Editors' Choice

Editors' Choice

Science  10 Mar 2017:
Vol. 355, Issue 6329, pp. 1036
  1. Ebola

    Superspreaders are local and disproportionate

    1. Caroline Ash

    Ebola virus isolated from patient blood samples

    PHOTO: NIAID

    Certain individuals, known as superspreaders, disproportionately infect more people with disease-causing organisms than the average infectious case. Lau et al. identified key drivers of Ebola virus (EBOV) superspreading during the 2014 West Africa outbreak. Unexpectedly, secondary cases largely did not transmit tertiary cases; thus, epidemic growth was fueled and sustained by a few superspreaders, and transmission occurred locally, within 2.5 km of the source. Community-based EBOV cases progressed more rapidly than those identified in clinical care settings. The most infectious age groups tended to be the young or people over 45 years old, which may reflect social structure, such as the intimacy of care needs, or immunological factors. This work helps to identify the most vulnerable groups and provide parameters for control efforts in future outbreaks of EBOV.

    Proc. Natl. Acad. Sci. U.S.A. 10.1073/pnas.1614595114 (2017).

  2. Cancer Therapy

    Exploiting cancer metabolism

    1. Lisa D. Chong

    Cancer-specific cell surface proteins can be targeted for the delivery of therapeutic agents. However, specific proteins may not always be expressed by a tumor. Wang et al. overcome this challenge by designing sugars to selectively label cancer cells. Small-molecule sugars (azides) can be metabolized by enzymes that are highly expressed in some tumors, including colon and breast cancer cells. Metabolized azides labeled endogenous cell surface proteins in cultured cancer cells and tumor-bearing mice. The azide moiety on the labeled proteins was subsequently recognized by another molecule carrying a drug, which was taken up by the cancer cells. Tumor growth was reduced, and animal survival improved by 86%.

    Nat. Chem. Biol. 10.1038/nchembio.2297 (2017).

  3. Diversity

    STEM = masculine + feminine

    1. Melissa McCartney

    Gender inequalities in science, technology, engineering, and mathematics (STEM) are well documented, but the underlying causes leading to these inequalities are less studied. To test the association between masculinity or femininity and choosing a STEM major, Simon et al. surveyed students at a major public university, using questions regarding academic climate and occupational values coupled with the Bem sex-role inventory, a widely used measure of gendered personality types. Resulting data suggest that the conventional model that men like science because it is “masculine,” whereas women do not like science because it is “antifeminine,” is flawed. Instead, results show that women pay a femininity penalty in STEM majors, whereas more abundant feminine personality traits in men render them more likely to major in a STEM field.

    J. Res. Sci. Teach. 10.1002/tea.21345 (2017).

  4. Psychology

    Sampling online workers globally

    1. Gilbert Chin

    Historically, experimental psychologists have relied heavily on undergraduates for their subject pool; over the past decade, they have recruited subjects online, employing people colloquially termed MTurkers through the Amazon Mechanical Turk website. Over the years, MTurkers have become so familiar with online surveys that there are concerns about the representativeness and reliability of these participants. Peer et al. compared MTurk with two other crowdsourcing sites, CrowdFlower and Prolific Academic. The latter two sites produced participants who were less familiar with the kinds of tasks assigned (good) but also less attentive to instructions (bad), and they had more European participants. In terms of reliability and reproducibility, Prolific Academic scored higher than CrowdFlower and about the same as MTurk.

    J. Exp. Soc. Psychol. 70, 153 (2017).

  5. Embryogenesis

    Breaking embryo symmetry

    1. Beverly A. Purnell

    Loss of cleavage symmetry in the early embryo

    PHOTO: E. KOROTKEVICH ET AL., DEV. CELL 40, 235 (6 FEBRUARY 2017) © ELSEVIER

    For the first few cleavages, cells of the mammalian embryo are considered identical. Subsequently, symmetry is broken to generate the inner cell mass, which specifies the embryo proper, or the extraembryonic trophectoderm. Korotkevich et al. used live imaging to visualize miniblastocysts generated from single 8-cell–stage blastomeres. The mitotic spindles of mini-blastocysts aligned along the apico-basal axis. The polar cell containing the apical domain, which expresses Cdx2, enveloped the apolar sister to adopt a trophectoderm fate. Transplantation of the apical domain showed that it is required and sufficient for the first lineage segregation. It is not yet known whether surface adhesion molecules or mechanical differences affect the assembly of the apical domain for subsequent lineage segregation.

    Dev. Cell. 40, 235 (2017).

  6. Biophysics

    The benefits of being young

    1. Marc S. Lavine

    In addition to chemical cues, the differentiation of stem cells can be influenced by mechanical forces, such as the stiffness of the underlying substrate, but these effects diminish with age. Barreto et al. compared the differentiation of mesenchymal stromal cells from donors aged 11 to 12 years and from young adults aged 20 to 30 years, when the skeleton has fully matured. The juvenile cells showed greater mechanosensitivity and enhanced angiogenesis and osteogenesis. From an examination of a number of growth factors, the authors found a key role for the protein JNK3, which might serve as a target for restoring the potential for regeneration in adults suffering from bone degeneration to that found in youth.

    Acta Biomater. 10.1016/j.actbio.2017.02.031 (2017).

  7. Optics

    A time to polarize the unpolarized

    1. Ian S. Osborne

    Wavelength, intensity, and polarization are several parameters that define a light field. Light from most natural and many artificial light sources is unpolarized. However, an instantaneous snapshot of a propagating light field shows that it may be completely polarized. Shevchenko et al. propose and demonstrate experimentally that there is a finite window of time for that snapshot in which the unpolarized light is polarized. Using a Michelson interferometer with polarization- sensitive components combined with two-photon absorption detectors, they show for two different unpolarized light sources that the polarization time window varies from 10 to 100 fs. The effect of a finite polarization time could be exploited in a number of applications such as communication and sensing.

    Optica 4, 64 (2017).