AAV-ITR单链DNA微载体在小鼠骨骼肌中的表达

AAV-ITR单链DNA微载体是一种基于腺相关病毒(AAV)倒置末端重复序列(ITR)的基因表达载体(AAV-ITR ss DNA mini vector)。前期研究已证明AAV-ITR单链DNA微载体在HEK 293T细胞中具有较高的转染、表达效率。本文中将相同拷贝数的AAV-ITR单链DNA微载体、3?-ITR末端错配的AAV-ITR单链DNA微载体(AAV-ITRmm ss DNA mutant vector)、AAV-ITR双链DNA和质粒分别用Turbo Fect转入小鼠骨骼肌中,比较检测AAV-ITR单链DNA微载体与其他基因表达载体在小鼠体内1周、1个月及3个月的表达效率。组织切片经荧光显微镜观察及荧光灰度值分析表明,相同分子摩尔数的AAV-ITR单链DNA微载体比AAV-ITR双链DNA和质粒在不同时期表达效率都要高且更稳定。提取注射3个月后的肌肉组织的DNA,用荧光定量PCR分析比较各载体的存留分子数。RT-PCR的结果显示AAV-ITR单链DNA微载体在注射3个月后的存留分子数较其他载体高。综合结果显示AAV-ITR单链DNA微载体在动物体内具有表达效率高和长久稳定的优势,有可能开发为基因治疗的一种高效、稳定的新型载体。     

Changes in the T-wave vector loop of the three-dimensional vectorcardiogram during exposure to cold pressor stress

Three-dimensional vectorcardiography was used to characterize changes in the T-wave vector loop during exposure to cold pressor stress. Data were collected from 8 subjects during baseline, cold pressor, and recovery periods. Maximum vector length, polar angle of the longest vector, azimuth angle of the longest vector, sum of all vectors, polar angle of the vector sum, azimuth angle of the vector sum, surface area of the loop, and maximum distance between adjacent vectors were computed from the T-wave vector loop. The amplitude of the one-dimensional T-wave (TWA) was also computed. Interbeat interval and TWA decreased during hand immersion and increased during recovery. Of the vectorcardiographic measures, only maximum vector length and vector sum showed statistically significant change; both decreased during the task and returned to baseline during recovery. TWA accounted for 46% of the task related variance compared to 53% and 47% respectively, for vector sum and maximum vector length. Changes in TWA probably reflect a true change in cardiac electrical potential rather than a change in T-wave vector loop shape or orientation.     

The significance of controlled conditions in lentiviral vector titration and in the use of multiplicity of infection (MOI) for predicting gene transfer events

BACKGROUND: Although lentiviral vectors have been widely used for in vitro and in vivo gene therapy researches, there have been few studies systematically examining various conditions that may affect the determination of the number of viable vector particles in a vector preparation and the use of Multiplicity of Infection (MOI) as a parameter for the prediction of gene transfer events. METHODS: Lentiviral vectors encoding a marker gene were packaged and supernatants concentrated. The number of viable vector particles was determined by in vitro transduction and fluorescent microscopy and FACs analyses. Various factors that may affect the transduction process, such as vector inoculum volume, target cell number and type, vector decay, variable vector - target cell contact and adsorption periods were studied. MOI between 0-32 was assessed on commonly used cell lines as well as a new cell line. RESULTS: We demonstrated that the resulting values of lentiviral vector titre varied with changes of conditions in the transduction process, including inoculum volume of the vector, the type and number of target cells, vector stability and the length of period of the vector adsorption to target cells. Vector inoculum and the number of target cells determine the frequencies of gene transfer event, although not proportionally. Vector exposure time to target cells also influenced transduction results. Varying these parameters resulted in a greater than 50-fold differences in the vector titre from the same vector stock. Commonly used cell lines in vector titration were less sensitive to lentiviral vector-mediated gene transfer than a new cell line, FRL 19. Within 0-32 of MOI used transducing four different cell lines, the higher the MOI applied, the higher the efficiency of gene transfer obtained. CONCLUSION: Several variables in the transduction process affected in in vitro vector titration and resulted in vastly different values from the same vector stock, thus complicating the use of MOI for predicting gene transfer events. Commonly used target cell lines underestimated vector titre. However, within a certain range of MOI, it is possible that, if strictly controlled conditions are observed in the vector titration process, including the use of a sensitive cell line, such as FRL 19 for vector titration, lentivector-mediated gene transfer events could be predicted.     

