Science 论文导读 0526
Peter J. Thul, Lovisa Åkesson et al.
（导读 柳寒石）搞清楚人类蛋白质组在亚细胞水平上的空间分布，能够极大地提高我们对人类生理和病理的理解。研究人员通过整合转录组学和抗体免疫荧光显微镜术，建立了一个基于图像的亚细胞蛋白分布图Cell Atlas。。在单细胞水平上将12003人类蛋白定位到30个亚细胞结构上，定义了13个主要细胞器的蛋白质组学。这一亚细胞图谱为解析高度复杂的人类细胞结构，提供了重要的资源。
Resolving the spatial distribution of the human proteome at a subcellular level can greatly increase our understanding of human biology and disease. Here we present a comprehensive image-based map of subcellular protein distribution, the Cell Atlas, built by integrating transcriptomics and antibody-based immunofluorescence microscopy with validation by mass spectrometry. Mapping the in situ localization of 12,003 human proteins at a single-cell level to 30 subcellular structures enabled the definition of the proteomes of 13 major organelles. Exploration of the proteomes revealed single-cell variations in abundance or spatial distribution and localization of about half of the proteins to multiple compartments. This subcellular map can be used to refine existing protein-protein interaction networks and provides an important resource to deconvolute the highly complex architecture of the human cell.
S. J. Bolton et al.
(导读 卓思琪) 朱诺号（Juno）航天器穿越木星两极发现其两极轮乱。微波探测显示了100巴尔及更深大气压出的天气特征是一个富氨的狭窄低纬度羽流主导的、像一个更深更广的哈得来环流圈。朱诺号所测的重力场不仅和最新估计的大有相异，而且更精确了一个数量级。这暗示木星内部分布着重元素。观察到的磁场比预想的空间变化更小，这说明谐波量丰富。
On 27 August 2016, the Juno spacecraft acquired science observations of Jupiter, passing less than 5000 kilometers above the equatorial cloud tops. Images of Jupiter’s poles show a chaotic scene, unlike Saturn’s poles. Microwave sounding reveals weather features at pressures deeper than 100 bars, dominated by an ammonia-rich, narrow low-latitude plume resembling a deeper, wider version of Earth’s Hadley cell. Near-infrared mapping reveals the relative humidity within prominent downwelling regions. Juno’s measured gravity field differs substantially from the last available estimate and is one order of magnitude more precise. This has implications for the distribution of heavy elements in the interior, including the existence and mass of Jupiter’s core. The observed magnetic field exhibits smaller spatial variations than expected, indicative of a rich harmonic content.
J. E. P. Connerney et al.
The Juno spacecraft acquired direct observations of the jovian magnetosphere and auroral emissions from a vantage point above the poles. Juno’s capture orbit spanned the jovian magnetosphere from bow shock to the planet, providing magnetic field, charged particle, and wave phenomena context for Juno’s passage over the poles and traverse of Jupiter’s hazardous inner radiation belts. Juno’s energetic particle and plasma detectors measured electrons precipitating in the polar regions, exciting intense aurorae, observed simultaneously by the ultraviolet and infrared imaging spectrographs. Juno transited beneath the most intense parts of the radiation belts, passed about 4000 kilometers above the cloud tops at closest approach, well inside the jovian rings, and recorded the electrical signatures of high-velocity impacts with small particles as it traversed the equator.
【植物】4 Ancestral alliances: Plant mutualistic symbioses with fungi and bacteria
Francis M. Martin, David G. Barker et al.
5 Submillihertz magnetic spectroscopy performed with a nanoscale quantum sensor
Liam P. McGuinness et al.
Precise timekeeping is critical to metrology, forming the basis by which standards of time, length, and fundamental constants are determined. Stable clocks are particularly valuable in spectroscopy because they define the ultimate frequency precision that can be reached. In quantum metrology, the qubit coherence time defines the clock stability, from which the spectral linewidth and frequency precision are determined. We demonstrate a quantum sensing protocol in which the spectral precision goes beyond the sensor coherence time and is limited by the stability of a classical clock. Using this technique, we observed a precision in frequency estimation scaling in time T as T–3/2 for classical oscillating fields. The narrow linewidth magnetometer based on single spins in diamond is used to sense nanoscale magnetic fields with an intrinsic frequency resolution of 607 microhertz, which is eight orders of magnitude narrower than the qubit coherence time.
