Editors' Choice

Science  24 Jan 2014:
Vol. 343, Issue 6169, pp. 352
  1. Climate Science

    More Than We Thought

    1. H. Jesse Smith

    One of the most worrying impacts of climate warming is the sea-level rise caused by melting or collapse of the polar ice sheets. The Antarctic Ice Sheet contains enough water to raise sea level by roughly 60 m were it to melt completely. Most of the work done to determine the influence of warming on the Antarctic Ice Sheet has focused on the West Antarctic Ice Sheet, which is thought to be the most unstable portion with respect to warming. Fogwill et al. consider the East Antarctic Ice Sheet (EAIS), which contains 90% of Antarctic ice, using a computer model to examine how much of that region may have melted or collapsed 135,000 to 116,000 years ago during the last interglacial, when the global average air temperature was about 2° C higher than it is now (a potential analog for the warmer climate of the next century). They focus particular attention on the effects of the Southern Hemisphere westerly winds on Southern Ocean circulation and the dynamics of the Antarctic ice sheet, concluding that the EAIS may have made a significantly greater contribution to sealevel rise over that period than currently is believed, with the implication that projected changes in the climate of the southern hemisphere may constitute a more serious threat to the future stability of the EAIS than has generally been appreciated until now.

    J. Quat. Sci. 29, 91 (2014).

  2. Ecology

    Count Consumers

    1. Andrew M. Sugden

    Invertebrate herbivores are an important component of tropical forest ecosystems, and new data from forests in Peru quantify their role in biogeochemical cycling. Metcalfe et al. surveyed patterns of herbivory in forests along an elevational transect from 300 to 3000 m in the Andes, over a full seasonal cycle, to calculate rates of herbivory and its effect on pathways of nutrient cycling (particularly N, P, and C). Herbivore activity was greater at lower elevations and higher temperatures and at high concentrations of foliar P, with up to 20% of foliar productivity diverted to herbivores over the year. Herbivory also contributed an unexpectedly high proportion of N and P inputs to the soil. These patterns in turn may have implications for future C cycling and sequestration in tropical forests, as changes in environmental conditions lead to shifts in abundances of herbivore populations. Complex as they may be, the activities and effects of consumers should be incorporated into global vegetation models in order to accurately predict the likely consequences of global change.

    Ecol. Lett. 10.1111/ele.12233 (2013).

  3. Biomedicine

    Happy Gut, Happy Mouse?

    1. Stella M. Hurtley

    Growing evidence suggests a role for perturbations in the gut microbe balance (dysbiosis) and gastrointestinal (GI) complications in autism spectrum disorders (ASD). Altered microbial composition is observed in autistic individuals, and subsets of these patients exhibit improved symptoms with antibiotic treatment or when placed on restricted diets. A strong correlation has also been observed between GI status and autism severity. Recent animal studies have revealed that the gut microbiota modulate a variety of behaviors, including anxiety-like and emotional behaviors. Indeed, the microbiota affect neurotransmitter levels, brain gene expression, and vagal nerve activation. Dysbiosis may contribute to allergy, autoimmune disease, obesity, and inflammatory bowel disease. Hsiao et al. were able to ameliorate behavioral abnormalities in a mouse model of ASD by treating animals with the human gut bacterium Bacteriodes fragilis. The treatment restored intestinal barrier integrity, modulated serum metabolites, and helped with behavioral symptoms.

    Cell 155, 1451 (2013).

  4. Biomaterials

    Glue for the Heart

    1. Marc S. Lavine

    The surgical attachment or closure of biological tissues typically requires sutures, staples, or glue. Both sutures and staples can cause additional tissue damage, particularly in damaged or juvenile tissue. Existing adhesives can be washed away under in vivo conditions or may not be strong enough to withstand large forces, such as those found in the cardiovascular system. Lang et al. designed a hydrophobic prepolymer based on poly(glycerol sebacate acrylate) (PGSA), which is composed of biocompatible and biodegradable components, and mixed in a photoinitiator. This adhesive was readily spread over a surface and provided a strong bond, even with wet tissue that had been in contact with blood, upon cross-linking during a few seconds of exposure to ultraviolet light. Tests in rats showed that the adhesive could be used to attach a polymer patch to seal up a left-ventricle wall defect, with similar success rates as a suture control group. A second set of tests looked at the closure of ventricular septal defects within a pig heart. Of the four animals that were tested, two were monitored for 24 hours, while the other two were exposed to accelerated heart rate and blood pressure, and in all cases the adhesive held firm.

    Sci. Transl. Med. 6, 218ra6 (2014).