Geonomics & Science News

Geonomics & Science News


[Editorial] Strength in members - 5 Feb 2016

A year ago on this page, I described some of the challenges that science faces in cultivating support from the society it serves. Stepping in as the new Chief Executive Officer of the American Association for the Advancement of Science (AAAS, the publisher of Science), my editorial asked, “Why science? Why AAAS?” My thoughts about the nature and service of science and the mission and goals of AAAS—the world's largest general science membership organization—have since been focusing on new and revitalized efforts that will continue to make AAAS the principal voice for science. A great example of this will be the AAAS Annual Meeting next week in Washington, DC (11 to 16 February), where we will bring together diverse leading voices from around the world to discuss how “Global Science Engagement” can move society toward a secure future. Author: Rush Holt

[Review] Why do batteries fail? - 5 Feb 2016

Battery failure and gradual performance degradation (aging) are the result of complex interrelated phenomena that depend on battery chemistry, design, environment, and the actual operation conditions. The current available knowledge on these matters results from a vast combination of experimental and modeling approaches. We explore the state of the art with respect to materials as well as usage (temperature, charge/discharge rate, etc.) for lead-acid, nickel-cadmium, nickel–metal hydride, and lithium-ion chemistries. Battery diagnosis strategies and plausible developments related to large-scale battery applications are also discussed. Authors: M. R. Palacín, A. de Guibert

[In Brief] News at a glance - 5 Feb 2016

In science news around the world, scientists lose their fight to study 9000-year-old bones in California, a twisty stellarator begins its scientific work in earnest, a U.K. scientist gets permission to modify human embryos, more than 300 Nobel laureates sign a letter calling on Iran to free a jailed chemist, the United States pledges $1 billion to jump-start its "moonshot" to cure cancer, and more. Also, disgraced stem cell researcher Haruko Obokata tells her side of the story of the unraveling of the discovery of stimulus-triggered acquisition of pluripotency cells. And the award-winning structure The Hive, a centerpiece of the U.K. Pavilion at the Milan Expo in Italy last year, is set to alight at the Royal Botanic Gardens, Kew, this summer.

[This Week in Science] Cancer therapy by entrapment - 5 Feb 2016

Author: Paula A. Kiberstis

[In Depth] The race for a Zika vaccine is on - 5 Feb 2016

Scientists first isolated Zika virus in 1947, but the disease it caused in humans was considered mild: It did nothing to 80% of the people it infected, and the ones who had symptoms only had temporary fevers and rashes. But last year, a high number of cases of brain-damaging microcephaly in newborns began to surface in Brazil in lockstep with the arrival of the Zika virus, which is spread by mosquitoes. The World Health Organization on 1 February declared these clusters of disease a "public health emergency of international concern," and a rush of vaccinemakers has jumped into the race to develop a preventive. Vaccines exist against several other flaviviruses, the family Zika belongs to, and experts predict that this won't be a major scientific challenge. They also say it may be possible to piggyback on the other flavivirus vaccines, like ones made for dengue and yellow fever. Then again, vaccine R&D takes time, and because this effort is starting from scratch, researchers say it will take at least a few years before a vaccine can prove itself safe and effective in large human efficacy studies. Author: Jon Cohen

[Report] Europe’s forest management did not mitigate climate warming - 5 Feb 2016

Afforestation and forest management are considered to be key instruments in mitigating climate change. Here we show that since 1750, in spite of considerable afforestation, wood extraction has led to Europe’s forests accumulating a carbon debt of 3.1 petagrams of carbon. We found that afforestation is responsible for an increase of 0.12 watts per square meter in the radiative imbalance at the top of the atmosphere, whereas an increase of 0.12 kelvin in summertime atmospheric boundary layer temperature was mainly caused by species conversion. Thus, two and a half centuries of forest management in Europe have not cooled the climate. The political imperative to mitigate climate change through afforestation and forest management therefore risks failure, unless it is recognized that not all forestry contributes to climate change mitigation. Authors: Kim Naudts, Yiying Chen, Matthew J. McGrath, James Ryder, Aude Valade, Juliane Otto, Sebastiaan Luyssaert