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6 Quantum sensing with arbitrary frequency resolution
J. M. Boss, K. S. Cujia et al.
Quantum sensing takes advantage of well-controlled quantum systems for performing measurements with high sensitivity and precision. We have implemented a concept for quantum sensing with arbitrary frequency resolution, independent of the qubit probe and limited only by the stability of an external synchronization clock. Our concept makes use of quantum lockin detection to continuously probe a signal of interest. Using the electronic spin of a single nitrogenvacancy center in diamond, we demonstrate detection of oscillating magnetic fields with a frequency resolution of 70 microhertz over a megahertz bandwidth. The continuous sampling further guarantees an enhanced sensitivity, reaching a signal-to-noise ratio in excess of 104 for a 170-nanotesla test signal measured during a 1hour interval. Our technique has applications in magnetic resonance spectroscopy, quantum simulation, and sensitive signal detection.
（导读 金庄维）量子传感利用控制良好的量子系统来进行高灵敏度、高精度测量。本研究利用量子锁定探测（quantum lock-in detection）对信号进行连续测量，实现了任意频率分辨率的量子传感。研究人员利用金刚石内单个氮-空穴色心的电子自旋，以70微赫的分辨率测量了振荡磁场（带宽 >1MHz）的频率。连续取样进一步保证了高灵敏度，并且提高了信噪比。
7 Release of mineral-bound water prior to subduction tied to shallow seismogenic slip off Sumatra
（导读 赵维娜 ）IODP第362航次取自苏门答腊北部近海沉积的样品揭示该区近期出现深部沉积物的淡水释放，模型显示其源自板块俯冲之前快速覆盖升温引发的硅酸盐完全脱水。这与俯冲过程中流体析出模型存在差异，但我们的结果适用于其它厚重沉积的俯冲地区。
Plate-boundary fault rupture during the 2004 Sumatra-Andaman subduction earthquake extended closer to the trench than expected, increasing earthquake and tsunami size. International Ocean Discovery Program Expedition 362 sampled incoming sediments offshore northern Sumatra, revealing recent release of fresh water within the deep sediments. Thermal modeling links this freshening to amorphous silica dehydration driven by rapid burial-induced temperature increases in the past 9 million years. Complete dehydration of silicates is expected before plate subduction, contrasting with prevailing models for subduction seismogenesis calling for fluid production during subduction. Shallow slip offshore Sumatra appears driven by diagenetic strengthening of deeply buried fault-forming sediments, contrasting with weakening proposed for the shallow Tohoku-Oki 2011 rupture, but our results are applicable to other thickly sedimented subduction zones including those with limited earthquake records.
8 An on/off Berry phase switch in circular graphene resonators
Fereshte Ghahari, Daniel Walkup, Christopher Gutiérrez, Joaquin F. Rodriguez-Nieva et al.
The phase of a quantum state may not return to its original value after the system’s parameters cycle around a closed path; instead, the wave function may acquire a measurable phase difference called the Berry phase. Berry phases typically have been accessed through interference experiments. Here, we demonstrate an unusual Berry phase–induced spectroscopic feature: a sudden and large increase in the energy of angular-momentum states in circular graphene p-n junction resonators when a relatively small critical magnetic field is reached. This behavior results from turning on a π Berry phase associated with the topological properties of Dirac fermions in graphene. The Berry phase can be switched on and off with small magnetic field changes on the order of 10 millitesla, potentially enabling a variety of optoelectronic graphene device applications.
（导读 金庄维）石墨烯中的电子绕狄拉克点运动一周后，波函数相位会改变π ，这就是所谓的“贝利相”。本研究证实了一种非同寻常的贝利相：当磁场达到某个较小的临界值时，环形石墨烯p-n结共振器中角动量态的能量突然剧增，这种行为源于贝利相被“打开”。研究人员能够利用10毫特斯拉量级的磁场变化开关贝利相，该性质有望应用于石墨烯光电器材。
9 Ring attractor dynamics in the Drosophila central brain
Sung Soo Kim, Hervé Rouault et al.
