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Science: Current Issue



The best in science news, commentary, and research



Published: 2016-12-08T13:37:06-05:00

 









[Editorial] Lifeline for refugee scholars

2016-12-09

The global refugee crisis now stands at 65 million forcibly displaced people, according to the United Nations. Could the world ever have imagined a number exceeding that produced by the Nazis and World War II? The conflict over Syria alone, raging since 2011, has so far resulted in more than 11 million refugees and internally displaced persons. Over the past year, international summits have convened to address this global crisis, including the United Nations Summit in September. There is a growing view that the world must recognize these individuals not as part of a temporary emergency, but as a long-term challenge, and one where higher education can play a major role. Author: Allan Goodman



[In Brief] News at a glance

2016-12-09

In science news around the world, the European Space Agency's funders give the second half of the ExoMars mission a go but kill the Asteroid Impact Mission, the hunt for gravitational waves resumes, Indonesia's government issues a permanent ban on converting peatlands for agriculture, and the U.S. Congress is poised to make a deal on legislation that determines how the National Science Foundation will fund research proposals. Also, scientists prepare to investigate the aftermath of fires that raged through the southern Appalachian Mountains last month. And a chunk of amber picked up in a Myanmar market turns out to contain an unusual treasure: a feathered dinosaur tail.



[In Depth] Corals tie stronger El Niños to climate change

2016-12-09

A detailed, long-term ocean temperature record derived from corals on Christmas Island in Kiribati and other islands in the tropical Pacific shows that the extreme warmth of recent El Niño events reflects not just the natural ocean-atmosphere cycle but a new factor: global warming caused by human activity. Over the last 7000 years, El Niños, which warm the eastern Pacific, waxed and waned. Then, during the 20th century, their intensity began to climb. The trend is likely to continue, boding ever-more-destructive El Niños in the future. The finding helps settle a long-standing debate about the role of global warming in these events, which had been hard to resolve because records are short and spotty in the remote parts of the Pacific where El Niño hits hardest. Author: Christopher Pala



[In Depth] Worries, confusion after cancer trial deaths

2016-12-09

An experimental cancer therapy is facing its biggest setback yet, after an unexpected complication killed seven people, five of them in a single clinical trial. The company, Seattle, Washington–based Juno Therapeutics, has its most troubled trial on hold and is racing to figure out why patients suffered fatal brain swelling, called cerebral edema. Researchers elsewhere are grappling with possible ramifications for the breakthrough treatment, in which a patient's T cells are genetically engineered to fight cancer. Called chimeric antigen receptor–T therapy, it goes up for drug approval next year. Doctors speculate that the cerebral edema could be due to the specific product tested and the trial's patient population, rather than the overall strategy itself. But they're mostly in the dark, and hope that additional research, including new animal models, could help explain what happened and why. Author: Jennifer Couzin-Frankel



[In Depth] U.S. Congress wants to know the weather weeks ahead

2016-12-09

The U.S. Congress is poised to pass a sweeping weather bill, the first in a generation, that, among its many provisions, aims to bolster the capacity of the National Oceanic and Atmospheric Administration (NOAA) to make seasonal weather predictions between 2 weeks and 2 years out. The bill also calls for NOAA to improve its hurricane and tornado research, directs the agency to improve tsunami warnings and research prehistoric surges, orders the agency to evaluate how well the public understands its weather alerts, offers a sharp response to NOAA's delayed and overbudget satellite missions, and requires NOAA to shift from relying exclusively on its own satellites and weather data and to look for commercial alternatives wherever possible. Author: Paul Voosen