YFP-CD18融合蛋白在U937细胞株中的表达与鉴定

目的：构建并表达Mac-1的β链CD18与黄色荧光蛋白（YFP）的融合蛋白YFP-CD18,为进一步直视研究Mac-1在白细胞内的分布、走向及归宿提供物质条件。方法：首先将CD18的全长cDNA与pEYFP-C1进行酶切,构建YFP与CD18的N末端连接的表达载体,并将其转染至U937细胞株中进行表达。通过荧光显微镜观察转染成功后的U937细胞黄色荧光是否存在,以及流式细胞术检测确定PMA刺激后YFP-CD18活化后可否由胞浆内转位至膜上和测定PMA活化前后转染的U937细胞与其配基ICAM-1粘附活性的变化等方面进行鉴定。结果：经酶切鉴定,pYFP-CD18构建正确,转染U937细胞株后,可见YFP-CD18融合蛋白发出的黄色荧光。结论：构建完成YFP-CD18融合基因并可以在U937细胞株中进行表达。     

端粒酶shRNA慢病毒载体的构建及转染人类胚胎干细胞

目的：构建端粒酶shRNA慢病毒载体及建立端粒酶稳定干扰的人类胚胎干细胞系。方法：将端粒酶基因特异性shRNA靶序列与慢病毒载体PLKO.1-puro连接、转化、挑取阳性克隆进行PCR及测序鉴定;利用包装细胞293T获得重组的慢病毒,感染人类胚胎干细胞,分为干扰组ShTert、载体组vector和野生型组wt;Realtime-PCR检测端粒酶mRNA的表达。结果：经PCR和DNA测序鉴定,成功构建端粒酶特异性shRNA慢病毒载体,并感染人类胚胎干细胞;经检测shTert组端粒酶mRNA表达较vector和wt组明显降低,vector组和wt组之间无明显差异。结论：通过成功构建的端粒酶特异性shRNA慢病毒载体对人类胚胎干细胞的转染实现了对其端粒酶mRNA的调控。     

Use of a Mixture Statistical Model in Studying Malaria Vectors Density

Vector control is a major step in the process of malaria control and elimination. This requires vector counts and appropriate statistical analyses of these counts. However, vector counts are often overdispersed. A non-parametric mixture of Poisson model (NPMP) is proposed to allow for overdispersion and better describe vector distribution. Mosquito collections using the Human Landing Catches as well as collection of environmental and climatic data were carried out from January to December 2009 in 28 villages in Southern Benin. A NPMP regression model with “village” as random effect is used to test statistical correlations between malaria vectors density and environmental and climatic factors. Furthermore, the villages were ranked using the latent classes derived from the NPMP model. Based on this classification of the villages, the impacts of four vector control strategies implemented in the villages were compared. Vector counts were highly variable and overdispersed with important proportion of zeros (75%). The NPMP model had a good aptitude to predict the observed values and showed that: i) proximity to freshwater body, market gardening, and high levels of rain were associated with high vector density; ii) water conveyance, cattle breeding, vegetation index were associated with low vector density. The 28 villages could then be ranked according to the mean vector number as estimated by the random part of the model after adjustment on all covariates. The NPMP model made it possible to describe the distribution of the vector across the study area. The villages were ranked according to the mean vector density after taking into account the most important covariates. This study demonstrates the necessity and possibility of adapting methods of vector counting and sampling to each setting.     

Development of Novel Types of Plastid Transformation Vectors and Evaluation of Factors Controlling Expression

Two new vector types for plastid transformation were developed and uidA reporter gene expression was compared to standard transformation vectors. The first vector type does not contain any plastid promoter, instead it relies on extension of existing plastid operons and was therefore named “operon-extension” vector. When a strongly expressed plastid operon like psbA was extended by the reporter gene with this vector type, the expression level was superior to that of a standard vector under control of the 16S rRNA promoter. Different insertion sites, promoters and 5′-UTRs were analysed for their effect on reporter gene expression with standard and operon-extension vectors. The 5′-UTR of phage 7 gene 10 in combination with a modified N-terminus was found to yield the highest expression levels. Expression levels were also strongly dependent on external factors like plant or leaf age or light intensity. In the second vector type, named “split” plastid transformation vector, modules of the expression cassette were distributed on two separate vectors. Upon co-transformation of plastids with these vectors, the complete expression cassette became inserted into the plastome. This result can be explained by successive co-integration of the split vectors and final loop-out recombination of the duplicated sequences. The split vector concept was validated with different vector pairs.     

