Anna A Fedorova, Franck Montmessin, Oleg Korablev, Mikhail Luginin, Alexander Trokhimovskiy, Denis A Belyaev, Nikolay I Ignatiev, Franck Lefèvre, Juan Alday, Patrick G J Irwin, Kevin S Olsen, Jean-Loup Bertaux, Ehouarn Millour, Anni Määttänen, Alexey Shakun, Alexey V Grigoriev, Andrey Patrakeev, Svyatoslav Korsa, Nikita Kokonkov, Lucio Baggio, Francois Forget, Colin F Wilson
The loss of water from Mars to space is thought to result from the transport of water to the upper atmosphere, where it is dissociated to hydrogen and escapes the planet. Recent observations have suggested large, rapid seasonal intrusions of water into the upper atmosphere, boosting the hydrogen abundance. We use the Atmospheric Chemistry Suite on the ExoMars Trace Gas Orbiter to characterize the water distribution by altitude. Water profiles during the 2018-2019 southern spring and summer stormy seasons show that high-altitude water is preferentially supplied close to perihelion, and supersaturation occurs even when clouds are present...
January 9, 2020: Science
Marc Rigau, Simone Ostrouska, Thomas S Fulford, Darryl N Johnson, Katherine Woods, Zheng Ruan, Hamish E G McWilliam, Christopher Hudson, Candani Tutuka, Adam K Wheatley, Stephen J Kent, Jose A Villadangos, Bhupinder Pal, Christian Kurts, Jason Simmonds, Matthias Pelzing, Andrew D Nash, Andrew Hammet, Anne M Verhagen, Gino Vairo, Eugene Maraskovsky, Con Panousis, Nicholas A Gherardin, Jonathan Cebon, Dale I Godfrey, Andreas Behren, Adam P Uldrich
Gamma delta (γδ) T cells are essential to protective immunity. In humans, most γδ T cells express Vγ9Vδ2+ T cell receptors (TCRs) that respond to phosphoantigens (pAg) produced by cellular pathogens and overexpressed by cancers. However, the molecular targets recognized by these γδTCRs are unknown. Here, we identify butyrophilin 2A1 (BTN2A1) as a key ligand that binds to the Vγ9+ TCR γ-chain. BTN2A1 associates with another butyrophilin, BTN3A1, which act together to initiate responses to pAg. Furthermore, binding of a second ligand, possibly BTN3A1, to a separate TCR domain incorporating Vδ2 is also required...
January 9, 2020: Science
Ke Chen, Bai Song, Navaneetha K Ravichandran, Qiye Zheng, Xi Chen, Hwijong Lee, Haoran Sun, Sheng Li, Geethal Amila Gamage, Fei Tian, Zhiwei Ding, Qichen Song, Akash Rai, Hanlin Wu, Pawan Koirala, Aaron J Schmidt, Kenji Watanabe, Bing Lv, Zhifeng Ren, Li Shi, David G Cahill, Takashi Taniguchi, David Broido, Gang Chen
Materials with high thermal conductivity (κ) are of technological importance and fundamental interest. We grew cubic boron nitride (cBN) crystals with controlled abundance of boron isotopes and measured κ over 1600 Wm-1 K-1 at room temperature in samples with enriched 10 B or 11 B. In comparison, we found the isotope enhancement of κ is considerably lower for boron phosphide and boron arsenide as the identical isotopic mass disorder becomes increasingly invisible to phonons. The ultrahigh κ in conjunction with its wide bandgap (6...
January 9, 2020: Science
Inha Cho, Zhi-Jun Jia, Frances H Arnold
No abstract text is available yet for this article.
January 2, 2020: Science
Solomon H Reisberg, Yang Gao, Allison S Walker, Eric J N Helfrich, Jon Clardy, Phil S Baran
Molecular shape defines function in both biological and material settings and, as such, chemists have developed an ever-increasing descriptive vernacular to describe these shapes. Non-canonical atropisomers-i.e., shape-defined molecules that are formally topologically trivial, but only interconvertible by complex, non-physical multibond torsions-form a unique subset of atropisomers that differ from both canonical atropisomers (e.g., binaphthyls) and topoisomers (i.e., molecules that have identical connectivity, but non-identical molecular graphs)...
