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Science 论文导读 0519

时间: 2017年06月01日 | 作者: admin | 来源: 未知


1 Three-dimensional Ca2+ imaging advances understanding of astrocyte biology



Erika Bindocci, Iaroslav Savtchouk, Nicolas Liaudet, Denise Becker, Giovanni Carriero, Andrea Volterra


Astrocyte communication is typically studied by two-dimensional calcium ion (Ca2+) imaging, but this method has not yielded conclusive data on the role of astrocytes in synaptic and vascular function. We developed a three-dimensional two-photon imaging approach and studied Ca2+ dynamics in entire astrocyte volumes, including during axon-astrocyte interactions. In both awake mice and brain slices, we found that Ca2+ activity in an individual astrocyte is scattered throughout the cell, largely compartmented between regions, preponderantly local within regions, and heterogeneously distributed regionally and locally. Processes and endfeet displayed frequent fast activity, whereas the soma was infrequently active. In awake mice, activity was higher than in brain slices, particularly in endfeet and processes, and displayed occasional multifocal cellwide events. Astrocytes responded locally to minimal axonal firing with time-correlated Ca2+ spots.


(导读 柳寒石)研究人员利用新发展的三维双光子成像技术研究了星形胶质细胞中以及轴突-星形胶质细胞相互作用时Ca2+的动态变化。结果表明Ca2+活动分布于单个星形胶质细胞的整个细胞中,但在不同细胞区域间存在差异,细胞局部可响应轴突最小放电产生时间相关的Ca2+斑点。

2 Ephrin B1–mediated repulsion and signaling control germinal center T cell territoriality and function

【生物】Ephrin B1介导的排斥作用与信号通路双重调控生发中心T细胞数目与功能

Peiwen Lu, Changming Shih, Hai Qi


Follicular T helper (TFH) cells orchestrate the germinal center (GC) reaction locally. Local mechanisms regulating their dynamics and helper functions are not well defined. Here we found that GC-expressed ephrin B1 (EFNB1) repulsively inhibited T cell to B cell adhesion and GC TFH retention by signaling through TFH-expressed EPHB6 receptor. At the same time, EFNB1 promoted interleukin-21 production from GC TFH cells by signaling predominantly through EPHB4. Consequently, EFNB1-null GCs were associated with defective production of plasma cells despite harboring excessive TFH cells. In a competitive GC reaction, EFNB1-deficient B cells more efficiently interacted with TFH cells and produced more bone-marrow plasma cells, likely as a result of gaining more contact-dependent help. Our results reveal a contact-dependent repulsive guidance system that controls GC TFH dynamics and effector functions locally.

(导读 严冰)滤泡辅助T细胞TFH通过向生发中心(GCB细胞传递CD40配体或细胞因子(如IL-21)等接触依赖性信号,促进B细胞增殖分化,形成浆细胞。本研究发现,在此过程中,GCB细胞表达的EFNB1蛋白通过与TFH表达的两种受体EPHB4/EPHB6相互作用而进行正负调节:(iEPHB1-EPHB6作用抑制B-TFH靠近,从而抑制GCTFH募集与滞留,抑制浆细胞形成;(iiEPHB1-EPHB4作用促进TFH分泌IL-21,从而促进浆细胞形成。

3 Blocking promiscuous activation at cryptic promoters directs cell type–specific gene expression



Jongmin Kim, Chenggang Lu, Shrividhya Srinivasan, Stephan Awe, Alexander Brehm, Margaret T. Fuller


To selectively express cell type–specific transcripts during development, it is critical to maintain genes required for other lineages in a silent state. Here, we show in the Drosophila male germline stem cell lineage that a spermatocyte-specific zinc finger protein, Kumgang (Kmg), working with the chromatin remodeler dMi-2 prevents transcription of genes normally expressed only in somatic lineages. By blocking transcription from normally cryptic promoters, Kmg restricts activation by Aly, a component of the testis-meiotic arrest complex, to transcripts for male germ cell differentiation. Our results suggest that as new regions of the genome become open for transcription during terminal differentiation, blocking the action of a promiscuous activator on cryptic promoters is a critical mechanism for specifying precise gene activation.