2A肽介导猪PID1与CuZnSOD双基因真核共表达载体的构建与细胞表达

构建PID1基因与CuZnSOD基因的真核共表达载体,在PK15细胞中鉴定基因的表达。PCR扩增的PID1与CuZnSOD两基因分别经双酶切后定向插入pIRES2-AcGFP1空载体,构建pIRES2-CuZnSOD-PID1真核双表达载体并进行测序与酶切鉴定。采用脂质体转染法将重组质粒转染至PK15细胞,细胞内荧光显微镜下观察其荧光的表达,RT-PCR、Westernblot技术分别检测PID1基因与CuZnSOD基因mRNA和蛋白表达情况。重组克隆载体插入目的片段序列与PID1基因与CuZnSOD基因序列完全一致。PIRES2-CuZnSOD-PID1真核双表达载体测序、酶切鉴定结果与预期结果一致。荧光显微镜下观察转染后的PK15细胞出现绿色荧光。RT-PCR检测结果显示,转染细胞中PID1基因与CuZnSOD基因表达量明显高于对照组（P〈0.05）。Westernblot检测结果表明pIRES2-CuZnSODPID1真核双表达载体稳定有效表达。成功构建pIRES2-CuZnSOD-PID1真核共表达载体,且双基因在真核细胞独立稳定表达,为转基因猪等育种新材料的制备奠定基础。     

Kinetic analysis for optimization of DNA ligation reactions.

Kinetic equations describing ligation of DNA to circular recombinant forms were developed and solved for four types of reactions: (a) a homogeneous population of singly restricted DNA fragments, (b) insertion of singly restricted insert into vector, (c) forced directional insertion of doubly restricted insert into vector, and (d) insertion of singly restricted insert into phosphatased vector. The effects of varying vector and insert sizes, starting concentrations, and phosphatase treatment on the yield of circular 1:1 recombinants were analyzed. Selected theoretical predictions were experimentally tested and verified. Our suggestions on optimizing ligation reactions in several cases are at variance with common practice. For example, optimum conditions in case (b) and (d) ligations are best specified as individual insert and vector concentrations rather than as insert/vector molar ratios, except in case (d) ligations involving very small insert size. In case (c) ligations, highest efficiencies are obtained when both vector and insert are at relatively low concentration.     

Changes in theT-wave vector loop of the three-dimensional vectorcardiogram during exposure to cold pressor stress

Three-dimensional vectorcardiography was used to characterize changes in the T-wave vector loop during exposure to cold pressor stress. Data were collected from 8 subjects during baseline, cold pressor, and recovery periods. Maximum vector length, polar angle of the longest vector, azimuth angle of the longest vector, sum of all vectors, polar angle of the vector sum, azimuth angle of the vector sum, surface area of the loop, and maximum distance between adjacent vectors were computed from the T-wave vector loop. The amplitude of the one-dimensional T-wave (TWA) was also computed. Interbeat interval and TWA decreased during hand immersion and increased during recovery. Of the vectorcardiographic measures, only maximum vector length and vector sum showed statistically significant change; both decreased during the task and returned to baseline during recovery. TWA accounted for 46% of the task related variance compared to 53% and 47% respectively, for vector sum and maximum vector length. Changes in TWA probably reflect a true change in cardiac electrical potential rather than a change in T-wave vector loop shape or orientation.This material was presented in part at the annual meeting of the Association for Applied Psychophysiology and Biofeedback, Washington, D.C., March 1990.We are indebted to Lawrence E. Widman, M.D., Ph.D. for his invaluable advice throughout this study.     

