桑德勒哮喘基本法研究中心（SABRE） 桑德勒基金会

第1部分：生产慢病毒转染的HEK 293细胞 * 24小时前转，板2.5 × 10 6细胞在50-70％，第二天汇合10厘米菜。 <ol><li>开始准备稍后会转染的细胞，使病毒的DNA与本议定书​​。首先，淡化FuGENE 6转染试剂罗氏公司，脂质体试剂，使细胞组成DNA。在1.5 ml管，移液器30μlFuGENE 6（SFDMEM）为600ul无血清培养基。小心不要让FuGENE触摸管方，因为它是进入中期交付。让这个FuGENE SFDMEM混合，在室温下孵育5分钟。 </li><li>管帽，混合4微克慢病毒质粒4微克每第三代病毒包装载体（pMDL，PRSV和pVSV - G）。慢病毒载体包含病毒插入基因组的每一个细胞，它感染，而包装载体含有慢病毒所需的所有其他蛋白质的基因的DNA。 </li><li>关闭颠倒离心管几次的盖子，混合。 </li><li>在室温下孵育15-20分钟。 </li><li>到293盘管吸取的全部内容。通过倾斜板混合轻轻地来回。 </li><li>返回细胞的孵化器，并允许病毒生产继续在收获前48-96小时。 </li><li>孵化过程中，293细胞转录从慢病毒质粒DNA的利益，创造慢病毒构建的RNA副本。他们还抄写并翻译成病毒蛋白的包装载体的基因。这些蛋白质进行病毒含有RNA的版本，你慢病毒构建将反向转录病毒，它感染的所有细胞的基因组插入。 </li></ol>第2部分：慢病毒丰收<ol><li>潜伏期后，细胞外的孵化器，并使用一个一次性的，10ml注射器，去除上清，它现在包含病毒。将有大约上清10毫升。 </li><li>将一个0.45μm的注射器过滤器，尖和病毒过滤成贝克曼超速离心机管。过滤器只允许病毒和细胞通过。 </li><li>在丢弃之前，孵化所有病毒产生细胞培养板中，注射器和10％的漂白水45分钟的过滤器。 </li></ol>第3部分：通过慢病毒超速离心浓缩<ol><li> SW - 41Ti或SW - 28转子水桶装入离心管。 </li><li>使用无血清DMEM，以平衡所有病毒含有管内0.2克。 </li><li>密封关闭转子桶和他们勾到转子前放置超速离心机转子</li><li>超速离心机在90分钟的旋转病毒在4 ° SW - 41Ti转子在25000转或24000 SW - 28转子的转速C。 </li><li>在组织培养罩，反转管倒挂倒入一个含有10％的漂白粉的货柜上清。 </li><li>使用Kimwipe周围的颗粒吸收多余的液体和倒置在一个不超过五分钟，方便机架管。 </li><li>要重新挂起的病毒颗粒，使用一个过滤嘴管加入100μL无菌PBS，然后吸管向上和向下的20倍左右。 </li><li>保留病毒在4 ° C过夜完成重新悬浮。一个可以存放在4度，约1周，在-80度长达一年的病毒​​PREPS。请记住10％丢弃前漂白处理所有空管。 </li><li>如果打算使用超过1周的病毒的准备，为未来的实验和1 3等份滴定5μL，最小的5 -20μL等分。