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Science 论文导读_0825

时间: 2017年09月05日 | 作者: admin | 来源: 未知
Science 20170825 1 Actin protects mammalian eggs against chromosome segregation errors 【生物】肌动蛋白保护哺乳动物卵细胞免受染色体错误分离 Binyam Mogessie, Melina Schuh http://science.sciencemag.org/content/357/63

Science 20170825

1 Actin protects mammalian eggs against chromosome segregation errors


Binyam Mogessie, Melina Schuh



Chromosome segregation is driven by a spindle that is made of microtubules but is generally thought to be independent of actin. Here, we report an unexpected actin-dependent mechanism that drives the accurate alignment and segregation of chromosomes in mammalian eggs. Prominent actin filaments permeated the microtubule spindle in eggs of several mammalian species, including humans. Disrupting actin in mouse eggs led to significantly increased numbers of misaligned chromosomes as well as lagging chromosomes during meiosis I and II. We found that actin drives accurate chromosome segregation by promoting the formation of functional kinetochore fibers, the microtubule bundles that align and segregate the chromosomes. Thus, actin is essential to prevent chromosome segregation errors in eggs, which are a leading cause of miscarriages, infertility, and Down syndrome.


(导读 郭怿暄)卵细胞中染色体分离错误是造成流产、不育和唐氏综合征的主要因素。本研究发现在哺乳动物卵细胞中,肌动蛋白可以促进功能性着丝粒纤维的形成,对染色体的准确排列和分离起到决定性作用。破坏肌动蛋白会导致减数分裂I期和II期中染色体的错误排列和迟滞染色体的明显增加。


2. Harvesting electrical energy from carbon nanotube yarn twist



Mechanical energy harvesters are needed for diverse applications, including self-powered wireless sensors, structural and human health monitoring systems, and the extraction of energy from ocean waves. We report carbon nanotube yarn harvesters that electrochemically convert tensile or torsional mechanical energy into electrical energy without requiring an external bias voltage. Stretching coiled yarns generated 250 watts per kilogram of peak electrical power when cycled up to 30 hertz, as well as up to 41.2 joules per kilogram of electrical energy per mechanical cycle, when normalized to harvester yarn weight. These energy harvesters were used in the ocean to harvest wave energy, combined with thermally driven artificial muscles to convert temperature fluctuations to electrical energy, sewn into textiles for use as self-powered respiration sensors, and used to power a light-emitting diode and to charge a storage capacitor.

(导读 张奕林)本研究介绍了一种借助电化学方法在不需要外加偏压的情形下,将碳纳米管线的延展与扭转机械能转化为电能的收集器件,这些能量收集器可应用在潮汐发电,热驱动人工肌肉,自供能呼吸传感器,发光二极管供能等方面



3 Ruthenium-catalyzed insertion of adjacent diol carbon atoms into C-C bonds: Entry to type II polyketides


Matthias Bender, Ben W. H. Turnbull, Brett R. Ambler, Michael J. Krische



Current catalytic processes involving carbon-carbon bond activation rely on π-unsaturated coupling partners. Exploiting the concept of transfer hydrogenative coupling, we report a ruthenium(0)-catalyzed cycloaddition of benzocyclobutenones that functionalizes two adjacent saturated diol carbon-hydrogen bonds. These regio- and diastereoselective processes enable convergent construction of type II polyketide substructures.


(导读 卓思琪)当前催化中对C-C键的激活依赖于不饱和π耦合基团。本研究利用转移加氢耦合的概念,报道了一种钌(0)催化的苯并环丁酮的环加成反应,此反应使两个相邻的饱和二醇碳氢键发生了功能化。该具有区域化、非对映选择性的过程使II型聚酮亚结构的归一化合成成为可能。


4 The turbulent cascade in five dimensions


José I. Cardesa, Alberto Vela-Martín, Javier Jiménez





To the naked eye, turbulent flows exhibit whirls of many different sizes. To each size, or scale, corresponds a fraction of the total energy resulting from a cascade in five dimensions: scale, time, and three-dimensional space. Understanding this process is critical to strategies for modeling geophysical and industrial flows. By tracking the flow regions containing energy in different scales, we have detected the statistical predominance of a cross-scale link whereby fluid lumps of energy at scale Δ appear within lumps of scale 2Δ and die within those of scale Δ/2. Our approach uncovers the energy cascade in a simple water-like fluid, offering insights for turbulence models while paving the way for similar analyses in conducting fluids, quantum fluids, and plasmas.


