The molecular architecture of the nuclear pore complex

Nuclear pore complexes (NPCs) are proteinaceous assemblies of approximately 50 MDa that selectively transport cargoes across the nuclear envelope. To determine the molecular architecture of the yeast NPC, we collected a diverse set of biophysical and proteomic data, and developed a method for using these data to localize the NPC's 456 constituent proteins (see the accompanying paper). Our structure reveals that half of the NPC is made up of a core scaffold, which is structurally analogous to vesicle-coating complexes. This scaffold forms an interlaced network that coats the entire curved surface of the nuclear envelope membrane within which the NPC is embedded. The selective barrier for transport is formed by large numbers of proteins with disordered regions that line the inner face of the scaffold. The NPC consists of only a few structural modules that resemble each other in terms of the configuration of their homologous constituents, the most striking of these being a 16-fold repetition of 'columns'. These findings provide clues to the evolutionary origins of the NPC.     

Functional architecture of an intracellular membrane t-SNARE

Lipid bilayer fusion is mediated by SNAREs (soluble N-ethylmaleimide-sensitive factor attachment protein receptors) located on the vesicle membrane (v-SNAREs) and the target membrane (t-SNAREs). The assembled v-SNARE/t-SNARE complex consists of a bundle of four helices, of which one is supplied by the v-SNARE and the other three by the t-SNARE. For t-SNAREs on the plasma membrane, the protein syntaxin supplies one helix and a SNAP-25 protein contributes the other two. Although there are numerous homologues of syntaxin on intracellular membranes, there are only two SNAP-25-related proteins in yeast, Sec9 and Spo20, both of which are localized to the plasma membrane and function in secretion and sporulation, respectively. What replaces SNAP-25 in t-SNAREs of intracellular membranes? Here we show that an intracellular t-SNARE is built from a 'heavy chain' homologous to syntaxin and two separate non-syntaxin 'light chains'. SNAP-25 may thus be the exception rather than the rule, having been derived from genes that encoded separate light chains that fused during evolution to produce a single gene encoding one protein with two helices.     

一种集成的复杂物流系统仿真体系结构

针对复杂物流系统的复杂性,提出了一种分布式多代理仿真体系结构,阐述了该体系结构在复杂物流系统仿真中的应用过程,将复杂物流系统分布式多代理仿真体系结构和集中式仿真体系结构相结合,提出了集成的复杂物流系统仿真体系结构．     

Fine-scale phylogenetic architecture of a complex bacterial community

Although molecular data have revealed the vast scope of microbial diversity, two fundamental questions remain unanswered even for well-defined natural microbial communities: how many bacterial types co-exist, and are such types naturally organized into phylogenetically discrete units of potential ecological significance? It has been argued that without such information, the environmental function, population biology and biogeography of microorganisms cannot be rigorously explored. Here we address these questions by comprehensive sampling of two large 16S ribosomal RNA clone libraries from a coastal bacterioplankton community. We show that compensation for artefacts generated by common library construction techniques reveals fine-scale patterns of community composition. At least 516 ribotypes (unique rRNA sequences) were detected in the sample and, by statistical extrapolation, at least 1,633 co-existing ribotypes in the sampled population. More than 50% of the ribotypes fall into discrete clusters containing less than 1% sequence divergence. This pattern cannot be accounted for by interoperon variation, indicating a large predominance of closely related taxa in this community. We propose that such microdiverse clusters arise by selective sweeps and persist because competitive mechanisms are too weak to purge diversity from within them.     

Functional cartography of complex metabolic networks

High-throughput techniques are leading to an explosive growth in the size of biological databases and creating the opportunity to revolutionize our understanding of life and disease. Interpretation of these data remains, however, a major scientific challenge. Here, we propose a methodology that enables us to extract and display information contained in complex networks. Specifically, we demonstrate that we can find functional modules in complex networks, and classify nodes into universal roles according to their pattern of intra- and inter-module connections. The method thus yields a 'cartographic representation' of complex networks. Metabolic networks are among the most challenging biological networks and, arguably, the ones with most potential for immediate applicability. We use our method to analyse the metabolic networks of twelve organisms from three different superkingdoms. We find that, typically, 80% of the nodes are only connected to other nodes within their respective modules, and that nodes with different roles are affected by different evolutionary constraints and pressures. Remarkably, we find that metabolites that participate in only a few reactions but that connect different modules are more conserved than hubs whose links are mostly within a single module.     

