Geonomics & Science News

Geonomics & Science News


[Report] Polysialylation controls dendritic cell trafficking by regulating chemokine recognition - 8 Jan 2016

The addition of polysialic acid to N- and/or O-linked glycans, referred to as polysialylation, is a rare posttranslational modification that is mainly known to control the developmental plasticity of the nervous system. Here we show that CCR7, the central chemokine receptor controlling immune cell trafficking to secondary lymphatic organs, carries polysialic acid. This modification is essential for the recognition of the CCR7 ligand CCL21. As a consequence, dendritic cell trafficking is abrogated in polysialyltransferase-deficient mice, manifesting as disturbed lymph node homeostasis and unresponsiveness to inflammatory stimuli. Structure-function analysis of chemokine-receptor interactions reveals that CCL21 adopts an autoinhibited conformation, which is released upon interaction with polysialic acid. Thus, we describe a glycosylation-mediated immune cell trafficking disorder and its mechanistic basis. Authors: Eva Kiermaier, Christine Moussion, Christopher T. Veldkamp, Rita Gerardy-Schahn, Ingrid de Vries, Larry G. Williams, Gary R. Chaffee, Andrew J. Phillips, Friedrich Freiberger, Richard Imre, Deni Taleski, Richard J. Payne, Asolina Braun, Reinhold Förster, Karl Mechtler, Martina Mühlenhoff, Brian F. Volkman, Michael Sixt

[Review] The Anthropocene is functionally and stratigraphically distinct from the Holocene - 8 Jan 2016

Human activity is leaving a pervasive and persistent signature on Earth. Vigorous debate continues about whether this warrants recognition as a new geologic time unit known as the Anthropocene. We review anthropogenic markers of functional changes in the Earth system through the stratigraphic record. The appearance of manufactured materials in sediments, including aluminum, plastics, and concrete, coincides with global spikes in fallout radionuclides and particulates from fossil fuel combustion. Carbon, nitrogen, and phosphorus cycles have been substantially modified over the past century. Rates of sea-level rise and the extent of human perturbation of the climate system exceed Late Holocene changes. Biotic changes include species invasions worldwide and accelerating rates of extinction. These combined signals render the Anthropocene stratigraphically distinct from the Holocene and earlier epochs. Authors: Colin N. Waters, Jan Zalasiewicz, Colin Summerhayes, Anthony D. Barnosky, Clément Poirier, Agnieszka Gałuszka, Alejandro Cearreta, Matt Edgeworth, Erle C. Ellis, Michael Ellis, Catherine Jeandel, Reinhold Leinfelder, J. R. McNeill, Daniel deB. Richter, Will Steffen, James Syvitski, Davor Vidas, Michael Wagreich, Mark Williams, An Zhisheng, Jacques Grinevald, Eric Odada, Naomi Oreskes, Alexander P. Wolfe

[In Brief] News at a glance - 8 Jan 2016

In science news around the world, Australian scientists slam the environmental impact assessment process behind projects such the expansion of the Abbot Point coal terminal near the Great Barrier Reef, and Iran offers a new science prize in the effort to become known as a research powerhouse. Also, new superheavy elements claim their places on the periodic table, researchers discover a way to predict side effects of the flu vaccine, and a unique orchid imitates human body odor to attract pollinating mosquitoes. And archaeologist Nicole Boivin talks to Science about the philosophy behind the new Max Planck Institute for the Science of Human History in Jena, Germany.

[This Week in Science] Going in with a BAM - 8 Jan 2016

Author: Valda Vinson

[In Depth] A race to explain Brazil's spike in birth defects - 8 Jan 2016

Brazil is facing a disturbing spike in a severe birth defect called microcephaly. Babies are born with heads that are far too small, a sign that the brain failed to fully develop. Doctors there have reported nearly 3000 cases since July 2015—more than 20 times the usual rate. Scientists are scrambling to understand what is going on. The leading theory so far is that the condition is caused by a little known mosquito-borne virus called Zika that surfaced in Brazil in March and is quickly spreading through Latin America. The news has prompted the government to declare a public health emergency; some doctors are recommending women not get pregnant until more is known. Researchers are trying to develop better diagnostic tests for the virus so they can track whether mothers of affected babies were infected during their pregnancies, and other groups are hoping to use stem cell models of the developing human brain to understand how the virus might affect fetal growth. Meanwhile, the virus is advancing fast. It surfaced in Colombia, Suriname, Guatemala, El Salvador, and Mexico in October and November; Puerto Rico reported its first cases in late December. Researchers warn that countries across the Americas should be prepared for a similar wave of birth defects in coming months. Author: Gretchen Vogel

[Report] Dominance of the suppressed: Power-law size structure in tropical forests - 8 Jan 2016

