Editors' Choice

Science  18 Aug 2017:
Vol. 357, Issue 6352, pp. 657
  1. Plant Science

    Breathing in the dark

    1. Pamela J. Hines

    Pineapple's water-thriftiness genes could help other crops.

    PHOTO: NARVIKK/ISTOCK

    Plants that use crassulacean acid metabolism (CAM) are often succulents. They tend to be drought-tolerant and thrifty with water. Thus, the CO2 uptake pores, or stomata, on the leaves are open during the cool nighttime when evapotranspiration rates are lower. Nonetheless, CAM is found in only a minority of plants. Wai et al. have mapped how the genes underlying CAM are deployed in the pineapple, with an eye toward transferring CAM and its attendant water use efficiency into other crop plants. Expression of key enzymes and regulatory microRNAs varied according to time of day. Sucrose was transported from source to sink in the morning, and at night, sucrose transport occurred in the opposite direction.

    Plant J. 10.1111/tpj.13630 (2017).

  2. Organic Chemistry

    A phenyl ring hops with a light step

    1. Jake Yeston

    It is generally rather difficult to break bonds connecting alkyl and aryl carbons. Shu et al. show that blue light and a nearby nitrogen can smooth the way. Specifically, they use a base and a light-activated iridium catalyst to deprotonate and oxidize a γ-diarylamine. The nitrogen can then reach around and swipe one of the aryl rings, which can be replaced by hydrogen, bromine, or a carbon center in a variety of Michael acceptors. The reaction proceeds at room temperature when irradiated by light-emitting diodes.

    Angew. Chem. Int. Ed. 10.1002/anie.201704068 (2017).

  3. Galaxy Evolution

    Heavy elements are intergalactic travelers

    1. Keith T. Smith

    The Crab Nebula, a remnant of a supernova

    PHOTO: STOCKTREK IMAGES/ALAMY STOCK PHOTO

    All elements heavier than helium are made in stars, which can eject them in a supernova explosion. In small dwarf galaxies, a single supernova has enough energy to completely expel enriched gas out of the galaxy and into the intergalactic medium. Anglés-Alcázar et al. have used hydrodynamic simulations to quantify how much of that gas later falls into another galaxy. This process preferentially transfers gas to larger galaxies, owing to their stronger gravity. For a galaxy such as our Milky Way at the present day, around half of its stars were formed from gas enriched in other galaxies. Given that Earth is made of these heavy elements, we are all part intergalactic travelers.

    Mon. Not. R. Astron. Soc. 470, 4698 (2017).

  4. Flexible Electronics

    Wired-up wash and go

    1. Marc S. Lavine

    A range of approaches have emerged for making flexible electronics and for their inclusion into textiles and fabrics. One challenge common to all those approaches is to make the conducting fibers robust enough to survive extensive usage, including the need to wash the fabrics on a regular basis. Le Floch et al. address that challenge by combining a hydrogel that provides flexibility, a hygroscopic salt that enables ionic conduction at fixed humidity, and an outer coating of butyl rubber to retain the water level of the hydrogel. A silane condensation reaction makes it possible to dip-coat the butyl rubber coating. Cyclical stretching of the fibers in a detergent solution and several machine washing cycles caused little change in the fiber conductivity.

    ACS Appl. Mater. Interfaces 10.1021/acsami.7b07361 (2017).

  5. Plant Science

    Protection by a parasitic plant

    1. L. Bryan Ray

    The parasitic Cuscuta plants do not have roots; instead, they adhere to host plants and draw water and nutrients from them. Cuscuta spp. form multiple bridges between plants that can even link different species of host. Far from devastation ensuing, Hettenhausen et al. found that the interconnections can be of benefit to the hosts. This is because, when under attack by insects, a leaf initiates systemic signaling processes that help protect the other leaves of the plant. These signals can also pass through the bridges made by the Cuscuta parasite to confer insect resistance to plants that have not yet been targeted by insects. The signaling molecules that are transferred are not yet known, but the process depends in part on production of the plant hormone jasmonic acid.

    Proc. Natl. Acad. Sci. U.S.A. 10.1073/pnas.1704536114 (2017).

  6. Cancer Chemotherapy

    Bugs and drugs: A work in progress

    1. Paula A. Kiberstis

    Gut microbes possibly influence not only the development of many human diseases, but also how these diseases respond to treatment. In tumor models, for example, gut microbes can modulate the efficacy and toxicity of chemotherapeutic drugs through their effects on drug metabolism or on the immune system. Yu et al. report that gut microbes can alter tumor chemosensitivity by rewiring tumor-cell signaling. In cell and mouse models of colorectal cancer, the Fusobacterium nucleatum promotes tumor resistance to 5-fluorouracil and oxaliplatin. The bacterium causes tumor cells to switch signaling from apoptosis to autophagy, thereby allowing them to escape the drugs' cytotoxic effects. The clinical significance of this intriguing mechanism remains to be studied.

    Cell 170, 548 (2017).

  7. Paleogenomics

    Human spit contains ancestral surprises

    1. Laura M. Zahn

    Non-African modern humans retain a limited genetic signature from ancestral hybridization events that occurred ∼60,000 years ago. Extinct archaic hominoids, such as Neandertals and Denisovans, appear to have had relations with anatomically modern humans. Some researchers have postulated that other archaic lineages may be found within the genomes of modern humans. For example, Xu et al. analyzed the extent of human variation of the MUC7 gene, which encodes a protein found at high levels in saliva. One variant appears to have originated in an unknown ancestor before the human-Neandertal split and is retained at high levels in modern people of sub-Saharan African descent.

    Molec. Biol. Evol. 10.1093/molbev/msx206 (2017).