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https://read.qxmd.com/read/30872536/arc-continent-collisions-in-the-tropics-set-earth-s-climate-state
#1
Francis A Macdonald, Nicholas L Swanson-Hysell, Yuem Park, Lorraine Lisiecki, Oliver Jagoutz
On multi-million-year timescales, Earth has experienced warm ice-free and cold glacial climates, but it is unknown if transitions between these background climate states were the result of changes in CO2 sources or sinks. Low-latitude arc-continent collisions are hypothesized to drive cooling by uplifting and eroding mafic and ultramafic rocks in the warm, wet tropics, thereby increasing Earth's potential to sequester carbon through chemical weathering. To better constrain global weatherability through time, the paleogeographic position of all major Phanerozoic arc-continent collisions was reconstructed and compared to the latitudinal distribution of ice-sheets...
March 14, 2019: Science
https://read.qxmd.com/read/30872535/observation-of-second-sound-in-graphite-at-temperatures-above-100-k
#2
S Huberman, R A Duncan, K Chen, B Song, V Chiloyan, Z Ding, A A Maznev, G Chen, K A Nelson
Wavelike thermal transport in solids, referred to as second sound, is an exotic phenomenon previously limited to a handful of materials at low temperatures. The rare occurrence of this effect restricted its scientific and practical significance. We directly observed second sound in graphite at temperatures above 100 K using time-resolved optical measurements of thermal transport on the micrometer-length scale. Our experimental results are in qualitative agreement with ab initio calculations that predict wavelike phonon hydrodynamics...
March 14, 2019: Science
https://read.qxmd.com/read/30872534/ultrapotent-chemogenetics-for-research-and-potential-clinical-applications
#3
Christopher J Magnus, Peter H Lee, Jordi Bonaventura, Roland Zemla, Juan L Gomez, Melissa H Ramirez, Xing Hu, Adriana Galvan, Jayeeta Basu, Michael Michaelides, Scott M Sternson
Chemogenetics enables non-invasive chemical control over cell populations in behaving animals. However, existing small molecule agonists show insufficient potency or selectivity. There is also need for chemogenetic systems compatible with both research and human therapeutic applications. We developed a new ion channel-based platform for cell activation and silencing that is controlled by low doses of the anti-smoking drug varenicline. We then synthesized novel sub-nanomolar potency agonists, called uPSEMs, with high selectivity for the chemogenetic receptors...
March 14, 2019: Science
https://read.qxmd.com/read/30872533/functional-degradation-a-mechanism-of-nlrp1-inflammasome-activation-by-diverse-pathogen-enzymes
#4
Andrew Sandstrom, Patrick S Mitchell, Lisa Goers, Edward W Mu, Cammie F Lesser, Russell E Vance
Inflammasomes are multi-protein platforms that initiate innate immunity by recruitment and activation of Caspase-1. The NLRP1B inflammasome is activated upon direct cleavage by the anthrax lethal toxin protease. However, the mechanism by which cleavage results in NLRP1B activation is unknown. Here we find that cleavage results in proteasome-mediated degradation of the N-terminal domains of NLRP1B, liberating a C-terminal fragment that is a potent Caspase-1 activator. Proteasome-mediated degradation of NLRP1B is both necessary and sufficient for NLRP1B activation...
March 14, 2019: Science
https://read.qxmd.com/read/30872532/architecture-of-the-heteromeric-glua1-2-ampa-receptor-in-complex-with-the-auxiliary-subunit-tarp-%C3%AE-8
#5
Beatriz Herguedas, Jake F Watson, Hinze Ho, Ondrej Cais, Javier García-Nafría, Ingo H Greger
AMPA-type glutamate receptors (AMPARs) mediate excitatory neurotransmission, and are central regulators of synaptic plasticity, a molecular mechanism underlying learning and memory. Although AMPARs act predominantly as heteromers, structural studies have focused on homomeric assemblies. Here we present a cryo-EM structure of the heteromeric GluA1/2 receptor associated with two TARP γ8 auxiliary subunits, the principle AMPAR complex at hippocampal synapses. Within the receptor, the core subunits arrange to give the GluA2 subunit dominant control of gating...
