This Week in Science

Science  05 May 2017:
Vol. 356, Issue 6337, pp. 497
  1. Computer Science

    Artificial intelligence masters poker

    1. Jelena Stajic

    Computers can beat humans at games as complex as chess or go. In these and similar games, both players have access to the same information, as displayed on the board. Although computers have the ultimate poker face, it has been tricky to teach them to be good at poker, where players cannot see their opponents' cards. Moravčík et al. built a code dubbed DeepStack that managed to beat professional poker players at a two-player poker variant called heads-up no-limit Texas hold'em. Instead of devising its strategy beforehand, DeepStack recalculated it at each step, taking into account the current state of the game. The principles behind DeepStack may enable advances in solving real-world problems that involve information asymmetry.

    Science, this issue p. 508

  2. Noise Pollution

    Shhh, you're disturbing the ecosystem

    1. Sacha Vignieri

    Species in nature reserves are experiencing increased pressure from human encroachment in many forms. One type of pressure that is rarely discussed but perennial is human-produced noise. Buxton et al. looked at the degree to which such noise has affected protected areas across the United States. Human-produced noise doubled background noise levels in a majority of protected areas and substantially affected critical habitat areas for endangered species.

    Science, this issue p. 531

  3. Human Genetics

    On the history of Bantu speakers

    1. Laura M. Zahn

    Genomic analysis of Bantu speakers elucidates human evolutionary history.

    CREDIT: JORGE FERNANDEZ/ALAMY STOCK PHOTO

    Africans are underrepresented in many surveys of genetic diversity, which hinders our ability to study human evolution and the health of modern populations. Patin et al. examined the genetic diversity of Bantu speakers, who account for one-third of sub-Saharan Africans. They then modeled the timing of migration and admixture during the Bantu expansion. The analysis revealed adaptive introgression of genes that likely originated in other African populations, including specific immune-related genes. Applying this information to African Americans suggests that gene flow from Africa into the Americas was more complex than previously thought.

    Science, this issue p. 543

  4. Inflammation

    A way to switch off IBD

    1. Priscilla N. Kelly

    Inflammatory bowel diseases (IBDs) such as ulcerative colitis and Crohn's disease are associated with defective interleukin-10 (IL-10) signaling. Although IL-10 plays an essential role in the control and resolution of inflammation, the mechanisms responsible for its anti-inflammatory actions remain unclear. Ip et al. show that in response to inflammation, IL-10 controls cellular metabolism in macrophages by inducing the mTOR inhibitor DDIT4 and preventing glucose uptake (see the Perspective by Kabat and Pearce). In mouse models and patient samples, defective IL-10 promoted accumulation of damaged macrophages and exacerbated inflammatory signals. Targeting mTORC1 thus might help to treat IBD and related disorders.

    Science, this issue p. 513; see also p. 488

  5. Methane Chemistry

    A watery route from methane to methanol

    1. Jake Yeston

    Methanol production is an expensive, energy-intensive process that initially overoxidizes methane to carbon monoxide. Sushkevich et al. used copper sites in a zeolite to oxidize methane to methoxy intermediates; they then added water to release methanol and hydrogen while reoxidizing the copper. This inexpensive process could prove useful at gas well sites for producing an easily stored and transported liquid from excess gas that at present is burned away.

    Science, this issue p. 523

  6. Neuroscience

    Give us our daily protein

    1. Peter Stern

    Flies have a neuronal pathway that tells them when to eat protein.

    PHOTO: DAVID BITHELL/EYEEM/ALAMY STOCK PHOTO

    Protein is an essential component of our food, and protein intake thus must be actively regulated. Liu et al. identified a neural circuit that encodes protein-specific hunger in fruit flies. In protein-deprived animals, this circuit acted to simultaneously promote protein consumption and restrict sugar intake. Lack of protein induced changes in the protein-specific, but not sugar-specific, branch of this circuit.

    Science, this issue p. 534

  7. Zika Virus

    LAMP shines a light on Zika virus

    1. Orla M. Smith

    Rapid and simple assays to detect infectious agents are key to tracking emerging epidemics. Chotiwan et al. describe a loop-mediated amplification (LAMP) assay that detects Zika virus RNA in human biofluids such as serum and semen, as well as in mosquitoes, the insect vector that transmits the disease. The assay successfully distinguished the Asian-lineage Zika virus, which is associated with the current outbreak in the Americas, from the African-lineage Zika virus. This approach should enable tracking of the Asian-lineage strain as it moves into new geographical locations.

    Sci. Transl. Med. 9, eaag0538 (2017).

  8. Drug Development

    Finding drugs for fragile X syndrome

    1. Leslie K. Ferrarelli

    The intellectual disability called fragile X syndrome is associated with abnormal synaptic morphology. Kashima et al. performed a high-throughput drug screen that used the hyperactive locomotion of a fly model of this disease as a behavioral marker. Inhibitors of LIMK1, a kinase involved in the pathogenesis of the disease, ameliorated the neurological and behavioral phenotypes in the fly model and also reduced hyperactivity in a mouse disease model. This method may aid in future drug development for fragile X syndrome, for which there are few treatment options at present.

    Sci. Signal. 10, eaai8133 (2017).

  9. Polymer Science

    When polymers behave like metals

    1. Marc S. Lavine

    Diblock copolymers, in which two dissimilar chains are chemically linked, can show a rich array of morphologies. These are usually attained by slow cooling to give the chains time to find their thermodynamically preferred arrangements. Rather than using slow cooling, Kim et al. rapidly quenched their materials from the disordered state and then annealed at low to moderate temperatures (see the Perspective by Stein). Different processing routes drove assembly into a variety of low-dimensional phases more typical of metal alloys.

