韩城党家村地域性特征解析

运用多学科交叉研究方法,从空间要素、空间组织、装饰意匠以及地域性营造技术4个方面对韩城党家村民居进行了深入的调研分析。研究在空间要素方面立足于宅院、厅房、厢房等建筑构造部分;在空间组织方面侧重于巷道空间、宅院的组合;在装饰意匠上突出了石雕装饰、砖雕装饰、木雕装饰;在营造技术上则从结构、材料、构造细部方面进行分析,以此来解析该地区传统民居的地域性特征。分析过程中强调了党家村传统民居建筑形式有其特定的历史条件,但随着社会、经济、文化的变迁,新农村住宅建设应充分尊重和继承传统建筑形式,运用新材料、新技术、新结构以及新的创作方法,以建设一种传承和体现地域性特色的时代建筑。     

Freezing as a path to build complex composites

Materials that are strong, ultralightweight, and tough are in demand for a range of applications, requiring architectures and components carefully designed from the micrometer down to the nanometer scale. Nacre, a structure found in many molluscan shells, and bone are frequently used as examples for how nature achieves this through hybrid organic-inorganic composites. Unfortunately, it has proven extremely difficult to transcribe nacre-like clever designs into synthetic materials, partly because their intricate structures need to be replicated at several length scales. We demonstrate how the physics of ice formation can be used to develop sophisticated porous and layered-hybrid materials, including artificial bone, ceramic-metal composites, and porous scaffolds for osseous tissue regeneration with strengths up to four times higher than those of materials currently used for implantation.     

Helix-rod host-guest complexes with shuttling rates much faster than disassembly

Dynamic assembly is a powerful fabrication method of complex, functionally diverse molecular architectures, but its use in synthetic nanomachines has been hampered by the difficulty of avoiding reversible attachments that result in the premature breaking apart of loosely held moving parts. We show that molecular motion can be controlled in dynamically assembled systems through segregation of the disassembly process and internal translation to time scales that differ by four orders of magnitude. Helical molecular tapes were designed to slowly wind around rod-like guests and then to rapidly slide along them. The winding process requires helix unfolding and refolding, as well as a strict match between helix length and anchor points on the rods. This modular design and dynamic assembly open up promising capabilities in molecular machinery.     

Structural insights into the assembly of the type III secretion needle complex

Type III secretion systems (TTSSs) mediate translocation of virulence factors into host cells. We report the 17-angstrom resolution structures of a central component of Salmonella typhimurium TTSS, the needle complex, and its assembly precursor, the bacterial envelope-anchored base. Both the base and the fully assembled needle complex adopted multiple oligomeric states in vivo, and needle assembly was accompanied by recruitment of the protein PrgJ as a structural component of the base. Moreover, conformational changes during needle assembly created scaffolds for anchoring both PrgJ and the needle substructure and may provide the basis for substrate-specificity switching during type III secretion.     

Tuned responses of astrocytes and their influence on hemodynamic signals in the visual cortex

Astrocytes have long been thought to act as a support network for neurons, with little role in information representation or processing. We used two-photon imaging of calcium signals in the ferret visual cortex in vivo to discover that astrocytes, like neurons, respond to visual stimuli, with distinct spatial receptive fields and sharp tuning to visual stimulus features including orientation and spatial frequency. The stimulus-feature preferences of astrocytes were exquisitely mapped across the cortical surface, in close register with neuronal maps. The spatially restricted stimulus-specific component of the intrinsic hemodynamic mapping signal was highly sensitive to astrocyte activation, indicating that astrocytes have a key role in coupling neuronal organization to mapping signals critical for noninvasive brain imaging. Furthermore, blocking astrocyte glutamate transporters influenced the magnitude and duration of adjacent visually driven neuronal responses.     

Model-driven engineering of RNA devices to quantitatively program gene expression

The models and simulation tools available to design functionally complex synthetic biological devices are very limited. We formulated a design-driven approach that used mechanistic modeling and kinetic RNA folding simulations to engineer RNA-regulated genetic devices that control gene expression. Ribozyme and metabolite-controlled, aptazyme-regulated expression devices with quantitatively predictable functions were assembled from components characterized in vitro, in vivo, and in silico. The models and design strategy were verified by constructing 28 Escherichia coli expression devices that gave excellent quantitative agreement between the predicted and measured gene expression levels (r = 0.94). These technologies were applied to engineer RNA-regulated controls in metabolic pathways. More broadly, we provide a framework for studying RNA functions and illustrate the potential for the use of biochemical and biophysical modeling to develop biological design methods.     