March 14, 2019: Science
https://read.qxmd.com/read/30872531/n-terminal-degradation-activates-the-nlrp1b-inflammasome
#6
Ashley J Chui, Marian C Okondo, Sahana D Rao, Kuo Gai, Andrew R Griswold, Darren C Johnson, Daniel P Ball, Cornelius Y Taabazuing, Elizabeth L Orth, Brooke A Vittimberga, Daniel A Bachovchin
Intracellular pathogens and danger signals trigger the formation of inflammasomes, which activate inflammatory caspases and induce pyroptosis. The anthrax lethal factor metalloprotease and small-molecule DPP8/9 inhibitors both activate the NLRP1B inflammasome, but the molecular mechanism of NLRP1B activation is unknown. Here, we used genome-wide CRISPR/Cas9 knockout screens to identify genes required for NLRP1B-mediated pyroptosis. We discovered that lethal factor induces cell death via the N-end rule proteasomal degradation pathway...
March 14, 2019: Science
https://read.qxmd.com/read/30872530/a-rights-revolution-for-nature
#7
Guillaume Chapron, Yaffa Epstein, José Vicente López-Bao
Introduction of legal rights for nature could protect natural systems from destruction.
March 14, 2019: Science
https://read.qxmd.com/read/30846612/cascading-impacts-of-large-carnivore-extirpation-in-an-african-ecosystem
#8
Justine L Atkins, Ryan A Long, Johan Pansu, Joshua H Daskin, Arjun B Potter, Marc E Stalmans, Corina E Tarnita, Robert M Pringle
The world's largest carnivores are declining and now occupy mere fractions of their historical ranges. Theory predicts that when apex predators disappear, large herbivores should become less fearful, occupy new habitats, and modify those habitats by eating new food plants. Yet experimental support for this prediction has been difficult to obtain in large-mammal systems. Following the extirpation of leopards and African wild dogs from Mozambique's Gorongosa National Park, forest-dwelling antelopes (bushbuck, Tragelaphus sylvaticus ) expanded into treeless floodplains, where they consumed novel diets and suppressed a common food plant (waterwort, Bergia mossambicensis )...
March 7, 2019: Science
https://read.qxmd.com/read/30846611/evidence-for-hormonal-control-of-heart-regenerative-capacity-during-endothermy-acquisition
#9
Kentaro Hirose, Alexander Y Payumo, Stephen Cutie, Alison Hoang, Hao Zhang, Romain Guyot, Dominic Lunn, Rachel B Bigley, Hongyao Yu, Jiajia Wang, Megan Smith, Ellen Gillett, Sandra E Muroy, Tobias Schmid, Emily Wilson, Kenneth A Field, DeeAnn M Reeder, Malcom Maden, Michael M Yartsev, Michael J Wolfgang, Frank Grützner, Thomas S Scanlan, Luke I Szweda, Rochelle Buffenstein, Guang Hu, Frederic Flamant, Jeffrey E Olgin, Guo N Huang
Tissue regenerative potential displays striking divergence across phylogeny and ontogeny, but the underlying mechanisms remain enigmatic. Loss of mammalian cardiac regenerative potential correlates with cardiomyocyte cell-cycle arrest and polyploidization, as well as the development of postnatal endothermy. We reveal that diploid cardiomyocyte abundance across 41 species conforms to Kleiber's law-the ¾-power law scaling of metabolism with bodyweight-and inversely correlates with standard metabolic rate, body temperature, and serum thyroxine level...