[In Depth] Risky reactor fuel to linger - 5 Feb 2016

Since 1978, the United States and other nations have been pushing to eliminate highly enriched uranium (HEU)—which a terrorist or rogue nation could use to make a bomb—as fuel in civilian research reactors. But achieving that goal will take far longer than previously hoped, according to a study from the National Academies of Sciences, Engineering, and Medicine. Instead of 2018, a timeframe of 2035 is more realistic, the 28 January report concludes. Dozens of civilian research reactors have closed or converted from HEU—uranium enriched to at least 20% of the fissile isotope U-235—to safer low enriched uranium (LEU), including 28 since 2009. But 74 of them still rely on HEU, and developing an LEU replacement fuel for them will take another 12 to 17 years, the report says. Moreover, Russia has expressed little interest in converting its 32 research reactors. Most controversially, as an interim step the report calls for converting the eight U.S. research reactors from running on 93% enriched weapons-grade uranium to 45% enriched HEU. Some nonproliferation experts argue that move would perpetuate commerce in HEU and torpedo the development the LEU fuel. Author: Adrian Cho

[This Week in Science] Disentangling intertwined orders - 5 Feb 2016

Author: Jelena Stajic

[In Depth] Good grades for Germany's project to build an Ivy League - 5 Feb 2016

The Excellence Initiative, a €4.6 billion program started in 2006 to strengthen research at select German universities, has worked well, an international panel has concluded. The initiative has had "very positive" effects all around and "has made the German university system more dynamic," the panel concludes in a report published on 29 January. Worries that it would lead to a tier of second-rate schools have not panned out, says the panel, which recommends a follow-up—with some important changes—after the initiative ends in 2017. German politicians have already pledged ​money to fund a successor program but have yet to decide how to shape it. Author: Gretchen Vogel

[Editors' Choice] Methylation for making a placenta - 5 Feb 2016

Author: Guy Riddihough

[In Depth] Karolinska to reopen inquiry into surgeon's work - 5 Feb 2016

Last summer, the Karolinska Institute (KI) in Stockholm cleared star surgeon Paolo Macchiarini of charges that he had overstated the success of his pioneering artificial trachea implants in a series of scientific papers. But KI may reopen its investigation into Macchiarini's work after a chilling three-part documentary on Swedish television suggested that he didn't fully inform his patients about the risks of his operations. Eight patients have received the implants; six have died. The film also raises questions about the way KI managers have handled the scandal so far; the institute's board of directors is expected to demand an independent investigation. Author: Gretchen Vogel

[Report] Diamond family of nanoparticle superlattices - 5 Feb 2016

Diamond lattices formed by atomic or colloidal elements exhibit remarkable functional properties. However, building such structures via self-assembly has proven to be challenging because of the low packing fraction, sensitivity to bond orientation, and local heterogeneity. We report a strategy for creating a diamond superlattice of nano-objects via self-assembly and demonstrate its experimental realization by assembling two variant diamond lattices, one with and one without atomic analogs. Our approach relies on the association between anisotropic particles with well-defined tetravalent binding topology and isotropic particles. The constrained packing of triangular binding footprints of truncated tetrahedra on a sphere defines a unique three-dimensional lattice. Hence, the diamond self-assembly problem is solved via its mapping onto two-dimensional triangular packing on the surface of isotropic spherical particles. Authors: Wenyan Liu, Miho Tagawa, Huolin L. Xin, Tong Wang, Hamed Emamy, Huilin Li, Kevin G. Yager, Francis W. Starr, Alexei V. Tkachenko, Oleg Gang

[In Depth] Japanese satellite targets the x-ray universe - 5 Feb 2016

Japan's ASTRO-H satellite, due to launch 12 February, is taking aim at the most turbulent corners of the x-ray universe. Because of previous rocket failures and equipment malfunctions, if launched successfully, ASTRO-H will be the first major x-ray mission put into orbit since 1999. A slew of new technological developments make the craft significantly more powerful than x-ray observatories currently in operation. These enhanced capabilities will allow scientists to observe the gas squeezed within galaxy clusters, determining its composition, motion, and turbulence, all for a better understanding of how chemical elements evolved within the universe and what role interstellar gases play in star and galaxy formation. ASTRO-H will also allow scientists to resolve questions about ultrafast outflows of gas from active galactic nuclei and whether mysterious emissions from certain galaxy clusters are evidence of dark matter annihilation. Author: Dennis Normile

