This Week in Science

Science  11 Mar 2016:
Vol. 351, Issue 6278, pp. 1162
  1. Biodegradation

    Some bacteria think plastic is fantastic

    1. Nicholas S. Wigginton

    Bacteria found near a plastics recycling plant can degrade plastic

    PHOTO: PAVLIHA/ISTOCKPHOTO.COM

    Bacteria isolated from outside a bottle-recycling facility can break down and metabolize plastic. The proliferation of plastics in consumer products, from bottles to clothing, has resulted in the release of countless tons of plastics into the environment. Yoshida et al. show how the biodegradation of plastics by specialized bacteria could be a viable bioremediation strategy (see the Perspective by Bornscheuer). The new species, Ideonella sakaiensis, breaks down the plastic by using two enzymes to hydrolyze PET and a primary reaction intermediate, eventually yielding basic building blocks for growth.

    Science, this issue p. 1196; see also p. 1154

  2. Heart Disease

    A scavenger that protects the heart

    1. Paula A. Kiberstis

    Coronary heart disease is a tale of two forms of plasma cholesterol. In contrast to the well-established effects of “bad” cholesterol (LDL-C), the role of “good” cholesterol (HDL-C) is mysterious. Elevated HDL-C correlates with a lower risk of heart disease, yet drugs that raise HDL-C levels do not reduce risk. Zanoni et al. found that some people with exceptionally high levels of HDL-C carry a rare sequence variant in the gene encoding the major HDL-C receptor, scavenger receptor BI. This variant destroys the receptor's ability to take up HDL-C. Interestingly, people with this variant have a higher risk of heart disease despite having high levels of HDL-C.

    Science, this issue p. 1166

  3. Spin Models

    One model to rule them all?

    1. Jelena Stajic

    The idea of finding an all-encompassing model to describe the world around us has appealed to generations of scientists. Although we are very far from this ultimate goal, more modest steps can be taken if we focus on particular problems. De las Cuevas and Cubitt used concepts borrowed from computer science to show that all classical spin models (introduced initially to study magnetism) can be solved by tackling a slightly more complex, universal model (see the Perspective by Wehner). Thanks to these findings, it may be possible to physically simulate systems with complex interactions, using the well-understood two-dimensional Ising model with fields.

    Science, this issue p. 1180; see also p. 1156

  4. Zeolites

    Radically faster synthesis

    1. Phil Szuromi

    Zeolite synthesis normally proceeds under basic conditions that allow the oxide bridges between aluminum and silicon atoms to break and reform. Feng et al. show that the formation of hydroxyl radicals, either by irradiation with ultraviolet light or with the Fenton reagent, can speed up the formation of the crystallized zeolite by about a factor of 2.

    Science, this issue p. 1188

  5. Neurodevelopment

    Signal problems in autism spectrum disorder

    1. Pamela J. Hines

    Autism spectrum disorders have many causes. Bidinosti et al. studied Phelan-McDermid syndrome (PMDS), one of the symptoms of which can be autism (see the Perspective by Burbach). The authors used neurons derived from these patients, as well as from mice, with the culprit gene disrupted and found that a chain of intracellular signals becomes imbalanced. Signaling and behavioral symptoms could be improved by a small-molecule therapeutic that inhibits a key kinase.

    Science, this issue p. 1199; see also p. 1153

  6. Cancer Therapy

    Tumors put in a vulnerable position

    1. Paula A. Kiberstis

    Cancer cells often display alterations in metabolism that help fuel their growth. Such metabolic “rewiring” may also work against the cancer cells, however, by creating new vulnerabilities that can be exploited therapeutically. A variety of human tumors show changes in methionine metabolism caused by loss of the gene coding for 5-methylthioadenosine phosphorylase (MTAP). Mavrakis et al. and Kryukov et al. found that the loss of MTAP renders cancer cell lines sensitive to growth inhibition by compounds that suppress the activity of a specific arginine methyltransferase called PRMT5. Conceivably, drugs that inhibit PRMT5 activity could be developed into a tailored therapy for MTAP-deficient tumors.

    Science, this issue pp. 1208 and 1214

  7. Topological Matter

    Sinking into the bulk of a Weyl semimetal

    1. Jelena Stajic

    Surface properties of the material TaA.

    INOUE ET AL.

    A recently discovered class of topological materials, Weyl semimetals, have surface states in the form of so-called Fermi arcs. Inoue et al. used a high-resolution scanning tunneling microscope to explore the properties of these states in the material TaAs. They mapped the scattering of electrons off impurities on the surface of the material and compared the data to the predictions of density functional theory. The data could be reconciled with the theory only if electrons associated with Ta orbitals on the Fermi arcs sank into the bulk of the material.

    Science, this issue p. 1184

  8. Immunology

    Sticking it to T cells

    1. John F. Foley

    The cytokine TGF-β is abundant in the tumor microenvironment, where it inhibits T cells that could attack and destroy tumors. However, targeting TGF-β throughout the body would interfere with other immune responses. Newman et al. found that T cells without the adhesion molecule PECAM-1 were less sensitive to inhibition by TGF-β. Furthermore, mice lacking PECAM-1 had smaller tumors than those in control mice. Thus, targeting PECAM-1 may enhance the antitumor activity of T cells.

    Sci. Signal. 9, ra27 (2016).