Tropical tree size distributions are remarkably consistent despite differences in the environments that support them. With data analysis and theory, we found a simple and biologically intuitive hypothesis to explain this property, which is the foundation of forest dynamics modeling and carbon storage estimates. After a disturbance, new individuals in the forest gap grow quickly in full sun until they begin to overtop one another. The two-dimensional space-filling of the growing crowns of the tallest individuals relegates a group of losing, slow-growing individuals to the understory. Those left in the understory follow a power-law size distribution, the scaling of which depends on only the crown area–to–diameter allometry exponent: a well-conserved value across tropical forests. Authors: C. E. Farrior, S. A. Bohlman, S. Hubbell, S. W. Pacala

[In Depth] Iraq confronts a new enemy—the Persian Gulf - 8 Jan 2016

Iraq, already struggling with war, poverty, and sectarian strife, faces a new threat. The loss of water in the Tigris and Euphrates rivers, which begin in Turkey and flow into the Persian Gulf, endangers farmers, city dwellers, and the famous Mesopotamian marshes that are home to a rich ecosystem. Turkish dams, a long drought, and water mismanagement mean that little freshwater reaches southern Iraq. As a result, the saltwater of the gulf is slowly working its way inland, with important ramifications for Iraq's future. University of Basra researchers are sounding the alarm. Author: Andrew Lawler

[This Week in Science] Decomposition spawns a microbial zoo - 8 Jan 2016

Author: Caroline Ash

[In Depth] Cesium fortifies next-generation solar cells - 8 Jan 2016

In a world looking for better, cheaper alternative energy, the solar cell materials called perovskites are a bright hope. Their efficiency at converting sunlight into electricity is climbing faster than that of any solar technology before them. They're cheap and easy to make, can be manufactured roll-to-roll like newsprint, and can even be layered atop conventional silicon solar cells to boost their output. But they are fragile stars: Moisture, air, heat, or even prolonged sunlight makes them fall apart. Now, these materials are toughening up. Over the past few months, three separate teams have reported that adding a dash of cesium to their perovskite recipes produces efficient solar cells that are far more stable when exposed to the elements. Meanwhile, other researchers report that their latest cells are as efficient as standard silicon cells and may soon rival costly gallium arsenide cells. Author: Robert F. Service

[Editors' Choice] Breaking DNA for gene expression - 8 Jan 2016

Author: Guy Riddihough

[In Depth] Conservation researchers get a new roost in Cambridge - 8 Jan 2016

Since 2007, the Cambridge Conservation Initiative (CCI) has helped support collaborations among the largest concentration of conservation scientists in the world, in Cambridge, U.K. Several years ago, CCI saw an opportunity to deepen such alliances after two university departments left a 1960s-era Brutalist concrete office building in the heart of the university. As part of a £58 million overhaul, architects designed spaces to foster collaborations. Planners say the relationships will be mutually beneficial: Up to 150 academics will find new opportunities to apply their research, while an estimated 350 conservation practitioners will bring new problems. Participants believe that by harnessing "the Cambridge brand" for conservation research, the hub will become a go-to resource for government, business, and philanthropy leaders. Author: Erik Stokstad

[Report] Ultrahigh power factor and thermoelectric performance in hole-doped single-crystal SnSe - 8 Jan 2016

Thermoelectric technology, harvesting electric power directly from heat, is a promising environmentally friendly means of energy savings and power generation. The thermoelectric efficiency is determined by the device dimensionless figure of merit ZTdev, and optimizing this efficiency requires maximizing ZT values over a broad temperature range. Here, we report a record high ZTdev ∼1.34, with ZT ranging from 0.7 to 2.0 at 300 to 773 kelvin, realized in hole-doped tin selenide (SnSe) crystals. The exceptional performance arises from the ultrahigh power factor, which comes from a high electrical conductivity and a strongly enhanced Seebeck coefficient enabled by the contribution of multiple electronic valence bands present in SnSe. SnSe is a robust thermoelectric candidate for energy conversion applications in the low and moderate temperature range. Authors: Li-Dong Zhao, Gangjian Tan, Shiqiang Hao, Jiaqing He, Yanling Pei, Hang Chi, Heng Wang, Shengkai Gong, Huibin Xu, Vinayak P. Dravid, Ctirad Uher, G. Jeffrey Snyder, Chris Wolverton, Mercouri G. Kanatzidis

[In Depth] DATA CHECK: For female scientists, mixed funding results at U.S. agencies - 8 Jan 2016

A new study by a congressional watchdog agency finds that female scientists are less likely than men to receive research grants from the U.S. government. But the analysis by the Government Accountability Office (GAO) comes with several caveats. Some agencies don't collect the data needed to reveal gender disparities in funding, which forced GAO to a find a novel way to address the concerns of the three Democratic congresswomen who requested the study. In addition, discrimination may not be the reason for the disparity. Finally, some agencies aren't doing what the law requires to track the impact of their investments on gender equity at U.S. universities. Author: Jeffrey Mervis

