Δευτέρα 29 Ιουνίου 2020

Reducing airborne transmission
Science: Current Issue
Thu Jun 25, 2020 20:38
The fate of genes after duplication
Science: Current Issue
Thu Jun 25, 2020 20:38
Erratum for the Report: "Estimating the burden of SARS-CoV-2 in France," by H. Salje, C. Tran Kiem, N. Lefrancq, N. Courtejoie, P. Bosetti, J. Paireau, A. Andronico, N. Hoze, J. Richet, C.-L. Dubost, Y. Le Strat, J. Lessler, D. Levy-Bruhl, A. Fontanet, L. Opatowski, P.-Y. Boelle, S. Cauchemez
Science: Current Issue
Thu Jun 25, 2020 20:38
Erratum for the Report "Forest microclimate dynamics drive plant responses to warming" by F. Zellweger, P. De Frenne, J. Lenoir, P. Vangansbeke, K. Verheyen, M. Bernhardt-Römermann, L. Baeten, R. Hedl, I. Berki, J. Brunet, H. Van Calster, M. Chudomelova, G. Decocq, T. Dirnböck, T. Durak, T. Heinken, B. Jaroszewicz, M. Kopecky, F. Malis, M. Macek, M. Marek, T. Naaf, T. A. Nagel, A. Ortmann-Ajkai, P. Petrik, R. Pielech, K. Reczynska, W. Schmidt, T. Standovar, K. Swierkosz, B. Teleki, O. Vild, M. Wulf, D. Coomes
Science: Current Issue
Thu Jun 25, 2020 20:38
Exploring whole-genome duplicate gene retention with complex genetic interaction analysis
Whole-genome duplication has played a central role in the genome evolution of many organisms, including the human genome. Most duplicated genes are eliminated, and factors that influence the retention of persisting duplicates remain poorly understood. We describe a systematic complex genetic interaction analysis with yeast paralogs derived from the whole-genome duplication event. Mapping of digenic interactions for a deletion mutant of each paralog, and of trigenic interactions for the double mutant,...
Science: Current Issue
Thu Jun 25, 2020 20:38
Muscle and neuronal guidepost-like cells facilitate planarian visual system regeneration
Neuronal circuits damaged or lost after injury can be regenerated in some adult organisms, but the mechanisms enabling this process are largely unknown. We used the planarian Schmidtea mediterranea to study visual system regeneration after injury. We identify a rare population of muscle cells tightly associated with photoreceptor axons at stereotyped positions in both uninjured and regenerating animals. Together with a neuronal population, these cells promote de novo assembly of the visual system...
Science: Current Issue
Thu Jun 25, 2020 20:38
The pressure to assimilate
Science: Current Issue
Thu Jun 25, 2020 20:38
Flexible recruitment of memory-based choice representations by the human medial frontal cortex
Decision-making in complex environments relies on flexibly using prior experience. This process depends on the medial frontal cortex (MFC) and the medial temporal lobe, but it remains unknown how these structures implement selective memory retrieval. We recorded single neurons in the MFC, amygdala, and hippocampus while human subjects switched between making recognition memory–based and categorization-based decisions. The MFC rapidly implemented changing task demands by using different subspaces...
Science: Current Issue
Thu Jun 25, 2020 20:38
Arctic-adapted dogs emerged at the Pleistocene-Holocene transition
Although sled dogs are one of the most specialized groups of dogs, their origin and evolution has received much less attention than many other dog groups. We applied a genomic approach to investigate their spatiotemporal emergence by sequencing the genomes of 10 modern Greenland sled dogs, an ~9500-year-old Siberian dog associated with archaeological evidence for sled technology, and an ~33,000-year-old Siberian wolf. We found noteworthy genetic similarity between the ancient dog and modern sled...
Science: Current Issue
Thu Jun 25, 2020 20:38
Quieting a noisy antenna reproduces photosynthetic light-harvesting spectra
Photosynthesis achieves near unity light-harvesting quantum efficiency yet it remains unknown whether there exists a fundamental organizing principle giving rise to robust light harvesting in the presence of dynamic light conditions and noisy physiological environments. Here, we present a noise-canceling network model that relates noisy physiological conditions, power conversion efficiency, and the resulting absorption spectra of photosynthetic organisms. Using light conditions in full solar exposure,...
Science: Current Issue
Thu Jun 25, 2020 20:38
Structural basis for inhibition of the RNA-dependent RNA polymerase from SARS-CoV-2 by remdesivir
The pandemic of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has become a global crisis. Replication of SARS-CoV-2 requires the viral RNA-dependent RNA polymerase (RdRp) enzyme, a target of the antiviral drug remdesivir. Here we report the cryo–electron microscopy structure of the SARS-CoV-2 RdRp, both in the apo form at 2.8-angstrom resolution and in complex with a 50-base template-primer RNA and remdesivir at 2.5-angstrom resolution....