    Science, this issue p. 520; see also p. 487

  10. Materials Science

    Wet, soft, squishy, and tunable

    1. Marc S. Lavine

    Hydrogels are highly cross-linked polymer networks that are heavily swollen with water. Hydrogels have been used as dynamic, tunable, degradable materials for growing cells and tissues. Zhang and Khademhosseini review the advances in making hydrogels with improved mechanical strength and greater flexibility for use in a wide range of applications.

    Science, this issue p. eaaf3627

  11. Neurodevelopment

    Self-organization for sensory brushes

    1. Pamela J. Hines

    Sensory hairs on the back of a fruit fly are lined up in neat rows. The orderliness of this arrangement has encouraged models based on organized specification of the hairs. Corson et al. now show that development is both less precise and more effective than that. They used mathematical modeling to recapitulate genetic effects as the developing epidermis becomes organized into enough rows and single lines of hairs. Their work suggests that the sensory field develops through self-organizing patterning that can adjust to the size of the epidermis.

    Science, this issue p. eaai7407

  12. DNA Methylation

    Positives and negatives of methylated CpG

    1. Beverly A. Purnell

    When the DNA bases cytosine and guanine are next to each other, a methyl group is generally added to the pyrimidine, generating a mCpG dinucleotide. This modification alters DNA structure but can also affect function by inhibiting transcription factor (TF) binding. Yin et al. systematically analyzed the effect of CpG methylation on the binding of 542 human TFs (see the Perspective by Hughes and Lambert). In addition to inhibiting binding of some TFs, they found that mCpGs can promote binding of others, particularly TFs involved in development, such as homeodomain proteins.

    Science, this issue p. eaaj2239; see also p. 489

  13. DNA Methylation

    Inducing DNA methylation where it wasn't

    1. Beverly A. Purnell

    The specific order of DNA's purines and pyrimidines encodes proteins, but chemically modified bases are important in regulating gene expression. In mammals, most cytosines are methylated when present in the CpG dinucleotide; however, stretches of mammalian DNA containing a high frequency of the CG sequence, termed CpG islands (CGIs), are typically unmethylated. The mechanism by which methylation of CGIs is blocked is unclear. Takahashi et al. interrupted CpG-rich sequences by targeted insertion of CpG-free DNA into CGIs in human pluripotent stem cells, which induced stable, heritable methylation. Some disorders result from improper methylation; this work provides an epigenome-editing tool to develop model systems for understanding CGI methylation in development and disease. It may also enable therapeutic strategies to correct aberrant imprinting diseases.

    Science, this issue p. 503

  14. Ocean Acidification

    Reconciling pH and future productivity

    1. Caroline Ash

    The differential effects of reduced seawater pH and increased carbon dioxide on marine phytoplankton productivity have not been resolved. Hong et al. found that previous experimentation did not account for variable metal concentrations or for ammonia contamination. After controlling for these variables, experimentation, protein expression analysis, and field data showed that low pH, coupled with the low ambient iron availability in the open ocean, inhibits nitrogen fixation, whereas elevated CO2 is fertilizing. Overall, the deleterious effects of decreased pH trump the beneficial effects of increased CO2. Thus, it seems that in a future, more acidic ocean, phytoplankton productivity is likely to be suppressed.

    Science, this issue p. 527

  15. Evolutionary Genetics

    Genetic interactions drive selection

    1. Laura M. Zahn

    Most individuals carry at least some potentially deleterious variants in their genome. But the effects of these mutations on individuals are not well understood. Sohail et al. examined loss-of-function (LOF) mutations in the genomes of humans and flies. They found that deleterious LOF mutations are further away from each other in the genome than expected by chance, which suggests that genetic interactions are driving selection. Thus, additional mutations do not exhibit an additive effect, and the overall selective parameter is not driven solely by the total number of mutations within the genome. This explains why high levels of variation can be maintained and why sex and recombination are advantageous.

    Science, this issue p. 539

  16. Complement

    Inter-innate cooperation

    1. Angela Colmone

    The different branches of the immune system work together like a well-oiled machine, but how this coordination occurs is not fully understood. Narni-Mancinelli et al. found one such mechanism: cross-talk between the alternative complement pathway and natural killer (NK) and innate lymphoid cells (ILCs). They report that complement factor P (CFP), a positive regulator of the alternative complement pathway, binds NKp46, which is expressed on subsets of NK cells and ILCs. Patients lacking CFP are more susceptible to Neisseria meningitidis infection, and, in mice, this CFP protection was dependent on NKp46 and group 1 ILCs. Thus, ILCs and the alternative complement pathway cooperate to fight off bacterial infection.

    Sci. Immunol. 2, eaam9628 (2017).

  17. Ecological Processes

    Climate extremes stress ecosystems

    1. Shahid Naeem

    Climate shocks, such as warming bursts or rapid freeze-thaw cycles, stress ecological systems, often adversely affecting carbon and nutrient cycling. Mooshammer et al. exposed soil microbial communities to such shocks to uncover the mechanisms underpinning stress responses. Changes in microbial composition and their enzyme chemistry are the likely causes for observed alterations in C, N, and P biogeochemistry. These findings may improve our ability to predict the environmental consequences of ever worsening climate variability.

    Sci. Adv. 10.1126/sciadv.1602781 (2017).