[Report] Accurate concentration control of mitochondria and nucleoids - 8 Jan 2016

All cellular materials are partitioned between daughters at cell division, but by various mechanisms and with different accuracy. In the yeast Schizosaccharomyces pombe, the mitochondria are pushed to the cell poles by the spindle. We found that mitochondria spatially reequilibrate just before division, and that the mitochondrial volume and DNA-containing nucleoids instead segregate in proportion to the cytoplasm inherited by each daughter. However, nucleoid partitioning errors are suppressed by control at two levels: Mitochondrial volume is actively distributed throughout a cell, and nucleoids are spaced out in semiregular arrays within mitochondria. During the cell cycle, both mitochondria and nucleoids appear to be produced without feedback, creating a net control of fluctuations that is just accurate enough to avoid substantial growth defects. Authors: Rishi Jajoo, Yoonseok Jung, Dann Huh, Matheus P. Viana, Susanne M. Rafelski, Michael Springer, Johan Paulsson

[Feature] A shot at migraine - 8 Jan 2016

Millions dread the onset of migraine headaches, which strike roughly 12% of the world's population at least once per year. Existing treatments can only head off migraines after they start, and don't work for many people. On the horizon, however, is a new class of drugs that many scientists believe can stop migraines at their root. Four pharmaceutical companies are racing to complete advanced clinical trials of antibody drugs that block the activity of a molecule called calcitonin gene-related peptide, or CGRP, which spikes during migraine attacks. The discovery of CGRP may also help to solve the centuries-old puzzle of what triggers a migraine's complex neurological events. Author: Emily Underwood

[Editorial] Biggest opportunity of our age - 8 Jan 2016

The importance of the agreement reached at the Paris climate Conference of Parties (COP21) last month cannot be overstated. It is a major step toward preventing some of the worst risks that climate change presents to the global economy and security. Now is the time to seize the opportunity that this moment represents. We must transform world economies away from fossil fuels toward a more sustainable low-carbon future. Author: David King

[Perspective] Ancient grasslands at risk - 8 Jan 2016

Concerns over deforestation have led to attempts to identify suitable areas for reforestation around the world (1). The most ambitious effort to date is the World Resources Institute (WRI) Atlas of Forest and Landscape Restoration Opportunities (1). This map is linked to a global plan to reforest degraded lands to offset anthropogenic CO2 emissions. The immediate target is the reforestation of 1.5 million km2 by 2020 (2, 3). Vast areas of open grassy vegetation have been identified as suitable for reforestation. But are all these grasslands secondary products of deforestations? Recent research shows that grasslands are often ancient and highly biodiverse, but it remains difficult to distinguish between primary and secondary grasslands on a large scale. Reforestation efforts thus risk converting ancient tropical grasslands to plantations. Author: William J. Bond

[This Week in Science] Mantle minerals won't share the strain - 8 Jan 2016

Author: Brent Grocholski

[Perspective] Lower-mantle materials under pressure - 8 Jan 2016

Modern high-pressure experimental techniques have enabled us to achieve the pressure and temperature at the center of Earth (about 360 GPa and 6000 K) in laboratories. However, studies of rheological properties of minerals under controlled strain rate (creep experiments) have been limited to the pressure equivalent to that in Earth's transition zone, a depth only about one-tenth of Earth's radius. Determinations of rheological laws that govern the flows and viscosities of minerals in Earth's deep mantle have been far beyond our reach. In the absence of such critical data, the nature of mantle dynamics—such as whether the convection involves the entire lower mantle, yielding a chemically homogeneous deep mantle—remains controversial. Discovery of the breakdown of ringwoodite into the denser bridgmanite and magnesiowüstite phases at 24 GPa (1) removed the need for a major chemical discontinuity in Earth inferred from observations of a strong seismic reflector at 660 km depth. On page 144 of this issue, Girard et al. (2) report on the detailed rheological nature of this bridgmanite plus magnesiowüstite mineral aggregate, shedding more light on the mantle convection. The integration of brilliant synchrotron radiations and rotating apposed anvils enables creep experiments for large strain at pressures equivalent to that in Earth's lower mantle. Author: Jiuhua Chen

[Editors' Choice] Following the bloodline downstream - 8 Jan 2016

Author: Laura M. Zahn

[Perspective] Finding merit in dividing neighbors - 8 Jan 2016

A large fraction of energy consumed by humankind is wasted as heat. Some of this energy can be recycled with thermoelectric devices that convert a thermal gradient into electricity. However, their wide adoption will require development of materials with high thermoelectric figure of merit (ZT) that lack rare or harmful elements. On page 141 of this issue, Zhao et al. (1) report on p-doped tin selenide (SnSe), which helps meet these goals. Author: Kamran Behnia