March 7, 2019: Science
https://read.qxmd.com/read/30846610/human-impact-erodes-chimpanzee-behavioral-diversity
#10
Hjalmar S Kühl, Christophe Boesch, Lars Kulik, Fabian Haas, Mimi Arandjelovic, Paula Dieguez, Gaëlle Bocksberger, Mary Brooke McElreath, Anthony Agbor, Samuel Angedakin, Emmanuel Ayuk Ayimisin, Emma Bailey, Donatienne Barubiyo, Mattia Bessone, Gregory Brazzola, Rebecca Chancellor, Heather Cohen, Charlotte Coupland, Emmanuel Danquah, Tobias Deschner, Orume Diotoh, Dervla Dowd, Andrew Dunn, Villard Ebot Egbe, Henk Eshuis, Rumen Fernandez, Yisa Ginath, Annemarie Goedmakers, Anne-Céline Granjon, Josephine Head, Daniela Hedwig, Veerle Hermans, Inaoyom Imong, Kathryn J Jeffery, Sorrel Jones, Jessica Junker, Parag Kadam, Mbangi Kambere, Mohamed Kambi, Ivonne Kienast, Deo Kujirakwinja, Kevin Langergraber, Juan Lapuente, Bradley Larson, Kevin Lee, Vera Leinert, Manuel Llana, Giovanna Maretti, Sergio Marrocoli, Tanyi Julius Mbi, Amelia C Meier, Bethan Morgan, David Morgan, Felix Mulindahabi, Mizuki Murai, Emily Neil, Protais Niyigaba, Lucy Jayne Ormsby, Liliana Pacheco, Alex Piel, Jodie Preece, Sebastien Regnaut, Aaron Rundus, Crickette Sanz, Joost van Schijndel, Volker Sommer, Fiona Stewart, Nikki Tagg, Elleni Vendras, Virginie Vergnes, Adam Welsh, Erin G Wessling, Jacob Willie, Roman M Wittig, Kyle Yurkiw, Klaus Zuberbuehler, Ammie K Kalan
Chimpanzees possess a large number of behavioral and cultural traits among non-human species. The 'disturbance hypothesis' predicts that human impact depletes resources and disrupts social learning processes necessary for behavioral and cultural transmission. We used an unprecedented data set of 144 chimpanzee communities, with information on 31 behaviors, to show that chimpanzees inhabiting areas with high human impact have a mean probability of occurrence reduced by 88%, across all behaviors, compared to low impact areas...
March 7, 2019: Science
https://read.qxmd.com/read/30819931/cytosine-but-not-adenine-base-editors-induce-genome-wide-off-target-mutations-in-rice
#11
Shuai Jin, Yuan Zong, Qiang Gao, Zixu Zhu, Yanpeng Wang, Peng Qin, Chengzhi Liang, Daowen Wang, Jin-Long Qiu, Feng Zhang, Caixia Gao
Cytosine and adenine base editors (CBEs and ABEs) are promising new tools for achieving the precise genetic changes required for disease treatment and trait improvement. However, genome-wide and unbiased analyses of their off-target effects in vivo are still lacking. Our whole genome sequencing (WGS) analysis of rice plants treated with BE3, high-fidelity BE3 (HF1-BE3), or ABE revealed that BE3 and HF1-BE3, but not ABE, induce substantial genome-wide off-target mutations, which are mostly the C→T type of single nucleotide variants (SNVs) and appear to be enriched in genic regions...
February 28, 2019: Science
https://read.qxmd.com/read/30819930/quantum-critical-conductivity-of-the-dirac-fluid-in-graphene
#12
Patrick Gallagher, Chan-Shan Yang, Tairu Lyu, Fanglin Tian, Rai Kou, Hai Zhang, Kenji Watanabe, Takashi Taniguchi, Feng Wang
Graphene near charge neutrality is expected to behave like a quantum-critical, relativistic plasma-the "Dirac fluid"-in which massless electrons and holes rapidly collide at a rapid rate. We measure the frequency-dependent optical conductivity of clean, micron-scale graphene at electron temperatures between 77 and 300 K using on-chip terahertz spectroscopy. At charge neutrality, we observe the quantum-critical scattering rate characteristic of the Dirac fluid. At higher doping, we uncover two distinct current-carrying modes with zero and nonzero total momenta, a manifestation of relativistic hydrodynamics...
