Editors' Choice

Science  09 Feb 2018:
Vol. 359, Issue 6376, pp. 649
  1. Nanomaterials

    Scalable h-BN sheets

    1. Phil Szuromi

    Large-area hexagonal boron nitride nanomesh can be grown on a single-crystalline rhodium thin film substrate (shown here).

    PHOTO: H. CUN ET AL., NANO LETT. 10.1021/ACS.NANOLETT.7B04752 (2018)

    Growth of two-dimensional material in situ is a scalable route for device production, especially if the films can be transferred to another substrate. Cun et al. grew single crystals of hexagonal boron nitride (h-BN) on ∼10-cm rhodium films supported on silicon wafers. After electrochemical treatment with an organic acid and spin-coating with a polymer layer, the h-BN was electrochemically exfoliated by generating hydrogen bubbles at the rhodium surface. These films could be transferred onto a germanium surface to prevent their high-temperature oxidation. Films in which nanovoids had been introduced into h-BN functioned as freestanding membranes after removal of the polymer support.

    Nano Lett. 10.1021/acs.nanolett.7b04752 (2018).

  2. Cell Biology

    Migration without a nucleus

    1. Stella M. Hurtley

    When cells migrate, they normally do so by adopting a characteristic polarized morphology with the nucleus seemingly pushing from behind. The internal cytoskeleton forms well-organized arrays, and the mechanics within the cell, as well as the interactions with the surface on which the cell is moving, are well understood. It has been assumed that the nucleus itself is important for directed migration. Graham et al. examined the migration of enucleated mammalian cells and found that the nucleus was dispensable for directed migration, at least along flat surfaces. When it came to migration in three-dimensional (3D) environments, the lack of a nucleus was important. It seems that the mechanical interactions between the cytoskeleton and the nucleoskeleton provide the physical robustness required for cells to push their way through 3D environments.

    J. Cell Biol. 10.1083/jcb.201706097 (2018).

  3. Photoreception

    Unfocused eyes in the stars

    1. Caroline Ash

    Brittle stars detect light with a network of opsincontaining cells.

    PHOTO: SARAH DAVIES

    Imagine having a whole-body-surface visual system. The brittle star Ophiocoma wendtii and its relatives are decorated with a surface layer of calcite hemispheres. Although these have been implicated in light focusing, there has been little anatomical evidence of an underlying photoreceptor network. Sumner-Rooney et al. found a comprehensive network connecting opsin-containing cells across the entire body surface of the stars. However, these cells project past the calcite structures, which apparently are not acting as microlenses, as previously thought. The projecting photoreceptors are thus not eyes in the sense of image-forming vision. Rather, the opsin-containing cells detect high-contrast light changes, evidently to coordinate shade-seeking, predator avoidance, and color-changing reflexes.

    Proc. R. Soc. B 285, 20172590 (2018).

  4. Lung Disease

    COPD risk: Clues from the tree branches

    1. Paula A. Kiberstis

    Chronic obstructive pulmonary disease (COPD) is estimated to affect 250 million people worldwide. Smoking is a major risk factor, but intrinsic host factors likely also play a role. Smith et al. hypothesized that variations in central airway tree branching might affect COPD risk. They studied large multiethnic populations by chest computed tomography (CT) and found variant branching patterns in one-quarter of the study participants. Certain branch variants were associated with COPD susceptibility and with broad structural changes in the lungs. Thus, variations in central airway anatomy detected by CT scans could potentially identify individuals at risk of COPD. Whether such scans will prevent COPD and/or improve patient care will require future longitudinal studies.

    Proc. Natl. Acad. Sci. U.S.A. 10.1073/pnas.1715564115 (2018).

  5. Education

    Chemistry assessments go 3D

    1. Melissa McCartney

    Student assessments should support meaningful learning while supplying faculty with information about what students know. Underwood et al. provide an evidence-based approach to modifying typical assessment questions to align them with the three-dimensional learning framework of the Next Generation Science Standards. Specifically, the Three-Dimensional Learning Assessment Protocol (3D-LAP) can be used to help identify the core concept of the assessment question (core idea), the criteria to evaluate students' ability to use this knowledge (scientific practices), and how that knowledge can relate to other science disciplines (crosscutting concepts). The 3D-LAP enables faculty to adapt their existing assessments to elicit stronger evidence about what students know and can do, ultimately making this process easier and less time-consuming than designing questions from scratch.

    J. Chem. Educ. 10.1021/acs.jchemed.7b00645 (2017).

  6. Immunotherapy

    Monocytes may shed light on melanoma therapy

    1. Priscilla N. Kelly

    Checkpoint blockade immunotherapy has shown considerable promise for the control of metastatic melanoma. Despite the success stories, there are still many patients who do not respond at all. Thus, identification of molecular markers to predict which patients could have beneficial treatment outcomes is key. Krieg et al. used high-dimensional single-cell mass cytometry to analyze the peripheral blood of melanoma patients. Samples were analyzed before and after the patients' 12-week course of treatment with PD-1 immunotherapy. Those patients who responded better had increased activation and frequency of monocytes (defined as CD14+CD16HLA-DRhi cells) in their blood before starting treatment. The researchers propose that monocyte profiling could be used to stratify patients before commencing PD-1 immunotherapy.

    Nat. Med. 10.1038/nm.4466 (2018).

  7. Drug Delivery

    Synergistic approach to localized delivery

    1. Marc S. Lavine

    An improved remedy for osteoarthritis could involve localized delivery of an agent to the affected joints to reduce the disease progression, rather than the current use of systemic or local delivery of drugs that only treat the symptoms. Maudens et al. explored the potential for long-term delivery of kartogenin, a pathway activator that enhances articular cartilage protection, by combining two ideas for slow drug release. Using wet milling, they prepared nanocrystals of kartogenin, which dissolve over time, and then embedded them in biodegradable polymer microparticles. The drug-loaded particles were tested in vitro with human synoviocytes and in vivo in a mouse model, in which prolonged delivery and bioactivity of kartogenin were observed.

    Small 10.1002/smll.201703108 (2018).