[Report] Foxc1 reinforces quiescence in self-renewing hair follicle stem cells - 5 Feb 2016

Stem cell quiescence preserves the cell reservoir by minimizing cell division over extended periods of time. Self-renewal of quiescent stem cells (SCs) requires the reentry into the cell cycle. In this study, we show that murine hair follicle SCs induce the Foxc1 transcription factor when activated. Deleting Foxc1 in activated, but not quiescent, SCs causes failure of the cells to reestablish quiescence and allows premature activation. Deleting Foxc1 in the SC niche of gene-targeted mice leads to loss of the old hair without impairing quiescence. In self-renewing SCs, Foxc1 activates Nfatc1 and bone morphogenetic protein (BMP) signaling, two key mechanisms that govern quiescence. These findings reveal a dynamic, cell-intrinsic mechanism used by hair follicle SCs to reinforce quiescence upon self-renewal and suggest a unique ability of SCs to maintain cell identity. Authors: Li Wang, Julie A. Siegenthaler, Robin D. Dowell, Rui Yi

[In Depth] Calling all failed replication experiments - 5 Feb 2016

A growing number of retracted papers have stirred concerns about irreproducible results in biomedical research. Now, the biotech company Amgen and prominent biochemist Bruce Alberts have created a new online journal that aims to lift the curtain on often-hidden data: failed efforts to confirm other groups' published papers. Amgen is seeding the publication with reports on its own futile attempts to replicate three studies in obesity and neurodegenerative disease and hopes other companies will follow suit. The contradictory results—along with successful confirmations—will be published by F1000Research, an open-access, online-only publisher. Its new Preclinical Reproducibility and Robustness channel, launched on 4 February, will allow both companies and academic scientists to share their replications so that others will be less likely to waste time following up on flawed findings. Author: Jocelyn Kaiser

[This Week in Science] Why batteries go bad - 5 Feb 2016

Author: Marc S. Lavine

[Feature] What makes DARPA tick? - 5 Feb 2016

Founded in 1958 in the aftermath of Sputnik, the Defense Advanced Research Projects Agency (DARPA) is supposed to make sure the U.S. military holds a technological edge over its enemies. Over the decades since, it has earned a reputation for using out-of-the-box thinking to solve what defense officials like to call "DARPA-hard" problems. The key to its success, say dozens of people who have worked for or with DARPA, is its cadre of program managers. Some call them DARPA's "secret sauce." Although they typically stay for only 4 to 5 years, they can have an enormous impact on the agency because of a combination of autonomy, authority, and ample resources that is rare in government. Author: Jeffrey Mervis

[This Week in Science] The more the merrier - 5 Feb 2016

Author: Yevgeniya Nusinovich

[Feature] Biology came late, and arrived with a bang - 5 Feb 2016

After the Cold War ended, U.S. military leaders began to worry that rogue states might wage bioterrorism attacks on both U.S. soldiers and civilian populations. That new threat exposed a significant hole in the Defense Advanced Research Projects Agency's (DARPA's) portfolio: the life sciences. Remarkably, the agency didn't hire its first biologist until 1990. But over the next quarter-century it made up for lost time, and in June 2014 DARPA put the life sciences on an equal footing with other disciplines by creating the Biology Technologies Office. Arriving late has allowed DARPA to take advantage of the stunning advances in biology over the past 50 years without losing sight of its unique mission. Author: Jeffrey Mervis

[Editors' Choice] To catch a photon nondestructively - 5 Feb 2016

Author: Ian S. Osborne

[Perspective] The mite that jumped, the bee that traveled, the disease that followed - 5 Feb 2016

European honeybees are among the best-studied and most widely recognized insect species in the world. Originally kept for honey production, they have become the flagship species for pollination and large-scale agriculture. Since large colony losses were reported across the United States in 2006, researchers have investigated the myriad factors that contribute to the decline in honeybee populations. In particular, the aptly named Varroa destructor mite (see the photo) and the deformed wing virus (DWV) have been clearly linked to colony collapse (1). On page 594 of this issue, Wilfert et al. use a phylogeographic analysis to examine the evolutionary origin and mechanisms for the global spread of the DWV (2). Author: Ethel M. Villalobos