用于植物基因研究的mCherry表达载体构建及定位表达

荧光蛋白在生物学研究中具有广泛的应用和重要的作用,其中红色荧光蛋白mCherry因其颜色和良好的特性,对于植物基因研究具有重要的使用价值,本研究将mCherry基因构建到pBI121植物表达载体系统中,构建了pBI121MCS-mCherry载体。利用基因枪转化法转入洋葱表皮进行表达验证,显微镜观察结果显示整个洋葱细胞具有红色荧光,证明该载体能够在植物细胞中表达红色荧光蛋白。利用双酶切连接法将转录因子BpMYB4基因构建到该载体上,得到融合表达载体pBI121MCS-mCherry-BpMYB4,在洋葱表皮中表达,结果显示细胞核具有红色荧光,证明该载体能够准确表达融合蛋白,进行亚细胞定位。同时融合基因时不再需要中间载体,构建简便,引入的KpnⅠ酶切位点,增加了可选择性。因此该载体可用于植物基因表达定位及转基因植株筛选研究中,为今后的白桦基因组学研究提供了材料。     

Efficiency of insertion versus replacement vector targeting varies at different chromosomal loci.

We have analyzed the targeting frequencies and recombination products generated with isogenic vectors at the fah and fgr loci in embryonic stem cells. A single vector which could be linearized at different sites to generate either a replacement or an insertion vector was constructed for each locus. A replacement event predominated when the vectors were linearized at the edge of the homologous sequences, while an insertion event predominated when the vectors were linearized within the homologous sequences. However, the ratio of the targeting frequencies exhibited by the different vector configurations differed for the two loci. When the fgr vector was linearized as an insertion vector, the ratio of targeted to random integrations was four- to eightfold greater than when the vector was linearized as a replacement vector. By contrast, the ratio of targeted to random integrations at the fah locus did not vary with the linearization site of the vector. The different relationships between the targeting frequency and the vector configuration at the fgr and fah loci may indicate a DNA sequence or chromatin structure preference for different targeting pathways.     

Vector potential as a channel of informational effect on living objects

The physical properties of the vector potential were considered in terms of the problem of bioactivity of electromagnetic fields. A possible primary mechanism underlying the effect of vector potentials on elementary processes of charge transport were considered by analogy with the well-known Aharonov-Bohms and Josephsons effects. The possibility of using the curl-free vector potential for "force-free" information effect on biochemical processes in the living cell was grounded. The technical possibilities of creation of vector potential free of magnetic field in laboratory are discussed.     

CXCR4慢病毒载体的构建及其在人脐带血间充质干细胞的表达

目的：构建趋化因子CXC亚族CXCR4的慢病毒表达载体并观察其转染人脐带间充质干细胞后的表达。方法：用逆转录PCR方法获取CXCR4基因编码区片段,将构建的慢病毒载体质粒pLVTHM-EGFP-CXCR4与包装质粒psPAX2和包膜质粒pMD2．G共转染293T细胞,包装生产慢病毒。用相同滴度的慢病毒转导等量间充质干细胞（Mesenchymal Stem Cell,MSCs）,后采用Real time PCR检测CXCR4 mRNA、Western Blot方法检测蛋白质的表达。结果：PCR、酶切和测序结果表明成功的构建了CXCR4基因重组慢病毒载体。同时用该慢病毒载体转染MSCs后可有效地增加MSCs中CXCR4的表达。结论：成功构建了CXCR4的慢病毒表达载体并能在MSCs中表达,为进一步研究其在干细胞移植中的应用奠定基础。’     

双报告基因真核表达载体的构建及其功能鉴定

目的:构建绿色荧光蛋白和海肾荧光素酶共同高效表达的双报告基因真核表达载体。方法:将增强型绿色荧光蛋白基因和海肾荧光素酶基因以昆虫病毒T2A序列相连接而后克隆进入pcDNA3.1(-)质粒,构建双报告基因真核表达载体。将该载体转染至COS-7细胞,通过荧光显微镜观察、照度计定量分析检测绿色荧光蛋白和海肾荧光素酶生物活性,Western Bolt检测T2A序列自剪切效率。结果:双报告基因真核表达载体能够同时表达非融合的绿色荧光蛋白和海肾荧光素酶,与单独表达载体产物具有相似的生物活性和表达效率。结论:双报告基因真核表达载体建立成功,为基因表达调控等相关领域研究提供辅助工具。     

介导大鼠结缔组织生长因子基因沉默的慢病毒载体转移质粒的构建及鉴定

目的：构建介导大鼠结缔组织生长因子（CTGF）基因沉默的慢病毒载体转移质粒pGCL-CTGF,为进一步包装慢病毒载体奠定基础。方法：以大鼠CTGF基因为靶基因,根据RNA干扰（RNAi）序列设计原则,设计4对有小发夹结构的RNAi靶点序列,退火形成双链DNA,双酶切后定向克隆到慢病毒载体转移质粒pGCL-GFP中,构建4个含靶基因片段的重组慢病毒载体转移质粒pGCL-CTGF,并对质粒进行PCR及测序鉴定。结果：CTGF的短发夹RNA（shRNA）片段被成功克隆到慢病毒载体转移质粒pGCL-GFP中,4个插入序列与设计的靶基因片段完全一致。结论：构建了能够表达4个含CTGF靶基因片段的慢病毒载体转移质粒,为进一步包装介导CTGF基因沉默的慢病毒载体奠定了基础。     

Adeno-associated virus vector for high-frequency integration, expression, and rescue of genes in mammalian cells.