5 Optical imaging of surface chemistry and dynamics in confinement


Carlos Macias-Romero, Igor Nahalka, Halil I. Okur, Sylvie Roke



(导读:阿金)本研究使用宽场、毫秒量级的二次谐波显微镜,对水微观局域空间内的界面结构和动力学进行了三维成像,揭示了界面水的定向有序性。同时跟踪浸入水溶液的玻璃微毛细管的化学变化,确定二氧化硅去质子化反应的空间分辨表面酸解离常数值在2.3  10.7之间。研究人员对沿着外部振荡电场旋转的水分子进行了成像。


We imaged the interfacial structure and dynamics of water  in a microscopically confined geometry, in three dimensions and on millisecond time scales, with a structurally illuminated wide-field second harmonic microscope. The second harmonic images reported on the orientational order of interfacial water, induced by charge-dipole interactions between water molecules and surface charges. The images were converted into surface potential maps. Spatially resolved surface  acid dissociation constant (pKa,s) values were determined for the silica deprotonation reaction by following pH-induced chemical changes on the curved and confined surfaces of a glass microcapillary immersed in aqueous solutions. These values ranged from 2.3 to 10.7 along the wall of a single capillary because of surface heterogeneities. Water molecules that rotate along an oscillating external electric field were also imaged.


6. Robust epitaxial growth of two-dimensional heterostructures, multiheterostructures, and superlattices



We report a general synthetic strategy for highly robust growth of diverse lateral heterostructures, multiheterostructures, and superlattices from two-dimensional (2D) atomic crystals. A reverse flow during the temperature-swing stage in the sequential vapor deposition growth process allowed us to cool the existing 2D crystals to prevent undesired thermal degradation and uncontrolled homogeneous nucleation, thus enabling highly robust block-by-block epitaxial growth. Raman and photoluminescence mapping studies showed that a wide range of 2D heterostructures (such as WS2-WSe2 and WS2-MoSe2), multiheterostructures (such as WS2-WSe2-MoS2 and WS2-MoSe2-WSe2), and superlattices (such as WS2-WSe2-WS2-WSe2-WS2) were readily prepared with precisely controlled spatial modulation. Transmission electron microscope studies showed clear chemical modulation with atomically sharp interfaces. Electrical transport studies of WSe2-WS2 lateral junctions showed well-defined diode characteristics with a rectification ratio up to 105.

(导读 张奕林)本研究介绍了一种从二维原子晶体上稳固生长侧向异质结,多异质结和超晶格的通用合成方案。研究人员在连续气相沉积生长过程中的温度波动阶段,向炉中通入反向氩气流,冷却了二维晶种,避免了热解损耗与不受控均质成核,从而实现了高稳定性的二维材料外延生长。




7 Enhanced water permeability and tunable ion selectivity in subnanometer carbon nanotube porins


Ramya H. Tunuguntla, Robert Y. Henley, Yun-Chiao Yao, Tuan Anh Pham, Meni Wanunu, Aleksandr Noy







Fast water transport through carbon nanotube pores has raised the possibility to use them in the next generation of water treatment technologies. We report that water permeability in 0.8-nanometer-diameter carbon nanotube porins (CNTPs) , which confine water down to a single-file chain, exceeds that of biological water transporters and of wider CNT pores by an order of magnitude. Intermolecular hydrogen-bond rearrangement, required for entry into the nanotube, dominates the energy barrier and can be manipulated to enhance water transport rates. CNTPs block anion transport, even at salinities that exceed seawater levels, and their ion selectivity can be tuned to configure them into switchable ionic diodes. These properties make CNTPs a promising material for developing membrane separation technologies.



8 Intonational speech prosody encoding in the human auditory cortex




C. Tang, L. S. Hamilton, E. F. Chang





Speakers of all human languages regularly use intonational pitch to convey linguistic meaning, such as to emphasize a particular word. Listeners extract pitch movements from speech and evaluate the shape of intonation contours independent of each speaker’s pitch range. We used high-density electrocorticography to record neural population activity directly from the brain surface while participants listened to sentences that varied in intonational pitch contour, phonetic content, and speaker. Cortical activity at single electrodes over the human superior temporal gyrus selectively represented intonation contours. These electrodes were intermixed with, yet functionally distinct from, sites that encoded different information about phonetic features or speaker identity. Furthermore, the representation of intonation contours directly reflected the encoding of speaker-normalized relative pitch but not absolute pitch.


(导读 郭怿暄)人类语言中常常通过语调传递一些语言信息,听者如何获取并提炼相关信息尚不清楚。这一研究利用高密度脑皮层电图直接记录被试者在听到不同语调句子时大脑表面的神经活动,发现人类大脑颞上回皮层的活动可反映校正后的相对音调信息,而这一功能独立于对声音特征以及讲话者身份的识别。


9 Seasonal cycling in the gut microbiome of the Hadza hunter-gatherers of Tanzania


Samuel A. Smits, Jeff Leach, Erica D. Sonnenburg…Maria Gloria Dominguez-Bello, Justin L. Sonnenburg


Although humans have cospeciated with their gut-resident microbes, it is difficult to infer features of our ancestral microbiome. Here, we examine the microbiome profile of 350 stool samples collected longitudinally for more than a year from the Hadza hunter-gatherers of Tanzania. The data reveal annual cyclic reconfiguration of the microbiome, in which some taxa become undetectable only to reappear in a subsequent season. Comparison of the Hadza data set with data collected from 18 populations in 16 countries with varying lifestyles reveals that gut community membership corresponds to modernization: Notably, the taxa within the Hadza that are the most seasonally volatile similarly differentiate industrialized and traditional populations. These data indicate that some dynamic lineages of microbes have decreased in prevalence and abundance in modernized populations.