[Editors' Choice] Unusual antibodies target malaria - 5 Feb 2016

Author: Kristen L. Mueller

[Perspective] Throttling back the heart's molecular motor - 5 Feb 2016

A young athlete collapses and dies during competition. Autopsy reveals an enlarged heart with thickened walls in which the cardiac muscle cells are in disarray and surrounded by fibrotic tissue. Until 1990, the cause of such sudden death was unknown. This devastating condition, called familial hypertrophic cardiomyopathy (HCM), was eventually linked to a mutation in myosin (1), the heart's molecular motor. Today, more than 300 separate HCM-causing mutations have been identified throughout the myosin molecule. On page 617 of this issue, Green et al. (2) describe a small molecule that binds to myosin and inhibits its activity, delaying the onset and progression of the disease in a mouse model. The study offers hope that a “simple” remedy for HCM may be possible. Author: David M. Warshaw

[Report] Nematicity in stripe-ordered cuprates probed via resonant x-ray scattering - 5 Feb 2016

In underdoped cuprate superconductors, a rich competition occurs between superconductivity and charge density wave (CDW) order. Whether rotational symmetry-breaking (nematicity) occurs intrinsically and generically or as a consequence of other orders is under debate. Here, we employ resonant x-ray scattering in stripe-ordered superconductors (La,M)2CuO4 to probe the relationship between electronic nematicity of the Cu 3d orbitals, structure of the (La,M)2O2 layers, and CDW order. We find distinct temperature dependences for the structure of the (La,M)2O2 layers and the electronic nematicity of the CuO2 planes, with only the latter being enhanced by the onset of CDW order. These results identify electronic nematicity as an order parameter that is distinct from a purely structural order parameter in underdoped striped cuprates. Authors: A. J. Achkar, M. Zwiebler, Christopher McMahon, F. He, R. Sutarto, Isaiah Djianto, Zhihao Hao, Michel J. P. Gingras, M. Hücker, G. D. Gu, A. Revcolevschi, H. Zhang, Y.-J. Kim, J. Geck, D. G. Hawthorn

[Perspective] Addressing an antiferromagnetic memory - 5 Feb 2016

Spintronics (1) is one of the most commercially successful nanotechnologies. The invention of the giant-magnetoresistance spin valve (2) revolutionized the magnetic recording industry, enabling the immensely cheap, high-density disk drive storage on which the data centers that support our insatiable demand for cloud computing, social networking, and video sharing technologies rely. The combination of magnetic tunneling junctions (3) and spin-transfer torque (STT) (4) has brought about the prospect of magnetic random-access memory (MRAM), written using STT, as a way to provide nonvolatile storage that can be written and operated using extremely low power. Such technologies have just entered the marketplace. Even more energy-efficient writing is possible using the recently discovered spin-orbit torque (SOT) (5). All of these technologies use ferromagnets—the type of magnetic materials that “stick to the fridge” because they possess a magnetic moment—to store the data; the direction of that magnetic moment (“north” or “south”) represents the 0 or 1 of a digital bit. In both STT and SOT, the flow of a spin-polarized electrical current exerts torques on the magnetic moments to affect the change in magnetization direction that writes this bit. On page 587 of this issue, Wadley et al. (6) show that a hitherto exotic class of magnetic materials, antiferromagnets, are candidates for an entirely new type of spintronic memory. Author: Christopher Marrows

[Report] Holocene deceleration of the Greenland Ice Sheet - 5 Feb 2016

Recent peripheral thinning of the Greenland Ice Sheet is partly offset by interior thickening and is overprinted on its poorly constrained Holocene evolution. On the basis of the ice sheet’s radiostratigraphy, ice flow in its interior is slower now than the average speed over the past nine millennia. Generally higher Holocene accumulation rates relative to modern estimates can only partially explain this millennial-scale deceleration. The ice sheet’s dynamic response to the decreasing proportion of softer ice from the last glacial period and the deglacial collapse of the ice bridge across Nares Strait also contributed to this pattern. Thus, recent interior thickening of the Greenland Ice Sheet is partly an ongoing dynamic response to the last deglaciation that is large enough to affect interpretation of its mass balance from altimetry. Authors: Joseph A. MacGregor, William T. Colgan, Mark A. Fahnestock, Mathieu Morlighem, Ginny A. Catania, John D. Paden, S. Prasad Gogineni