(导读 卓思琪)本研究发现雄性果蝇生殖干细胞中,一种精母细胞特异性的锌指蛋白KumgangKmg)和染色体重塑剂dMi-2阻止了可在体细胞中正常表达的基因的表达Kmg限制了Aly对神秘启动子的激活,使由此开始转录的大量基因沉默,从而完成雄性生殖细胞分化。该结果为发育过程中细胞类型特异性的基因沉默机制提供了解读

4 Lineage-dependent spatial and functional organization of the mammalian enteric nervous system



Reena Lasrado, Werend Boesmans, Jens Kleinjung…Pieter Vanden Berghe, Vassilis Pachnis


The enteric nervous system (ENS) is essential for digestive function and gut homeostasis. Here we show that the amorphous neuroglia networks of the mouse ENS are composed of overlapping clonal units founded by postmigratory neural crest–derived progenitors. The spatial configuration of ENS clones depends on proliferation-driven local interactions of ENS progenitors with lineally unrelated neuroectodermal cells, the ordered colonization of the serosa-mucosa axis by clonal descendants, and gut expansion. Single-cell transcriptomics and mutagenesis analysis delineated dynamic molecular states of ENS progenitors and identified RET as a regulator of neurogenic commitment. Clonally related enteric neurons exhibit synchronous activity in response to network stimulation. Thus, lineage relationships underpin the organization of the peripheral nervous system.

(导读 卓思琪)本研究发现小鼠肠神经系统(ENS)中的不定形神经胶质网是由迁移后神经嵴衍生祖细胞构成的同源单元组成。ENS克隆的空间配置与ENS祖细胞和线性不相关的神经外胚层细胞相互作用、浆膜-黏膜轴的有序定植和肠道的扩展有关。这些同源相关的肠神经元表现同步以响应网络应激。因此,谱系关系是组织周围神经系统的基础。

5 Global drainage patterns and the origins of topographic relief on Earth, Mars, and Titan


Benjamin A. Black, J. Taylor Perron, Douglas Hemingway, Elizabeth Bailey, Francis Nimmo, Howard Zebker


Rivers have eroded the topography of Mars, Titan, and Earth, creating diverse landscapes. However, the dominant processes that generated topography on Titan (and to some extent on early Mars) are not well known. We analyzed drainage patterns on all three bodies and found that large drainages, which record interactions between deformation and erosional modification, conform much better to long-wavelength topography on Titan and Mars than on Earth. We use a numerical landscape evolution model to demonstrate that short-wavelength deformation causes drainage directions to diverge from long-wavelength topography, as observed on Earth. We attribute the observed differences to ancient long-wavelength topography on Mars, recent or ongoing generation of long-wavelength relief on Titan, and the creation of short-wavelength relief by plate tectonics on Earth.

(导读 邓卓) 造成土卫六和早期火星上地貌起伏的主导水系过程目前尚不明确。本研究通过分析地球、火星和土卫六上的水系类型模式,发现火星和土卫六上的长程地貌主要与大型水系相关。利用数值形貌演变模型,研究人员认为地球上的短程地貌起伏主要由板块构造论产生。

6 Hydrolytically stable fluorinated metal-organic frameworks for energy-efficient dehydration



Amandine Cadiau, Youssef Belmabkhout, Karim Adil…Guillaume Maurin, Mohamed Eddaoudi


Natural gas must be dehydrated before it can be transported and used, but conventional drying agents such as activated alumina or inorganic molecular sieves require an energy-intensive desiccant-regeneration step. We report a hydrolytically stable fluorinated metal-organic framework, AlFFIVE-1-Ni (KAUST-8), with a periodic array of open metal coordination sites and fluorine moieties within the contracted square-shaped one-dimensional channel. This material selectively removed water vapor from gas streams containing CO2, N2, CH4, and higher hydrocarbons typical of natural gas, as well as selectively removed both H2O and CO2 in N2-containing streams. The complete desorption of the adsorbed water molecules contained by the AlFFIVE-1-Ni sorbent requires relatively moderate temperature (~105°C) and about half the energy input for commonly used desiccants.

