Editors' Choice

Editors' Choice

Science  12 Jan 2018:
Vol. 359, Issue 6372, pp. 173
  1. Cell Biology

    Seeing the real thing

    1. Stella M. Hurtley

    Colorized view of the Golgi complex surrounded by COPI-coated vesicles and other organelles

    CREDIT: Y. S. BYKOV ET AL., ELIFE 10.7554/ELIFE.32493 (2017)

    Membrane trafficking within the Golgi complex is mediated by COPI (coat protein complex I)-coated vesicles. Much is known about these vesicles and coats from in vitro studies, but their makeup in situ is less well understood. Bykov et al. used cryo-electron tomography of vitrified Chlamydomonas reinhardtii cells to analyze COPI-coated vesicles directly. The native algal structure resembled a previously described structure of in vitro reconstituted mammalian COPI-coated vesicle, but it also revealed bound cargo. The observations suggest that coat components disassemble simultaneously shortly after vesicle budding. The distribution of vesicles around the morphologically polarized Golgi complex allowed the authors to parse out the stage of vesicles in the transport pathway. The COPI-coated vesicles increased in size as they progressed from cis to trans Golgi compartments, and the density of their cargoes varied. Nevertheless, the structure of the coat machinery itself remained the same.

    eLife 10.7554/eLife.32493 (2017).

  2. Cancer

    A death knell for relapsed leukemia?

    1. Paula A. Kiberstis

    A subset of patients with acute myeloid leukemia (AML) experience partial or even complete remissions after treatment with conventional chemotherapeutic drugs. Almost invariably, however, the disease returns and is often fatal. Relapse has been attributed to the expansion of preexisting leukemic clones that are resistant to therapy. In a preclinical study, Pan et al. investigated whether better efficacy might be achieved by using a class of drugs that work by inducing apoptotic cell death. They found that mice with drug-resistant AML showed dramatically extended survival after treatment with a combination of two drugs that promote apoptosis by distinct mechanisms. This combination therapy of venetoclax (a Bcl-2 inhibitor) and idasanutlin (a p53 activator) is now in clinical trials for relapsed AML.

    Cancer Cell 32, 748 (2017).

  3. Agriculture

    Multiple strategies needed to improve agricultural productivity

    1. Pamela J. Hines

    Shifts in behavior and process will facilitate the integration of organic farming as a large-scale, sustainable agricultural approach.

    PHOTO: DON KLUMPP/ALAMY STOCK PHOTO

    The world will need 50% more agricultural output by 2050 to keep up with global population growth. Muller et al. ask whether organic agriculture is compatible with producing enough food to feed the world in a sustainable manner. Analysis of various production and environmental factors showed the pluses and minuses of large-scale organic farming. Organic farming needs more land than conventional farming, although that need could be counterbalanced if food waste and demand for animal products were reduced. An anticipated deficiency in nitrogen supply could be ameliorated by recycling and by using legumes and crops optimized for nitrogen-use efficiency. Thus, organic farming could be part of a strategy that includes shifts in diet, reductions in food waste, and changes in crops to move toward an agricultural system that is both more productive and more sustainable.

    Nat. Comm. 10.1038/s41467-017-01410-w (2017).

  4. Education

    Labs, lectures, and gender differences

    1. Melissa McCartney

    Gendered performance differences (GPDs) remain an issue in ensuring equitable access in science, technology, engineering, and mathematics (STEM). Matz et al. systematically measured performance gaps across STEM courses to further investigate the contribution of GPDs to performance and/or persistence in STEM. This report is the first wide-ranging, multi-institution assessment of GPDs, encompassing more than a million student enrollments at five universities. Controlling for factors relating to academic performance, the team found evidence that GPDs in many courses were statistically significant and consistent from term to term. GPDs in STEM lecture courses tended to favor men, although these differences were not seen in the corresponding laboratory courses, suggesting further research is needed on the structure and evaluative schemes of STEM lecture courses.

    AERA Open 10.1177/2332858417743754 (2017).

  5. Gene Therapy

    CRISPR corrects deafness in mice

    1. Priscilla N. Kelly

    Limited treatment options are available for individuals with hereditary hearing loss. CRISPR-Cas9 editing can be used as molecular scissors that snip out mutant DNA sequences to permit gene repair. Gao et al. asked whether the Cas9 cutting enzyme could be used to correct genetic deafness caused by dominant mutations in the Tmc1 gene. The researchers performed a lipid-mediated delivery of Cas9-RNA complexes to the inner ear of neonatal mice. They were able edit the mutant Tmc1 gene within the cochlear hair cells that sense acoustic vibrations. Mice showed signs of improved cochlear function and hearing restoration.

    Nature 10.1038/nature25164 (2017).

  6. Biomaterials

    Make no bones about titanium

    1. Marc S. Lavine

    Titanium and its alloys with aluminum or niobium have been used for medical implants, such as metal plates to hold fractured bones together, because titanium bonds well to bone. However, pure titanium is much stiffer than bone material, and it can shield the surrounding bone from normal loads and stresses. This causes the bone to weaken because remodeling depends on stress history. Takizawa et al. compressed and sheared titanium fibers to make plates with the same elastic modulus of bone cortex. By being porous, these plates become suitable scaffolds for cell infiltration and bone repair. In vivo studies in rabbits showed that the plates could help immobilize small bone fragments, without the risk of leaching niobium or aluminum into the host.

    Adv. Mater. 10.1002/adma.201703608 (2017).

  7. Framework Catalysis

    Shifting zwitterion reactivity

    1. Phil Szuromi

    Phosphines are often ligands for transition metal catalysts, but they can catalyze reactions at unsaturated carbon atoms by forming phosphonium zwitterions. For example, triphenylphosphine forms a zwitterion with methylvinylketone that acts as a nucleophile to convert n-alkyl aldehydes to β-hydroxy enones (the Morita-Baylis-Hillman reaction). Bauer et al. show that when the reaction is conducted in metal-organic framework compounds with linkers bearing amino groups, rather than in solution, the phosphonium zwitterion can act as an electrophile. The products—1- and 3-n-alkylesters of 2-alkyl-1,3-diols—form through the Aldol-Tishchenko reaction.

    J. Am. Chem. Soc. 10.1021/jacs.7b10928 (2017).