Editors' Choice

Science  04 May 2018:
Vol. 360, Issue 6388, pp. 504
  1. Foraging Ecology

    Winter can be hard

    1. Sacha Vignieri

    Changes in climate affect the abundance of red-legged kittiwakes.

    PHOTO: NICK PECKER/SHUTTERSTOCK.COM

    The largest breeding colony of the red-legged kittiwake, an Arctic seabird, has undergone drastic declines and recovery over the past 40 years. It has been assumed that these changes have been driven by climate-induced shifts in food supply during breeding. Will et al. examined feathers collected from living birds and museum specimens to characterize isotopic signatures (which give a picture of food intake) and corticosterone levels (which relate to stress) over a 100-year period. They found that birds were less stressed when oceanic conditions in the eastern Pacific were warmer in both summer and winter and when sea ice was less extensive in the winter. Further, during years with more extensive ice, nitrogen isotope levels were higher, potentially indicating a higher reliance on energy stores. These results suggest that climate variability can directly affect population size and persistence and that winter conditions are important to reproductive success.

    Mar. Ecol. Prog. Ser. 10.3354/meps12509 (2018).

  2. Immunology

    Watching the clock in asthma

    1. Seth Thomas Scanlon

    Asthma symptoms often show variations based on circadian rhythms. Ehlers et al. report that mice missing a functional circadian clock (Bmal1−/−) are more susceptible to acute bronchiolitis and chronic asthma-like inflammation after infection with Sendai virus. Similar, though less potent, effects were observed when wild-type mice were subjected to a chronic jet lag model. Concordantly, airway cells from human asthmatics show altered clock gene expression patterns. The disruption of circadian rhythms alters interferon-related antiviral responses and enhances the M2 macrophage phenotype. Thus, one way that the circadian clock may play a role in some forms of asthma is by regulating immune responses to respiratory viral infections. Still uncertain is the role of these genes in other forms of the disease, including atopic asthma.

    Mucosal Immunol. 11, 97 (2018).

  3. Neuroscience

    Synaptic downscaling during “up” states

    1. Peter Stern

    During slow-wave sleep, cortical networks oscillate between periods of high activity, known as “up” states, and quieter periods, known as “down” states. González-Rueda et al. compared synaptic plasticity during up and down states in the mouse barrel cortex during slow-wave sleep–like cortical dynamics. They studied connections between cortical layers 4 and 2/3 in young animals at postnatal days 16 to 21. This age corresponds to the end of the critical period of development of these synapses. Plasticity rules were modulated by up states: Spike timing–dependent synaptic potentiation was absent, and active synapses failing to contribute to postsynaptic spiking were selectively depressed. This synaptic down-scaling mechanism promotes the elimination of weak and the preservation of strong synapses, thus enhancing the signal-to-noise ratio.

    Neuron 97, 1244 (2018).

  4. Cell Biology

    Mitochondria fight Toxoplasma for fat

    1. Stella M. Hurtley

    Toxoplasma parasites (blue), shown here in their encysted stage within liver tissue, compete with mitochondria for lipids.

    CREDIT: MOREDUN SCIENTIFIC LTD./SCIENCE SOURCE

    Mitochondria provide platforms for innate immunity. The intracellular parasite Toxoplasma gondii infects almost 50% of individuals in western countries and up to 90% in developing countries. Pernas et al. wanted to understand the role of mitochondrial morphology in the control of Toxoplasma growth. They discovered that parasite-infected cells displayed a marked reduction in host lipid droplets caused by Toxoplasma-induced droplet autophagy (lipophagy). Fatty acid flux analysis revealed the path of fatty acids from the droplets to the Toxoplasma-containing vacuole. Elongated mitochondria congregated around the vacuole and competed with Toxoplasma for the lipophagy-liberated fatty acids. When mitochondria could not fuse and elongate, or could not oxidize fatty acids, parasite growth was enhanced.

    Cell Metab. 27, 886 (2018).

  5. Education

    You can't be what you can't see

    1. Melissa McCartney

    Identity-based motivation theory, which explains how people's identities motivate them, is relevant in science, technology, engineering, and mathematics (STEM) education because the STEM professoriate traditionally leans male. Most research on this topic focuses on student achievement outcomes. Solanki and Xu instead examined the relationship between instructor gender and student nonperformance outcomes, such as behavioral engagement, academic self-efficacy, interest, and utility value. Pre- and post-experience surveys from STEM gateway courses were analyzed, revealing a reduction in the gap between female and male students' course engagement and attitudes toward a STEM subject when a course was taught by a female instructor. Additionally, both female and male students were found to respond to instructor gender. Future studies should focus on understanding the variables underlying these behaviors.

    Am. Educ. Res. J. 10.3102/0002831218759034 (2018).

  6. Porous Materials

    Metallacycles in carbon supports

    1. Phil Szuromi

    Metallacycles are large organometallic rings in which metal complexes coordinate ligand assembly. The assembly process is dynamic, so, although convenient, these compounds can reassemble into larger, unwanted aggregates. Chen et al. found that a metallacycle formed from an acceptor ligand bearing platinum end groups and a donor bearing a porphyrin group was more stable when assembled within a mesoporous carbon material. The dispersion of the metallacycle was evidenced by a sixfold increase in singlet oxygen production for the porphyrin group compared with the free metallacycle in solution.

    J. Am. Chem. Soc. 10.1021/jacs.8b02386 (2018).

  7. Chemistry

    Reusable protein-based sensors

    1. Marc S. Lavine

    Targeted sensors for ions, molecules, proteins, or DNA can be made by immobilizing specific biomolecules onto a surface. However, it can be difficult to control the surface patterning or reversibly deposit the target molecules, which would allow for reusable surfaces. Ananth et al. selectively immobilized proteins onto silica-covered flat or porous surfaces, with control over orientation and surface density, by incorporating polyhistidine tags into the target proteins. The anchoring is reversible, as demonstrated by real-time switching. For devices that contain both gold and silica surfaces, the authors show that they can passivate the gold by using thiol chemistry while selectively coating the silica with the desired target molecules.

    Small 10.1002/smll.201703357 (2018).