Editors' Choice

Science  08 Jan 2021:
Vol. 371, Issue 6525, pp. 138
  1. Marine Ecology

    Turbulent relationships

    1. Andrew M. Sugden

    Copepods use pheromone trails and hydrodynamic signals to track down females under turbulent conditions.

    IMAGE: D.P. WILSON/FLPA/SCIENCE SOURCE

    Surface water in oceans and estuaries can be a turbulent habitat, posing challenges for the tiny and abundant organisms of the plankton. In a series of experiments and modeling studies, Michalec et al. investigated how planktonic copepods, the abundant and ubiquitous components of marine zooplankton, manage to find mates in turbulent conditions. Under calm conditions, male copepods locate females by pheromonal trails, but in turbulent conditions, these trails are broken. Using a three-dimensional particle tracking technique, the authors show that males can differentiate between hydrodynamic signals generated by a nearby female and those generated by turbulence. Determined swimming then leads to successful mating.

    eLife 9, e62014 (2020).

  2. Synthetic Biology

    A microfactory in yeast peroxisomes

    1. Valda Vinson

    Considerable synthetic biology efforts are focused on engineering yeast to produce valuable metabolites. Production in the cytosol can be challenging because of toxicity or crosstalk with cellular pathways. Dusséaux et al. harnessed the yeast peroxisome to produce geranyl diphosphate (GPP), a precursor to monoterpenoids, monoterpene indole alkoids, and cannabinoids. Targeting the entire pathway for GPP synthesis, along with an enzyme that converts GPP to the monoterpene limonene, to the peroxisome gives a 125-fold improvement in yield of limonene compared with production in the cytoplasm. Additional monoterpenes can be synthesized with the same platform using the appropriate monoterpene synthase. Peroxisomal production also facilitates downstream processing involving oxidation by cytochrome P450 enzymes. Peroxisome microfactories could be used for the modular assembly and optimization of other complex pathways.

    Proc. Natl. Acad. Sci. U.S.A. 117, 31789 (2020).

  3. Scientific Workforce

    Keep calm and measure the gap

    1. Melissa McCartney

    Academic conferences are fertile ground for data collection on gender inequities, owing to their importance in career development, networking, and increasing visibility. Corona-Sobrino et al. developed a tool based on performance indicators that allows for real-time monitoring and evaluation of gender roles and inequalities at academic conferences. In developing the tool, three relevant perspectives (participation, organizational structure, and attitudes) were identified, along with a specific list of performance indicators for each, allowing for both individual and combined analysis. Results are shown as a traffic light visualization, with red meaning bad and green meaning good, making it easy to see which areas are, or are not, performing well. Recommendations are provided to ensure that one's academic conference stays in the green.

    PLOS ONE 15, e0243549 (2020).

  4. Symbiosis

    Tiny tomato suppressor

    1. Caroline Ash

    Tomato russet mites disable the immune responses of tomato plants.

    PHOTO: CROWN COPYRIGHT COURTESY OF CENTRAL SCIENCE LABORATORY/SCIENCE SOURCE

    Acarid arthropods are common and economically important pests of crop plants. The tomato russet mite Aculops lycopersici is only 175 micrometers long but can potently suppress the host plant's natural resistance. It has a highly streamlined genome of 32.5 megabases, more closely resembling that of a protist than a metazoan. Greenhalgh et al. discovered that this mite leaves no room in its genome for hangers-on. It contains few transposons, has slimmed intergenic spaces to almost none, has almost done away with chemosensory apparatus and detox pathways, and has even reduced its number of legs from eight to four in the interests of economy. However, it has retained the capacity to suppress the tomato's jasmonic acid signaling pathway, which blocks the ability of the tomato host plant to produce defensive metabolites and proteins. However, the selective forces resulting in this genome diminution remain a puzzle—perhaps one is the poor nutritional value of tomato plants.

    eLife 9, e56689 (2020).

  5. Wound Repair

    Sensing and repairing epidermal injury

    1. Beverly A. Purnell

    The skin protects underlying tissues and organs from potentially damaging microbes and other agents. Epithelial integrity must be reestablished after a skin injury that results in a surface break. For this to happen, cells use altered signaling and mechanical cues to trigger the repair process. Kennard and Theriot examined the mechanism of repair after injury to the zebrafish tailfin. By imaging the actin cytoskeleton, they noted different initial wound responses in zebrafish larvae in different environmental conditions. Cells are sensitive to external sodium chloride at the wound site, suggesting that a change in electrical potential is involved. Applying electric fields triggers actin polarization and basal cell migration, even in absence of wounding. Understanding how skin responds to osmotic and electrical changes may lead to methods for tissue repair.

    eLife 9, e62386 (2020).

  6. Materials Science

    Tuning boron-carbon-nitride films

    1. Phil Szuromi

    Thin films formed from boron, carbon, and nitrogen (BCN films) can exhibit a wide range of optical and electronic properties if they can be made as phase-pure materials. Giusto et al. report on a simple solution-based route to hydrogenated BCN films. Gels formed with different melamine and boric acid ratios (1:1 and 2:1) were deposited on substrates and then heated in dry nitrogen to produce homogeneous, optically transparent films with optical bandgaps of 2.9 and 3.4 electron volts, respectively. The material derived from the 2:1 gel exhibited sp2 bonding and avoided segregation into graphene and hexagonal boron nitride. Addition of small amounts of benzoguanamine to the gels allowed for additional compositional and bandgap tuning.

    J. Am. Chem. Soc. 142, 20883 (2020).

  7. Atmospheric Chemistry

    HONO formation in the troposphere

    1. Yury Suleymanov

    Nitrous acid (HONO) is an important tropospheric intermediate. Current atmospheric models, which assume its formation in the heterogeneous reaction of nitrogen dioxide (NO2) and water, fail to correctly predict the high concentrations of HONO that are detected in the troposphere. Using subnanosecond first-principles molecular dynamics simulations, Martins-Costa et al. show that HONO forms from NO2 preferentially in bulk water with very low probability of its desorption from the surface of liquid water. The present results call into question the catalytic role of the air-water interface and suggest that further studies that take into account various tropospheric chemical species adsorbed on the aqueous droplets are required to elucidate the mechanism of this important atmospheric chemistry.

    J. Am. Chem. Soc. 142, 20937 (2020).

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