[Editors' Choice] Testing a cell signaling circuit - 8 Jan 2016

Author: L. Bryan Ray

[Perspective] Disrupted nuclear import-export in neurodegeneration - 8 Jan 2016

The major human neurodegenerative diseases, including Alzheimer's, amyotrophic lateral sclerosis, Parkinson's, and Huntington's diseases, are associated with accumulation and aggregation of misfolded proteins. In most cases, the majority of aberrantly aggregated proteins are found in the cell cytoplasm. However, in disorders caused by the expansion of a trinucleotide repeat, including Huntington's disease and spinocerebellar ataxia, the corresponding aggregates of proteins containing the encoded polyglutamine expansions are predominantly nuclear. Whether differences in intracellular location matter for the toxicity generated by such proteins has not been determined. On page 173 of this issue, Woerner et al. (1) report that the location does indeed matter, with toxicity arising from the cytoplasmic accumulation of a pair of artificial proteins designed to mimic the properties of amyloid aggregates. Surprisingly, forcing the same artificial proteins into the nucleus substantially reduces their toxicity. Authors: Sandrine Da Cruz, Don W. Cleveland

[Research Article] Distinct routes of lineage development reshape the human blood hierarchy across ontogeny - 8 Jan 2016

In a classical view of hematopoiesis, the various blood cell lineages arise via a hierarchical scheme starting with multipotent stem cells that become increasingly restricted in their differentiation potential through oligopotent and then unipotent progenitors. We developed a cell-sorting scheme to resolve myeloid (My), erythroid (Er), and megakaryocytic (Mk) fates from single CD34+ cells and then mapped the progenitor hierarchy across human development. Fetal liver contained large numbers of distinct oligopotent progenitors with intermingled My, Er, and Mk fates. However, few oligopotent progenitor intermediates were present in the adult bone marrow. Instead, only two progenitor classes predominate, multipotent and unipotent, with Er-Mk lineages emerging from multipotent cells. The developmental shift to an adult “two-tier” hierarchy challenges current dogma and provides a revised framework to understand normal and disease states of human hematopoiesis. Authors: Faiyaz Notta, Sasan Zandi, Naoya Takayama, Stephanie Dobson, Olga I. Gan, Gavin Wilson, Kerstin B. Kaufmann, Jessica McLeod, Elisa Laurenti, Cyrille F. Dunant, John D. McPherson, Lincoln D. Stein, Yigal Dror, John E. Dick

[Perspective] Potency finds its niches - 8 Jan 2016

Hematopoietic stem cells (HSCs) located atop the hematopoietic hierarchy are responsible for the lifelong production of all mature blood cells. These partly dormant, long-term self-renewing, multipotent HSCs in the bone marrow generate multipotent progenitors (MPPs) with reduced self-renewal activity before lineage determination and differentiation are initiated (1, 2). For decades, it was thought that MPPs lose their multipotent capacity in a stepwise fashion, generating first a series of oligopotent and from there unipotent progenitors to finally make all hematopoietic cell types. The presence of oligopotent intermediates such as common lymphoid progenitors (CLPs) and common myeloid progenitors (CMPs) is crucial to this model because they define the path from multipotent to unipotent cells. A study by Notta et al. on page 139 of this issue (3) and another study by Paul et al. (4) provide strong evidence for the nonexistence of CMPs in human and mouse bone marrow. And on page 176 of this issue, Khan et al. (5) report a niche population in the fetal liver that maintains proliferating HSCs. Authors: Nina Cabezas-Wallscheid, Andreas Trumpp

[Report] Repeated catastrophic valley infill following medieval earthquakes in the Nepal Himalaya - 8 Jan 2016

Geomorphic footprints of past large Himalayan earthquakes are elusive, although they are urgently needed for gauging and predicting recovery times of seismically perturbed mountain landscapes. We present evidence of catastrophic valley infill following at least three medieval earthquakes in the Nepal Himalaya. Radiocarbon dates from peat beds, plant macrofossils, and humic silts in fine-grained tributary sediments near Pokhara, Nepal’s second-largest city, match the timing of nearby M > 8 earthquakes in ~1100, 1255, and 1344 C.E. The upstream dip of tributary valley fills and x-ray fluorescence spectrometry of their provenance rule out local sources. Instead, geomorphic and sedimentary evidence is consistent with catastrophic fluvial aggradation and debris flows that had plugged several tributaries with tens of meters of calcareous sediment from a Higher Himalayan source >60 kilometers away. Authors: Wolfgang Schwanghart, Anne Bernhardt, Amelie Stolle, Philipp Hoelzmann, Basanta R. Adhikari, Christoff Andermann, Stefanie Tofelde, Silke Merchel, Georg Rugel, Monique Fort, Oliver Korup