[In Depth] AIDS epidemic nears control in three African countries

2016-12-09

This World AIDS Day, 1 December, surprisingly good news came out of southern Africa, the region in the world that has suffered the most from HIV. A random household survey done of some 80,000 people in Malawi, Zambia, and Zimbabwe—each of which has more than 10% of adults living with the virus—found that more than 86% of the people on treatment had fully suppressed their virus. This means they can stave off AIDS and it vastly reduces the likelihood that they will transmit the virus to others. In keeping with this finding, the massive survey effort led by Columbia University's Mailman School of Health discovered that the rate of new infections in Zimbabwe and Zambia was substantially lower than previously estimated by modeling done by the Joint United Nations Programme on HIV/AIDS (UNAIDS) that relied on less rigorous data. This bolsters hopes that these countries are on the path to the UNAIDS goal of controlling their AIDS epidemics by 2030. Author: Jon Cohen



[In Depth] Perovskite solar cells gear up to go commercial

2016-12-09

Cheap photovoltaic materials called perovskites are continuing their march to commercialization. At a meeting in Boston last week, researchers reported new results on tandem solar photovoltaics in which perovskite cells are layered atop conventional silicon solar cells. In this configuration, the perovskite cells absorb more bluish photons, whereas the silicon cells absorb photons toward the red end of the visible spectrum. The new tandems already generate more energy than either of the component cells by themselves. And it's expected they will continue to improve over the next year, perhaps converting as much as 30% of incoming light energy into electricity. Steady progress is also being made in making perovskites rugged and durable enough to survive in real-world conditions. If all goes well, the first commercially made perovskite-silicon tandems could be ready for field tests in 2018. Author: Robert F. Service



[In Depth] Carbon monoxide, the silent killer, may have met its match

2016-12-09

Given off by engines, heaters, and fireplaces, the tasteless, odorless gas known as carbon monoxide (CO) sends more than 50,000 Americans to the emergency room—and kills approximately 500—every year. CO poisons in at least two ways. First, it binds tightly to the hemoglobin in blood and prevents it from delivering oxygen throughout the body. Second, it inhibits the process of respiration in mitochondria, cells' powerhouses. About the best physicians can now offer in cases of poisoning is a treatment developed more than 50 years ago: high-pressure oxygen. But a research team has repurposed the protein neuroglobin into a highly effective CO scavenger and a study in mice gives hope it may become the first true antidote for CO poisoning. Author: Wudan Yan



[In Depth] Curator resigns after sexual misconduct investigations

2016-12-09

Paleoanthropologist Brian Richmond, who allegedly sexually assaulted a research assistant and harassed trainees in a field school, has resigned his prestigious position as curator of human origins at the American Museum of Natural History in New York City, the museum said this week. Richmond, who has been the subject of repeated investigations over the past 2 years for violating policies on sexual harassment, will continue to work off-site until 31 December, and will be paid 1 year of salary, as his contract, which included tenure, requires. Richmond's case convulsed the field of paleoanthropology, and reaction to the news of his resignation was swift. Author: Ann Gibbons



[Feature] When DNA and culture clash

2016-12-09

Largely because many Arabs marry cousins or other close relatives, Saudi Arabia, like much of the Middle East, has a high rate of inherited genetic diseases. Research on these diseases has been booming here, culminating in a project called the Saudi Human Genome Program. Fowzan Alkuraya, a young geneticist who may be the country's leading gene sleuth, and colleagues are harnessing cheap, next-generation DNA sequencing to pin down mutations underlying unexplained diseases. They have analyzed the DNA of more than 10,000 patients in the past 5 years, solving many cases and turning up many new disease genes. Saudi researchers hope the growing catalog of disease mutations they have found will help individual families with inherited diseases have healthy babies. Their work could also lead to premarriage DNA tests for young people that could bring down the prevalence of those diseases here. But first, Saudi geneticists will have to get past the worsening budget crisis here triggered by the global drop in oil prices. Author: Jocelyn Kaiser



[Feature] Qatar's genome effort slowly gears up

2016-12-09

Like neighboring Saudi Arabia, the small, oil- and gas-rich country of Qatar has ambitious plans to sequence the DNA of many thousands of its citizens, hoping ultimately to provide them with better health care. The Qatar Genome Programme (QGP) announced in late 2013 set a controversial goal of sequencing the complete genomes of all 300,000 native Qataris. QGP collaborators have now sequenced the full genomes of 3000 generally healthy citizens for a pilot project. Local and expat researchers from Qatari institutions are planning more than a dozen studies based on these initial DNA sequences, which were completed in June. But so far, no outside researchers have gotten their hands on the information, as QGP officials and scientists wrestle over data access issues. Author: Jocelyn Kaiser