(导读 何丽莹)虽然人类与肠道里的微生物共同进化,但它们的祖先特征仍然难以推断。本研究分析了来自坦桑尼亚营狩猎采集哈扎人的粪便样本,显示其肠道微生物的季节性变化比工业化和传统居民更强,与16个国家不同生活方式的人群比较的结果表明一些动态微生物谱系在现代人群中的广度和丰度有所下降。


10 Lactobacillus reuteri induces gut intraepithelial CD4+CD8αα+ T cells

【生物】罗伊乳杆菌诱导肠上皮内的CD4 +CD8αα + T细胞

Luisa Cervantes-Barragan, Jiani N. Chai, Ma. Diarey Tianero…Chyi-Song Hsieh, Marco Colonna


The small intestine contains CD4+CD8αα+ double-positive intraepithelial lymphocytes (DP IELs), which originate from intestinal CD4+ T cells through down-regulation of the transcription factor Thpok and have regulatory functions. DP IELs are absent in germ-free mice, which suggests that their differentiation depends on microbial factors. We found that DP IEL numbers in mice varied in different vivaria, correlating with the presence of Lactobacillus reuteri. This species induced DP IELs in germ-free mice and conventionally-raised mice lacking these cells. L. reuteri did not shape the DP-IEL-TCR (TCR, T cell receptor) repertoire but generated indole derivatives of tryptophan that activated the aryl-hydrocarbon receptor in CD4+ T cells, allowing Thpok down-regulation and differentiation into DP IELs. Thus, L. reuteri, together with a tryptophan-rich diet, can reprogram intraepithelial CD4+ T cells into immunoregulatory T cells.

(导读 何丽莹)小肠中的CD4 + CD8αα+ 双阳性上皮内淋巴细胞(DP IELs)具有调节功能,无菌小鼠中缺乏该类细胞,暗示其由肠道微生物诱导形成。本文发现罗伊乳杆菌可以产生色氨酸的吲哚衍生物,激活CD4+T细胞中的烃受体,使Thpok下调分化成DP IELs。因此,罗伊乳杆菌配合富含色氨酸的饮食可以将上皮细胞CD4+T细胞重组为免疫调节T细胞。


11 Emergent cellular self-organization and mechanosensation initiate follicle pattern in the avian skin


Amy E. Shyer, Alan R. Rodrigues, Grant G. Schroeder, Elena Kassianidou, Sanjay Kumar, Richard M. Harland


The spacing of hair in mammals and feathers in birds is one of the most apparent morphological features of the skin. This pattern arises when uniform fields of progenitor cells diversify their molecular fate while adopting higher-order structure. Using the nascent skin of the developing chicken embryo as a model system, we find that morphological and molecular symmetries are simultaneously broken by an emergent process of cellular self-organization. The key initiators of heterogeneity are dermal progenitors, which spontaneously aggregate through contractility-driven cellular pulling. Concurrently, this dermal cell aggregation triggers the mechanosensitive activation of β-catenin in adjacent epidermal cells, initiating the follicle gene expression program. Taken together, this mechanism provides a means of integrating mechanical and molecular perspectives of organ formation.

(导读 何丽莹)利用发育鸡胚的初生皮肤作为模型系统,我们发现细胞自组织过程打破了形态学和分子对称性。真皮祖细胞通过收缩驱动的细胞牵拉而自发聚集,从而通过机械感知激活相邻表皮细胞的β-catenin引发毛囊基因表达程序。提供了一种整合器官形成的机械分子观点的方法。


12 Structure and assembly mechanism of plant C2S2M2-type PSII-LHCII supercomplex


Xiaodong Su, Jun Ma, Xuepeng Wei…Xinzheng Zhang, Mei Li






(导读:阿金)植物光合作用的捕光系统(PSII)与各种不同的捕光复合物(LHCIIs)结合成超级复合物用来适应弱光条件。本研究报道了豌豆(Pisum sativum两种C2S2M2PSII-LHCII超级复合物的冷冻电镜结构。揭示了LHCII结合外围天线复合物CP24-CP29建立色素网络高效捕光并完成能量转换的分子机制,为进一步理解植物捕光系统提供新思路。


In plants, the photosynthetic machinery photosystem II (PSII) consists of a core complex associated with variable numbers of light-harvesting complexes II (LHCIIs). The supercomplex, comprising a dimeric core and two strongly bound and two moderately bound LHCIIs (C2S2M2), is the dominant form in plants acclimated to limited light. Here we report cryo–electron microscopy structures of two forms of C2S2M2 (termed stacked and unstacked) from Pisum sativum at 2.7- and 3.2-angstrom resolution, respectively. In each C2S2M2, the moderately bound LHCII assembles specifically with a peripheral antenna complex CP24-CP29 heterodimer and the strongly bound LHCII, to establish a pigment network that facilitates light harvesting at the periphery and energy transfer into the core. The high mobility of peripheral antennae, including the moderately bound LHCII and CP24, provides insights into functional regulation of plant PSII.