[Policy Forum] Balancing hydropower and biodiversity in the Amazon, Congo, and Mekong - 8 Jan 2016

The world's most biodiverse river basins—the Amazon, Congo, and Mekong—are experiencing an unprecedented boom in construction of hydropower dams. These projects address important energy needs, but advocates often overestimate economic benefits and underestimate far-reaching effects on biodiversity and critically important fisheries. Powerful new analytical tools and high-resolution environmental data can clarify trade-offs between engineering and environmental goals and can enable governments and funding institutions to compare alternative sites for dam building. Current site-specific assessment protocols largely ignore cumulative impacts on hydrology and ecosystem services as ever more dams are constructed within a watershed (1). To achieve true sustainability, assessments of new projects must go beyond local impacts by accounting for synergies with existing dams, as well as land cover changes and likely climatic shifts (2, 3). We call for more sophisticated and holistic hydropower planning, including validation of technologies intended to mitigate environmental impacts. Should anything less be required when tampering with the world's great river ecosystems? Authors: K. O. Winemiller, P. B. McIntyre, L. Castello, E. Fluet-Chouinard, T. Giarrizzo, S. Nam, I. G. Baird, W. Darwall, N. K. Lujan, I. Harrison, M. L. J. Stiassny, R. A. M. Silvano, D. B. Fitzgerald, F. M. Pelicice, A. A. Agostinho, L. C. Gomes, J. S. Albert, E. Baran, M. Petrere, C. Zarfl, M. Mulligan, J. P. Sullivan, C. C. Arantes, L. M. Sousa, A. A. Koning, D. J. Hoeinghaus, M. Sabaj, J. G. Lundberg, J. Armbruster, M. L. Thieme, P. Petry, J. Zuanon, G. Torrente Vilara, J. Snoeks, C. Ou, W. Rainboth, C. S. Pavanelli, A. Akama, A. van Soesbergen, L. Sáenz

[Report] The 5300-year-old Helicobacter pylori genome of the Iceman - 8 Jan 2016

The stomach bacterium Helicobacter pylori is one of the most prevalent human pathogens. It has dispersed globally with its human host, resulting in a distinct phylogeographic pattern that can be used to reconstruct both recent and ancient human migrations. The extant European population of H. pylori is known to be a hybrid between Asian and African bacteria, but there exist different hypotheses about when and where the hybridization took place, reflecting the complex demographic history of Europeans. Here, we present a 5300-year-old H. pylori genome from a European Copper Age glacier mummy. The “Iceman” H. pylori is a nearly pure representative of the bacterial population of Asian origin that existed in Europe before hybridization, suggesting that the African population arrived in Europe within the past few thousand years. Authors: Frank Maixner, Ben Krause-Kyora, Dmitrij Turaev, Alexander Herbig, Michael R. Hoopmann, Janice L. Hallows, Ulrike Kusebauch, Eduard Egarter Vigl, Peter Malfertheiner, Francis Megraud, Niall O’Sullivan, Giovanna Cipollini, Valentina Coia, Marco Samadelli, Lars Engstrand, Bodo Linz, Robert L. Moritz, Rudolf Grimm, Johannes Krause, Almut Nebel, Yoshan Moodley, Thomas Rattei, Albert Zink

[Book Review] The supercollider that wasn't - 8 Jan 2016

When a multibillion-dollar physics experiment is canceled, it's tempting to look for lessons that can be applied to future megascience projects. A new book on the rise and fall of the Superconducting Supercollider (SSC) by a trio of science historians takes on that challenge. And while the authors do an excellent job of describing what occurred in the decade from its inception to its demise, they stumble when trying to assign blame. Author: Jeffrey Mervis

[Report] Fetal liver hematopoietic stem cell niches associate with portal vessels - 8 Jan 2016

Whereas the cellular basis of the hematopoietic stem cell (HSC) niche in the bone marrow has been characterized, the nature of the fetal liver niche is not yet elucidated. We show that Nestin+NG2+ pericytes associate with portal vessels, forming a niche promoting HSC expansion. Nestin+NG2+ cells and HSCs scale during development with the fractal branching patterns of portal vessels, tributaries of the umbilical vein. After closure of the umbilical inlet at birth, portal vessels undergo a transition from Neuropilin-1+Ephrin-B2+ artery to EphB4+ vein phenotype, associated with a loss of periportal Nestin+NG2+ cells and emigration of HSCs away from portal vessels. These data support a model in which HSCs are titrated against a periportal vascular niche with a fractal-like organization enabled by placental circulation. Authors: Jalal A. Khan, Avital Mendelson, Yuya Kunisaki, Alexander Birbrair, Yan Kou, Anna Arnal-Estapé, Sandra Pinho, Paul Ciero, Fumio Nakahara, Avi Ma’ayan, Aviv Bergman, Miriam Merad, Paul S. Frenette