[Perspective] Aging, alopecia, and stem cells - 5 Feb 2016

Many tissues turn over during adult life, and declines in this process are associated with the progression of aging. Whether renewal is continual (as in the intestinal villi) or episodic (as in hair follicles), it is mainly attributed to somatic stem cells. One fundamental question is whether a decline of tissue renewal reflects the lifelong accumulation of external insults or the internal progression of a clock within stem cells? On pages 613 and 575 of this issue, Wang et al. (1) and Matsumura et al. (2), respectively, gain insight into this phenomenon by examining hair follicle growth and aging. Authors: Mingxing Lei, Cheng-Ming Chuong

[Report] Allele-specific inhibitors inactivate mutant KRAS G12C by a trapping mechanism - 5 Feb 2016

It is thought that KRAS oncoproteins are constitutively active because their guanosine triphosphatase (GTPase) activity is disabled. Consequently, drugs targeting the inactive or guanosine 5′-diphosphate–bound conformation are not expected to be effective. We describe a mechanism that enables such drugs to inhibit KRASG12C signaling and cancer cell growth. Inhibition requires intact GTPase activity and occurs because drug-bound KRASG12C is insusceptible to nucleotide exchange factors and thus trapped in its inactive state. Indeed, mutants completely lacking GTPase activity and those promoting exchange reduced the potency of the drug. Suppressing nucleotide exchange activity downstream of various tyrosine kinases enhanced KRASG12C inhibition, whereas its potentiation had the opposite effect. These findings reveal that KRASG12C undergoes nucleotide cycling in cancer cells and provide a basis for developing effective therapies to treat KRASG12C-driven cancers. Authors: Piro Lito, Martha Solomon, Lian-Sheng Li, Rasmus Hansen, Neal Rosen

[Perspective] Nanoparticles meet their sticky ends - 5 Feb 2016

The first studies showing that DNA could be grafted onto the surfaces of metal nanoparticles (NPs) (1, 2) provided a glimpse into the potential of using genetic material to program NP assembly. With major advances in DNA nanotechnology (3, 4) in the subsequent years, researchers have just begun to harness the molecular and nanoscale precision that DNA offers in the construction of ordered three-dimensional (3D) NP superlattices. In this issue, two studies show how hierarchically structured DNA imparts valency and symmetry to spherical gold NPs that are otherwise chemically and geometrically isotropic. On page 582, Liu et al. (5) demonstrate the rational assembly of NPs into diamond and diamond-family superlattices using DNA origami linkers. On page 579, Kim et al. (6) demonstrate how DNA hairpins serve as addressable NP linkers that can be activated or deactivated with chemical precision. Author: Andrea R. Tao

[New Products] New Products - 5 Feb 2016

A weekly roundup of information on newly offered instrumentation, apparatus, and laboratory materials of potential interest to researchers.

[Perspective] Ice sheet in peril - 5 Feb 2016

Earth's large ice sheets in Greenland and Antarctica are major contributors to sea level change. At present, the Greenland Ice Sheet (see the photo) is losing mass in response to climate warming in Greenland (1), but the present changes also include a long-term response to past climate transitions. On page 590 of this issue, MacGregor et al. (2) estimate the mean rates of snow accumulation and ice flow of the Greenland Ice Sheet over the past 9000 years based on an ice sheet-wide dated radar stratigraphy (3). They show that the present changes of the Greenland Ice Sheet are partly an ongoing response to the last deglaciation. The results help to clarify how sensitive the ice sheet is to climate changes. Author: Christine S. Hvidberg