February 28, 2019: Science
https://read.qxmd.com/read/30819929/measuring-hall-viscosity-of-graphene-s-electron-fluid
#13
A I Berdyugin, S G Xu, F M D Pellegrino, R Krishna Kumar, A Principi, I Torre, M Ben Shalom, T Taniguchi, K Watanabe, I V Grigorieva, M Polini, A K Geim, D A Bandurin
An electrical conductor subjected to a magnetic field exhibits the Hall effect in the presence of current flow. Here we report a qualitative deviation from the standard behavior in electron systems with high viscosity. We find that the viscous electron fluid in graphene responds to non-quantizing magnetic fields by producing an electric field opposite to that generated by the ordinary Hall effect. The viscous contribution is substantial and identified by studying local voltages that arise in the vicinity of current-injecting contacts...
February 28, 2019: Science
https://read.qxmd.com/read/30819928/cytosine-base-editor-generates-substantial-off-target-single-nucleotide-variants-in-mouse-embryos
#14
Erwei Zuo, Yidi Sun, Wu Wei, Tanglong Yuan, Wenqin Ying, Hao Sun, Liyun Yuan, Lars M Steinmetz, Yixue Li, Hui Yang
Genome editing holds promise for correcting pathogenic mutations. However, it is difficult to determine off-target effects of editing due to single nucleotide polymorphism in individuals. Here, we developed a method named GOTI (Genome-wide Off-target analysis by Two-cell embryo Injection) to detect off-target mutations by editing one blastomere of two-cell mouse embryos using either CRISPR-Cas9 or base editors. Comparison of the whole genome sequences of progeny cells of edited vs. non-edited blastomeres at E14...
February 28, 2019: Science
https://read.qxmd.com/read/30808816/animal-cultures-matter-for-conservation
#15
Philippa Brakes, Sasha R X Dall, Lucy M Aplin, Stuart Bearhop, Emma L Carroll, Paolo Ciucci, Vicki Fishlock, John K B Ford, Ellen C Garland, Sally A Keith, Peter K McGregor, Sarah L Mesnick, Michael J Noad, Giuseppe Notarbartolo di Sciara, Martha M Robbins, Mark P Simmonds, Fernando Spina, Alex Thornton, Paul R Wade, Martin J Whiting, James Williams, Luke Rendell, Hal Whitehead, Andrew Whiten, Christian Rutz
Understanding the rich social lives of animals benefits international conservation efforts.
February 26, 2019: Science
https://read.qxmd.com/read/30792361/vernier-spectrometer-using-counterpropagating-soliton-microcombs
#16
Qi-Fan Yang, Boqiang Shen, Heming Wang, Minh Tran, Zhewei Zhang, Ki Youl Yang, Lue Wu, Chengying Bao, John Bowers, Amnon Yariv, Kerry Vahala
Determination of laser frequency with high resolution under continuous and abrupt tuning conditions is important for sensing, spectroscopy, and communications. We show that a single microresonator provides rapid and broadband measurement of optical frequencies with a relative frequency precision comparable to that of conventional dual-frequency comb systems. Dual-locked counterpropagating solitons having slightly different repetition rates were used to implement a vernier spectrometer, which enabled characterization of laser tuning rates as high as 10 terahertz per second, broadly step-tuned lasers, multiline laser spectra, and molecular absorption lines...