复杂动力管路系统多Agent自治控制结构研究

针对下一代舰船动力平台对自治能力的要求,提出了适用于复杂动力管路系统自治控制的多Agent智能控制结构,将系统的控制智能分布于单个Agent的结构和多Agent系统的拓扑结构与协作决策机制之中,并依此设计了控制系统.以舰船冷却水系统为实证研究对象,搭建了以控制器硬件在环仿真为核心的多Agent控制系统试验研究平台,分析了任务切换和故障恢复中冷却水系统的状态重构过程.试验表明:所设计的智能控制系统能够减少对操作者的依赖,有效地提高复杂动力管路系统的任务效率和自治控制能力.     

城市建筑复合绿化方法研究

探讨了当代城市中绿化建设的理想化模式,对城市复合绿化模式进行了比较、分析,并结合建筑师爱米利奥的覆盖理论,提出了与建筑空间紧密结合的,多层次、多维度的复合绿化模式.针对当前城市绿化中仅注重局部利益,忽视整体效益的弊病,提倡将城市绿化及建筑两大系统加以整合,突出其综合效益的最大化.     

Functional architecture of cortex revealed by optical imaging of intrinsic signals

Optical imaging of cortical activity offers several advantages over conventional electrophysiological and anatomical techniques. One can map a relatively large region, obtain successive maps to different stimuli in the same cortical area and follow variations in response over time. In the intact mammalian brain this imaging has been accomplished with the aid of voltage sensitive dyes. However, it has been known for many years that some intrinsic changes in the optical properties of the tissue are dependent on electrical or metabolic activity. Here we show that these changes can be used to study the functional architecture of cortex. Optical maps of whisker barrels in the rat and the orientation columns in the cat visual cortex, obtained by reflection measurements of the intrinsic signal, were confirmed with voltage sensitive dyes or by electrophysiological recordings. In addition, we describe an intrinsic signal originating from small arteries which can be used to investigate the communication between local neuronal activity and the microvasculature. One advantage of the method is that it is non-invasive and does not require dyes, a clear benefit for clinical applications.     

一种复杂适应系统仿真的Agent混合结构模型

分析了复杂适应系统的Agent建模方法以及系统仿真框架，提出了一种复杂适应系统仿真的Agent混合结构模型，在该模型中构造了基于知识的协调控制器，通过它来协调慎思式过程和反应式过程．最后，结合跨流域调水管理这一复杂过程，对跨流域调水管理复杂适应系统仿真的Agent结构模型的应用进行了实例分析．     

一种复杂曲流带储层三维构型建模新方法

基于河道迁移演化模拟、侧积层定量三维分布模式及沉积过程模拟提出一种复杂曲流带储层三维构型建模新方法,并根据井数据构建渤海湾盆地A油田明化镇组下段曲流河相储层三维构型机制模型。结果表明:该方法能够在三维空间模拟复杂曲流带储层内部构型元素的大小、三维形态及其空间结构关系,实现对储层连通性、连续性及非均质性的定量表征,是一种快速有效的复杂曲流带储层构型建模新方法。     

校园老建筑的新生命--关于旧建筑改造

对待校园建筑应该采用-种积极的思维--再生的建筑.通过适当改造,适当取舍,使校园建筑具有新的内涵.以适应现代生活的需要,从而使其获得新的"生命”.     

建筑中的动

文章以建筑中的"动"为切人点,从建筑形态、空间、环境、文脉、真正的动的建筑等方面,探析建筑中的动态元素.从人的需求和外部环境的角度,结合相应的实际案例对这一新型建筑设计方向进行研究和思考.解析了动态建筑的基本精神一动态与自然;动态建筑的基本特征--多文化、多维度、复杂动态的功能空间、回归自然的梦想;剖析了动态建筑思想的...     

Functional interaction between human T-cell protein CD4 and the major histocompatibility complex HLA-DR antigen

Mature T cells segregate phenotypically into one of two classes: those that express the surface glycoprotein CD4, and those that express the glycoprotein CD8. The CD4 molecule is expressed primarily on helper T cells whereas CD8 is found on cytotoxic and suppressor cells. A more stringent association exists, however, between these T-cell subsets and the major histocompatibility complex (MHC) gene products recognized by their T-cell receptors (TCRs). CD8+ lymphocytes interact with targets expressing class I MHC gene products, whereas CD4+ cells interact with class II MHC-bearing targets. To explain this association, it has been proposed that these 'accessory' molecules bind to monomorphic regions of the MHC proteins on the target cell, CD4 to class II and CD8 to class I products. This binding could hold the T cell and its target together, thus improving the probability of the formation of the trimolecular antigen: MHC: TCR complex. Because the TCR on CD4+ cells binds antigen in association with class II MHC, it has been difficult to design experiments to detect the association of CD4 with a class II molecule. To address this issue, we devised a xenogeneic system in which human CD4 complementary DNA was transfected into the murine CD4-, CD8- T-cell hybridoma 3DT-52.5.8, the TCR of which recognizes the murine class I molecule H-2Dd. The murine H-2Dd-bearing target cell line, P815, was cotransfected with human class II HLA-DR alpha, beta and invariant chain cDNAs. Co-culture of the parental T-cell and P815 lines, or of one parental and one transfected line resulted in a low baseline response. In contrast, a substantial increase in response was observed when CD4+ 3DT-52.5.8 cells were co-cultured with HLA-DR+ P815 cells. This result strongly indicates that CD4:HLA-DR binding occurs in this system and that this interaction augments T-cell activation.     