(导读 卓思琪) 果蝇大脑内的一组环状神经元网络被认为是果蝇头部方向感形成中的重要元件。本文利用双光子钙成像和光遗传学操作，对头部固定的飞翔中果蝇的神经进行研究，观察到了一组局部兴奋、全局抑制的环状神经元，这一元件可以改变自身连接方向，以反映果蝇的头部取向。该研究在环状神经元元件研究和技术层面都具有重要意义。
Ring attractors are a class of recurrent networks hypothesized to underlie the representation of heading direction. Such network structures, schematized as a ring of neurons whose connectivity depends on their heading preferences, can sustain a bump-like activity pattern whose location can be updated by continuous shifts along either turn direction. We recently reported that a population of fly neurons represents the animal’s heading via bump-like activity dynamics. We combined two-photon calcium imaging in head-fixed flying flies with optogenetics to overwrite the existing population representation with an artificial one, which was then maintained by the circuit with naturalistic dynamics. A network with local excitation and global inhibition enforces this unique and persistent heading representation. Ring attractor networks have long been invoked in theoretical work; our study provides physiological evidence of their existence and functional architecture.
10 Rapid binge-like eating and body weight gain driven by zona incerta GABA neuron activation
Anthony N. van den Pol et al.
(导读 郭思瑶) 导致暴饮暴食的神经机制尚不清楚。研究人员发现影响摄食行为的关键脑区。实验显示光遗传刺激小鼠丘脑底部未定区(zona incerta ，ZI) GABA神经元能引起PVT脑区神经兴奋并引发暴饮暴食。而选择性切除ZI脑区GABA神经元或光激活ZI区谷氨酸能神经元能引起体重减少。该研究显示了ZI脑区GABA神经元在促进食欲上的潜在作用。
The neuronal substrate for binge eating, which can at times lead to obesity, is not clear. We find that optogenetic stimulation of mouse zona incerta (ZI) γ-aminobutyric acid (GABA) neurons or their axonal projections to paraventricular thalamus (PVT) excitatory neurons immediately (in 2 to 3 seconds) evoked binge-like eating. Minimal intermittent stimulation led to body weight gain; ZI GABA neuron ablation reduced weight. ZI stimulation generated 35% of normal 24-hour food intake in just 10 minutes. The ZI cells were excited by food deprivation and the gut hunger signal ghrelin. In contrast, stimulation of excitatory axons from the parasubthalamic nucleus to PVT or direct stimulation of PVT glutamate neurons reduced food intake. These data suggest an unexpected robust orexigenic potential for the ZI GABA neurons.
11 Tudor-SN–mediated endonucleolytic decay of human cell microRNAs promotes G1/S phase transition
Reyad A. Elbarbary, Keita Miyoshi et al.
MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression. The pathways that mediate mature miRNA decay are less well understood than those that mediate miRNA biogenesis. We found that functional miRNAs are degraded in human cells by the endonuclease Tudor-SN (TSN). In vitro, recombinant TSN initiated the decay of both protein-free and Argonaute 2–loaded miRNAs via endonucleolytic cleavage at CA and UA dinucleotides, preferentially at scissile bonds located more than five nucleotides away from miRNA ends. Cellular targets of TSN-mediated decay defined using microRNA sequencing followed this rule. Inhibiting TSN-mediated miRNA decay by CRISPR-Cas9 knockout of TSN inhibited cell cycle progression by up-regulating a cohort of miRNAs that down-regulates mRNAs that encode proteins critical for the G1-to-S phase transition. Our study indicates that targeting TSN nuclease activity could inhibit pathological cell proliferation.
12 RNA polymerase motions during promoter melting
Andrey Feklistov et al.
（导读 郭思瑶）所有细胞内RNA聚合酶(RNAP)都有一个钳，普遍认为其打开可使启动子DNA双链分离 。研究人员通过RNAP和DNA上的荧光信号实时解析了细菌RNAP启动时的连续动作，意外发现RNAP钳的瞬时关闭是DNA双链打开的准备动作。该结果和解析出的晶体结构解释了RNAP是如何控制启动子和DNA双链分离的。
All cellular RNA polymerases (RNAPs), from those of bacteria to those of man, possess a clamp that can open and close, and it has been assumed that the open RNAP separates promoter DNA strands and then closes to establish a tight grip on the DNA template. Here, we resolve successive motions of the initiating bacterial RNAP by studying real-time signatures of fluorescent reporters placed on RNAP and DNA in the presence of ligands locking the clamp in distinct conformations. We report evidence for an unexpected and obligatory step early in the initiation involving a transient clamp closure as a prerequisite for DNA melting. We also present a 2.6-angstrom crystal structure of a late-initiation intermediate harboring a rotationally unconstrained downstream DNA duplex within the open RNAP active site cleft. Our findings explain how RNAP thermal motions control the promoter search and drive DNA melting in the absence of external energy sources.
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