January 2, 2020: Science
K Reinhard, B Rengstl, P Oehm, K Michel, A Billmeier, N Hayduk, O Klein, K Kuna, Y Ouchan, S Wöll, E Christ, D Weber, M Suchan, T Bukur, M Birtel, V Jahndel, K Mroz, K Hobohm, L Kranz, M Diken, K Kühlcke, Ö Türeci, U Sahin
Chimeric antigen receptor (CAR)-T cells have shown efficacy in patients with B cell malignancies. Yet their application for solid tumors has challenges that include limited cancer-specific targets and non-persistence of adoptively transferred CAR-T cells. Here we introduce the developmentally regulated tight junction protein claudin 6 (CLDN6) as a CAR target in solid tumors, and a strategy to overcome inefficient CAR-T cell stimulation in vivo. We demonstrate that a nanoparticulate RNA vaccine, designed for body-wide delivery of the CAR antigen into lymphoid compartments, stimulates adoptively transferred CAR-T cells...
January 2, 2020: Science
Nicholas Heitman, Rachel Sennett, Ka-Wai Mok, Nivedita Saxena, Devika Srivastava, Pieter Martino, Laura Grisanti, Zichen Wang, Avi Ma'ayan, Panteleimon Rompolas, Michael Rendl
Tissue homeostasis requires the balance of growth by cell production and regression through cell loss. In the hair cycle during follicle regression, the niche traverses the skin through an unknown mechanism to reach the stem cell reservoir and trigger new growth. Here we identify the dermal sheath that lines the follicle as the key driver of tissue regression and niche relocation via the smooth muscle contractile machinery that generates centripetal constriction force. We reveal that the calcium/calmodulin/myosin light chain kinase pathway controls sheath contraction...
December 19, 2019: Science
M Serlin, C L Tschirhart, H Polshyn, Y Zhang, J Zhu, K Watanabe, T Taniguchi, L Balents, A F Young
The quantum anomalous Hall (QAH) effect combines topology and magnetism to produce precisely quantized Hall resistance at zero magnetic field. We report the observation of a QAH effect in twisted bilayer graphene aligned to hexagonal boron nitride. The effect is driven by intrinsic strong interactions, which polarize the electrons into a single spin and valley resolved moiré miniband with Chern number C = 1. In contrast to magnetically doped systems, the measured transport energy gap is larger than the Curie temperature for magnetic ordering, and quantization to within 0...
December 19, 2019: Science
Csaba Cserép, Balázs Pósfai, Nikolett Lénárt, Rebeka Fekete, Zsófia I László, Zsolt Lele, Barbara Orsolits, Gábor Molnár, Steffanie Heindl, Anett D Schwarcz, Katinka Ujvári, Zsuzsanna Környei, Krisztina Tóth, Eszter Szabadits, Beáta Sperlágh, Mária Baranyi, László Csiba, Tibor Hortobágyi, Zsófia Maglóczky, Bernadett Martinecz, Gábor Szabó, Ferenc Erdélyi, Róbert Szipőcs, Michael M Tamkun, Benno Gesierich, Marco Duering, István Katona, Arthur Liesz, Gábor Tamás, Ádám Dénes
Microglia are the main immune cells in the brain with roles in brain homeostasis and neurological diseases. Mechanisms underlying microglia-neuron communication remain elusive. Here, we identified an interaction site between neuronal cell bodies and microglial processes in mouse and human brain. Somatic microglia-neuron junctions possessed specialized nanoarchitecture optimized for purinergic signaling. Activity of neuronal mitochondria was linked with microglial junction formation, which was induced rapidly in response to neuronal activation and blocked by inhibition of P2Y12 receptors (P2Y12R)...