[Book Review] Origin stories - 8 Jan 2016

A Brief History of Creation, like many popular books about the origin of life, approaches the topic with a broad sweep. But unlike many others, which tend to recycle old versions of Francesco Redi and his experiments on maggots, or Louis Pasteur and his swan-necked flasks, unaware that they are repeating inaccuracies historians have set straight, this book renders new information from the professional history of science literature accessible to a wide audience. Author: James Strick

[Podcast] Science Podcast: 8 January Show - 8 Jan 2016

On this week's show: Mitigating migraines, clocking corpse decomposition, and a news roundup.

[Books et al.] Books Received - 8 Jan 2016

In an effort to better serve our readers, we're working on some exciting new offerings for 2016. These projects have necessitated a shift in resources that precludes the continued curation of our weekly list of books received. We thank you for understanding, and look forward to continuing to serve as your go-to source for smart commentary on scientific books and media in the coming year.

[This Week in Science] Nepal's quake-driven landslide hazards - 8 Jan 2016

Author: Brent Grocholski

[Letter] Call for conservation: Abandoned pasture - 8 Jan 2016

Author: Joseph A. C. Poore

[This Week in Science] Mitochondria migration during mitosis - 8 Jan 2016

Author: L. Bryan Ray

[Letter] Recognizing thermal plasticity in fish - 8 Jan 2016

Authors: Anthony P. Farrell, Craig E. Franklin

[This Week in Science] A chemokine's sugary release - 8 Jan 2016

Author: Kristen L. Mueller

[Letter] HIV/AIDS epidemic: The whole truth - 8 Jan 2016

Author: Neal Nathanson

[Editors' Choice] A global census of lake nutrients - 8 Jan 2016

Author: Nicholas S. Wigginton

[This Week in Science] Stomach ache for a European mummy - 8 Jan 2016

Author: Caroline Ash

[Editors' Choice] Setting the table for a new plate - 8 Jan 2016

Author: Brent Grocholski

[This Week in Science] Perovskites for tandem solar cells - 8 Jan 2016

Author: Phil Szuromi

[Editors' Choice] Tuning graphene at a stretch - 8 Jan 2016

Author: Ian S. Osborne

[This Week in Science] How HSCs populate the fetal liver - 8 Jan 2016

Author: Beverly A. Purnell

[Editors' Choice] A protein assist for brain border crossings - 8 Jan 2016

Author: Kristen L. Mueller

[This Week in Science] The difference is all in the water - 8 Jan 2016

Author: H. Jesse Smith

[Research Article] Gating of hippocampal activity, plasticity, and memory by entorhinal cortex long-range inhibition - 8 Jan 2016

The cortico-hippocampal circuit is critical for storage of associational memories. Most studies have focused on the role in memory storage of the excitatory projections from entorhinal cortex to hippocampus. However, entorhinal cortex also sends inhibitory projections, whose role in memory storage and cortico-hippocampal activity remains largely unexplored. We found that these long-range inhibitory projections enhance the specificity of contextual and object memory encoding. At the circuit level, these γ-aminobutyric acid (GABA)–releasing projections target hippocampal inhibitory neurons and thus act as a disinhibitory gate that transiently promotes the excitation of hippocampal CA1 pyramidal neurons by suppressing feedforward inhibition. This enhances the ability of CA1 pyramidal neurons to fire synaptically evoked dendritic spikes and to generate a temporally precise form of heterosynaptic plasticity. Long-range inhibition from entorhinal cortex may thus increase the precision of hippocampal-based long-term memory associations by assessing the salience of mnemonormation to the immediate sensory input. Authors: Jayeeta Basu, Jeffrey D. Zaremba, Stephanie K. Cheung, Frederick L. Hitti, Boris V. Zemelman, Attila Losonczy, Steven A. Siegelbaum

[This Week in Science] The ART of HIV prevention - 8 Jan 2016

Author: Angela Colmone

[Research Article] Geomorphic and geologic controls of geohazards induced by Nepal’s 2015 Gorkha earthquake - 8 Jan 2016

