Editors' Choice

Science  11 Mar 2016:
Vol. 351, Issue 6278, pp. 1163
  1. Climate Change

    What you foresee is what you get

    1. H. Jesse Smith

    Monument Valley, Arizona, in the arid southwest of the United States

    © DUNCAN PHILLIPS/ALAMY STOCK PHOTO

    Climate models predict that the U.S. southwest will receive less precipitation over the next century, while the northeast and midwest will experience significant increases. Observations show that these projected trends have already begun in the northeast and midwest, but the large natural variability of rainfall in the southwest has made the identification of any trends there equivocal. Prein et al. present an analysis that shows that observations do in fact indicate that a transition to a drier climate state in the southwest is under way. They attribute this shift to a decrease in the frequency of precipitation events in the region, in contrast to the increases in storm intensity that are causing more precipitation to fall in other parts of the country.

    Geophys. Res. Lett. 10.1002/2015GL066727 (2016).

  2. β-Amyloid Processing

    Making the right cut in the right location

    1. Stella M. Hurtley

    In Alzheimer's disease, pathogenic β-amyloid (Aβ) accumulates in the brain. Two enzymes, γ- and β-secretase, produce Aβ by cleaving amyloid precursor protein. Therapeutically, the β-secretase cleavage reaction would be a good one to target, but inhibiting the enzyme also inhibits the cleavage of other key substrates, and so it can be harmful. Ben Halima et al. exploited the fact that Aβ cleavage occurs within an endocytic compartment, whereas γ- and β-secretase cleave other important substrates at the cell surface. They targeted a β-secretase inhibitor to endosomes and successfully inhibited Aβ production in a variety of different cells. These encouraging findings may help in the search for an Alzheimer's disease therapy with minimal off-target side effects.

    Cell Rep. 10.1016/j.celrep.2016.01.076 (2016).

  3. Sensory Biology

    Animal magnetoreception

    1. Lisa D. Chong

    A protein in birds that senses the Earth's magnetic field is also present in some mammals.

    PHOTO: MYCTERIA/SHUTTERSTOCK.COM

    Migratory birds orient to Earth's magnetic field when blue-to-ultraviolet light stimulates a protein called cryptochrome 1a (Cry1a), present in the birds' retinal photoreceptor cone cells. Using an antibody that recognizes light-activated avian Cry1a, Nieβner et al. detected the mammalian homolog Cry1 in the blue light–sensitive cones of Carnivora families, including Canidae (dogs, wolves, and foxes), Mustelidae (badgers, otters, and ferrets), Ursidae (bears), and some primates (macaques and orangutans). Its location suggests that Cry1 does not regulate circadian rhythms or help animals perceive color. Whether Cry1 functions in a magnetic sense or whether mammals have different magnetoreception mechanisms remains unclear.

    Sci. Rep. 10.1038/srep21848 (2016).

  4. Reprogramming

    Gastric tissue makes insulin

    1. Beverly A. Purnell

    Diabetics lack insulin-producing pancreatic beta cells. One therapeutic strategy involves generating these cells from other sources and then transplanting them into patients. To withstand the pathological diabetic environment, a renewable source of beta cells is crucial. Ariyachet et al. demonstrate that stomach cells fit the bill. Like the pancreas, the stomach arises from the endoderm and harbors many stem and progenitor cells. Introducing the trio of proteins into mouse endocrine cells from the lower stomach reprograms them into insulin-producing beta cells. Transplanting reprogrammed stomach mini-organs into diabetic mice allowed them to control their hyperglycemia, suggesting a viable gastric source for the production of insulin.

    Cell Stem Cell 10.1016/j.stem.2016.01.003 (2016).

  5. Public Economics

    Making roads safer and raising revenue

    1. Gilbert Chin

    London's congestion tax led to fewer traffic accidents

    PHOTO: © BJANKA KADIC/ALAMY STOCK PHOTO

    Road space is not infinite, and drivers impose costs on other travelers by delaying or hitting them. The London congestion charge instituted in 2003 makes those costs visible to drivers, who can then decide whether to pay it. As expected, congestion did diminish within central London, and travel by alternative means of transport, such as bicycles, increased. The declining trend in accidents and fatalities from 2000 to 2009 has made it difficult to identify the precise effect of the congestion charge. Now Green et al. use a weighted aggregate of Birmingham, Leeds, Manchester, and Liverpool to calculate that there are 28 fewer accidents per month, 43 fewer serious accidents per year, and 4.3 fewer fatalities per year in central London.

    J. Pub. Econ. 133, 11 (2016).

  6. Dwarf Galaxies

    An unusual satellite of the Milky Way

    1. Keith T. Smith

    Cosmological simulations indicate that large galaxies such as our Milky Way should be surrounded by numerous “dwarf” galaxies. Only in recent years have large surveys enabled systematic searches for these faint objects. Martin et al. have investigated one recently identified candidate, Triangulum II. They find that it is indeed a dwarf galaxy, but one with odd properties. Its fraction of elements heavier than helium (its metallicity) is among the lowest known, and its stars move about more in the outskirts than in the center of the dwarf galaxy. This implies a dynamically recent interaction with a passing body—perhaps another dwarf galaxy.

    Astrophys. J. 10.3847/0004-637X/818/1/40 (2016).

  7. Biocomputation

    Replacing electrons with filaments

    1. Jelena Stajic

    Conventional computers struggle with problems that require them to explore a large number of potential solutions; as the size of the problem grows, the computational time may quickly reach the age of the universe. Nicolau Jr. et al. offer an inherently parallel approach to solving such problems. Using the so-called subset sum problem as an illustration, the authors built a proof-of-principle device in which biological filaments, such as actin and microtubules, performed the computation. Powered by molecular motors, the filaments moved along a network of nanostructured channels tailored to the problem, and the solutions were read off from the positions at which they exited the network.

    Proc. Natl. Acad. Sci. U.S.A. 10.1073/pnas.1510825113 (2016).