冻结和储存在零下80等份。 </li></ol>第4部分：用流式细胞仪的慢病毒滴定<ol><li>下一步是通过流式细胞仪来确定病毒滴度。这种方法只适用于在包含一个荧光报告基因的慢病毒载体。我们的想法是，当病毒感染细胞，它引入到该细胞的基因组慢病毒质粒DNA。被感染的细胞，然后将抄写和翻译的慢病毒载体的基因，包括，如果你包括一个荧光报告基因，感染的细胞会发出荧光。荧光水平的效用，或病毒滴度。 </li><li>对于每一个病毒的股票滴度，浓缩病毒液稀释成1.5毫升（DMEM培养液，钢笔链球菌，谷氨酰胺，FBS），完整的媒体。 </li><li>在1-6井在96孔板单列，执行以下的系列稀释：所有6个井加100μL完全DMEM媒体。第一添加媒体100μL无病毒（这是你的未染色的控制），第二孔加100μL稀释后的病毒（这相当于TO1毫升未经稀释的病毒），第三孔加100μL从第二口井的组合，第四以及100毫升，添加以及从第三至第五好添加100μL从4井，到第六孔加100μL从5井。最后采取100ul第六以及丢弃在漂白剂。串行稀释，每口井有一半的病毒量相比之前。 </li><li>带来的所有井的总体积为200μL。请注意，这些只是建议的稀释，这应该为滴定最集中的病毒。如果病毒滴度低，或花心，可能需要调整稀释。 </li><li>任何未使用的稀释病毒治疗丢弃前45分钟与10％的漂白水溅入一个生物危险废物的容器。 </li><li> 6口井，每年新增〜15000健康，积极除以293细胞。一个单一的96孔板，可用于病毒滴度16 PREPS。 </li><li>返回细胞至37度的孵化器，5％CO 2，并允许进行至少48小时的感染。 </li><li>潜伏期后，细胞对记者表达，流式细胞仪（在本例中荧光）分析。病毒颗粒定量％，每口井的荧光细胞。 </li></ol>用下面的公式计算出每毫升传染性单位： <div style="text-align:center;"> （每口井每天感染X记者阳性细胞的细胞）× 1000 ______________________________________________________ 载体毫升补充嘛 </div>第5部分：代表性的成果： 经过48小时的潜伏期后转染293细胞的板应在90％左右，荧光。一个荧光细胞的高比例是高比例的病毒产生细胞的迹象。 离心后，病毒颗粒resuspending时隐约可见。颗粒是明确的和非常小的，这是正常的的。 解释流式细胞仪检测结果时，请注意，只可以实现准确的效价计算，当受感染的细胞（日光灯）已经收到不超过每一个细胞病毒融合。为了确保这种情况下，使用细胞&lt;15％计算感染率。细胞具有较高的感染率可能已经收到了每个单元的多个病毒integrants。在步骤2中建议的稀释应该产生这种感染的范围内的几个样本。理想的情况下，使用几个样本生成滴定曲线（线性），从中可以计算出最终的滴度，但你可以使用单个样本计算滴度，如有必要。可以预期，滴度为1.0 × 10 7涂/毫升联合国浓缩病毒和1.0 × 10 8恩/毫升浓缩病毒。