Science: Current Issue
Thu Jun 25, 2020 20:38
Changes in contact patterns shape the dynamics of the COVID-19 outbreak in China
Intense nonpharmaceutical interventions were put in place in China to stop transmission of the novel coronavirus disease 2019 (COVID-19). As transmission intensifies in other countries, the interplay between age, contact patterns, social distancing, susceptibility to infection, and COVID-19 dynamics remains unclear. To answer these questions, we analyze contact survey data for Wuhan and Shanghai before and during the outbreak and contact-tracing information from Hunan province. Daily contacts were...
Science: Current Issue
Thu Jun 25, 2020 20:38
A multiplanet system of super-Earths orbiting the brightest red dwarf star GJ 887
The closet exoplanets to the Sun provide opportunities for detailed characterization of planets outside the Solar System. We report the discovery, using radial velocity measurements, of a compact multiplanet system of super-Earth exoplanets orbiting the nearby red dwarf star GJ 887. The two planets have orbital periods of 9.3 and 21.8 days. Assuming an Earth-like albedo, the equilibrium temperature of the 21.8-day planet is ~350 kelvin. The planets are interior to, but close to the inner edge of,...
Science: Current Issue
Thu Jun 25, 2020 20:38
Metalens-array-based high-dimensional and multiphoton quantum source
The development of two-dimensional metasurfaces has shown great potential in quantum-optical technologies because of the excellent flexibility in light-field manipulation. By integrating a metalens array with a nonlinear crystal, we demonstrate a 100-path spontaneous parametric down-conversion photon-pair source in a 10 x 10 array, which shows promise for high-dimensional entanglement and multiphoton-state generation. We demonstrate two-, three- and four-dimensional two-photon path entanglement with...
Science: Current Issue
Thu Jun 25, 2020 20:38
Meridional flow in the Suns convection zone is a single cell in each hemisphere
The Sun’s magnetic field is generated by subsurface motions of the convecting plasma. The latitude at which the magnetic field emerges through the solar surface (as sunspots) drifts toward the equator over the course of the 11-year solar cycle. We use helioseismology to infer the meridional flow (in the latitudinal and radial directions) over two solar cycles covering 1996–2019. Two data sources are used, which agree during their overlap period of 2001–2011. The time-averaged meridional flow is shown...
Science: Current Issue
Thu Jun 25, 2020 20:38
Mass-resolved electronic circular dichroism ion spectroscopy
DNA and proteins are chiral: Their three-dimensional structures cannot be superimposed with their mirror images. Circular dichroism spectroscopy is widely used to characterize chiral compounds, but data interpretation is difficult in the case of mixtures. We recorded the electronic circular dichroism spectra of DNA helices separated in a mass spectrometer. We studied guanine-rich strands having various secondary structures, electrosprayed them as negative ions, irradiated them with an ultraviolet...
Science: Current Issue
Thu Jun 25, 2020 20:38
Micelle-directed chiral seeded growth on anisotropic gold nanocrystals
Surfactant-assisted seeded growth of metal nanoparticles (NPs) can be engineered to produce anisotropic gold nanocrystals with high chiroptical activity through the templating effect of chiral micelles formed in the presence of dissymmetric cosurfactants. Mixed micelles adsorb on gold nanorods, forming quasihelical patterns that direct seeded growth into NPs with pronounced morphological and optical handedness. Sharp chiral wrinkles lead to chiral plasmon modes with high dissymmetry factors (~0.20)....
Science: Current Issue
Thu Jun 25, 2020 20:38
Cryo-EM structure of the human cohesin-NIPBL-DNA complex
As a ring-shaped adenosine triphosphatase (ATPase) machine, cohesin organizes the eukaryotic genome by extruding DNA loops and mediates sister chromatid cohesion by topologically entrapping DNA. How cohesin executes these fundamental DNA transactions is not understood. Using cryo–electron microscopy (cryo-EM), we determined the structure of human cohesin bound to its loader NIPBL and DNA at medium resolution. Cohesin and NIPBL interact extensively and together form a central tunnel to entrap a 72–base...
Science: Current Issue
Thu Jun 25, 2020 20:38
Single-molecule regulatory architectures captured by chromatin fiber sequencing
Gene regulation is chiefly determined at the level of individual linear chromatin molecules, yet our current understanding of cis-regulatory architectures derives from fragmented sampling of large numbers of disparate molecules. We developed an approach for precisely stenciling the structure of individual chromatin fibers onto their composite DNA templates using nonspecific DNA N6-adenine methyltransferases. Single-molecule long-read sequencing of chromatin stencils enabled nucleotide-resolution...
Science: Current Issue
Thu Jun 25, 2020 20:38
Mechanisms of OCT4-SOX2 motif readout on nucleosomes
Transcription factors (TFs) regulate gene expression through chromatin where nucleosomes restrict DNA access. To study how TFs bind nucleosome-occupied motifs, we focused on the reprogramming factors OCT4 and SOX2 in mouse embryonic stem cells. We determined TF engagement throughout a nucleosome at base-pair resolution in vitro, enabling structure determination by cryo–electron microscopy at two preferred positions. Depending on motif location, OCT4 and SOX2 differentially distort nucleosomal DNA....