[Book Review] Calling all kid scientists

2016-12-09

"One day, my sister will be bigger than me," a friend's 3-year-old recently announced. "How do you know that?" her mother asked, preparing for a preschooler's take on polygenic inheritance. Leaning in closer, she whispered: "An owl told me." What tickles me about this response is how perfectly it illustrates the creativity and open-mindedness with which children approach the world. Like the best scientists, they tackle the unknown with minimal preconceptions and aren't afraid to employ a little outside-the-box thinking. Helping kids identify the right questions and the best ways to answer them is our happy task, a job made easier by this year's finalists for the Science Books and Films (SB&F) Prizes for Excellence in Science Books. Sponsored by Suburu and AAAS (the publisher of Science), this annual competition highlights books that promote science literacy among children and young adults. Read on to see reviews of the finalists written by the staff (and families) of Science and our sister journals. Author: Valerie Thompson



[Perspective] A fast radio boom

2016-12-09

The mystery of the fast radio bursts (FRBs) continues to deepen. First reported in 2007 (1), FRBs are a few-millisecond-duration flashes of radio waves that appear to be coming from far outside our Milky Way galaxy, possibly from cosmological distances. Astronomers estimate, from the nearly two dozen FRBs seen thus far, that these events occur several thousands of times per day across the whole sky, implying that the phenomenon is surprisingly common in the universe. Of those published, only one has been seen to repeat (2). Although there are presently more published theories on the physical nature of FRBs than there are published sources, the origin of FRBs is still a curious cosmic conundrum. On page 1249 of this issue, Ravi et al. (3) report on the brightest FRB yet detected, FRB 150807, and on its utility for placing constraints on properties of the intergalactic medium. Using the Parkes radio telescope in Australia, the team observed an “exceptionally intense” FRB, weighing in at a booming 120 janskys [the unit of 1 jansky, a favorite of radio astronomers, honors American Karl Jansky (1905–1950), one of the fathers of the field, and amounts to 10−26 watts per square meter per hertz of bandwidth]. Author: Victoria M. Kaspi



[Perspective] Why does time seem to fly when we're having fun?

2016-12-09

Animals use the neurotransmitter dopamine to encode the relationship between their responses and reward. Reinforcement learning theory (1) successfully explains the role of phasic bursts of dopamine in terms of future reward maximization. Yet, dopamine clearly plays other roles in shaping behavior that have no obvious relationship to reinforcement learning, including modulating the rate at which our subjective sense of time grows in real time. On page 1273 of this issue, Soares et al. (2) closely examine the role of dopamine in mice performing a task in which they keep track of the time between two events and make decisions about this temporal duration. The results suggest the need to reassess the leading theory of dopamine function in timing—the dopamine clock hypothesis (3). They may also help explain empirical phenomena that challenge the reinforcement learning account of dopamine function. Authors: Patrick Simen, Matthew Matell



[Perspective] Swimming in polluted waters

2016-12-09

Human activities alter ecosystems around the planet, often rendering environmental conditions unfavorable for plant and animal survival. In the salt marshes along North America's Atlantic coast, the influx of industrial waste has caused chemical pollutants to accumulate at lethal levels, causing the disappearance of many species from affected sites. Yet, multiple populations of the Atlantic killifish (Fundulus heteroclitus) have adapted to cope with levels of pollution orders of magnitude higher than those that members of the same species from unaffected habitats can tolerate. On page 1305 of this issue, Reid et al. (1) provide strong evidence that adaptation has occurred rapidly and through similar genetic changes in multiple populations of killifish that have independently colonized polluted habitats. Authors: Michael Tobler, Zachary W. Culumber



