1【生物】Eye patches: Protein assembly of index-gradient squid lenses
A. M. Sweeney et al.
A parabolic relationship between lens radius and refractive index allows spherical lenses to avoid spherical aberration. We show that in squid, patchy colloidal physics resulted from an evolutionary radiation of globular S-crystallin proteins. Small-angle x-ray scattering experiments on lens tissue show colloidal gels of S-crystallins at all radial positions. Sparse lens materials form via low-valence linkages between disordered loops protruding from the protein surface. The loops are polydisperse and bind via a set of hydrogen bonds between disordered side chains. Peripheral lens regions with low particle valence form stable, volume-spanning gels at low density, whereas central regions with higher average valence gel at higher densities. The proteins demonstrate an evolved set of linkers for self-assembly of nanoparticles into volumetric materials.
2 【生物】Microbiota-activated PPAR-γ signaling inhibits dysbiotic Enterobacteriaceae expansion
Andreas J. Bäumler et al.
Perturbation of the gut-associated microbial community may underlie many human illnesses, but the mechanisms that maintain homeostasis are poorly understood. We found that the depletion of butyrate-producing microbes by antibiotic treatment reduced epithelial signaling through the intracellular butyrate sensor peroxisome proliferator–activated receptor (PPAR-γ). Nitrate levels increased in the colonic lumen because epithelial expression of Nos2, the gene encoding inducible nitric oxide synthase, was elevated in the absence of PPAR-γ signaling. Microbiota-induced PPAR-γ signaling also limits the luminal bioavailability of oxygen by driving the energy metabolism of colonic epithelial cells (colonocytes) toward β-oxidation. Therefore, microbiota-activated PPAR-γ signaling is a homeostatic pathway that prevents a dysbiotic expansion of potentially pathogenic Escherichia and Salmonella by reducing the bioavailability of respiratory electron acceptors to Enterobacteriaceae in the lumen of the colon.
(导读：阿金)本研究发现PPAR- γ通路是维持肠道菌群稳态的关键信号通路。由肠道微生物产生的丁酸可激活肠道上皮细胞中的PPAR- γ通路，使肠道中的硝酸盐和氧含量维持在低水平，从而抑制大肠杆菌和沙门氏菌等潜在致病微生物的有氧呼吸和过度增殖。这一机制为预防肠道疾病提供了新的思路。
Song Lin et al.
Vicinal diamines are a common structural motif in bioactive natural products, therapeutic agents, and molecular catalysts, motivating the continuing development of efficient, selective, and sustainable technologies for their preparation. We report an operationally simple and environmentally friendly protocol that converts alkenes and sodium azide—both readily available feedstocks—to 1,2-diazides. Powered by electricity and catalyzed by Earth-abundant manganese, this transformation proceeds under mild conditions and exhibits exceptional substrate generality and functional group compatibility. Using standard protocols, the resultant 1,2-diazides can be smoothly reduced to vicinal diamines in a single step, with high chemoselectivity. Mechanistic studies are consistent with metal-mediated azidyl radical transfer as the predominant pathway, enabling dual carbon-nitrogen bond formation.
4【地球科学】A unified continental thickness from seismology and diamonds suggests a melt-defined plate
Saikiran Tharimena et al.
Thick, rigid continents move over the weaker underlying mantle, although geophysical and geochemical constraints on the exact thickness and defining mechanism of the continental plates are widely discrepant. Xenoliths suggest a chemical continental lithosphere ~175 kilometers thick, whereas seismic tomography supports a much thicker root (>250 kilometers) and a gradual lithosphere-asthenosphere transition, consistent with a thermal definition. We modeled SS precursor waveforms from continental interiors and found a 7 to 9% velocity drop at depths of 130 to 190 kilometers. The discontinuity depth is well correlated with the origin depths of diamond-bearing xenoliths and corresponds to the transition from coarse to deformed xenoliths. At this depth, the xenolith-derived geotherm also intersects the carbonate-silicate solidus, suggesting that partial melt defines the plate boundaries beneath the continental interior.
5【经济】The dual frontier: Patented inventions and prior scientific advance
Benjamin F. Jones et al.
The extent to which scientific advances support marketplace inventions is largely unknown. We study 4.8 million U.S. patents and 32 million research articles to determine the minimum citation distance between patented inventions and prior scientific advances. We find that most cited research articles (80%) link forward to a future patent. Similarly, most patents (61%) link backward to a prior research article. Linked papers and patents typically stand 2 to 4 degrees distant from the other domain. Yet, advances directly along the patent-paper boundary are notably more impactful within their own domains. The distance metric further provides a typology of the fields, institutions, and individuals involved in science-to-technology linkages. Overall, the findings are consistent with theories that emphasize substantial and fruitful connections between patenting and prior scientific inquiry.
（导读 陈月欣） 目前人们对于前沿科学的进展对市场发明的推动支持程度尚不了解。本研究对480万份美国专利和3200万篇科学论文对比后发现，专利技术发明与前沿科学发表存在着紧密的联系，大部分学术论文都会导致后续的专利发明，而专利都可追溯到对应的论文。其中，生物医学、计算机科学和工程学等学科的学界-业界联系尤为密切。
6【地球科学】Changing climate shifts timing of European floods
Günter Blöschl et al.