Science: Current Issue
Thu Jun 25, 2020 20:38
The double punch of perchlorate
Science: Current Issue
Thu Jun 25, 2020 20:38
Loss of shelf
Science: Current Issue
Thu Jun 25, 2020 20:38
Charmed excitations
Science: Current Issue
Thu Jun 25, 2020 20:38
Not just for the trees
Science: Current Issue
Thu Jun 25, 2020 20:38
Pol II kicks out histone variant
Science: Current Issue
Thu Jun 25, 2020 20:38
Avoiding multiphoton artifacts
Science: Current Issue
Thu Jun 25, 2020 20:38
Intuitive CD8+ T cells sense DNA
Science: Current Issue
Thu Jun 25, 2020 20:38
Lighting a spark from the lysosome
Science: Current Issue
Thu Jun 25, 2020 20:38
Seeds of change
Science: Current Issue
Thu Jun 25, 2020 20:38
Pairs of peaks stabilize output power
Science: Current Issue
Thu Jun 25, 2020 20:38
A nearby multiplanet system
Science: Current Issue
Thu Jun 25, 2020 20:38
Sled dog arctic adaptations go far back
Science: Current Issue
Thu Jun 25, 2020 20:38
A blueprint to understand cohesin
Science: Current Issue
Thu Jun 25, 2020 20:38
Engaging the nucleosome
Science: Current Issue
Thu Jun 25, 2020 20:38
DNA circular dichroism in gas phase
Science: Current Issue
Thu Jun 25, 2020 20:38
Guiding regeneration
Science: Current Issue
Thu Jun 25, 2020 20:38
The adaptive human frontal cortex
Science: Current Issue
Thu Jun 25, 2020 20:38
A wrench in the works of COVID-19
Science: Current Issue
Thu Jun 25, 2020 20:38
Sex, age, and the macrophage
Science: Current Issue
Thu Jun 25, 2020 20:38
The flow of plasma inside the Sun
Science: Current Issue
Thu Jun 25, 2020 20:38
Who and what next?
Science: Current Issue
Thu Jun 25, 2020 20:38
Metalens-array-based quantum source
Science: Current Issue
Thu Jun 25, 2020 20:38
Easier polar plunge for penguins
Science: Current Issue
Thu Jun 25, 2020 20:38
Groovy chiral gold particles
Science: Current Issue
Thu Jun 25, 2020 20:38
Primary architecture of chromatin fibers
Science: Current Issue
Thu Jun 25, 2020 20:38
Afforestation falls short as a biodiversity strategy
Science: Current Issue
Thu Jun 25, 2020 20:38
Screeners needed for journalism awards
Science: Current Issue
Thu Jun 25, 2020 20:38
A view from my basement
Science: Current Issue
Thu Jun 25, 2020 20:38
Humankind: A Hopeful History
Science: Current Issue
Thu Jun 25, 2020 20:38
Misguided forest action in EU Biodiversity Strategy
Science: Current Issue
Thu Jun 25, 2020 20:38
COVID-19's unsustainable waste management
Science: Current Issue
Thu Jun 25, 2020 20:38
"Explaining" machine learning reveals policy challenges
Science: Current Issue
Thu Jun 25, 2020 20:38
Like other species, we have always been on the move
Science: Current Issue
Thu Jun 25, 2020 20:38
Confronting bias
Science: Current Issue
Thu Jun 25, 2020 20:38
Guide cells help navigate axon regeneration
Science: Current Issue
Thu Jun 25, 2020 20:38
Multiple, quiet, and close by
Science: Current Issue
Thu Jun 25, 2020 20:38
Microplastic in terrestrial ecosystems
Science: Current Issue
Thu Jun 25, 2020 20:38
Evolution after genome duplication
Science: Current Issue
Thu Jun 25, 2020 20:38
The simplicity of robust light harvesting
Science: Current Issue
Thu Jun 25, 2020 20:38
Action spectra of chiral secondary structure
Science: Current Issue
Thu Jun 25, 2020 20:38
Martian chronicler
Science: Current Issue
Thu Jun 25, 2020 20:38
Reducing transmission of SARS-CoV-2
Science: Current Issue
Thu Jun 25, 2020 20:38
Mars mission would put China among space leaders
Science: Current Issue
Thu Jun 25, 2020 20:38
Could a blood 'observatory stop pandemics?
Science: Current Issue
Thu Jun 25, 2020 20:38
Senate bill to curb foreign threats raises alarms
Science: Current Issue
Thu Jun 25, 2020 20:38
Online GRE test heightens equity concerns
Science: Current Issue
Thu Jun 25, 2020 20:38
Lawsuit alleges scientific misconduct at weapons lab
Science: Current Issue
Thu Jun 25, 2020 20:38
Charities that fund research face deep revenue declines
Science: Current Issue
Thu Jun 25, 2020 20:38
Dawn of the chicken revealed in Southeast Asia
Science: Current Issue
Thu Jun 25, 2020 20:38
Persuasive words are not enough
Science: Current Issue
Thu Jun 25, 2020 20:38
Hope grows for targeting the brain with ultrasound
Science: Current Issue
Thu Jun 25, 2020 20:38
News at a glance
Science: Current Issue
Thu Jun 25, 2020 20:38

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