Editors' Choice

Science  19 Jun 2015:
Vol. 348, Issue 6241, pp. 1328
  1. Biogeochemistry

    Measuring carbon uptake by tropical forests

    1. Julia Fahrenkamp-Uppenbrink

    Canopy of a carbon-rich tropical forest in the Amazon

    PHOTO: SALPARADIS/ISTOCK PHOTO

    The carbon uptake by tropical forests is a key part of the global carbon budget. Yet accurately measuring this quantity—termed the net primary production or NPP—in tropical forests is challenging, hampering efforts to predict how it may respond to climatic and environmental change. Cleveland et al. have compared NPP estimates from small-scale observations, satellite data, and biogeochemical models. Although the large-scale estimates are similar for all three approaches, the spatial and temporal patterns are very different. Each approach is sensitive to different environmental drivers (such as drought), and it remains unclear which results are correct. The authors explain how an integrated monitoring network could capture the diversity of tropical forest landscapes.

    Global Biogeochem. Cycles 10.1002/2014GB005022 (2015).

  2. Chromosomes

    Y genes find new chromosomal homes

    1. Lisa D. Chong

    A color-enhanced scanning electron micrograph of the human Y chromosome

    PHOTO: BIOPHOTO ASSOCIATES/SCIENCE SOURCE

    The mammalian Y chromosome has lost many genes throughout evolution. However, they are not lost for good, as Hughes et al. report. The authors found that in eight mammals, including humans, apes, rodents, cattle, and marsupials, four genes formerly found on the Y chromosome now reside on other, nonsex chromosomes. A handful of genes on the X chromosome met a similar fate. In some cases, the transposed genes acquired broad tissue expression, perhaps to maintain a gene dosage required for fitness. In other cases, the relocated genes were expressed specifically in the testes, pointing to newly acquired functions in spermatogenesis.

    Genome Biol. 16, 104 (2015).

  3. Behavior

    Differences in strategy across the globe

    1. Gilbert Chin

    Economists measure the extent of a person's preference for risk in a number of ways. Most commonly, they ask people to make choices between gambles—such as a 40% chance of winning $2.00 and a 60% chance of winning $1.60 versus a 40% chance of winning $3.85 and a 60% chance of winning $0.10. Chassy and Gobet offer a new measure of risk derived from the choice of opening moves in chess. They document global risk preference based on more than half a million games played by people ranked expert and above from 11 different civilizations. Civilizations differed in their risk preferences: Some favored settling for peace, whereas others preferred riskier moves.

    Cognition 141, 36 (2015).

  4. Plant Science

    Leaf recycling requires a two-step process

    1. Pamela J. Hines

    During leaf senescence, plants recycle nutrients and other molecules from unneeded leaves for use by seeds and other new growth. Hormones, including ethylene, regulate this process. Studying the leaves of Arabidopsis plants, Ueda and Kusaba found that those carrying mutations affecting the synthesis of the hormone strigolactone did not curl up and die in the dark as did the leaves of normal plants. Dark-induced leaf senescence required another hormone, strigolactone, which the plant synthesized in the leaves in response to ethylene. Separately, ethylene induced leaf senescence better than strigolactone. But together, they synergized. This multistep process probably preserves leaves when possible, only carrying through to leaf senescence when the stress becomes too much.

    Plant Physiol. 10.1104/pp.15.00325 (2015).

  5. Chemistry

    Boroxine cages

    1. Phil Szuromi

    Boronic acids, in which a boron atom bears two hydroxyl (OH) groups and an organic group, can trimerize by dehydration to form six-membered boroxine rings, and molecules bearing more than one boronoic acid group can form polymer networks. Ono et al. extend the architectures that can be formed to cages. They designed pincer-like organic groups that set B(OH)2 groups at desired angles. After heating and dehydration, the molecule with an 84° angle between hydroxyl groups formed an octahedron from six units, with a 1.5-nanometer cavity, and the molecule with a 117° angle formed a cuboctahedron from 12 units with a 2.5-nanometer cavity.

    J. Am. Chem. Soc. 10.1021/jacs.5b02716 (2015).

  6. Virology

    Virus dynamics in human lungs

    1. Caroline Ash

    People with cystic fibrosis suffer from progressive bacterial lung infections, often by Pseudomonas aeruginosa. This occurs despite a diversity of viruses, known as bacteriophage, that attack these bacteria. For more than 2 years, James et al. followed the ecological dynamics of active bacteriophage in the sputa of 10 people with cystic fibrosis. Overall, ongoing lysis triggered by bacteriophage reduced bacterial density in the lung. Different patients' sputa contained different combinations of phage strains, indicating that these different strains compete. Phage may also exclude infection by different strains of P. aeruginosa, which might influence disease among patients. These results indicate that phage may show some therapeutic promise in combination with specific antibiotics.

    ISME J. 9, 1391 (2015).

  7. Climate Change

    Weather underground

    1. H. Jesse Smith

    Bacteriophages are viruses that can infect and kill bacteria

    ILLUSTRATION: V. ALTOUNIAN/SCIENCE

    Climate models indicate that as global temperatures increase, global precipitation also will rise, but that it will become more heterogeneous as well. How will that affect soil moisture, a quantity that often is ignored but has large impacts on agriculture, flooding, and weather? Wu et al. report results from a suite of climate models that show that soils in middle and high northern latitudes will get wetter in the wettest months and drier in the driest months. This increase in the annual range of soil water content will affect water resource management, plant adaption, and agriculture, particularly in regions where snowmelt supplies a significant portion of the seasonal water supply.

    Geophys. Res. Lett. 10.1002/2015GL064110 (2015).