(导读 卓思琪)用于天然气脱水的传统媒介通常需要一个高能耗的干燥剂再生过程。本研究报道了一种水解稳定的含氟金属-有机框架除水剂AlFFIVE-1-Ni (KAUST-8),其收缩的一维方形通道内包含了周期性的开放金属配位点和氟离子阵列。处理AlFFIVE-1-Ni 所吸附的水所需的温度相对较低105)且所需要的能耗仅仅是一般干燥剂的一半。



7 High-harmonic generation in graphene enhanced by elliptically polarized light excitation


Naotaka Yoshikawa, Tomohiro Tamaya, Koichiro Tanaka


The electronic properties of graphene can give rise to a range of nonlinear optical responses. One of the most desirable nonlinear optical processes is high-harmonic generation (HHG) originating from coherent electron motion induced by an intense light field. Here, we report on the observation of up to ninth-order harmonics in graphene excited by mid-infrared laser pulses at room temperature. The HHG in graphene is enhanced by an elliptically polarized laser excitation, and the resultant harmonic radiation has a particular polarization. The observed ellipticity dependence is reproduced by a fully quantum mechanical treatment of HHG in solids. The zero-gap nature causes the unique properties of HHG in graphene, and our findings open up the possibility of investigating strong-field and ultrafast dynamics and nonlinear behavior of massless Dirac fermions.

(导读 邓卓)石墨烯最引人注目的一种非线性光学现象是在强光场激发下的高次谐波产生(HHG)。本研究报导了利用中红外激光脉冲激发石墨烯在室温下观察到了高达九阶的HHG。这些HHG能被椭圆偏振的激发光增强,使产生的谐波具有特定的偏振。研究结果为探究狄拉克费米子在强场下的超快速非线性动力学提供了参考。

8 Bragg coherent diffractive imaging of single-grain defect dynamics in polycrystalline films


Allison Yau, Wonsuk Cha, Matthew W. Kanan, G. Brian Stephenson, Andrew Ulvestad


Polycrystalline material properties depend on the distribution and interactions of their crystalline grains. In particular, grain boundaries and defects are crucial in determining their response to external stimuli. A long-standing challenge is thus to observe individual grains, defects, and strain dynamics inside functional materials. Here we report a technique capable of revealing grain heterogeneity, including strain fields and individual dislocations, that can be used under operando conditions in reactive environments: grain Bragg coherent diffractive imaging (gBCDI). Using a polycrystalline gold thin film subjected to heating, we show how gBCDI resolves grain boundary and dislocation dynamics in individual grains in three-dimensional detail with 10-nanometer spatial and subangstrom displacement field resolution. These results pave the way for understanding polycrystalline material response under external stimuli and, ideally, engineering particular functions.

(导读 卓思琪)多晶材料的性质与其晶体颗粒的分布和相互作用有关。本研究报导了一种基于晶粒布拉格相干衍射成像(gBCDI)来揭示晶粒不均匀性的技术。研究人员在一块加热后的多晶金薄膜中展示了gBCDI如何在单个晶粒中分辨晶界和位错,且其三维空间分辨率高达10纳米。研究结果为进一步了解多晶材料在外部激励下的响应提供了指引。


9 Higher predation risk for insect prey at low latitudes and elevations



Tomas Roslin, Bess Hardwick, Vojtech Novotny…Vital Zhukovich, Eleanor M. Slade


Biotic interactions underlie ecosystem structure and function, but predicting interaction outcomes is difficult. We tested the hypothesis that biotic interaction strength increases toward the equator, using a global experiment with model caterpillars to measure predation risk. Across an 11,660-kilometer latitudinal gradient spanning six continents, we found increasing predation toward the equator, with a parallel pattern of increasing predation toward lower elevations. Patterns across both latitude and elevation were driven by arthropod predators, with no systematic trend in attack rates by birds or mammals. These matching gradients at global and regional scales suggest consistent drivers of biotic interaction strength, a finding that needs to be integrated into general theories of herbivory, community organization, and life-history evolution.

(导读 郭思瑶)生物交互作用是生态系统结构和功能的基础,但很难预测交互结果。研究人员通过全球尺度毛的实验估测捕食风险,验证了生物交互强度随纬度降低而增加假说,并发现这一模式受节肢动物捕食者驱动,该结果有助于完善生物基础理论。

10 A dedicated network for social interaction processing in the primate brain



J. Sliwa, W. A. Freiwald


Primate cognition requires interaction processing. Interactions can reveal otherwise hidden properties of intentional agents, such as thoughts and feelings, and of inanimate objects, such as mass and material. Where and how interaction analyses are implemented in the brain is unknown. Using whole-brain functional magnetic resonance imaging in macaque monkeys, we discovered a network centered in the medial and ventrolateral prefrontal cortex that is exclusively engaged in social interaction analysis. Exclusivity of specialization was found for no other function anywhere in the brain. Two additional networks, a parieto-premotor and a temporal one, exhibited both social and physical interaction preference, which, in the temporal lobe, mapped onto a fine-grain pattern of object, body, and face selectivity. Extent and location of a dedicated system for social interaction analysis suggest that this function is an evolutionary forerunner of human mind-reading capabilities.