The Gorkha earthquake (magnitude 7.8) on 25 April 2015 and later aftershocks struck South Asia, killing ~9000 people and damaging a large region. Supported by a large campaign of responsive satellite data acquisitions over the earthquake disaster zone, our team undertook a satellite image survey of the earthquakes’ induced geohazards in Nepal and China and an assessment of the geomorphic, tectonic, and lithologic controls on quake-induced landslides. Timely analysis and communication aided response and recovery and informed decision-makers. We mapped 4312 coseismic and postseismic landslides. We also surveyed 491 glacier lakes for earthquake damage but found only nine landslide-impacted lakes and no visible satellite evidence of outbursts. Landslide densities correlate with slope, peak ground acceleration, surface downdrop, and specific metamorphic lithologies and large plutonic intrusions. Authors: J. S. Kargel, G. J. Leonard, D. H. Shugar, U. K. Haritashya, A. Bevington, E. J. Fielding, K. Fujita, M. Geertsema, E. S. Miles, J. Steiner, E. Anderson, S. Bajracharya, G. W. Bawden, D. F. Breashears, A. Byers, B. Collins, M. R. Dhital, A. Donnellan, T. L. Evans, M. L. Geai, M. T. Glasscoe, D. Green, D. R. Gurung, R. Heijenk, A. Hilborn, K. Hudnut, C. Huyck, W. W. Immerzeel, Jiang Liming, R. Jibson, A. Kääb, N. R. Khanal, D. Kirschbaum, P. D. A. Kraaijenbrink, D. Lamsal, Liu Shiyin, Lv Mingyang, D. McKinney, N. K. Nahirnick, Nan Zhuotong, S. Ojha, J. Olsenholler, T. H. Painter, M. Pleasants, K. C. Pratima, Q. I. Yuan, B. H. Raup, D. Regmi, D. R. Rounce, A. Sakai, Shangguan Donghui, J. M. Shea, A. B. Shrestha, A. Shukla, D. Stumm, M. van der Kooij, K. Voss, Wang Xin, B. Weihs, D. Wolfe, Wu Lizong, Yao Xiaojun, M. R. Yoder, N. Young

[This Week in Science] Location, location, location - 8 Jan 2016

Author: Stella M. Hurtley

[Report] Shear deformation of bridgmanite and magnesiowüstite aggregates at lower mantle conditions - 8 Jan 2016

Rheological properties of the lower mantle have strong influence on the dynamics and evolution of Earth. By using the improved methods of quantitative deformation experiments at high pressures and temperatures, we deformed a mixture of bridgmanite and magnesiowüstite under the shallow lower mantle conditions. We conducted experiments up to about 100% strain at a strain rate of about 3 × 10−5 second−1. We found that bridgmanite is substantially stronger than magnesiowüstite and that magnesiowüstite largely accommodates the strain. Our results suggest that strain weakening and resultant shear localization likely occur in the lower mantle. This would explain the preservation of long-lived geochemical reservoirs and the lack of seismic anisotropy in the majority of the lower mantle except the boundary layers. Authors: Jennifer Girard, George Amulele, Robert Farla, Anwar Mohiuddin, Shun-ichiro Karato

[This Week in Science] Size distributions of tropical trees - 8 Jan 2016

Author: Andrew M. Sugden

[Report] A mixed-cation lead mixed-halide perovskite absorber for tandem solar cells - 8 Jan 2016

Metal halide perovskite photovoltaic cells could potentially boost the efficiency of commercial silicon photovoltaic modules from ∼20 toward 30% when used in tandem architectures. An optimum perovskite cell optical band gap of ~1.75 electron volts (eV) can be achieved by varying halide composition, but to date, such materials have had poor photostability and thermal stability. Here we present a highly crystalline and compositionally photostable material, [HC(NH2)2]0.83Cs0.17Pb(I0.6Br0.4)3, with an optical band gap of ~1.74 eV, and we fabricated perovskite cells that reached open-circuit voltages of 1.2 volts and power conversion efficiency of over 17% on small areas and 14.7% on 0.715 cm2 cells. By combining these perovskite cells with a 19%-efficient silicon cell, we demonstrated the feasibility of achieving >25%-efficient four-terminal tandem cells. Authors: David P. McMeekin, Golnaz Sadoughi, Waqaas Rehman, Giles E. Eperon, Michael Saliba, Maximilian T. Hörantner, Amir Haghighirad, Nobuya Sakai, Lars Korte, Bernd Rech, Michael B. Johnston, Laura M. Herz, Henry J. Snaith

[This Week in Science] Plants send out a bacterial mimic - 8 Jan 2016

Author: Nancy R. Gough

[Report] Microbial community assembly and metabolic function during mammalian corpse decomposition - 8 Jan 2016