[Perspective] Encoding vocal culture

2016-12-09

How does an inexperienced young animal acquire proper communication skills that will serve it well as an adult in a complex social environment? Juvenile songbirds acquire their vocal repertoire by imitating songs from adults. But song imitation per se is not the ultimate goal of their vocal development (1). Birdsong may carry information about species identity, group identity (local culture), individual identity, and—perhaps most important—about a bird's qualities as a potential mate (2, 3). There is some tension between these developmental goals: Because birds can imitate songs very accurately, local song convergence could compromise individual identity. Similarly, the accumulation of geographical drifts in song structure could potentially compromise the species-specific “signature” of the song. On pages 1278 and 1282 of this issue, Gadagkar et al. (4) and Araki et al. (5), respectively, discover neuronal coding of singing performance error and of species song identity. Together, their findings reveal an elegant natural solution that alleviates the tension between cultural transmission and retaining a species-specific “signature” in songs over generations. Authors: Ofer Tchernichovski, Dina Lipkind



[Perspective] The smoking gun of the ice ages

2016-12-09

Forty years ago, Hays, Imbrie, and Shackleton in a paper in Science tested the hypothesis that small changes in Earth's orbital geometry—namely precession, obliquity, and eccentricity—were responsible for the waxing and waning of the great continental ice sheets during the Quaternary period, which began about 2.58 million years ago (1). The paper is considered to be the “smoking gun” in support of the astronomical hypothesis of the Ice Ages, which is over a century old and most often ascribed to Milutin Milankovitch (2). Author: David A. Hodell



[Policy Forum] What life scientists should know about security threats

2016-12-09

Although concerns about biological weapons and terrorism were discussed by a few scientists before 2001, the broader life-sciences community was not engaged until after the 2001 anthrax-laced letters. The events of 2001 led to efforts in the United States to strengthen biological security for pathogens that could adversely affect public health and safety (i.e., Biological Select Agents and Toxins) and research that could be directly misapplied for harmful purposes (i.e., Dual Use Life Sciences Research of Concern). Resulting policy and practices required scientists to assess security risks of certain types of pathogen research and to identify and implement risk reduction measures. However, scientists have argued for years that their lack of access to or knowledge about malicious actors limits effective assessment and communication of security risks (1–3). How much information is available in the public domain for scientists to understand, evaluate, and communicate plausible biosecurity risks; and what can be done to prevent such threats? Author: Kavita M. Berger



[Policy Forum] Enhancing reproducibility for computational methods

2016-12-09

Over the past two decades, computational methods have radically changed the ability of researchers from all areas of scholarship to process and analyze data and to simulate complex systems. But with these advances come challenges that are contributing to broader concerns over irreproducibility in the scholarly literature, among them the lack of transparency in disclosure of computational methods. Current reporting methods are often uneven, incomplete, and still evolving. We present a novel set of Reproducibility Enhancement Principles (REP) targeting disclosure challenges involving computation. These recommendations, which build upon more general proposals from the Transparency and Openness Promotion (TOP) guidelines (1) and recommendations for field data (2), emerged from workshop discussions among funding agencies, publishers and journal editors, industry participants, and researchers representing a broad range of domains. Although some of these actions may be aspirational, we believe it is important to recognize and move toward ameliorating irreproducibility in computational research. Authors: Victoria Stodden, Marcia McNutt, David H. Bailey, Ewa Deelman, Yolanda Gil, Brooks Hanson, Michael A. Heroux, John P.A. Ioannidis, Michela Taufer