[This Week in Science] Metastatic breast tumors break down bone - 5 Feb 2016

Author: Wei Wong

[Policy Forum] Taking race out of human genetics - 5 Feb 2016

In the wake of the sequencing of the human genome in the early 2000s, genome pioneers and social scientists alike called for an end to the use of race as a variable in genetic research (1, 2). Unfortunately, by some measures, the use of race as a biological category has increased in the postgenomic age (3). Although inconsistent definition and use has been a chief problem with the race concept, it has historically been used as a taxonomic categorization based on common hereditary traits (such as skin color) to elucidate the relationship between our ancestry and our genes. We believe the use of biological concepts of race in human genetic research—so disputed and so mired in confusion—is problematic at best and harmful at worst. It is time for biologists to find a better way. Authors: Michael Yudell, Dorothy Roberts, Rob DeSalle, Sarah Tishkoff

[This Week in Science] Quiescent and aging hair follicle stem cells - 5 Feb 2016

Author: Beverly A. Purnell

[Perspective] Alfred Gilman (1941–2015) - 5 Feb 2016

Alfred Goodman Gilman died on 23 December, after a protracted battle with pancreatic cancer. We lost an extraordinary scientist, academic leader, and “mensch.” Al pioneered our understanding of the biochemical mechanisms that drive signal transduction and (with Martin Rodbell) shared the 1994 Nobel Prize in Physiology or Medicine for his role in the discovery of heterotrimeric guanine nucleotide-binding proteins (G proteins). He went on to describe the basic design of G protein-mediated cellular signaling circuits that regulate an enormous number of physiological responses and are the targets of a large fraction of today's drugs. Author: Melvin Simon

[This Week in Science] Keeping a stiff upper layer - 5 Feb 2016

Author: H. Jesse Smith

[Book Review] Losing our taste for diversity - 5 Feb 2016

Our modern food system is not driven by taste but instead by factors like consistency, predictability, low cost, and high yield. In Bread Wine Chocolate, Simran Sethi explores how the same features that enabled the worldwide distribution of once-exotic foods like coffee and chocolate have now so drastically altered how those products are made that we risk losing them altogether. Author: Christopher Kemp

[This Week in Science] It's not only the carbon in the trees - 5 Feb 2016

Author: H. Jesse Smith

[Book Review] Public enemy - 5 Feb 2016

Four years after his death, one of the most important figures of the Chinese scientific establishment has given us a first-person account of growing to manhood and eminence in revolutionary China. The Most Wanted Man in China is both a memoir and a personal testament of Fang Lizhi—a renowned scientist, humane scholar, political activist, intractable enemy of authoritarian government, and courageous advocate of human rights. Author: Irving A. Lerch

[Editors' Choice] Ecological legacy of a civil war - 5 Feb 2016

Author: Andrew M. Sugden

[Retraction] Editorial retraction - 5 Feb 2016

Author: Marcia McNutt

[Editors' Choice] Imaging to improve drug target mapping - 5 Feb 2016

Author: L. Bryan Ray

[Letter] Social cost of carbon: Domestic duty - 5 Feb 2016

Authors: Art Fraas, Randall Lutter, Susan Dudley, Ted Gayer, John Graham, Jason F. Shogren, W. Kip Viscusi

[Editors' Choice] Cationic biofilm inhibitors - 5 Feb 2016

Author: Phil Szuromi

[Letter] False positives are statistically inevitable - 5 Feb 2016

Author: R. D. Fricker

[Editors' Choice] A shallow explanation for tsunamis - 5 Feb 2016

Author: Brent Grocholski

[Letter] Psychosocial factors key to healthy aging - 5 Feb 2016

Author: Theodore D. Cosco

[Research Article] Hair follicle aging is driven by transepidermal elimination of stem cells via COL17A1 proteolysis - 5 Feb 2016