A warming climate is expected to have an impact on the magnitude and timing of river floods; however, no consistent large-scale climate change signal in observed flood magnitudes has been identified so far. We analyzed the timing of river floods in Europe over the past five decades, using a pan-European database from 4262 observational hydrometric stations, and found clear patterns of change in flood timing. Warmer temperatures have led to earlier spring snowmelt floods throughout northeastern Europe; delayed winter storms associated with polar warming have led to later winter floods around the North Sea and some sectors of the Mediterranean coast; and earlier soil moisture maxima have led to earlier winter floods in western Europe. Our results highlight the existence of a clear climate signal in flood observations at the continental scale.
7【生物】Two areas for familiar face recognition in the primate brain
Sofia M. Landi and Winrich A. Freiwald
Familiarity alters face recognition: Familiar faces are recognized more accurately than unfamiliar ones and under difficult viewing conditions when unfamiliar face recognition fails. The neural basis for this fundamental difference remains unknown. Using whole-brain functional magnetic resonance imaging, we found that personally familiar faces engage the macaque face-processing network more than unfamiliar faces. Familiar faces also recruited two hitherto unknown face areas at anatomically conserved locations within the perirhinal cortex and the temporal pole. These two areas, but not the core face-processing network, responded to familiar faces emerging from a blur with a characteristic nonlinear surge, akin to the abruptness of familiar face recognition. In contrast, responses to unfamiliar faces and objects remained linear. Thus, two temporal lobe areas extend the core face-processing network into a familiar face-recognition system.
8【生物】Pavlovian conditioning–induced hallucinations result from overweighting of perceptual priors
P. R. Corlett et al.
Some people hear voices that others do not, but only some of those people seek treatment. Using a Pavlovian learning task, we induced conditioned hallucinations in four groups of people who differed orthogonally in their voice-hearing and treatment-seeking statuses. People who hear voices were significantly more susceptible to the effect. Using functional neuroimaging and computational modeling of perception, we identified processes that differentiated voice-hearers from non–voice-hearers and treatment-seekers from non–treatment-seekers and characterized a brain circuit that mediated the conditioned hallucinations. These data demonstrate the profound and sometimes pathological impact of top-down cognitive processes on perception and may represent an objective means to discern people with a need for treatment from those without.
【导读 陈月欣】 有些人存在幻听，会在脑中听到其他人听不见的声音。本研究采用巴浦洛夫式习得性任务，在有/没有幻听和接受/未接受治疗的4组被试者中建立了条件诱导性的幻觉，其中有幻听的受试者更容易被诱导。研究还借助功能性神经成像鉴别出与这一幻听过程相关的脑神经回路，为基础和临床提供帮助。
9【生物】Single-cell methylomes identify neuronal subtypes and regulatory elements in mammalian cortex
Eran A. Mukamel, M. Margarita Behrens, Joseph R. Ecker et al.
The mammalian brain contains diverse neuronal types, yet we lack single-cell epigenomic assays that are able to identify and characterize them. DNA methylation is a stable epigenetic mark that distinguishes cell types and marks regulatory elements. We generated >6000 methylomes from single neuronal nuclei and used them to identify 16 mouse and 21 human neuronal subpopulations in the frontal cortex. CG and non-CG methylation exhibited cell type–specific distributions, and we identified regulatory elements with differential methylation across neuron types. Methylation signatures identified a layer 6 excitatory neuron subtype and a unique human parvalbumin-expressing inhibitory neuron subtype. We observed stronger cross-species conservation of regulatory elements in inhibitory neurons than in excitatory neurons. Single-nucleus methylomes expand the atlas of brain cell types and identify regulatory elements that drive conserved brain cell diversity.
10 【生物】A cyclic oligonucleotide signaling pathway in type III CRISPR-Cas systems
III型 CRISPR-Cas 系统中的环核苷酸信号通路
Gintautas Tamulaitis, Virginijus Siksnys et al.
Type III CRISPR-Cas systems in prokaryotes provide immunity against invading nucleic acids through the coordinated degradation of transcriptionally active DNA and its transcripts by the Csm effector complex. The Cas10 subunit of the complex contains an HD nuclease domain that is responsible for DNA degradation and two Palm domains with elusive functions. In addition, Csm6, a ribonuclease that is not part of the complex, is also required to provide full immunity. We show here that target RNA binding by the Csm effector complex of Streptococcus thermophilus triggers Cas10 to synthesize cyclic oligoadenylates (cAn; n = 2 to 6) by means of the Palm domains. Acting as signaling molecules, cyclic oligoadenylates bind Csm6 to activate its nonspecific RNA degradation. This cyclic oligoadenylate–based signaling pathway coordinates different components of CRISPR-Cas to prevent phage infection and propagation.
11 【生物】Structure of histone-based chromatin in Archaea
Karolin Luger et al.
Small basic proteins present in most Archaea share a common ancestor with the eukaryotic core histones. We report the crystal structure of an archaeal histone-DNA complex. DNA wraps around an extended polymer, formed by archaeal histone homodimers, in a quasi-continuous superhelix with the same geometry as DNA in the eukaryotic nucleosome. Substitutions of a conserved glycine at the interface of adjacent protein layers destabilize archaeal chromatin, reduce growth rate, and impair transcription regulation, confirming the biological importance of the polymeric structure. Our data establish that the histone-based mechanism of DNA compaction predates the nucleosome, illuminating the origin of the nucleosome.
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