Editors' Choice

Science  06 Mar 2015:
Vol. 347, Issue 6226, pp. 1110
  1. Metabolic Engineering

    Making biofuels greener

    1. Nicholas S. Wigginton

    Plant biomass, rich in hemicellulose, can be converted by microorganisms into ethanol for use as biofuel. However, some materials derived from plant cell walls, including sugars such as xylodextrin, are more difficult for microorganisms to metabolize, making the overall biofuel production process less efficient. Li et al. characterized a widely distributed xylodextrin consumption pathway from the fungus Neurospora crassa that is required for its growth on hemicellulose. Engineering this pathway into yeast produces previously unknown intermediate metabolites from xylodextrin that are then broken down to xylose and xylitol and fermented to ethanol.

    eLife 10.7554/eLife.05896#sthash.pkIMD1GC.dpuf (2015).

  2. Eye Development

    Eye development from both sides

    1. Beverly A. Purnell

    In vertebrates, eye development begins with the outgrowth of the optic vesicle from the brain. The optic vesicle then transforms into a bilayered structure called the optic cup after extensive morphological movements, which scientists do not completely understand. In order to visualize these events, Heermann et al. used four-dimensional in vivo microscopy to track the movements of cells in the eyes of developing zebrafish. They found that cells from both sides of the optic vesicle generate the neuroretinal layer of the optic cup, rather than just the side that faces the lens as previously thought. The growth factor bone morphogenic protein facilitated this process.

    eLife 4, e05216 (2015).

  3. Evolution

    Wisdom of the elders

    1. Sacha Vignieri

    Older female killer whales provide a fitness advantage to their kin

    PHOTO: © JOHN HYDE/DESIGN PICS/CORBIS

    Menopause is something that humans share with only two other mammal species: killer whales and pilot whales. Menopause is at odds with classic evolutionary theory, which posits that once animals stop reproducing, natural selection stops too. However, Brent et al. now demonstrate the importance of keeping elders around. They found that older female killer whales lead their pods to salmon feeding grounds and that this leadership is especially important in years when food is scarce. Thus, older females can act as crucial repositories of ecological knowledge, improving their own inclusive fitness and the fitness of their younger relatives.

    Curr. Biol. 10.1016/j.cub.2015.01.037 (2015).

  4. Medical Imaging

    A clearer view of type 1 diabetes

    1. Paula A. Kiberstis

    Nanoparticles help to visualize pancreatic inflammation in people with type 1 diabetes

    PHOTO: J. L. GAGLIA ET AL., PNAS 112, 7 (17 FEBRUARY 2015) © NATIONAL ACADEMY OF SCIENCES

    Pancreatic beta cells keep blood glucose levels in check by secreting insulin, which removes glucose from blood. In type 1 diabetes, beta cells stop functioning because the immune system destroys them. Noninvasive imaging of pancreatic inflammation—an early sign of this immune attack—could provide scientists with new insights into how the disease begins and progresses. In a pilot study, Gaglia et al. used magnetic resonance imaging to generate three-dimensional high-resolution maps of pancreatic inflammation in patients with recent-onset type 1 diabetes. Key to their success was an imaging agent called ferumoxytol, a clinically approved magnetic nanoparticle taken up by macrophages.

    Proc. Natl. Acad. Sci. U.S.A. 112, 2139 (2015).

  5. Biofuels

    Starting out by making the most of lignin

    1. Jake Yeston

    The woody lignin component of biomass, rich in aromatic carbon rings, ultimately could prove a cost-effective source of numerous commodity chemicals. Parsell et al. make a step in that direction with a zinc and palladium catalyst that transforms lignin into a tractable product stream composed predominantly of two phenol derivatives. These in turn can be further transformed by downstream chemistry. The method does not require preliminary isolation of the lignin; rather, it works on minimally pretreated biomass and leaves behind a cellulose component that's easily broken down into fermentable sugars for biofuels production.

    Green Chem. 10.1039/c4gc01911c (2014).

  6. Viral Spread

    Enteroviruses have got to hitch a ride...

    1. Stella M. Hurtley

    Viruses are thought to come in two flavors: enveloped—surrounded with a membrane like the cells they infect, or non-enveloped—naked protein and nucleic acid particles that can invade target cells. However, it now seems that non-enveloped viruses might nevertheless sneakily co-opt host cell membranes to help them spread from cell to cell. Chen et al. now show that cells release clusters of newly synthesized enteroviruses, including poliovirus, coxsackievirus B3, and rhinovirus, into the extracellular environment within lipid vesicles. Compared with free viruses, the enclosed viruses do a better job of infecting new cells.

    Cell 160, 619 (2015).

  7. Climate Change Ecology

    Long-term warming and vegetation change

    1. Andrew M. Sugden

    How climate change specifically affects ecosystems can be difficult to sort out. To determine cause and effect, Harte et al. examined changes to vegetation and soil in plots of land in the U.S. Rocky Mountains that they either warmed experimentally or left untouched (ambient) over 23 years. They found that both experimental warming and the natural warming of the Rockies over that time period led to a shift from herbaceous meadow to woody shrub vegetation. Soil carbon declined, too (although in both cases more slowly in the ambient plots). These results demonstrate that climate change caused the observed vegetation and soil changes.

    Global Change Biol.10.1111/gcb.12831 (2015).