Catalytic nanoarchitectures--the importance of nothing and the unimportance of periodicity

Heterogeneous catalysis has always been an inherently nanoscopic phenomenon with important technological and societal consequences for energy conversion and the production of chemicals. New opportunities for improved performance arise when the multifunctionality inherent in catalytic processes, including molecular transport of reactants and products, is rethought in light of architectures designed and fabricated from the appropriate nanoscale building blocks, including the use of "nothing" (void space) and deliberate disorder as design components. Architectures with all of the appropriate electrochemical and catalytic requirements, including large surface areas readily accessible to molecules, may now be assembled on the benchtop. Designing catalytic nanoarchitectures that depart from the hegemony of periodicity and order offers the promise of even higher activity.     

DNA origami with complex curvatures in three-dimensional space

We present a strategy to design and construct self-assembling DNA nanostructures that define intricate curved surfaces in three-dimensional (3D) space using the DNA origami folding technique. Double-helical DNA is bent to follow the rounded contours of the target object, and potential strand crossovers are subsequently identified. Concentric rings of DNA are used to generate in-plane curvature, constrained to 2D by rationally designed geometries and crossover networks. Out-of-plane curvature is introduced by adjusting the particular position and pattern of crossovers between adjacent DNA double helices, whose conformation often deviates from the natural, B-form twist density. A series of DNA nanostructures with high curvature--such as 2D arrangements of concentric rings and 3D spherical shells, ellipsoidal shells, and a nanoflask--were assembled.     

Structures of SAS-6 suggest its organization in centrioles

Centrioles are cylindrical, ninefold symmetrical structures with peripheral triplet microtubules strictly required to template cilia and flagella. The highly conserved protein SAS-6 constitutes the center of the cartwheel assembly that scaffolds centrioles early in their biogenesis. We determined the x-ray structure of the amino-terminal domain of SAS-6 from zebrafish, and we show that recombinant SAS-6 self-associates in vitro into assemblies that resemble cartwheel centers. Point mutations are consistent with the notion that centriole formation in vivo depends on the interactions that define the self-assemblies observed here. Thus, these interactions are probably essential to the structural organization of cartwheel centers.     

Ribosomes: effect of interferon on their interaction with rapidly labeled cellular and viral RNA's

Rapidly labeled RNA of mouse L cells and labeled RNA of Mengo virus, unlike cellular RNA labeled under steady-state conditions, form detectable complexes with L-cell ribosomes. These ribosome-RNA complexes formed in vitro appear analogous to those assembled during polysome formation in vivo. When ribosomes are prepared from L cells exposed to homologous interferon, their capacity to associate with cell messenger is preserved, while their ability to interact with viral RNA is markedly reduced. The ribosomes from cells exposed to interferon are thus altered selectively to permit only certain messages to be bound and translated.     

Scaffold proteins: hubs for controlling the flow of cellular information

The spatial and temporal organization of molecules within a cell is critical for coordinating the many distinct activities carried out by the cell. In an increasing number of biological signaling processes, scaffold proteins have been found to play a central role in physically assembling the relevant molecular components. Although most scaffolds use a simple tethering mechanism to increase the efficiency of interaction between individual partner molecules, these proteins can also exert complex allosteric control over their partners and are themselves the target of regulation. Scaffold proteins offer a simple, flexible strategy for regulating selectivity in pathways, shaping output behaviors, and achieving new responses from preexisting signaling components. As a result, scaffold proteins have been exploited by evolution, pathogens, and cellular engineers to reshape cellular behavior.     

Nanoparticle superlattice engineering with DNA

A current limitation in nanoparticle superlattice engineering is that the identities of the particles being assembled often determine the structures that can be synthesized. Therefore, specific crystallographic symmetries or lattice parameters can only be achieved using specific nanoparticles as building blocks (and vice versa). We present six design rules that can be used to deliberately prepare nine distinct colloidal crystal structures, with control over lattice parameters on the 25- to 150-nanometer length scale. These design rules outline a strategy to independently adjust each of the relevant crystallographic parameters, including particle size (5 to 60 nanometers), periodicity, and interparticle distance. As such, this work represents an advance in synthesizing tailorable macroscale architectures comprising nanoscale materials in a predictable fashion.     