<ol>
	<li>Reiser, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Production+and+concentration+of+pseudotyped+HIV-1-based+gene+transfer+vectors..">Production and concentration of pseudotyped HIV-1-based gene transfer vectors..</a> Gene Therapy. , 72-7211 (2000).</li><li>Dull, T., Zufferey, R., Kelly, M., Mandel, R. J., Nguyen, M., Trono, D., Naldini, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> J Virol. 72 (11), 8463-8471 (1998).</li></ol>

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		<div>
		<table border="1">
		<thead>
		<tr>
		<th>Material Name</th>
		<th>Type</th>
		<th>Company</th>
		<th>Catalogue Number</th>
		<th>Comment</th>
		</tr>
		</thead>
		<tbody>
		
<tr>
<td>DMEM HEK 293T cells Penicillin-streptomycin Glutamine Phosphate-buffered saline FBS</td>
<td>&nbsp;</td>
<td>Invitrogen</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>FuGENE 6 transfection reagent pSico mCherry pMDL pRSV pVSVG</td>
<td>&nbsp;</td>
<td>Roche</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Bleach</td>
<td>&nbsp;</td>
<td>Clorox</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>10-cm cell culture dishes 96 well cell culture dishes </td>
<td>&nbsp;</td>
<td>Falcon</td>
<td>353003</td>
<td>&nbsp;</td>
<tr>
<td>Multichannel pipette</td>
<td>&nbsp;</td>
<td>Rainin</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Filtered pipette tips</td>
<td>&nbsp;</td>
<td>Rainin</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>1.5ml Eppendorf tubes Syringe Syinge filter (0.45-&mu;m)</td>
<td>&nbsp;</td>
<td>Eppendorf</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Ultracentrifuge tubes</td>
<td>&nbsp;</td>
<td>Beckman</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Tissue culture incubator at 5% CO2</td>
<td>&nbsp;</td>
<td>Coulter</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Beckman SW41T.I rotor</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Beckman ultracentrifuge</td>
<td>&nbsp;</td>
<td>Beckman </td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Fluorescent microscope</td>
<td>&nbsp;</td>
<td>Coulter</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>FACS Array</td>
<td>&nbsp;</td>
<td>Beckman</td>
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lentivirus production

RNA干扰（RNAi）是在活细胞中的基因沉默系统。 RNA干扰，基因同源序列短干扰RNA（siRNA）的沉默转录后的状态。短发夹RNA的siRNA的前体，可使用慢病毒，允许在多种细胞类型中的RNAi表达。慢病毒，如人类免疫缺陷病毒，能够感染分裂和非分裂细胞。我们将描述一个程序包慢病毒。包装是指主管病毒DNA载体的准备。慢病毒载体的生产系统是基于一个“分裂”的制度，其中病毒的天然基因组已分割成单独的辅助质粒结构。这种不同的病毒分子分裂成4个独立的向量，减少不定的慢病毒基因组的重组创造了复制能力的病毒的风险。在这里，一个载体，利息和3个包装载体的shRNA（P - VSVG，PRSV，pMDL）瞬时转染到人293细胞。至少48小时的潜伏期后，病毒上清收获和集中。最后，记者（荧光灯）的表达，流式细胞仪，是由病毒滴度。

Watch this Scientific Journal Video about Lentivirus Production at JoVE.com

Lentivirus Production

为了使慢病毒，DNA载体转染到人293细胞。收获后，集中上清液，荧光表达，流式细胞仪，是由病毒滴度。

慢病毒生产

RNA interference (RNAi) is a system of gene silencing in living cells. In RNAi, genes homologous in sequence to short interfering RNAs (siRNA) are ...

Research

JoVE Journal

Biology

65.6K 次观看.  University of California, San Francisco - UCSF. 为了使慢病毒，DNA载体转染到人293细胞。收获后，集中上清液，荧光表达，流式细胞仪，是由病毒滴度。

视频: Lentivirus Production

Technical Demonstration of Whole Genome Array Comparative Genomic Hybridization

Array comparative genomic hybridization (array CGH) is a method for detecting gains and losses of DNA segments or gene dosage in the genome 1. Recent advances in this technology have enabled high resolution comparison of whole genomes for the identification of genetic alterations in cancer and other genetic diseases 2. The Sub-Megabase Resolution Tiling-set array (or SMRT) array is comprised of a set of approximately thirty thousand overlapping bacterial artificial chromosome (BAC) clones that span the human genome in ~100 kilobase pair (kb) segments 2. These BAC targets are individually synthesized and spotted in duplicate on a single glass slide 2-4. Array CGH is based on the principle of competitive hybridization. Sample and reference DNA are differentially labeled with Cyanine-3 and Cyanine-5 fluorescent dyes, and co-hybridized to the array. After an incubation period the unbound samples are washed from the slide and the array is imaged. A freely available custom software package called SeeGH (www.flintbox.ca) is used to process the large volume of data collected - a single experiment generates 53,892 data points. SeeGH visualizes the log2 signal intensity ratio between the 2 samples at each BAC target which is vertically aligned with chromosomal position 5,6. The SMRT array can detect alterations as small as 50 kb in size 7. The SMRT array can detect a variety of DNA rearrangement events including DNA gains, losses, amplifications and homozygous deletions. A unique advantage of the SMRT array is that one can use DNA isolated from formalin fixed paraffin embedded samples. When combined with the low input requirements of unamplified DNA (25-100ng) this allows profiling of precious samples such as those produced by microdissection 7,8. This is attributed to the large size of each BAC hybridization target that allows the binding of sufficient labeled samples to produce signals for detection. Another advantage of this platform is the tolerance of tissue heterogeneity, decreasing the need for tedious tissue microdissection 8. This video protocol is a step-by-step tutorial from labeling the input DNA through to signal acquisition for the whole genome tiling path SMRT array.