Hair thinning and loss are prominent aging phenotypes but have an unknown mechanism. We show that hair follicle stem cell (HFSC) aging causes the stepwise miniaturization of hair follicles and eventual hair loss in wild-type mice and in humans. In vivo fate analysis of HFSCs revealed that the DNA damage response in HFSCs causes proteolysis of type XVII collagen (COL17A1/BP180), a critical molecule for HFSC maintenance, to trigger HFSC aging, characterized by the loss of stemness signatures and by epidermal commitment. Aged HFSCs are cyclically eliminated from the skin through terminal epidermal differentiation, thereby causing hair follicle miniaturization. The aging process can be recapitulated by Col17a1 deficiency and prevented by the forced maintenance of COL17A1 in HFSCs, demonstrating that COL17A1 in HFSCs orchestrates the stem cell–centric aging program of the epithelial mini-organ. Authors: Hiroyuki Matsumura, Yasuaki Mohri, Nguyen Thanh Binh, Hironobu Morinaga, Makoto Fukuda, Mayumi Ito, Sotaro Kurata, Jan Hoeijmakers, Emi K. Nishimura

[This Week in Science] Small bats in damp places doomed - 5 Feb 2016

Author: SN

[Report] Transmutable nanoparticles with reconfigurable surface ligands - 5 Feb 2016

Unlike conventional inorganic materials, biological systems are exquisitely adapted to respond to their surroundings. Proteins and other biological molecules can process a complex set of chemical binding events as informational inputs and respond accordingly via a change in structure and function. We applied this principle to the design and synthesis of inorganic materials by preparing nanoparticles with reconfigurable surface ligands, where interparticle bonding can be programmed in response to specific chemical cues in a dynamic manner. As a result, a nascent set of “transmutable nanoparticles” can be driven to crystallize along multiple thermodynamic trajectories, resulting in rational control over the phase and time evolution of nanoparticle-based matter. Authors: Youngeun Kim, Robert J. Macfarlane, Matthew R. Jones, Chad A. Mirkin

[This Week in Science] A bacterial defense mechanism - 5 Feb 2016

Author: Valda Vinson

[Report] Electrical switching of an antiferromagnet - 5 Feb 2016

Antiferromagnets are hard to control by external magnetic fields because of the alternating directions of magnetic moments on individual atoms and the resulting zero net magnetization. However, relativistic quantum mechanics allows for generating current-induced internal fields whose sign alternates with the periodicity of the antiferromagnetic lattice. Using these fields, which couple strongly to the antiferromagnetic order, we demonstrate room-temperature electrical switching between stable configurations in antiferromagnetic CuMnAs thin-film devices by applied current with magnitudes of order 106 ampere per square centimeter. Electrical writing is combined in our solid-state memory with electrical readout and the stored magnetic state is insensitive to and produces no external magnetic field perturbations, which illustrates the unique merits of antiferromagnets for spintronics. Authors: P. Wadley, B. Howells, J. Železný, C. Andrews, V. Hills, R. P. Campion, V. Novák, K. Olejník, F. Maccherozzi, S. S. Dhesi, S. Y. Martin, T. Wagner, J. Wunderlich, F. Freimuth, Y. Mokrousov, J. Kuneš, J. S. Chauhan, M. J. Grzybowski, A. W. Rushforth, K. W. Edmonds, B. L. Gallagher, T. Jungwirth

[This Week in Science] Controlled colloid bonding using DNA - 5 Feb 2016

Author: Marc S. Lavine

[Report] Deformed wing virus is a recent global epidemic in honeybees driven by Varroa mites - 5 Feb 2016

Deformed wing virus (DWV) and its vector, the mite Varroa destructor, are a major threat to the world’s honeybees. Although the impact of Varroa on colony-level DWV epidemiology is evident, we have little understanding of wider DWV epidemiology and the role that Varroa has played in its global spread. A phylogeographic analysis shows that DWV is globally distributed in honeybees, having recently spread from a common source, the European honeybee Apis mellifera. DWV exhibits epidemic growth and transmission that is predominantly mediated by European and North American honeybee populations and driven by trade and movement of honeybee colonies. DWV is now an important reemerging pathogen of honeybees, which are undergoing a worldwide manmade epidemic fueled by the direct transmission route that the Varroa mite provides. Authors: L. Wilfert, G. Long, H. C. Leggett, P. Schmid-Hempel, R. Butlin, S. J. M. Martin, M. Boots

[This Week in Science] Manipulating a stubborn magnet - 5 Feb 2016

Author: Jelena Stajic

[Report] Biophysical climate impacts of recent changes in global forest cover - 5 Feb 2016

