? A new twist on peritoneal dialysis—an older method for replacing the function of failing kidneys—may provide the answer. Forster et al. injected nanosized lipid vesicles into the peritoneal cavity of rats. Charged toxins such as ammonia were driven inside the acidic vesicles by the pH gradient. Peritoneal dialysis with these loaded liposomes also rescued rats suffering from deadly amounts of verapamil, a heart drug that can cause lethal overdoses. The approach also worked for other drugs. Such liposomes may thus provide an all-purpose antidote.

    Sci. Transl. Med. 6, 258ra141 (2014).

  4. Developmental Biology

    Ensuring a one-way flow of lymph

    1. Wei Wong

    Without lymphatic vessels and valves to ensure unidirectional flow, fluid and immune cells that have gone into tissues from the blood—lymph—would build up and cause swelling. Liu et al. noted that the regions of developing lymphatic vessels destined to become valves had high levels of the receptor VEGFR3 but low levels of epsin 1 and 2, proteins involved in endocytosis. Epsin 1 and 2 suppressed VEGFR3 signaling in collecting lymphatic trunks by triggering the endocytosis and breakdown of VEGFR3. Mice lacking epsin 1 and 2 in the endothelial cells lining lymphatic vessels had defective lymphatic valves and impaired drainage.

    Sci. Signal. 7, ra97 (2014).

  5. Trophic Cascades

    A thorny defense keeps grazers at bay

    1. Sacha Vignieri

    Fear and avoidance of predators are known to influence how and where herbivore prey species, such as impala, forage. This in turn has cascading effects on plant morphologies and communities. Plants, however, have their own defenses, and so may not just be hapless victims of the predator-prey “dance.” Ford et al. found that thorny Acacia trees are more common in areas where impala experience a low risk of predation by wild dogs. A related Acacia, without thorns, is most abundant in areas where risk of predation is high, and so the number of hungry impala is low.

    Science, this issue p. 346

  6. Quantum Electronics

    Complex light and matter interactions

    1. Ian S. Osborne

    When electrons are confined to a plane, lowered in temperature, and subjected to a magnetic field, they can interact and organize themselves into so-called many-body states and exhibit complex quantum electronic behavior. However, discerning the underlying interactions can be difficult. Adding light to the mix, Smolka et al. now show that these self-organized electronic states can be controlled and manipulated to unravel the details of the exotic electronic behavior.

    Science, this issue p. 332

  7. Strategic Reasoning

    Smart monkeys can outwit a computer

    1. Peter Stern

    What happens in the brain when we are learning to compete against an opponent? Seo et al. observed monkeys competing against a computer that can adapt to the monkey's behavior. The monkeys switched their learning strategies when they worked out that their opponent was reacting to their behavior. The responses of the dorsomedial prefrontal cortex cells in the monkey brains predicted their choices and switches in strategies.

    Science, this issue p. 340

  8. Ion Channels

    Ions knock each other across the membrane

    1. Valda Vinson

    Potassium channels play a key role in regulating a cell's membrane potential, which in turn affects diverse processes. The channels contain four potassium binding sites that are thought to be alternately occupied by potassium and water. Starting from high-resolution crystal structures, Köpfer et al. simulated over a thousand potassium ions crossing the channel (see the Perspective by Hummer). They found that ions are in direct contact rather than being separated by water as previously assumed. It seems that repulsion between the ions is the key to their efficient movement through the channel.

    Science, this issue p. 352; see also p. 303

  9. Autoimmunity

    Finding the targets of T cells gone bad

    1. Kristen L. Mueller

    Autoimmune diseases such as rheumatoid arthritis can result when the immune system attacks its own body. If we could identify the specific proteins targeted by autoimmune T cells, we might then be able to block this interaction, which might be useful therapeutically. Ito et al. identified one such target in mice that develop a disease similar to rheumatoid arthritis. Disease-causing T cells recognized a protein that is part of the ribosome, a large protein complex that catalyzes protein synthesis. They also found T cells specific for this protein in people with rheumatoid arthritis.

    Science, this issue p. 363

  10. Applied Evolution

    Exploiting evolution for humanity's sake

    1. Sacha Vignieri

    Using artificial selection, humans have tapped into evolutionary processes for thousands of years. The results of this process we see all around us, from the dogs we share our homes with to the food we put on our table. Carroll et al. review the ways that a more intentional harnessing of evolution may be able to help us meet some of Earth's most pressing challenges, including disease, climate change, and food security.

    Science, this issue 10.1126/science.1245993

  11. Skill Development

    Learning requires the brain to change

    1. Pamela J. Hines

    We may be leveraging change in our brains more than we have thought. Ohayon et al. knocked out cells responsible for laying down insulating myelin along neuronal axons in the brains of otherwise normal adult mice (see the Perspective by Long and Corfas). The mice lacking the myelin-forming cells were less able to learn a new motor skill involving running on a wheel with unevenly spaced bars. Although we may not run on a wheel, when trying to master new motor skills such as juggling, we too may well rely on similar myelin-producing cells.