端粒酶RNA亚基的shRNA对细胞端粒酶活性影响的研究

[目的]探讨端粒酶RNA亚基（chTR）的短发RNA（shRNA）shRNA对MDCC-MSB1细胞端粒酶活性的影响。[方法]设计合成chTRshRNA并构建表达载体,转染MDCC-MSB1细胞,应用改良TRAP法检测端粒酶活性。[结果]与对照组相比,转染24 h后,各组端粒酶活性变化不明显;转染48 h后,端粒酶活性均显著地下降,且针对模板区设计的干扰载体pSi-chTR-sh1转染后抑制效果最明显。[结论]chTRshRNA表达载体能够有效地抑制MDCC-MSB1细胞的端粒酶活性。     

蔬菜作物的RNA原位杂交技术

RNA原位杂交技术是在细胞水平上研究基因时空表达的最直接、有效的方法之一,在拟南芥和玉米上应用广泛,但在蔬菜作物上应用很少,尚未形成成熟的技术体系。结合拟南芥、玉米上的RNA原位杂交技术和自己的试验经验,以黄瓜为例,对蔬菜作物RNA原位杂交技术方法进行优化,并对其具体流程和注意事项进行阐述。     

油菜GDSL脂肪酶基因BnLIP1的克隆及其原核表达

克隆油菜GDSL脂肪酶基因BnLIP1,实现该基因在原核系统中重组表达,为研究其功能奠定基础。采用TRIzol法提取总RNA,通过RT-PCR法扩增BnLIP1编码序列,构建原核表达载体pEL1并转化大肠杆菌,IPTG诱导表达后通过SDS-PAGE检测目的蛋白。根据GenBank报道的序列设计引物,从萌发的油菜种子黄化幼苗中成功克隆到BnLIP1的编码序列,长度为1170bp。将该编码序列构建到原核表达载体pET32a( )并与标签序列融合,在E.coliBL21菌株中成功表达了与标签蛋白融合的BnLIP1蛋白,大小约为61kDa。首次实现了油菜GDSL脂肪酶基因在原核系统中的表达,为GDSL脂肪酶Bn-LIP1蛋白的分离纯化及活性研究奠定了基础。     

中国瘰螈皮肤转录组测序及活性多肽分析

首次对中国瘰螈皮肤组织进行了转录组测序并分析其活性多肽。提取中国瘰螈皮肤组织总RNA用于构建cDNA文库，采用Illumina HiSeq 4000进行测序。测序数据处理后获得unigene，并对其进行基因注释和生物信息学分析。共组装获得了74 371 个非冗余unigene（平均长度为762 bp），其中33 627个unigene在七大功能数据库中得到功能注释，5 137个unigene的注释结果来自两栖类物种，约占注释总数的15%。另外，从转录组数据中识别了一些皮肤活性多肽如胆囊收缩素、防御素、伤口愈合肽、蛋白激酶抑制剂、胸腺素，它们大多数具有皮肤免疫或防御功能，且在其他两栖动物种类中均发现有较高序列相似性的同源多肽。结果为阐明蝾螈皮肤免疫或防御机制提供了前期基础资料。     

Computational design of self-assembling protein nanomaterials with atomic level accuracy

We describe a general computational method for designing proteins that self-assemble to a desired symmetric architecture. Protein building blocks are docked together symmetrically to identify complementary packing arrangements, and low-energy protein-protein interfaces are then designed between the building blocks in order to drive self-assembly. We used trimeric protein building blocks to design a 24-subunit, 13-nm diameter complex with octahedral symmetry and a 12-subunit, 11-nm diameter complex with tetrahedral symmetry. The designed proteins assembled to the desired oligomeric states in solution, and the crystal structures of the complexes revealed that the resulting materials closely match the design models. The method can be used to design a wide variety of self-assembling protein nanomaterials.     

De novo computational design of retro-aldol enzymes

The creation of enzymes capable of catalyzing any desired chemical reaction is a grand challenge for computational protein design. Using new algorithms that rely on hashing techniques to construct active sites for multistep reactions, we designed retro-aldolases that use four different catalytic motifs to catalyze the breaking of a carbon-carbon bond in a nonnatural substrate. Of the 72 designs that were experimentally characterized, 32, spanning a range of protein folds, had detectable retro-aldolase activity. Designs that used an explicit water molecule to mediate proton shuffling were significantly more successful, with rate accelerations of up to four orders of magnitude and multiple turnovers, than those involving charged side-chain networks. The atomic accuracy of the design process was confirmed by the x-ray crystal structure of active designs embedded in two protein scaffolds, both of which were nearly superimposable on the design model.