Editors' Choice

Science  24 Apr 2015:
Vol. 348, Issue 6233, pp. 409
  1. Applied Optics

    A stretch to change color

    1. Ian S. Osborne

    The structured surface of a leaf beetle carapace diffracts light to produce spectacular colors


    The reflection of white light from structured surfaces often results in a spectacular display of color as the white light is split into its different wavelengths through diffraction. Structure gives rise to the intense iridescent colors that distinguish some members of the animal kingdom, such as beetles and butterflies. Human-made materials, such as DVD or CD surfaces, also diffract light into a rainbow. Zhu et al. combine surface structure with membrane flexibility to show that they can locally select the color of reflected light, as they stretch the membrane and change the periodicity of the structure. This technique could be used in a range of applications, including camouflage coatings, optical sensing and steering, and displays.

    Optica 2, 255 (2015).

  2. Cellular Biomechanics

    The mechanics of cellular left and right

    1. Monika S. Magon

    Cells need to know their own left and right in order to coordinate with neighboring cells in collective movement or embryonic development. To do so, each cell has to establish left/right asymmetry. Tee et al. studied actin organization in human cells to understand underlying mechanisms, using fluorescence and electron microscopy and simulations. Actin fibers forming the cellular skeleton rearranged from a symmetric to an asymmetric pattern through interplay between two types of fibers. The fibers stretching along the cell edge swirled towards the center, whereas the radially assembled fibers tilted unidirectionally. The contractile stress and rotational growth of the fibers drove the motions, while an actin cross-linking protein controlled the clockwise or anticlockwise directionality.

    Nat. Cell Biol. 10.1038/ncb3137 (2015).

  3. Social Psychology

    Stereotyping sticks

    1. Gilbert Chin

    Perception of angry faces is shaped by stereotypes


    A person better remembers faces of people who are members of one's own group—as defined, for instance, by sex or race—than of those who belong to an outgroup. An angry expression might reduce this difference, because threatening stimuli capture one's attention. Alternatively, it might increase the difference were it to trigger stereotyping. In a careful study using white and black faces and undergraduates, Gwinn et al. show that both white and black students better remembered individual neutral black faces than angry black faces, whereas their memories for angry and neutral white faces were similar, consistent with a stereotypical association of black faces and threat in the United States.

    J. Exp. Soc. Psychol. 58, 1 (2015).

  4. Materials Science

    Ordering up just the right temperature

    1. Marc S. Lavine

    One typically thinks of glassy or amorphous materials as having little of the order or structure that is found in a crystal. However, the molecules of organic glasses deposited from the vapor phase, like those that form the active layer in a light-emitting diode or solar cell, can show a preferential molecular orientation. Dalal et al. use high-throughput screening to show that the quality of this orientation can be tuned through control over the substrate temperature during deposition, which influences the molecular mobility at the surface. This ability may give a simple route to optimizing active layers in organic electronics, because the molecular orientation can affect light emission, charge mobility, and device lifetimes.

    Proc. Nat. Acad. Sci. 10.1073/pnas.1421042112 (2015).

  5. Cell Differentiation

    Differentiating blood stem cells

    1. Beverly A. Purnell

    Hematopoietic stem cells (HSCs), which generate all blood cell types, contain hundreds of long noncoding RNAs (lncRNAs). Luo et al. identify 159 lncRNAs that are likely to be HSC-specific (lncHSCs) through deep RNA sequencing of primitive long-term HSCs from mouse bone marrow. As HSC function decreases with age, lncHSCs show reduced expression. Furthermore, like HSC-specific protein genes, promoters of lncRNAs are bound specifically by HSC transcription factors for regulated expression. Analysis of two specific lncRNAs reveals a role for lncHSC-1 in myeloid differentiation and lncHSC-2 involvement in HSC self-renewal and T cell differentiation. Analysis of the many other HSC-specific lncRNAs is likely to reveal varied mechanisms in regulating the self-renewal and differentiation of blood types.

    Cell Stem Cell 10.1016/j.stem.2015.02.002 (2015).

  6. Neurodevelopment

    Catching it early

    1. Pamela J. Hines

    Differences in language maps of young autistic brains predict future abilities


    Communication difficulties associated with autism spectrum disorders (ASD) vary, making treatment more difficult. To anticipate language capability among those with ASD, Lombardo et al. used functional magnetic resonance imaging to analyze responses of toddlers to language during sleep. In individuals who later displayed poor language development, the superior temporal cortex responded differently than in individuals with better language development. Linkages between large-scale brain systems, such as those driving emotion, reward, and motor function, were atypical in toddlers with poor language outcomes. For those with better language outcomes, brain systems were at first abnormal but later normalized. Given the variation in severity of ASD, this early identification could inform ongoing treatments.

    Neuron 10.1016/j.neuron.2015.03.023 (2015).

  7. Subsurface Microbes

    Generating archeal diversity

    1. Nicholas S. Wigginton

    Retroelements—gene sequences that are introduced into DNA through an RNA intermediate—in subsurface archaea help increase gene and protein diversity. Paul et al. identified an archeal virus from a methane seep in a California borderlands basin that contains a complete and active diversity-generating retroelement (DGR). Furthermore, published metagenomes of two uncultivated nanoarchaea from the marine subsurface contain at least four DGRs, more than any other bacteria or virus known to date. Because anaerobic archaea in the subsurface grow so slowly, and thus have low background genome mutations, DGRs may be a widespread source of genetic diversity in these environments.

    Nat. Comm. 10.1038/ncomms7585 (2015).

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