Changes in forest cover affect the local climate by modulating the land-atmosphere fluxes of energy and water. The magnitude of this biophysical effect is still debated in the scientific community and currently ignored in climate treaties. Here we present an observation-driven assessment of the climate impacts of recent forest losses and gains, based on Earth observations of global forest cover and land surface temperatures. Our results show that forest losses amplify the diurnal temperature variation and increase the mean and maximum air temperature, with the largest signal in arid zones, followed by temperate, tropical, and boreal zones. In the decade 2003–2012, variations of forest cover generated a mean biophysical warming on land corresponding to about 18% of the global biogeochemical signal due to CO2 emission from land-use change. Authors: Ramdane Alkama, Alessandro Cescatti

[This Week in Science] Europe's managed forests contribute to warming - 5 Feb 2016

Author: Andrew M. Sugden

[Report] Structures of aminoarabinose transferase ArnT suggest a molecular basis for lipid A glycosylation - 5 Feb 2016

Polymyxins are antibiotics used in the last line of defense to combat multidrug-resistant infections by Gram-negative bacteria. Polymyxin resistance arises through charge modification of the bacterial outer membrane with the attachment of the cationic sugar 4-amino-4-deoxy-l-arabinose to lipid A, a reaction catalyzed by the integral membrane lipid-to-lipid glycosyltransferase 4-amino-4-deoxy-l-arabinose transferase (ArnT). Here, we report crystal structures of ArnT from Cupriavidus metallidurans, alone and in complex with the lipid carrier undecaprenyl phosphate, at 2.8 and 3.2 angstrom resolution, respectively. The structures show cavities for both lipidic substrates, which converge at the active site. A structural rearrangement occurs on undecaprenyl phosphate binding, which stabilizes the active site and likely allows lipid A binding. Functional mutagenesis experiments based on these structures suggest a mechanistic model for ArnT family enzymes. Authors: Vasileios I. Petrou, Carmen M. Herrera, Kathryn M. Schultz, Oliver B. Clarke, Jérémie Vendome, David Tomasek, Surajit Banerjee, Kanagalaghatta R. Rajashankar, Meagan Belcher Dufrisne, Brian Kloss, Edda Kloppmann, Burkhard Rost, Candice S. Klug, M. Stephen Trent, Lawrence Shapiro, Filippo Mancia

[This Week in Science] Varroa-vectored virus pandemic - 5 Feb 2016

Author: Caroline Ash

[Report] A small-molecule inhibitor of sarcomere contractility suppresses hypertrophic cardiomyopathy in mice - 5 Feb 2016

Hypertrophic cardiomyopathy (HCM) is an inherited disease of heart muscle that can be caused by mutations in sarcomere proteins. Clinical diagnosis depends on an abnormal thickening of the heart, but the earliest signs of disease are hyperdynamic contraction and impaired relaxation. Whereas some in vitro studies of power generation by mutant and wild-type sarcomere proteins are consistent with mutant sarcomeres exhibiting enhanced contractile power, others are not. We identified a small molecule, MYK-461, that reduces contractility by decreasing the adenosine triphosphatase activity of the cardiac myosin heavy chain. Here we demonstrate that early, chronic administration of MYK-461 suppresses the development of ventricular hypertrophy, cardiomyocyte disarray, and myocardial fibrosis and attenuates hypertrophic and profibrotic gene expression in mice harboring heterozygous human mutations in the myosin heavy chain. These data indicate that hyperdynamic contraction is essential for HCM pathobiology and that inhibitors of sarcomere contraction may be a valuable therapeutic approach for HCM. Authors: Eric M. Green, Hiroko Wakimoto, Robert L. Anderson, Marc J. Evanchik, Joshua M. Gorham, Brooke C. Harrison, Marcus Henze, Raja Kawas, Johan D. Oslob, Hector M. Rodriguez, Yonghong Song, William Wan, Leslie A. Leinwand, James A. Spudich, Robert S. McDowell, J. G. Seidman, Christine E. Seidman

[This Week in Science] Powering down yields a healthier heart - 5 Feb 2016

Author: Paula A. Kiberstis

[Working Life] Retire the letter of reference - 5 Feb 2016

Author: Rima Wilkes

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