[Letter] Editorial expression of concern

2016-12-09

Author: Jeremy Berg



[Letter] Instilling integrity

2016-12-09

Author: James M. DuBois



[Letter] Respect for the ancients

2016-12-09

Author: Felicia Beardsley



[Letter] Now is the time to protect the Arctic

2016-12-09

Authors: Nigel E. Hussey, Robert G. Harcourt, Marie Auger-Méthé

































[This Week in Science] Aspects of the design

2016-12-09

Author: Marc S. Lavine


















[This Week in Science] Pacemaker of the ice ages, 40 years on

2016-12-09

Author: Julia Fahrenkamp-Uppenbrink






[Editors' Choice] Steel goes for the quick draw

2016-12-09

Author: Brent Grocholski



[Editors' Choice] mRNA quality control

2016-12-09

Author: Guy Riddihough



[Editors' Choice] Blocking PI3Kγ makes cold tumors hot

2016-12-09

Author: Kristen L. Mueller



[Editors' Choice] How fiber feeds a healthy gut

2016-12-09

Author: L. Bryan Ray



[Editors' Choice] Housemates

2016-12-09

Author: Sacha Vignieri



[Editors' Choice] An on-chip cold-atom gravimeter

2016-12-09

Author: Ian S. Osborne



[Editors' Choice] Forcing iron to bond to bismuth

2016-12-09

Author: Phil Szuromi



[Review] The broadening reach of frustrated Lewis pair chemistry

2016-12-09

The revelation that combinations of Lewis acids and bases for which dative bonding is impeded can activate dihydrogen led to the concept of “frustrated Lewis pairs” (FLPs). Over the past decade, a range of FLP systems and substrate molecules have precipitated a paradigm change in main-group chemistry and metal-free catalysis. The FLP motif has also found application in a growing body of chemical problems in organic synthesis, transition metal and free radical chemistry, materials, enzymatic models, and surface chemistry. The current state of FLP chemistry is assessed herein, and the outlook for the future considered. Author: Douglas W. Stephan



[Report] The magnetic field and turbulence of the cosmic web measured using a brilliant fast radio burst

2016-12-09

Fast radio bursts (FRBs) are millisecond-duration events thought to originate beyond the Milky Way galaxy. Uncertainty surrounding the burst sources, and their propagation through intervening plasma, has limited their use as cosmological probes. We report on a mildly dispersed (dispersion measure 266.5 ± 0.1 parsecs per cubic centimeter), exceptionally intense (120 ± 30 janskys), linearly polarized, scintillating burst (FRB 150807) that we directly localize to 9 square arc minutes. On the basis of a low Faraday rotation (12.0 ± 0.7 radians per square meter), we infer negligible magnetization in the circum-burst plasma and constrain the net magnetization of the cosmic web along this sightline to <21 nanogauss, parallel to the line-of-sight. The burst scintillation suggests weak turbulence in the ionized intergalactic medium. Authors: V. Ravi, R. M. Shannon, M. Bailes, K. Bannister, S. Bhandari, N. D. R. Bhat, S. Burke-Spolaor, M. Caleb, C. Flynn, A. Jameson, S. Johnston, E. F. Keane, M. Kerr, C. Tiburzi, A. V. Tuntsov, H. K. Vedantham



[Report] How boundaries shape chemical delivery in microfluidics

2016-12-09

Many microfluidic systems—including chemical reaction, sample analysis, separation, chemotaxis, and drug development and injection—require control and precision of solute transport. Although concentration levels are easily specified at injection, pressure-driven transport through channels is known to spread the initial distribution, resulting in reduced concentrations downstream. Here we document an unexpected phenomenon: The channel’s cross-sectional aspect ratio alone can control the shape of the concentration profile along the channel length. Thin channels (aspect ratio << 1) deliver solutes arriving with sharp fronts and tapering tails, whereas thick channels (aspect ratio ~ 1) produce the opposite effect. This occurs for rectangular and elliptical pipes, independent of initial distributions. Thus, it is possible to deliver solute with prescribed distributions, ranging from gradual buildup to sudden delivery, based only on the channel dimensions. Authors: Manuchehr Aminian, Francesca Bernardi, Roberto Camassa, Daniel M. Harris, Richard M. McLaughlin



[Report] Sensitive electromechanical sensors using viscoelastic graphene-polymer nanocomposites