This video is a technical demonstration of the hybridization protocol for whole genome tiling path array CGH, which scans the entire human genome using only 25-100 ng of DNA that can be isolated from a variety of sources, including archival formalin fixed material.

全基因组阵列比较基因组杂交技术示范

Array comparative genomic hybridization (array CGH) is a method for detecting gains and losses of DNA segments or gene dosage in the genome 1.  Recent ...

科研

生物学

Large Insert Environmental Genomic Library Production

The vast majority of microbes in nature currently remain inaccessible to traditional cultivation methods. Over the past decade, culture-independent environmental genomic (i.e. metagenomic) approaches have emerged, enabling researchers to bridge this cultivation gap by capturing the genetic content of indigenous microbial communities directly from the environment. To this end, genomic DNA libraries are constructed using standard albeit artful laboratory cloning techniques. Here we describe the construction of a large insert environmental genomic fosmid library with DNA derived from the vertical depth continuum of a seasonally hypoxic fjord. This protocol is directly linked to a series of connected protocols including coastal marine water sampling [1], large volume filtration of microbial biomass [2] and a DNA extraction and purification protocol [3]. At the outset, high quality genomic DNA is end-repaired with the creation of 5 -phosphorylated blunt ends. End-repaired DNA is subjected to pulsed-field gel electrophoresis (PFGE) for size selection and gel extraction is performed to recover DNA fragments between 30 and 60 thousand base pairs (Kb) in length. Size selected DNA is purified away from the PFGE gel matrix and ligated to the phosphatase-treated blunt-end fosmid CopyControl vector pCC1 (EPICENTRE <a href="http://www.epibio.com/item.asp?ID=385">http://www.epibio.com/item.asp?ID=385</a>). Linear concatemers of pCC1 and insert DNA are subsequently headfull packaged into phage particles by lambda terminase, with subsequent infection of phage-resistant E. coli cells. Successfully transduced clones are recovered on LB agar plates under antibiotic selection and archived in 384-well plate format using an automated colony picking robot (Qpix2, GENETIX). The current protocol draws from various sources including the CopyControl Fosmid Library Production Kit from EPICENTRE and the published works of multiple research groups [4-7]. Each step is presented with best practice in mind. Whenever possible we highlight subtleties in execution to improve overall quality and efficiency of library production. The whole process of fosmid library production and automated colony picking takes at least 7-10 days as there are many incubation steps included. However, there are several stopping points possible which are mentioned within the protocol.

Construction of a fosmid library with environmental genomic DNA isolated from the vertical depth continuum of a seasonally hypoxic fjord is described. The resulting clone library is picked into 384-well plates and archived for downstream sequencing and functional screening by the application of an automated colony picking system.

大型插入环境基因组文库生产

The vast majority of microbes in nature currently remain inaccessible to traditional cultivation methods. Over the past decade, culture-independent ...

Generation of Induced Pluripotent Stem Cells by Reprogramming Human Fibroblasts with the Stemgent Human TF Lentivirus Set

