真核DNA复制起始点的结构与功能研究进展

DNA复制是细胞分裂的中心环节之一，在细胞周期中受到严谨的调控。染色体DNA的复制是由许多复制起点处形成的起始复制叉开始的。复制原点的结构和功能是控制染色体复制的关键因素。在DNA复制起始与RNA转录启动这两种不同的基因表达关键过程之间存在着共有顺式作用序列和共用反式作用因子。对DNA复制的研究是分子生物学的一项基本内容，具有重要的理论意义。本文主要对涉及DNA复制起始的顺式元件的结构和功能及其与RNA转录的关系进行了评述和总结。     

棉花曲叶病毒外壳蛋白基因启动子的表达方式

通过农杆菌介导的转基因烟草研究表明,棉花曲叶病毒外壳蛋白基因启动子驱动的ＵＧＳ基因表达活性不仅存在于韧皮部,而且出现在叶肉组织和根尖分生组织中,基因抢轰击的瞬时表达研究表明,ＡＣ２激活后的ＣＰ启动子在叶肉及叶脉均有表达活性,暗示该启动子为近组成型的启动子。     

脆壁克鲁维酵母KFade5，7基因的克隆及其5′非编码区结构与功能研究

通过补偿乳酸克鲁维酵母(Kluyveromyces lactis)KlADE5，7基因突变，从脆壁克鲁维酵母(Kluyveromyces fragilis)基因组文库中克隆了KfADE5，7基因。该基因全长4975bp，编码793个氨基酸，氨基酸序列与已知的酿酒酵母(Saccharomyces cerevisiae)ScADE5，7基因编码区有68．3％的同源度。利用KfADE5,7-lacZ融合基因，对5′非编码区进行缺失分析，发现了具有完整启动子功能的区域，在启动子上游还发现了两个增强转录和两个减弱转录的区域。     

一种新型双向启动子--棉花曲叶病毒启动子的分离、序列分析与功能初探

以棉花曲叶病毒(CLCuV)侵染的烟草叶片组织总DNA为模板,通过聚合酶链反应扩增CLCuV双向启动子片段并插入克隆载体.序列分析和同源性比较表明,克隆的启动子长436bp,与目前发现的9种CLCuV株系的启动子序列均不相同,同源性最高达99.32%.将启动子片段分别以不同方向与GUS报告基因和nos终止子融合,构建了瞬时表达载体.通过基因枪法将质粒载体导入烟草和棉花叶片细胞中进行瞬时表达,结果表明,互补链基因方向启动子属强启动子,在叶肉及维管组织均有较高的活性;病毒链基因方向启动子表达活性较低.本文初步证实分离的互补链基因启动子可作为新型强启动子应用于双子叶植物尤其棉花的遗传转化.     

部分缺失的棉花曲叶病毒互补链基因启动子具有超强活性

棉花曲叶病毒（CLCuV)互补链基因启动子是一种新近鉴定的启动子,它能驱动外源基因在植物体内高效表达,为了研究其最佳启动子区域,对启动子5端进行了一系列缺失,得到5种不同长度的启动子片段与GUS基因融合的植物表达载体,继而导入根癌农杆菌,采用叶盘法转化烟草,并检测转基因植株的GUS活性,实验结果表明,自启动子5端缺失至翻译起始位点上游－287,－271时启动子活性分别是全长启动子的5倍,3倍。首次对棉花曲叶病毒互补链基因启动子的功能区进行了分析比较,发现缺失负调控元件的启动子比全长启动子具有更强的活性,平均活性是CaMV35S启动子的12倍,暗示该启动子具有应用潜力。     

应用AFM观察小白鼠心肌核DNA片段的基因体外转录

用AFM直接观察到心肌核DMA片段中各种活性基因两头的调控序列可能与某些特定蛋白质等活性因子特异结合,形成大小不同的“基因节”,“基因节”之间有“间隔”起分隔作用。用AFM意外观察到在转录中心肌核DNA片段由3－4－5个基因节及其相对应的“间隔”,它们可能按某种“排列组合”,同时形成多种大小不同的“基因系”。各种“基因系”转录时分别形成相对应3倍基因节数量的多种RNA链状复合体,每一多种RNA链状复合体与相对应的“基因系”两边的接口相连。DNA片段上同一“基因节”可能按不同的排列组合,可能参与形成不同的基因系,故形成与基因系相对应的RNA链状复合体相交叉,可能参与形成不同的基因系,故形成与不同的基因系相对应的RNA链状复合体相交叉,起始转录点与基因系个数相同,DNA分子中全部基因系从相对应的起始转录点可能同时高效转录。本工作展示了未来运用AFM来研究在转录过程DNA分子中的基因节组成基因系的多样性和基因节转录的高效性等生物学反应的前景。     

酵母菌BOD微生物传感器的研究

以性能优良的酿酒酵母菌作为敏感材料，采用聚乙烯醇包埋方法获得了响应大、测量范围广，稳定性和准确度较好的BOD微生物传感器，该传感器测定BOD，其线性响应范围为0－200mg/L，线性相关系数达到0．99以上，响应时间在15min内，测定结果与标准五天法具有良好的相关性，连续稳定工作寿命在1个月以上。     