2016-12-09

Despite its widespread use in nanocomposites, the effect of embedding graphene in highly viscoelastic polymer matrices is not well understood. We added graphene to a lightly cross-linked polysilicone, often encountered as Silly Putty, changing its electromechanical properties substantially. The resulting nanocomposites display unusual electromechanical behavior, such as postdeformation temporal relaxation of electrical resistance and nonmonotonic changes in resistivity with strain. These phenomena are associated with the mobility of the nanosheets in the low-viscosity polymer matrix. By considering both the connectivity and mobility of the nanosheets, we developed a quantitative model that completely describes the electromechanical properties. These nanocomposites are sensitive electromechanical sensors with gauge factors >500 that can measure pulse, blood pressure, and even the impact associated with the footsteps of a small spider. Authors: Conor S. Boland, Umar Khan, Gavin Ryan, Sebastian Barwich, Romina Charifou, Andrew Harvey, Claudia Backes, Zheling Li, Mauro S. Ferreira, Matthias E. Möbius, Robert J. Young, Jonathan N. Coleman



[Report] Synthesis of resveratrol tetramers via a stereoconvergent radical equilibrium

2016-12-09

Persistent free radicals have become indispensable in the synthesis of organic materials through living radical polymerization. However, examples of their use in the synthesis of small molecules are rare. Here, we report the application of persistent radical and quinone methide intermediates to the synthesis of the resveratrol tetramers nepalensinol B and vateriaphenol C. The spontaneous cleavage and reconstitution of exceptionally weak carbon-carbon bonds has enabled a stereoconvergent oxidative dimerization of racemic materials in a transformation that likely coincides with the biogenesis of these natural products. The efficient synthesis of higher-order oligomers of resveratrol will facilitate the biological studies necessary to elucidate their mechanism(s) of action. Authors: Mitchell H. Keylor, Bryan S. Matsuura, Markus Griesser, Jean-Philippe R. Chauvin, Ryan A. Harding, Mariia S. Kirillova, Xu Zhu, Oliver J. Fischer, Derek A. Pratt, Corey R. J. Stephenson



[Report] A general, modular method for the catalytic asymmetric synthesis of alkylboronate esters

2016-12-09

Alkylboron compounds are an important family of target molecules, serving as useful intermediates, as well as end points, in fields such as pharmaceutical science and organic chemistry. Facile transformation of carbon-boron bonds into a wide variety of carbon-X bonds (where X is, for example, carbon, nitrogen, oxygen, or a halogen), with stereochemical fidelity, renders the generation of enantioenriched alkylboronate esters a powerful tool in synthesis. Here we report the use of a chiral nickel catalyst to achieve stereoconvergent alkyl-alkyl couplings of readily available racemic α-haloboronates with organozinc reagents under mild conditions. We demonstrate that this method provides straightforward access to a diverse array of enantioenriched alkylboronate esters, in which boron is bound to a stereogenic carbon, and we highlight the utility of these compounds in synthesis. Authors: Jens Schmidt, Junwon Choi, Albert Tianxiang Liu, Martin Slusarczyk, Gregory C. Fu



[Report] Robust spin-polarized midgap states at step edges of topological crystalline insulators

2016-12-09

Topological crystalline insulators are materials in which the crystalline symmetry leads to topologically protected surface states with a chiral spin texture, rendering them potential candidates for spintronics applications. Using scanning tunneling spectroscopy, we uncover the existence of one-dimensional (1D) midgap states at odd-atomic surface step edges of the three-dimensional topological crystalline insulator (Pb,Sn)Se. A minimal toy model and realistic tight-binding calculations identify them as spin-polarized flat bands connecting two Dirac points. This nontrivial origin provides the 1D midgap states with inherent stability and protects them from backscattering. We experimentally show that this stability results in a striking robustness to defects, strong magnetic fields, and elevated temperature. Authors: Paolo Sessi, Domenico Di Sante, Andrzej Szczerbakow, Florian Glott, Stefan Wilfert, Henrik Schmidt, Thomas Bathon, Piotr Dziawa, Martin Greiter, Titus Neupert, Giorgio Sangiovanni, Tomasz Story, Ronny Thomale, Matthias Bode



