Editors' Choice

Science  23 Feb 2018:
Vol. 359, Issue 6378, pp. 881
  1. Quantum Optics

    Quantum-secure satellite communication

    1. Ian S. Osborne

    Illustration of the Chinese low-Earth-orbiting satellite, Micius

    CREDIT: C. BICKEL/SCIENCE

    The distribution of secret quantum keys between interested parties is a critical requirement to establish secure and unhackable communication links. Liao et al. demonstrate quantum key distribution between the Chinese low-Earth-orbiting satellite Micius and ground stations located in China and Austria. Once the quantum keys have been distributed, a secure communication channel can be established between the stations, some 7600 kilometers apart. The link is robust enough that information and images can be transmitted, as well as allowing a quantum-secured video conference call to be held between the Chinese and Austrian Academies of Sciences. A network of satellites could establish a worldwide quantum-secure internet.

    Phys. Rev. Lett. 120, 030501 (2018).

  2. Stem Cells

    Cholesterol and stem cell proliferation

    1. Beverly A. Purnell

    Cells require basic building components such as nucleotides, amino acids, and lipids. The lipid cholesterol regulates specific signaling pathways for proper cell function. Wang et al. report an additional role, one that affects the critical balance between proliferation and differentiation. When the phospholipid-remodeling enzyme Lpcat3 is inhibited, cholesterol biosynthesis increases, with resultant intestinal stem cell proliferation. This increase in cell number is normalized if cholesterol synthesis is blocked pharmacologically. Similarly, crypt organoid growth increased with cholesterol levels, and loss of Lpcat3 enhances tumor formation. This work reveals a critical role for phospholipid remodeling and cholesterol metabolism in intestinal stem cell homeostasis and cancer development.

    Cell Stem Cell 10.1016/j.stem.2017.12.017 (2018).

  3. Biogeography

    Different responses to climate change in mountain plants

    1. Andrew M. Sugden

    Climate-driven changes in abundance could increase competition between high- and low-altitude plant species.

    PHOTO: CULTURA RM/ALAMY STOCK PHOTO

    In a warming climate, the distributions of plant species inhabiting mountain slopes tend to move uphill. However, species abundance may also change, leading to altered dynamics in the plant communities. Rumpf et al., in a study of nearly 200 mountain species in the European Alps, recorded trends toward increased local abundance in the majority of species. In particular, plants from lower elevations tended to increase in abundance as their upper range limits shifted uphill, whereas those from higher elevations showed the opposite trend. Thus, higher-elevation species are more likely to lose out through the combined effects of climate change and competition.

    Proc. Natl Acad. Sci. 10.1073/pnas.1713936115 (2018).

  4. Biomedicine

    How endothelial cells change identity

    1. Paula A. Kiberstis

    The development of healthy heart valves during mammalian embryogenesis requires that endothelial cells morph into a distinct cell type. When this identity change, called endothelial-to-mesenchymal transition (EndoMT), occurs inappropriately in adults, it can lead to disorders such as atherosclerosis, organ fibrosis, and pulmonary hypertension. To investigate the mechanisms regulating EndoMT, Xiong et al. studied cultured endothelial cells and mice deficient in a certain metabolic enzyme. They discovered that loss of endothelial fatty acid oxidation promotes EndoMT, most likely through changes in intracellular acetyl coenzyme A levels. These results suggest that therapies aimed at increasing fatty acid oxidation, including several drugs that already exist for other purposes, could potentially be used to treat disorders caused by aberrant EndoMT.

    Mol. Cell 69, 689 (2018).

  5. Neuroscience

    Tackling the mechanisms behind depression

    1. Peter Stern

    The anaesthetic drug ketamine also has a rapid antidepressant effect. Although ketamine is known to block N-methyl-d-aspartate (NMDA) receptors, its exact target—which brain region and which cell groups—has remained elusive. Yang et al. found that neuronal burst firing in a single brain region called the lateral habenula drove robust depressive-like behaviors. These behaviors could be rapidly blocked by local ketamine infusion. Instead of acting on GABAergic neurons as previously suggested, ketamine blocked glutamatergic neurons in the “anti-reward center” lateral habenula to disinhibit downstream dopaminergic and serotonergic neurons. Lateral habenula bursting strongly required the synergistic action of NMDA receptors and voltage-sensitive T-type calcium channels. The latter may therefore be another promising target for the development of new rapid-acting antidepressants.

    Nature 10.1038/nature25509 (2018).

  6. Physics

    A stringy magnet

    1. Jelena Stajic

    In one-dimensional antiferromagnetic materials, the neighboring spins align opposite to each other, but if the material is put in a strong enough magnetic field, the spins will eventually all point in the direction of the field. In intermediate fields, according to a long-standing prediction, strings of spins pointing opposite to the magnetic field will form. Wang et al. observed these so-called Bethe strings in the compound SrCo2V2O8 by using terahertz spectroscopy in magnetic fields up to 30 T. By comparing with calculations, the researchers were able to identify the signatures of two- and three-string states in the spectra.

    Nature 554, 219 (2018).

  7. Climate Change

    The shape of things to come

    1. H. Jesse Smith

    A widespread and intense heat wave struck western and central Europe in June 2017, ranking as one of the most intense mega–heat waves since 1948. Like similar episodes in 2003 and 2010, it affected a wide area and displayed exceptional intensity. What set it apart from those events, however, is how early in the year it occurred. Sánchez-Benítez et al. analyzed its characteristics and attributed its occurrence to the formation of an intense subtropical ridge like those more typically occurring in July and August. They conclude that this episode could be a good example of what the future may bring, with high-summer mega–heat waves occurring earlier in the year.

    Geophys. Res. Lett. 10.1002/2018GL077253 (2018).

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