December 12, 2019: Science
Shiyu Zhu, Lingyuan Kong, Lu Cao, Hui Chen, Michał Papaj, Shixuan Du, Yuqing Xing, Wenyao Liu, Dongfei Wang, Chengmin Shen, Fazhi Yang, John Schneeloch, Ruidan Zhong, Genda Gu, Liang Fu, Yu-Yang Zhang, Hong Ding, Hong-Jun Gao
Majorana zero modes (MZMs) are spatially-localized zero-energy fractional quasiparticles with non-Abelian braiding statistics that hold promise for topological quantum computing. Owing to the particle-antiparticle equivalence, MZMs exhibit quantized conductance at low temperature. By utilizing variable-tunnel-coupled scanning tunneling spectroscopy, we study tunneling conductance of vortex bound states on FeTe0.55 Se0.45 superconductors. We report observations of conductance plateaus as a function of tunnel coupling for zero-energy vortex bound states with values close to or even reaching the 2 e 2 / h quantum conductance (here e is the electron charge and h is Planck's constant)...
December 12, 2019: Science
Torsten Neubert, Nikolai Østgaard, Victor Reglero, Olivier Chanrion, Matthias Heumesser, Krystallia Dimitriadou, Freddy Christiansen, Carl Budtz-Jørgensen, Irfan Kuvvetli, Ib Lundgaard Rasmussen, Andrey Mezentsev, Martino Marisaldi, Kjetil Ullaland, Georgi Genov, Shiming Yang, Pavlo Kochkin, Javier Navarro-Gonzalez, Paul H Connell, Chris J Eyles
Terrestrial gamma-ray flashes (TGFs) are transient gamma-ray emissions from thunderstorms, generated by electrons accelerated to relativistic energies in electric fields. Elves are ultraviolet and optical emissions excited in the lower ionosphere by electromagnetic waves radiated from lightning current pulses. We observe a TGF and an associated Elve using the Atmosphere-Space Interactions Monitor on the International Space Station. The TGF occurs at the onset of a lightning current pulse that generates an Elve, in the early stage of a lightning flash...
December 11, 2019: Science
Jianzhong Liu, Cheng Zhang, Ziyao Zhang, Xiaojin Wen, Xiaodong Dou, Jialiang Wei, Xu Qiu, Song Song, Ning Jiao
The Schmidt reaction has been an efficient and widely used synthetic approach to amides and nitriles since its discovery in 1923. However, its application often entails the use the of volatile, potentially explosive and highly toxic azide reagents. Here we report a sequence whereby triflic anhydride, formic and acetic acids activate the bulk chemical nitromethane to serve as a nitrogen donor in place of azides in Schmidt-like reactions. This protocol further expands the substrate scope to alkynes and simple alkyl benzenes for the preparation of amides and nitriles...
December 5, 2019: Science
Sanjay R Srivatsan, José L McFaline-Figueroa, Vijay Ramani, Lauren Saunders, Junyue Cao, Jonathan Packer, Hannah A Pliner, Dana L Jackson, Riza M Daza, Lena Christiansen, Fan Zhang, Frank Steemers, Jay Shendure, Cole Trapnell
High-throughput chemical screens typically employ coarse assays, e.g. cell survival, limiting what can be learned about mechanisms of action, off-target effects, and heterogeneous responses. Here we introduce sci-Plex, which uses 'nuclear hashing' to quantify global transcriptional responses to thousands of independent perturbations at single-cell resolution. As a proof-of-concept, we applied sci-Plex to screen 3 cancer cell lines exposed to 188 compounds. In total, we profiled ~650,000 single-cell transcriptomes across ~5,000 independent samples in one experiment...
December 5, 2019: Science
Spencer A Freeman, Stefan Uderhardt, Amra Saric, Richard F Collins, Catherine M Buckley, Sivakami Mylvaganam, Parastoo Boroumand, Jonathan Plumb, Ronald N Germain, Dejian Ren, Sergio Grinstein
Despite ongoing (macro)pinocytosis of extracellular fluid, the volume of the endocytic pathway remains unchanged. To investigate the underlying mechanism, we used high-resolution video imaging to analyze the fate of macropinosomes formed by macrophages in vitro and in situ. Na+ , the primary cationic osmolyte internalized, exited endocytic vacuoles via two pore channels (TPC), accompanied by parallel efflux of Cl- and osmotically-coupled water. The resulting shrinkage caused crenation of the membrane which fostered recruitment of curvature-sensing proteins...