[Report] Midbrain dopamine neurons control judgment of time

2016-12-09

Our sense of time is far from constant. For instance, time flies when we are having fun, and it slows to a trickle when we are bored. Midbrain dopamine neurons have been implicated in variable time estimation. However, a direct link between signals carried by dopamine neurons and temporal judgments is lacking. We measured and manipulated the activity of dopamine neurons as mice judged the duration of time intervals. We found that pharmacogenetic suppression of dopamine neurons decreased behavioral sensitivity to time and that dopamine neurons encoded information about trial-to-trial variability in time estimates. Last, we found that transient activation or inhibition of dopamine neurons was sufficient to slow down or speed up time estimation, respectively. Dopamine neuron activity thus reflects and can directly control the judgment of time. Authors: Sofia Soares, Bassam V. Atallah, Joseph J. Paton



[Report] Dopamine neurons encode performance error in singing birds

2016-12-09

Many behaviors are learned through trial and error by matching performance to internal goals. Yet neural mechanisms of performance evaluation remain poorly understood. We recorded basal ganglia–projecting dopamine neurons in singing zebra finches as we controlled perceived song quality with distorted auditory feedback. Dopamine activity was phasically suppressed after distorted syllables, consistent with a worse-than-predicted outcome, and was phasically activated at the precise moment of the song when a predicted distortion did not occur, consistent with a better-than-predicted outcome. Error response magnitude depended on distortion probability. Thus, dopaminergic error signals can evaluate behaviors that are not learned for reward and are instead learned by matching performance outcomes to internal goals. Authors: Vikram Gadagkar, Pavel A. Puzerey, Ruidong Chen, Eliza Baird-Daniel, Alexander R. Farhang, Jesse H. Goldberg



[Report] Mind the gap: Neural coding of species identity in birdsong prosody

2016-12-09

Juvenile songbirds learn vocal communication from adult tutors of the same species but not from adults of other species. How species-specific learning emerges from the basic features of song prosody remains unknown. In the zebra finch auditory cortex, we discovered a class of neurons that register the silent temporal gaps between song syllables and are distinct from neurons encoding syllable morphology. Behavioral learning and neuronal coding of temporal gap structure resisted song tutoring from other species: Zebra finches fostered by Bengalese finch parents learned Bengalese finch song morphology transposed onto zebra finch temporal gaps. During the vocal learning period, temporal gap neurons fired selectively to zebra finch song. The innate temporal coding of intersyllable silent gaps suggests a neuronal barcode for conspecific vocal learning and social communication in acoustically diverse environments. Authors: Makoto Araki, M. M. Bandi, Yoko Yazaki-Sugiyama



[Report] The long-run poverty and gender impacts of mobile money

2016-12-09

Mobile money, a service that allows monetary value to be stored on a mobile phone and sent to other users via text messages, has been adopted by the vast majority of Kenyan households. We estimate that access to the Kenyan mobile money system M-PESA increased per capita consumption levels and lifted 194,000 households, or 2% of Kenyan households, out of poverty. The impacts, which are more pronounced for female-headed households, appear to be driven by changes in financial behavior—in particular, increased financial resilience and saving—and labor market outcomes, such as occupational choice, especially for women, who moved out of agriculture and into business. Mobile money has therefore increased the efficiency of the allocation of consumption over time while allowing a more efficient allocation of labor, resulting in a meaningful reduction of poverty in Kenya. Authors: Tavneet Suri, William Jack



[Report] Transient compartmentalization of RNA replicators prevents extinction due to parasites

2016-12-09

The appearance of molecular replicators (molecules that can be copied) was probably a critical step in the origin of life. However, parasitic replicators would take over and would have prevented life from taking off unless the replicators were compartmentalized in reproducing protocells. Paradoxically, control of protocell reproduction would seem to require evolved replicators. We show here that a simpler population structure, based on cycles of transient compartmentalization (TC) and mixing of RNA replicators, is sufficient to prevent takeover by parasitic mutants. TC tends to select for ensembles of replicators that replicate at a similar rate, including a diversity of parasites that could serve as a source of opportunistic functionality. Thus, TC in natural, abiological compartments could have allowed life to take hold. Authors: Shigeyoshi Matsumura, Ádám Kun, Michael Ryckelynck, Faith Coldren, András Szilágyi, Fabrice Jossinet, Christian Rick, Philippe Nghe, Eörs Szathmáry, Andrew D. Griffiths