  9. Infectious Disease

    Toxic tenant promotes bad bugs

    1. Angela Colmone

    There are many benefits to a good roommate, but the wrong choice can be toxic. Cohen et al. found that alpha toxin produced by Staphylococcus aureus worsened lung co-infection by Gram-negative bacteria. The alpha toxin prevented acidification of bacteria-containing phagosomes, thus increasing bacterial proliferation, spread, and lethality. However, early treatment or prophylaxis with a neutralizing antibody to alpha toxin prevented this effect and promoted S. aureus clearance in a humanized mouse model.

    Sci. Transl. Med. 8, 329ra31 (2016).

  10. Bacterial Pili

    How the bacterial pilus works

    1. Stella M. Hurtley

    Many bacteria, including important pathogens, move by projecting grappling-hook–like extensions called type IV pili from their cell bodies. After these pili attach to other cells or objects in their environment, the bacteria retract the pili to pull themselves forward. Chang et al. used electron cryotomography of intact cells to image the protein machines that extend and retract the pili, revealing where each protein component resides. Putting the known structures of the individual proteins in place like pieces of a three-dimensional puzzle revealed insights into how the machine works, including evidence that ATP hydrolysis by cytoplasmic motors rotates a membrane-embedded adaptor that slips pilin subunits back and forth from the membrane onto the pilus.

    Science, this issue p. 10.1126/science.aad2001

  11. Chemical Physics

    Describing dispersion forces

    1. Phil Szuromi

    Dispersion or van der Waals interactions are attractive forces that arise from induced dipoles. They are not seen just in atoms and molecules but also in larger nanostructures and even macroscopic objects. Ambrosetti et al. created a qualitatively correct description of van der Waals interactions between polarizable nanostructures over a wide range of finite distances. This required delocalized electrons that have wavelike electron density fluctuations, unlike the more common approaches with dipoles fixed on atoms. Furthermore, the authors observed an enhancement in the nonlocality of the charge density response on the scale of 10 to 20 nm.

    Science, this issue p. 1171

  12. Fungal Enzymes

    Mining gut fungi to break down biomass

    1. Nicholas S. Wigginton

    The recalcitrance of plant biomass remains a formidable bottleneck in the production of biofuels and other chemicals from renewable sources. Enzymes from microbial communities found within ruminants and hindgut fermenters, however, show considerable promise to break down plant material into simple sugars efficiently. Solomon et al. used 'omics-level and biochemical assays to reveal a suite of lignocellulose-degrading enzymes from early-diverging anaerobic fungi isolated from the guts of horses, goats, and sheep. This approach not only reveals the regulation of these pathways but also represents a method to identify enzymes with no known homologs that would be unidentifiable using conventional screening methods.

    Science, this issue p. 1192

  13. Cancer Biology

    Timing the attack on cancer cells

    1. L. Bryan Ray

    Cell regulatory systems have dynamic properties that will need to be taken into account when planning therapeutic strategies. Chen et al. found that the timing of a radiation treatment of human breast cancer–derived cells in culture determined whether cell survival was enhanced or reduced. Depletion of the oncogene product MDMX caused an initial burst of expression of the tumor suppressor protein p53 within the first 24 hours, and then oscillations of lower amplitude. When the radiation treatment coincided with the first phase, 95% of the cells died, but if radiation was applied in the second phase, fewer than 20% of the cells died.

    Science, this issue p. 1204

  14. Transcription

    Stochastic properties of phage promoter

    1. L. Bryan Ray

    Full understanding of regulated gene expression requires characterization of stochastic variation in the activity of individual promoters. To avoid cell-to-cell variability and variation between the activity of specific gene copies, Sepúlveda et al. investigated the behavior of the lysogeny maintenance promoter of phage lambda in individual Escherichia coli cells. They measured the concentration of transcription factor and the actual number of mRNAs produced, and used mathematical modeling to discern the stochastic activity of the regulated promoter. The promoter underwent switching between configurations that occurred more rapidly than the lifetime of mRNA molecules produced, and individual copies of the same gene functioned independently in the same cell. Such studies can reveal new aspects of systems that have been well studied by more conventional techniques.

    Science, this issue p. 1218

  15. Microbiology

    Hidden fungal diversity

    1. Julia Fahrenkamp-Uppenbrink

    How many species of fungi exist, and how are they related to each other? Recent environmental surveys have provided evidence of entire branches of the fungal tree of life that were unknown. In a Perspective, Hibbett explains that nevertheless, few of these discoveries have led to new species being named. One reason is that the evidence comes from genome data, which are considered insufficient for naming new species. Given that the type specimens or cultures required for naming a species are often hard to come by, it may be time to revise the taxonomic codes for naming species.

    Science, this issue p. 1150

  16. Quantum Optics

    Entangled frequency combs

    1. Ian S. Osborne

    The ability to generate optical frequency combs in which the output light is made up of millions of sharp lines precisely spaced apart has been important for optical applications and for fundamental science. Reimer et al. now show that frequency combs can be taken into the quantum regime. They took individual teeth of the combs and quantum-mechanically entangled them to form complex optical states. Because the method is compatible with existing fiber and semiconductor technology, the results demonstrate a possible scalable and practical platform for quantum technologies.

    Science, this issue p. 1176

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