February 21, 2019: Science
https://read.qxmd.com/read/30792360/compact-radio-emission-indicates-a-structured-jet-was-produced-by-a-binary-neutron-star-merger
#17
G Ghirlanda, O S Salafia, Z Paragi, M Giroletti, J Yang, B Marcote, J Blanchard, I Agudo, T An, M G Bernardini, R Beswick, M Branchesi, S Campana, C Casadio, E Chassande-Mottin, M Colpi, S Covino, P D'Avanzo, V D'Elia, S Frey, M Gawronski, G Ghisellini, L I Gurvits, P G Jonker, H J van Langevelde, A Melandri, J Moldon, L Nava, A Perego, M A Perez-Torres, C Reynolds, R Salvaterra, G Tagliaferri, T Venturi, S D Vergani, M Zhang
The binary neutron star merger event GW170817 was detected through both electromagnetic radiation and gravitational waves. Its afterglow emission may have been produced by either a narrow relativistic jet or an isotropic outflow. High-spatial-resolution measurements of the source size and displacement can discriminate between these scenarios. We present very-long-baseline interferometry observations, performed 207.4 days after the merger by using a global network of 32 radio telescopes. The apparent source size is constrained to be smaller than 2...
February 21, 2019: Science
https://read.qxmd.com/read/30792359/coherent-single-photon-emission-from-colloidal-lead-halide-perovskite-quantum-dots
#18
Hendrik Utzat, Weiwei Sun, Alexander E K Kaplan, Franziska Krieg, Matthias Ginterseder, Boris Spokoyny, Nathan D Klein, Katherine E Shulenberger, Collin F Perkinson, Maksym V Kovalenko, Moungi G Bawendi
Chemically made colloidal semiconductor quantum dots have long been proposed as scalable and color-tunable single emitters in quantum optics, but they have typically suffered from prohibitively incoherent emission. We now demonstrate that individual colloidal lead halide perovskite quantum dots (PQDs) display highly efficient single photon emission with optical coherence times as long as 80 ps, an appreciable fraction of their 210 ps radiative lifetimes. These measurements suggest that PQDs should be explored as building blocks in sources of indistinguishable single photons and entangled photon pairs...
February 21, 2019: Science
https://read.qxmd.com/read/30792358/quantum-interface-of-an-electron-and-a-nuclear-ensemble
#19
D A Gangloff, G Éthier-Majcher, C Lang, E V Denning, J H Bodey, D M Jackson, E Clarke, M Hugues, C Le Gall, M Atatüre
Coherent excitation of an ensemble of quantum objects underpins quantum many-body phenomena and offers the opportunity to realize a memory that stores quantum information. Thus far, a deterministic and coherent interface between a spin qubit and such an ensemble has remained elusive. Here, we first use an electron to cool the mesoscopic nuclear-spin ensemble of a semiconductor quantum dot to the nuclear sideband-resolved regime. We then implement an all-optical approach to access individual quantized electronic-nuclear spin transitions...
February 21, 2019: Science
https://read.qxmd.com/read/30765607/parallel-adaptation-of-rabbit-populations-to-myxoma-virus
#20
Joel M Alves, Miguel Carneiro, Jade Y Cheng, Ana Lemos de Matos, Masmudur M Rahman, Liisa Loog, Paula F Campos, Nathan Wales, Anders Eriksson, Andrea Manica, Tanja Strive, Stephen C Graham, Sandra Afonso, Diana J Bell, Laura Belmont, Jonathan P Day, Susan J Fuller, Stéphane Marchandeau, William J Palmer, Guillaume Queney, Alison K Surridge, Filipe G Vieira, Grant McFadden, Rasmus Nielsen, M Thomas P Gilbert, Pedro J Esteves, Nuno Ferrand, Francis M Jiggins
In the 1950s the myxoma virus was released into European rabbit populations in Australia and Europe, decimating populations and resulting in the rapid evolution of resistance. We investigated the genetic basis of resistance by comparing the exomes of rabbits collected before and after the pandemic. We found a strong pattern of parallel evolution, with selection on standing genetic variation favoring the same alleles in Australia, France and the United Kingdom. Many of these changes occurred in immunity-related genes, supporting a polygenic basis of resistance...
February 14, 2019: Science
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