Editors' Choice

Science  13 Jan 2017:
Vol. 355, Issue 6321, pp. 144
  1. Plants and Climate

    Effects of drought on tree performance

    1. Andrew M. Sugden

    Drought limits pinyon pine growth, whereas high temperatures have little effect.

    CREDIT: LARRY GEDDIS/ALAMY STOCK PHOTO

    Global climate change has many components, with temperature and precipitation dominating. Grossiord et al. experimentally compared the effects of temperature increase and precipitation reduction on pinyon pine trees in a warm semiarid site in New Mexico, USA. The 3-year experiment in open-topped chambers revealed that temperature increase on its own had little effect on tree physiology and morphology, whereas drought had pronounced effects: Low precipitation led to reductions in photosynthesis and needle growth, among other plant traits that the authors examined. In addition, there were no discernible synergistic effects of drought and increased temperature. It appears that reduced precipitation will be the driving force in any ecological change that results from changed plant performance.

    J. Ecol. 105, 163 (2017).

  2. Quantum Fluids

    Observing peculiar vortices

    1. Jelena Stajic

    When a vessel filled with a superfluid is rotated, the superfluid, instead of moving with the vessel the way water would, develops an array of whirlpools called vortices. The flow around a vortex is “quantized,” characterized by discrete, integer numbers. It has long been suspected that in a particular kind of superfluid—3He at very low temperatures—it would be possible to observe vortices that are associated with half-integer numbers. Autti et al. observed the signature of these half-quantum vortices (HQVs) in the nuclear magnetic resonance (NMR) spectra of superfluid 3He confined in a porous medium. Pairs of HQVs caused the appearance of an additional NMR peak, whose position and dependence on the various parameters were consistent with theoretical expectations.

    Phys. Rev. Lett. 117, 255301 (2016).

  3. Medical Diagnostics

    Fast point-of-care detection of biomarkers

    1. Julia Fahrenkamp-Uppenbrink

    Many diseases can be diagnosed by detecting nucleic acid or protein biomarkers, but, with few exceptions, this detection requires complex and costly instruments. Du et al. adapted commercially available pregnancy kits for affordable and fast point-of-care diagnostics. In the detection method, nucleic acid is first amplified and then captured by a DNA oligonucleotide–human chorionic gonadotropin conjugate. The latter is detected by the commercial kits. The method allowed detection of just 20 copies of an Ebola virus template and could distinguish a melanoma-related biomarker from the wild-type sequence. It should be possible to adapt it for low-cost detection of other biomarkers in clinical settings.

    Angew. Chem. Int. Ed. Engl. 10.1002/anie.201609108 2016).

  4. Cancer Biology

    Cancer and nerves: A tuf(t) partnership

    1. Paula A. Kiberstis

    Stomach tumor growth is accompanied by an expansion of surrounding nerves. Whether and how these two events are functionally related has been unclear. Studying mouse models, Hayakawa et al. showed that a molecular conversation occurs between nerves and the epithelial cells that give rise to cancer. This cross-talk relies in part on tuft cells, a mysterious cell type in the epithelial lining of the gastrointestinal tract. Tuft cells and nerves produce the neurotransmitter acetylcholine, which stimulates expression of nerve growth factor (NGF) in the gastric epithelium. NGF in turn acts to promote neuronal expansion and aberrant growth of gastric epithelial cells, which ultimately leads to cancer. Drugs that block NGF signaling inhibited gastric tumor growth in mice.

    Cancer Cell 10.1016/j.ccell.2016.11.005 (2017).

  5. Meteoroid Streams

    Did Phaethon father the Geminids?

    1. Keith T. Smith

    The Geminids meteor shower may originate from an asteroid rather than a comet.

    PHOTO: DAVID KINGHAM/FLICKR

    Meteor showers are caused by Earth passing through a stream of debris left by a comet. The Geminids shower seems to originate from (3200) Phaethon, but that is an asteroid, not a comet, with an unusual elliptical orbit that takes it close to the Sun. Hui and Li examined images of Phaethon as it passed the Sun in August 2016, showing that it generated a small tail. Although this comet-like behavior could feed the meteor stream, the mass of material ejected is far too small. If Phaethon is indeed the origin of the Geminids, it must have been much more active in the recent past.

    Astron. J. 153, 23 (2017).

  6. Microbiota

    Gut communities form a history of connection

    1. Caroline Ash

    An individual's gut microbial community is nested within a “cloud” of the shared microbiota of relatives, friends, and acquaintances. Unique combinations of selective pressures, including antibiotics and diet, shape an individual's microbiota. Using gnotobiotic mice as a lens for humans, Griffin et al. observed the effect of plantrich, calorie-restricted diets on microbiota establishment and metabolic responses in fecal transplant experiments. The calorie-restricted participants had far richer and more diverse communities that even lean people on western diets. Cohousing and cross-diet experiments in the mice showed the relative influences of microbial exchange and diet diversity on indicator species and the role a western diet may play in extirpation of key microbiota taxa.

    Cell Host Microbe 10.1016/j.chom.2016.12.006 (2017).

  7. Sperm Competition

    Speedy sperm

    1. Sacha Vignieri

    Sperm compete with each other for a chance to fertilize an egg, competition that is especially fierce when the sperm competing are from different individuals, as is the case for promiscuous species. Fisher et al. looked at sister species of Peromyscus, a well-studied genus of North American mouse, and found that differences in mating system are associated with differences in sperm morphology and reproductive success among hybrids. Specifically, in the promiscuous white-footed mouse, the section of the sperm containing energy-generating mitochrondia is longer than it is in the monogamous old-field mouse. Genome mapping showed that the length of this midpiece is largely associated with a single gene, Prkar1a.

    Nat. Comm. 10.1038/ncomms13652 (2016).