(导读 董堃)对外界信息的交互处理是灵长类认知产生的重要基础。本研究使用全脑功能性核磁共振成像技术,在恒河猴的内侧和腹外侧前额叶皮层发现了一个专门负责社会性交互分析的神经网络。此外,还有位于颞叶的网络涉及社会性和物理性交互分析。这些交互网络是人类读心能力产生的进化基础



11 21st-century rise in anthropogenic nitrogen deposition on a remote coral reef


Haojia Ren, Yi-Chi Chen, Xingchen T. Wang…Horng-Sheng Mii, Daniel M. Sigman


With the rapid rise in pollution-associated nitrogen inputs to the western Pacific, it has been suggested that even the open ocean has been affected. In a coral core from Dongsha Atoll, a remote coral reef ecosystem, we observe a decline in the 15N/14N of coral skeleton–bound organic matter, which signals increased deposition of anthropogenic atmospheric N on the open ocean and its incorporation into plankton and, in turn, the atoll corals. The first clear change occurred just before 2000 CE, decades later than predicted by other work. The amplitude of change suggests that, by 2010, anthropogenic atmospheric N deposition represented 20 ± 5% of the annual N input to the surface ocean in this region, which appears to be at the lower end of other estimates.

(导读 郭思瑶)污染引起的氮输入逐渐影响西太平洋开放海域。在东沙环礁,研究人员发现珊瑚骨架的15N/14N有所下降,标志着开放水域中人为造成的大气氮含量增加并被浮游生物吸收。据估计,到2020年,该区域人为的大气氮含量输入将达到全年氮输入总量的四分之一。


12 ATP as a biological hydrotrope


Avinash Patel, Liliana Malinovska, Shambaditya Saha, Jie Wang, Simon Alberti, Yamuna Krishnan, Anthony A. Hyman


Hydrotropes are small molecules that solubilize hydrophobic molecules in aqueous solutions. Typically, hydrotropes are amphiphilic molecules and differ from classical surfactants in that they have low cooperativity of aggregation and work at molar concentrations. Here, we show that adenosine triphosphate (ATP) has properties of a biological hydrotrope. It can both prevent the formation of and dissolve previously formed protein aggregates. This chemical property is manifested at physiological concentrations between 5 and 10 millimolar. Therefore, in addition to being an energy source for biological reactions, for which micromolar concentrations are sufficient, we propose that millimolar concentrations of ATP may act to keep proteins soluble. This may in part explain why ATP is maintained in such high concentrations in cells.

 (导读 郭思瑶)助水溶物是增加疏水分子在水中溶解度的小分子。研究人员发现三磷酸腺苷(ATP)具有生物助水溶物的特性。它既能阻止蛋白质聚合物的形成又能溶解已形成的蛋白质聚合物。ATP发挥该功能的生理浓度是5-10mmol,可解释细胞中ATP浓度远高于为生物反应供能所需的现象。


13 A placental growth factor is silenced in mouse embryos by the zinc finger protein ZFP568


Peng Yang, Yixuan Wang, Don Hoang…Che-Kun James Shen, Todd S. Macfarlan


Insulin-like growth factor 2 (IGF2) is the major fetal growth hormone in mammals. We identify zinc finger protein 568 (ZFP568), a member of the rapidly evolving Kruppel-associated box–zinc finger protein (KRAB-ZFP) family linked primarily to silencing of endogenous retroelements, as a direct repressor of a placental-specific Igf2 transcript (designated Igf2-P0) in mice. Loss of Zfp568, which causes gastrulation failure, or mutation of the ZFP568-binding site at the Igf2-P0 promoter causes inappropriate Igf2-P0 activation. Deletion of Igf2 can completely rescue Zfp568 gastrulation phenotypes through late gestation. Our data highlight the exquisite selectivity with which members of the KRAB-ZFP family repress their targets and identify an additional layer of transcriptional control of a key growth factor regulating fetal and placental development.

(导读 卓思琪)本研究发现锌指蛋白568ZFP568)是小鼠的胎盘特异性Igf2转录物(特指lgf-P0)的直接抑制因子。导致原肠胚形成失败的ZFP58缺失或其结合位点突变会导致lgf-P0不适当激活。实验数据证明KRAB-ZFP家族成员的选择性抑制了其靶标,并确定调控胎儿和胎盘发育的关键生长因子的另一转录控制。