Vertebrate corpse decomposition provides an important stage in nutrient cycling in most terrestrial habitats, yet microbially mediated processes are poorly understood. Here we combine deep microbial community characterization, community-level metabolic reconstruction, and soil biogeochemical assessment to understand the principles governing microbial community assembly during decomposition of mouse and human corpses on different soil substrates. We find a suite of bacterial and fungal groups that contribute to nitrogen cycling and a reproducible network of decomposers that emerge on predictable time scales. Our results show that this decomposer community is derived primarily from bulk soil, but key decomposers are ubiquitous in low abundance. Soil type was not a dominant factor driving community development, and the process of decomposition is sufficiently reproducible to offer new opportunities for forensic investigations. Authors: Jessica L. Metcalf, Zhenjiang Zech Xu, Sophie Weiss, Simon Lax, Will Van Treuren, Embriette R. Hyde, Se Jin Song, Amnon Amir, Peter Larsen, Naseer Sangwan, Daniel Haarmann, Greg C. Humphrey, Gail Ackermann, Luke R. Thompson, Christian Lauber, Alexander Bibat, Catherine Nicholas, Matthew J. Gebert, Joseph F. Petrosino, Sasha C. Reed, Jack A. Gilbert, Aaron M. Lynne, Sibyl R. Bucheli, David O. Carter, Rob Knight

[This Week in Science] Heat conversion gets a power boost - 8 Jan 2016

Author: Brent Grocholski

[Report] Reconciliation of the Devils Hole climate record with orbital forcing - 8 Jan 2016

The driving force behind Quaternary glacial-interglacial cycles and much associated climate change is widely considered to be orbital forcing. However, previous versions of the iconic Devils Hole (Nevada) subaqueous calcite record exhibit shifts to interglacial values ~10,000 years before orbitally forced ice age terminations, and interglacial durations ~10,000 years longer than other estimates. Our measurements from Devils Hole 2 replicate virtually all aspects of the past 204,000 years of earlier records, except for the timing during terminations, and they lower the age of the record near Termination II by ~8000 years, removing both ~10,000-year anomalies. The shift to interglacial values now broadly coincides with the rise in boreal summer insolation, the marine termination, and the rise in atmospheric CO2, which is consistent with mechanisms ultimately tied to orbital forcing. Authors: Gina E. Moseley, R. Lawrence Edwards, Kathleen A. Wendt, Hai Cheng, Yuri Dublyansky, Yanbin Lu, Ronny Boch, Christoph Spötl

[This Week in Science] Evidence of an Anthropocene epoch - 8 Jan 2016

Author: Nicholas S. Wigginton

[Report] Cytoplasmic protein aggregates interfere with nucleocytoplasmic transport of protein and RNA - 8 Jan 2016

Amyloid-like protein aggregation is associated with neurodegeneration and other pathologies. The nature of the toxic aggregate species and their mechanism of action remain elusive. Here, we analyzed the compartment specificity of aggregate toxicity using artificial β-sheet proteins, as well as fragments of mutant huntingtin and TAR DNA binding protein–43 (TDP-43). Aggregation in the cytoplasm interfered with nucleocytoplasmic protein and RNA transport. In contrast, the same proteins did not inhibit transport when forming inclusions in the nucleus at or around the nucleolus. Protein aggregation in the cytoplasm, but not the nucleus, caused the sequestration and mislocalization of proteins containing disordered and low-complexity sequences, including multiple factors of the nuclear import and export machinery. Thus, impairment of nucleocytoplasmic transport may contribute to the cellular pathology of various aggregate deposition diseases. Authors: Andreas C. Woerner, Frédéric Frottin, Daniel Hornburg, Li R. Feng, Felix Meissner, Maria Patra, Jörg Tatzelt, Matthias Mann, Konstanze F. Winklhofer, F. Ulrich Hartl, Mark S. Hipp

[This Week in Science] Reforest with care - 8 Jan 2016

Author: Julia Fahrenkamp-Uppenbrink

[Report] The structure of the β-barrel assembly machinery complex - 8 Jan 2016

β-Barrel outer membrane proteins (OMPs) are found in the outer membranes of Gram-negative bacteria and are essential for nutrient import, signaling, and adhesion. A 200-kilodalton five-component complex called the β-barrel assembly machinery (BAM) complex has been implicated in the biogenesis of OMPs. We report the structure of the BAM complex from Escherichia coli, revealing that binding of BamCDE modulates the conformation of BamA, the central component, which may serve to regulate the BAM complex. The periplasmic domain of BamA was in a closed state that prevents access to the barrel lumen, which indicates substrate OMPs may not be threaded through the barrel during biogenesis. Further, conformational shifts in the barrel domain lead to opening of the exit pore and rearrangement at the lateral gate. Authors: Jeremy Bakelar, Susan K. Buchanan, Nicholas Noinaj

[This Week in Science] Fine-tuned information flow in the brain - 8 Jan 2016

Author: Peter Stern

[New Products] New Products - 8 Jan 2016

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

[This Week in Science] Adjusting hematopoietic hierarchy - 8 Jan 2016

Author: Beverly A. Purnell

[Working Life] Want a letter? You write it for me - 8 Jan 2016

Author: Roger S. Day

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