[Report] β-cell–mimetic designer cells provide closed-loop glycemic control

2016-12-09

Chronically deregulated blood-glucose concentrations in diabetes mellitus result from a loss of pancreatic insulin-producing β cells (type 1 diabetes, T1D) or from impaired insulin sensitivity of body cells and glucose-stimulated insulin release (type 2 diabetes, T2D). Here, we show that therapeutically applicable β-cell–mimetic designer cells can be established by minimal engineering of human cells. We achieved glucose responsiveness by a synthetic circuit that couples glycolysis-mediated calcium entry to an excitation-transcription system controlling therapeutic transgene expression. Implanted circuit-carrying cells corrected insulin deficiency and self-sufficiently abolished persistent hyperglycemia in T1D mice. Similarly, glucose-inducible glucagon-like peptide 1 transcription improved endogenous glucose-stimulated insulin release and glucose tolerance in T2D mice. These systems may enable a combination of diagnosis and treatment for diabetes mellitus therapy. Authors: Mingqi Xie, Haifeng Ye, Hui Wang, Ghislaine Charpin-El Hamri, Claude Lormeau, Pratik Saxena, Jörg Stelling, Martin Fussenegger



[Report] Ecological speciation of bacteriophage lambda in allopatry and sympatry

2016-12-09

Understanding the conditions that allow speciation to occur is difficult because most research has focused on either long-lived organisms or asexual microorganisms. We propagated bacteriophage λ, a virus with rapid generations and frequent recombination, on two Escherichia coli host genotypes that expressed either the LamB or OmpF receptor. When supplied with either single host (allopatry), phage λ improved its binding to the available receptor while losing its ability to use the alternative. When evolving on both hosts together (sympatry), the viruses split into two lineages with divergent receptor preferences. Although the level of divergence varied among replicates, some lineages evolved reproductive isolation via genetic incompatibilities. This outcome indicates that, under suitable conditions, allopatric and sympatric speciation can occur with similar ease. Authors: Justin R. Meyer, Devin T. Dobias, Sarah J. Medina, Lisa Servilio, Animesh Gupta, Richard E. Lenski



[Report] The genomic landscape of rapid repeated evolutionary adaptation to toxic pollution in wild fish

2016-12-09

Atlantic killifish populations have rapidly adapted to normally lethal levels of pollution in four urban estuaries. Through analysis of 384 whole killifish genome sequences and comparative transcriptomics in four pairs of sensitive and tolerant populations, we identify the aryl hydrocarbon receptor–based signaling pathway as a shared target of selection. This suggests evolutionary constraint on adaptive solutions to complex toxicant mixtures at each site. However, distinct molecular variants apparently contribute to adaptive pathway modification among tolerant populations. Selection also targets other toxicity-mediating genes and genes of connected signaling pathways; this indicates complex tolerance phenotypes and potentially compensatory adaptations. Molecular changes are consistent with selection on standing genetic variation. In killifish, high nucleotide diversity has likely been a crucial substrate for selective sweeps to propel rapid adaptation. Authors: Noah M. Reid, Dina A. Proestou, Bryan W. Clark, Wesley C. Warren, John K. Colbourne, Joseph R. Shaw, Sibel I. Karchner, Mark E. Hahn, Diane Nacci, Marjorie F. Oleksiak, Douglas L. Crawford, Andrew Whitehead



[New Products] New Products

2016-12-09

A weekly roundup of information on newly offered instrumentation, apparatus, and laboratory materials of potential interest to researchers.



[Working Life] Following my lucky star

2016-12-09

Author: Nancy Grace Roman