    Science, this issue p. 318; see also p. 298

  12. Social Evolution

    The evolutionary benefits of behaving fairly

    1. Sacha Vignieri

    Humans have a deep and innate sense of fairness. Humans, however, are not the only species to react to apparent inequities. Brosnan and de Waal propose that inequity aversion can be broken down into two levels. At the most basic level, individuals react to immediate unequal distribution of a reward for equal effort expended, whereas at the second, they show the ability to accept a current unequal distribution with the expectation that over time distribution will equalize. This second level facilitates cooperation over time and requires the cognitive abilities both to assess current distribution and envision future opportunities for equalization. As cognitive abilities advanced across the primate lineage, this more complex accounting of equal distribution and cooperation may have developed into the complete sense of fairness we see in humans today.

    Science, this issue 10.1126/science.1251776

  13. Lab Astrophysics

    Stellar outflows replicated in miniature

    1. Margaret M. Moerchen

    Astronomers observe tight bright jets beaming from the poles of many celestial objects. But what focuses them so well? Albertazzi et al. recreated a scaled-down plasma jet in a laboratory setting to match the behavior of those in young stellar objects. The experiments show that the jets are collimated by a poloidal magnetic field aligned with the same axis. A conelike shock also emerges, as the expanding plasma is abruptly confined by the magnetic field.

    Science, this issue p. 325

  14. Optics

    Achieving gain despite increasing loss

    1. Ian S. Osborne

    When energy is pumped into an optically active material, the buildup (or gain) of excitations within the material can reach a critical point where the emission of coherent light, or lasing, can occur. In many systems, however, the buildup of the excitations is suppressed by losses within the material. Overturning conventional wisdom that loss is bad and should be minimized, Peng et al. show that carefully tweaking the coupling strength between the various components of a coupled optical system can actually result in an enhancement of the optical properties by adding more loss into the system (see the Perspective by Schwefel). The results may provide a clever design approach to counteract loss in optical devices.

    Science, this issue p. 328; see also p. 304

  15. Attosecond Dynamics

    A very quick look at phenylalanine

    1. Jake Yeston

    Over the past decade, laser technology has pushed back the fastest directly observable time scale from femtoseconds (quadrillionths of a second) to attoseconds (quintillionths of a second). For the most part, attosecond studies so far have probed very simple molecules such as H2 and O2. Calegari et al. now look at a more elaborate molecule—the amino acid phenylalanine. They tracked changes in the electronic structure of the compound after absorption of an ultrafast pulse, before the onset of conventional vibrational motion.

    Science, this issue p. 336

  16. Nitrogen Uptake

    Getting to the root of a root problem

    1. Pamela J. Hines

    Although a plant's root system reaches through the soil in search of nutrients, its search is not indiscriminate. If some section of the root is unable to deliver the amount of nitrogen that the rest of the plant demands, other sections of the root compensate and ramp up their delivery of nitrogen. Tabata et al. have now found a small peptide that delivers a signal involved in this process (see the Perspective by Bisseling and Scheres). Only with perception of the signal by the matching receptor in the shoot can the root system compensate for unproductive members.

    Science, this issue p. 343; see also p. 300

  17. Ion Channels

    Insight into a retinal degeneration disease

    1. Valda Vinson

    Human bestrophin 1 (hBest1) is a membrane protein that forms a chloride channel in the retinal pigment epithelium. Mutations in hBest1 can lead to a retinal degeneration disease known as Best disease. Yang et al. describe the structure of KpBest, a bacterial homolog of hBest1. KpBest forms a pentamer with an ion channel at its center. In contrast to hBest1, KpBest1 is a sodium channel. The structure suggests a mechanism for ion selectivity that was confirmed by mutagenesis of KpBest and hBest1. A model of the hBest1 channel structure based on the KpBest structure reveals how mutations cause disease.

    Science, this issue p. 355

  18. Aging

    Cytoskeleton protects from stress and aging

    1. L. Bryan Ray

    The transcription factor HSF-1 has an unexpected second function that allows it to extend longevity in worms. Baird et al. expressed a modified form of HSF-1 in nematodes. The modified protein could not activate genes encoding protein chaperones. Such chaperones are thought to protect many cellular proteins from heat shock and other damage during aging However, the modified protein still extended the worm life span by regulating the transcription of other genes. One gene it regulated was pat-10, which encodes a troponin-like calcium binding protein. Overexpression of PAT-10 also extended worm life span, apparently by changing the stability of the actin cytoskeleton.

    Science, this issue p. 360