Editors' Choice

Science  08 Dec 2017:
Vol. 358, Issue 6368, pp. 1267
  1. Stem Cells

    Skin stem cells regenerate a human epidermis

    1. Priscilla N. Kelly

    Skin stem cells have been successfully used in life-saving therapy.

    PHOTO: STEVE GSCHMEISSNER/SCIENCE SOURCE

    In a landmark study, Hirsch et al. used engineered autologous skin stem cells to replace more than 80% of the epidermis of a critically ill 7-year-old boy. The child suffered from junctional epidermolysis bullosa (JEB), a rare skin condition affecting fewer than 1 in 1 million people. Affected individuals have fragile skin that is prone to blisters and erosions, making them susceptible to life-threatening infections. The researchers obtained a small biopsy from a nonblistering skin section, which was used to grow keratinocyte cultures in the laboratory. Cells were engineered to express a skin protein called LAMB3 (which is defective in JEB), and grafts were transplanted onto the boy's denuded surfaces during multiple surgeries. At the 21-month follow-up stage, the boy's skin had healed normally, was blister-free, and was deemed fully functional with normal elasticity.

    Nature 10.1038/nature24487 (2017).

  2. Plant Science

    Multifactorial response to drought

    1. Pamela J. Hines

    Drought is not just characteristic of the desert, but also occurs as transient dry spells in agricultural settings. Plants respond to drought by waterproofing their surfaces, closing pores, and adjusting internally, largely in response to the hormone abscisic acid. The hormones strigolactone, which triggers germination of parasitic plants, and karrikin, a component of smoke that triggers seed germination after fire, also promote tolerance to drought. The signaling pathways for strigolactone and karrikin converge on MAX2, which functions as part of the ubiquitin-regulated protein degradation system. Studying the small mustard relative Arabidopsis, Li et al. analyzed the cross-talk between signaling pathways for these three hormones that allow thirsty plants to survive.

    PLOS Gen. 10.1371/journal.pgen.1007076 (2017).

  3. Cancer

    The health hazards of fiber intake

    1. Paula A. Kiberstis

    Carbon nanotube fibers cause mesothelioma in mice.

    ILLUSTRATION: SCIENCE PICTURE CO/SCIENCE SOURCE

    Carbon nanotubes (CNTs) are used in a variety of commercial applications, from automotive parts to computers. Increased human exposure to these nanomaterials has sparked concerns about possible health risks because CNTs have structural similarities to asbestos, which causes the incurable cancer mesothelioma. A new study in mice does not alleviate these concerns. Chernova et al. delivered either long-fiber asbestos or long-fiber CNTs into the pleural cavity of mice and found that the treatments both induced chronic inflammation and activated the same signaling pathways. By 12 to 20 months after exposure, at least 10% of the mice in each group had developed mesothelioma. These results suggest that CNTs pose health risks similar to those of asbestos and that human exposure to them should be monitored.

    Curr. Biol. 27, 3302 (2017).

  4. Diversity

    Downplaying versus embracing differences

    1. Melissa McCartney

    Inclusive teaching practices are often taught during workshops aimed at increasing student diversity. Aragón et al. analyzed data from an intensive workshop on inclusive teaching practices held by the National Academies of Sciences Summer Institutes on Undergraduate Education to model how educators adopt such practices. Two ideologies were considered: colorblindness, which downplays differences based on gender or color, and multiculturalism, which embraces differences. Overall, participants reported implementing more inclusive teaching practices than they had before attending the Summer Institute. However, stronger endorsements by participants of multicultural ideology predicted higher reports of inclusive teaching practices, whereas stronger endorsements of colorblind ideology predicted lower reports. Results from this study will help bridge basic theory and application in the implementation of future inclusive teaching workshops.

    J. Divers. High. Educ. 10.1037/dhe0000026 (2017).

  5. Immunology

    The metabolic needs of migrating Tregs

    1. Seth Thomas Scanlon

    Regulatory T cells (Tregs) are thought to rely primarily on oxidative metabolism, in contrast to CD4+ T helper subsets (TH1, TH2, and TH17 cells), which are highly glycolytic. However, Kishore et al. find that integrins (LFA-1) and costimulatory molecules (CD28) can enhance Treg glycolysis, whereas the coinhibitory receptor CTLA-4 can block it. Glycolysis is required for Treg migration and depends on the enzyme glucokinase, which is induced by the PI3K-mTORC2 signaling pathway. Tregs lacking elements of this pathway are unable to migrate effectively to sites of inflammation. Likewise, Tregs from patients with a polymorphism endowing increased glucokinase activity showed enhanced chemokine-induced motility. This work opens the possibility of targeting specific glycolytic enzymes to selectively manipulate the migration of different T cell subsets.

    Immunity 47, 875–889 (2017).

  6. Robotics

    Softly getting a grip

    1. Marc S. Lavine

    For delicate work, our fingers can softly grasp an object such as an egg, whereas when precision is called for, we can hold something like a pencil or fine tool with a stiff grasp. In robotic arms, soft pneumatic actuation allows for dexterity and flexibility, but the stiffness of the arm cannot be decoupled from the position of the device at its end. Giannaccini et al. used a combination of contracting and expanding muscles that increased the bending angle that the arm could achieve while also decoupling the stiffness of the manipulator at the end of the arm from its position in space. Further, increasing the payload on the arm had minimal effect on its bending.

    Soft Robot. 10.1089/soro.2016.0066 (2017).

  7. Mechanochemistry

    Pulling versus heating

    1. Phil Szuromi

    Mechanical force can activate and break bonds in ways that differ from thermal mechanisms or photoactivation. Stevenson and Bu studied the effects of substituent positions on retro-Diels-Alder reactions in which a bridged ring opened to form substituted furans and malemides. Thermal activation depended on stereochemistry (endo or exo configurations), but mechanochemistry (activating the molecule with ultrasound) depended instead on regiochemistry (proximal or distal geometries). The thermally reactive distal-exo adduct was unreactive in the ultrasound experiments.

    J. Am. Chem. Soc. 10.1021/jacs.7b08895 (2017).

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