December 5, 2019: Science
Fangyuan Mao, Yaoming Hu, Chuankui Li, Yuanqing Wang, Morgan Hill Chase, Andrew K Smith, Jin Meng
Based on multiple 3D skeletal specimens we report a new Cretaceous stem therian mammal that displays decoupling of hearing and chewing apparatuses and functions. The auditory bones, including the surangular, have no bone contact with the ossified Meckel's cartilage; the latter is loosely lodged on the medial rear of the dentary. This configuration probably represents the initial morphological stage of the definitive mammalian middle ear. Evidence shows that hearing and chewing apparatuses have evolved in a modular fashion...
December 5, 2019: Science
Yoori Kim, Zhubing Shi, Hongshan Zhang, Ilya J Finkelstein, Hongtao Yu
Cohesin is a chromosome-bound multisubunit ATPase complex. Following its loading onto chromosomes, cohesin generates chromosome loops to regulate chromosome functions. It has been suggested that cohesin organizes the genome via loop extrusion, but direct evidence is lacking. Here, we use single-molecule imaging to show that recombinant human cohesin-NIPBL complex compacts both naked and nucleosome-bound DNA by extruding DNA loops. DNA compaction by cohesin requires ATP hydrolysis, and is force-sensitive. This compaction is processive over tens of kilobases (kb) at an average rate of 0...
November 28, 2019: Science
Avik Dutt, Qian Lin, Luqi Yuan, Momchil Minkov, Meng Xiao, Shanhui Fan
The concept of synthetic dimensions has generated interest in many branches of science ranging from ultracold-atomic physics to photonics, as it provides a versatile platform for realizing effective gauge potentials and topological physics. Previous experiments have augmented the real-space dimensionality by one additional physical synthetic dimension. We endow a single ring resonator with two independent physical synthetic dimensions. Our system consists of a temporally modulated ring resonator with spatial coupling between the clockwise and counterclockwise modes, creating a synthetic Hall ladder along the frequency and pseudospin degrees of freedom for photons propagating in the ring...
November 28, 2019: Science
Ina Yoon, Miso Nam, Hoi Kyoung Kim, Hee-Sun Moon, Sungmin Kim, Jayun Jang, Ji Ae Song, Seung Jae Jeong, Sang Bum Kim, Seongmin Cho, YounHa Kim, Jihye Lee, Won Suk Yang, Hee Chan Yoo, Kibum Kim, Min-Sun Kim, Aerin Yang, Kyukwang Cho, Hee-Sung Park, Geum-Sook Hwang, Kwang Yeon Hwang, Jung Min Han, Jong Hyun Kim, Sunghoon Kim
Despite the importance of glucose and amino acids for energy metabolism, interactions between the two nutrients are not well understood. We provide evidence for a role of leucyl-tRNA synthetase 1 (LARS1) in glucose-dependent control of leucine usage. Upon glucose starvation, LARS1 was phosphorylated by Unc-51 like autophagy activating kinase 1 (ULK1) at the residues crucial for leucine-binding. The phosphorylated LARS1 showed decreased leucine-binding, which may inhibit protein synthesis and help save energy...
November 28, 2019: Science
Miao Song, Gang Zhou, Ning Lu, Jaewon Lee, Elias Nakouzi, Hao Wang, Dongsheng Li
Natural and synthetic nanoparticles composed of five-fold twinned crystals domains have unique properties. The formation mechanism of these five-fold twinned nanoparticles is poorly understood. We used in situ high-resolution transmission electron microscopy combined with molecular dynamics simulations to demonstrate that five-fold twinning occurs via repeated oriented attachment of ~3 nm gold, platinum, and palladium nanoparticles. We discovered two different mechanisms for forming five-fold twinned nanoparticles that are driving by the accumulation and elimination of strain...
November 28, 2019: Science
H Holden Thorp, Magdalena Skipper, Veronique Kiermer, May Berenbaum, Deborah Sweet, Richard Horton
No abstract text is available yet for this article.
November 26, 2019: Science
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