解构主义建筑浅谈

自二十世纪九十年代以来,世界各地出现了一些引人注目的解构主义建筑作品。它们的数量不多,影响力却不小,直接原因就是这些作品以完全违反常规的方式和手段来处理建筑形式问题,人们的传统价值观和审美标准等产生了一定冲击。从解构主义建筑产生的思想来源来阐述解构主义建筑的建筑意象和审美价值,为大家理解解构主义建筑提供一点参考。     

建筑学专业“建筑材料”课程教学改革研究

城市建设的高速发展需要高素质的建筑设计人员,但传统建筑学专业的教学模式无法满足新世纪人才培养的要求。针对建筑学专业的特点和原有建筑材料课程教学模式存在的主要问题,讨论了课程的重新定位及在教学目标、内容、方法等方面的改革尝试,最后评析了改革后该课程教学的应用实效。     

Transforming the architecture of compound eyes

Eyes differ markedly in the animal kingdom, and are an extreme example of the evolution of multiple anatomical solutions to light detection and image formation. A salient feature of all photoreceptor cells is the presence of a specialized compartment (disc outer segments in vertebrates, and microvillar rhabdomeres in insects), whose primary role is to accommodate the millions of light receptor molecules required for efficient photon collection. In insects, compound eyes can have very different inner architectures. Fruitflies and houseflies have an open rhabdom system, in which the seven rhabdomeres of each ommatidium are separated from each other and function as independent light guides. In contrast, bees and various mosquitoes and beetle species have a closed system, in which rhabdomeres within each ommatidium are fused to each other, thus sharing the same visual axis. To understand the transition between open and closed rhabdom systems, we isolated and characterized the role of Drosophila genes involved in rhabdomere assembly. Here we show that Spacemaker, a secreted protein expressed only in the eyes of insects with open rhabdom systems, acts together with Prominin and the cell adhesion molecule Chaoptin to choreograph the partitioning of rhabdomeres into an open system. Furthermore, the complete loss of spacemaker (spam) converts an open rhabdom system to a closed one, whereas its targeted expression to photoreceptors of a closed system markedly reorganizes the architecture of the compound eyes to resemble an open system. Our results provide a molecular atlas for the construction of microvillar assemblies and illustrate the critical effect of differences in a single structural protein in morphogenesis.     

建筑之美

建筑在满足功能合理、技术先进、结构经济的条件下,还要满足美观的要求。不仅要赋予它实用的属性,还要赋予它美观的属性。建筑的审美,通常包括外观形态美和建筑环境美。     

夏克尔建筑与西藏建筑的比较研究

建筑形式的生成原本不是以成就某种风格为目的,它受制于各种影响因素,这其中不仅仅是自然环境及气候因素,还包括生活方式及观念上的影响.本文将通过夏克尔建筑与西藏建筑的比较研究,特别是探讨它们艺术风格的宗教背景、风格特征以及它们在建筑与家具设计方面的影响,力图通过对两者比较分析,寻找到建筑形式生成的实质.     

近代中国西方古典建筑的细部分析

近代中国西方古典形式的建筑异常丰富，多变的细部表现是一个重要因素。这些形式中包含了它特有的细部特征，它既有自己一定的细部法则，也反映了中西融合与变异的历史背景，同时还带有装饰与象征的效果，在细部做法中，折中形式较之正统古典手法有着更多的应用，其中，巴洛克和洛可可成为中国工匠折中处理的主要素材。这应归因于这两种形式与中国传统文化的相通以及当时的社会风尚，折中建筑出现的意义还在于它取代了传统官式建筑而成为新兴官僚身份的象征，同时也反映出民众从伊洋到崇洋的社会心理变化过程。     

浅谈建筑美多元和谐

文章对建筑美的主要结构和理论价值进行了探索.从建筑美的产生机制,建筑的美观形态及建筑美的进展来看,建筑是自然环境、美学、建筑技术、空间、城市景观的复杂的艺术多元体,其和谐是建筑美的基础.