乙肝病毒融合表面抗原SA—28基因在酵母中的表达

利用基因工程技术，先将乙肝病毒表面抗原Ｓ－ｐｒｅＳ１融合基因ＳＡ－２８置于酵母杂合启动子ＡＤＨ２－ＳＵＣ２的控制下，然后将ＳＡ－２８基因的表达单元插入高稳定质粒ｐＨＣｌ１的ＢａｍＨＩ位点，构建成表达质粒ＹＦＤ１５０和ＹＦＤ１５０－ｏ并将其转化酿酒酵母Ｙ１９。对转化子表达ＳＡ－２８基因的研究表明：表达受葡萄糖浓度调控；表达产物具有Ｓ和ｐｒｅＳ１双重抗原性，并形成密度为１．２０－１．２２ｇ／ｍｌ的颗粒     

Analysis of DNA Replication by Optical Mapping in Nanochannels

DNA replication is essential to maintain genome integrity in S phase of the cell division cycle. Accumulation of stalled replication forks is a major source of genetic instability, and likely constitutes a key driver of tumorigenesis. The mechanisms of regulation of replication fork progression have therefore been extensively investigated, in particular with DNA combing, an optical mapping technique that allows the stretching of single molecules and the mapping of active region for DNA synthesis by fluorescence microscopy. DNA linearization in nanochannels has been successfully used to probe genomic information patterns along single chromosomes, and has been proposed to be a competitive alternative to DNA combing. Yet this conjecture remains to be confirmed experimentally. Here, two complementary techniques are established to detect the genomic distribution of tracks of newly synthesized DNA in human cells by optical mapping in nanochannels. Their respective advantages and limitations are compared, and applied them to detect deregulations of the replication program induced by the antitumor drug hydroxyurea. The developments here thus broaden the field of applications accessible to nanofluidic technologies, and can be used in the future as part for molecular diagnostics in the context of high throughput cancer drug screening.     

Engineering Cell Surface Function with DNA Origami

A specific and reversible method is reported to engineer cell‐membrane function by embedding DNA‐origami nanodevices onto the cell surface. Robust membrane functionalization across epithelial, mesenchymal, and nonadherent immune cells is achieved with DNA nanoplatforms that enable functions including the construction of higher‐order DNA assemblies at the cell surface and programed cell–cell adhesion between homotypic and heterotypic cells via sequence‐specific DNA hybridization. It is anticipated that integration of DNA‐origami nanodevices can transform the cell membrane into an engineered material that can mimic, manipulate, and measure biophysical and biochemical function within the plasma membrane of living cells.     

Tetrahedral DNA Nanostructure: A Potential Promoter for Cartilage Tissue Regeneration via Regulating Chondrocyte Phenotype and Proliferation

Utilizing biomaterials to regulate the phenotype and proliferation of chondrocytes is a promising approach for effective cartilage tissue regeneration. Recently, a significant amount of effort has been invested into directing chondrocytes toward a desired location and function by utilizing biomaterials to control the dedifferentiation and phenotypic loss of chondrocytes during in vitro monolayer culture. Here, the transmission signals resulting from tetrahedral DNA nanostructures (TDNs) in the regulation of chondrocyte phenotype and proliferation are exploited. TDNs, new DNA nanomaterials, have been considered as promising materials in biomedical fields. Upon exposure to TDNs, chondrocyte phenotype is significantly enhanced, accompanied by lower gene expression related to Notch signaling pathway and higher expression of type II collagen. In addition, the cell proliferation and morphology of chondrocytes are changed after exposure to TDNs. In conclusion, this work demonstrates that TDNs are potentially useful mechanism in cartilage tissue regeneration from chondrocytes, whereby chondrocyte phenotype and proliferation can be retained.     

全息图软模压复制用光敏聚合材料

本文探讨了一种适用于全息图软模压复制的光敏聚合材料。用丙烯酸和环氧树脂合成了丙烯酸环氧酯。研究了光敏剂和交联剂对光敏聚合材料固化速度和固化膜性能的影响，筛选出光敏聚合材料的最佳配方。     

A DNA Nanodevice-Based Platform with Diverse Capabilities

Social biotic colonies often perform intricate tasks by interindividual communication and cooperation. Inspired by these biotic behaviors, a DNA nanodevice community is proposed as a universal and scalable platform. The modular nanodevice as the infrastructure of platform contains a DNA origami triangular prism framework and a hairpin-swing arm machinery core. By coding and decoding a signal domain on the shuttled output strand in different nanodevices, an orthogonal inter-nanodevice communication network is established to connect multi-nanodevices into a functional platform. The nanodevice platform enables implementation of diverse tasks, including signal cascading and feedback, molecular input recording, distributed logic computing, and modeling of simulation for virus transmission. The nanodevice platform with powerful compatibility and programmability presents an elegant example of the combination of the distributed operation of multiple devices and the complicated interdevice communication network, and may become a new generation of intelligent DNA nanosystems.     

A New Model for Repairable Systems with Nonmonotone Intensity Function

In this study, a new model based on the mixture of bounded Burr XII failure intensity and bounded intensity process is proposed to describe the failure intensity of minimally repaired systems with approximate bathtub behavior. The estimates of the model parameters are easily obtained using the maximum likelihood estimation method. The confidence intervals for the model parameters are also provided. Other existing models, such as superposed power law process, log‐linear process–power law process, and bounded bathtub intensity process are used to compare with our proposed model. Through numerical examples, the results show that our proposed model performs well regarding the Akaike information criterion value and the mean of square errors. Copyright © 2014 John Wiley & Sons, Ltd.