We describe the construction of an adeno-associated virus (AAV) vector in which the coding sequence of the procaryotic gene neo is expressed under the control of the major AAV promoter p40. This AAV-neo vector allowed stable expression of neo as a dominant selective marker in mammalian cells by selection of cells which were resistant to the antibiotic geneticin (G418). When the vector was introduced into human (293 or HeLa) cell lines by a DNA transfection procedure, stable geneticin-resistant colonies were obtained. When the vector was first packaged into AAV particles and then introduced into cells via particle infection, geneticin-resistant cells were obtained at higher frequencies than those obtained by DNA transfection. In geneticin-resistant cells the AAV-neo vector was integrated at low copy number and could be rescued by subsequent infection with wild-type AAV and the helper adenovirus or, in some cases, by infection with adenovirus alone. The rescued AAV-neo vector could then be recovered as amplified unintegrated DNA from a Hirt lysate. These results demonstrate that AAV can be used as a transducing viral vector for stable integration and expression of a foreign gene in mammalian cells. The high frequency of integration and the ability to rescue the integrated vector suggest that this vector system may be useful for selecting genes from cDNA libraries. This vector may also be useful for introduction of genes into cells which are refractory to transfection in procedures such as those involving the use of CaPO4 or DEAE-dextran.     

利用RNA干扰抑制细丝蛋白A基因的表达

目的：构建细丝蛋白A（FLNa）基因的小干扰RNA（siRNA）表达载体,并观察其对FLNa基因表达的抑制作用。方法：利用RNA干扰（RNAi）技术设计并合成1条针对FLNa的siRNA,将其克隆到siRNA表达载体pSilencer4．1-CMV-hygro中;将重组质粒pSilencer-FLNa、pSilencer-negative（阴性对照）转染293T人胚肾细胞,通过Western印迹检测FLNa的表达;通过潮霉素筛选建立干扰FLNa表达的前列腺癌细胞。结果：PCR鉴定证明构建了FLNa基因RNAi载体;Western印迹表明构建的FLNa基因干扰载体能够有效地抑制FLNa基因的表达;建立了稳定干扰FLNa表达的前列腺癌C4-2细胞。结论：构建了FLNa基因RNAi载体,该载体能够有效地抑制FLNa基因的表达。     

小鼠MPI基因的打靶载体的构建和筛选

目的　构建小鼠MPI基因的基因打靶载体转染ES细胞 ,构建用于同源重组筛选的对照载体。方法根据计算机分析小鼠MPI基因的基因组序列 ,构建用于同源重组载体的长臂和短臂并且转染小鼠ES细胞 ,经抗性筛选后得到阳性克隆 ,抽提基因组DNA后用PCR的方法进行重组子的初步筛选。结果　成功构建了MPI基因的基因打靶载体并且摸索了用PCR的方法进行重组细胞初步筛选的方法。结论　这个载体的构建为MPI基因功能的研究打下了基础 ,同时用PCR方法进行初步筛选大大减少了Southern杂交的工作量 ;利用实验小鼠来研究印迹基因是非常有效的方法 ,它不仅能了解印迹基因在小鼠生长发育过程中的功能 ,而且进而有助于研究人的相应印迹区。     

骨形态发生蛋白-7真核表达载体的构建及鉴定

从转录水平上对原有载体进行改造,以期提高外源蛋白的表达量,为进一步研究改建载体后蛋白表达量奠定基础。将pBI—EGFP载体上的反应元件Pbi-1切下,连在pTet-On载体上PCMV的下游;然后将外源基因BMP-7重组到原有的pBI—EGFP载体内,进行酶切和序列鉴定。成功地构建了pTet—0n—Pbi-1载体和其核表达载体pBI／BMP—7。