In 2006, Yamanaka and colleagues first demonstrated that retrovirus-mediated delivery and expression of Oct4, Sox2, c-Myc and Klf4 is capable of inducing the pluripotent state in mouse fibroblasts.1 The same group also reported the successful reprogramming of human somatic cells into induced pluripotent stem (iPS) cells using human versions of the same transcription factors delivered by retroviral vectors.2 Additionally, James Thomson et al. reported that the lentivirus-mediated co-expression of another set of factors (Oct4, Sox2, Nanog and Lin28) was capable of reprogramming human somatic cells into iPS cells.3
iPS cells are similar to ES cells in morphology, proliferation and the ability to differentiate into all tissue types of the body. Human iPS cells have a distinct advantage over ES cells as they exhibit key properties of ES cells without the ethical dilemma of embryo destruction. The generation of patient-specific iPS cells circumvents an important roadblock to personalized regenerative medicine therapies by eliminating the potential for immune rejection of non-autologous transplanted cells.
Here we demonstrate the protocol for reprogramming human fibroblast cells using the Stemgent Human TF Lentivirus Set. We also show that cells reprogrammed with this set begin to show iPS morphology four days post-transduction. Using the Stemolecule Y27632, we selected for iPS cells and observed correct morphology after three sequential rounds of colony picking and passaging. We also demonstrate that after reprogramming cells displayed the pluripotency marker AP, surface markers TRA-1-81, TRA-1-60, SSEA-4, and SSEA-3, and nuclear markers Oct4, Sox2 and Nanog.

We demonstrate the protocol for the generation of induced pluripotent stem cells from human somatic cells using lentivirus-mediated delivery of the human factors Oct4, Sox2, Nanog, and Lin28. Pluripotency was confirmed by morphology and the presence of embryonic stem (ES) cell-specific markers.

由Stemgent人类TF慢病毒重新编程人类成纤维细胞生成诱导多能干细胞

In 2006, Yamanaka and colleagues first demonstrated that retrovirus-mediated delivery and expression of Oct4, Sox2, c-Myc and Klf4 is capable of inducing ...

A Protocol for the Production of KLRG1 Tetramer

Killer cell lectin-like receptor G1 (KLRG1) is a type II transmembrane glycoprotein inhibitory receptor belonging to the C type lectin-like superfamily. KLRG1 exists both as a monomer and as a disulfide-linked homodimer. This well-conserved receptor is found on the most mature and recently activated NK cells as well as on a subset of effector/memory T cells.
Using KLRG1 tetramer as well as other methods, E-, N-, and R-cadherins were identified as KLRG1 ligands. These Ca2+-dependent cell-cell adhesion molecules comprises of an extracellular domain containing five cadherin repeats responsible for cell-cell interactions, a transmembrane domain and a cytoplasmic domain that is linked to the actin cytoskeleton. 
Generation of the KLRG1 tetramer was essential to the identification of the KLRG1 ligands. KLRG1 tetramer is also a unique tool to elucidate the roles cadherin and KLRG1 play in regulating the immune response and tissue integrity.

This protocol describes the production of KLRG1 tetramer, which is a powerful tool for the analysis of KLRG1 ligands.

KLRG1四聚体的生产协议

Killer cell lectin-like receptor G1 (KLRG1) is a type II transmembrane glycoprotein inhibitory receptor belonging to the C type lectin-like superfamily. ...

DNA Extraction from Paraffin Embedded Material for Genetic and Epigenetic Analyses

Disease development and progression are characterized by frequent genetic and epigenetic aberrations including chromosomal rearrangements, copy number gains and losses and DNA methylation. Advances in high-throughput, genome-wide profiling technologies, such as microarrays, have significantly improved our ability to identify and detect these specific alterations. However as technology continues to improve, a limiting factor remains sample quality and availability. Furthermore, follow-up clinical information and disease outcome are often collected years after the initial specimen collection. Specimens, typically formalin-fixed and paraffin embedded (FFPE), are stored in hospital archives for years to decades. DNA can be efficiently and effectively recovered from paraffin-embedded specimens if the appropriate method of extraction is applied. High quality DNA extracted from properly preserved and stored specimens can support quantitative assays for comparisons of normal and diseased tissues and generation of genetic and epigenetic signatures 1. To extract DNA from paraffin-embedded samples, tissue cores or microdissected tissue are subjected to xylene treatment, which dissolves the paraffin from the tissue, and then rehydrated using a series of ethanol washes. Proteins and harmful enzymes such as nucleases are subsequently digested by proteinase K. The addition of lysis buffer, which contains denaturing agents such as sodium dodecyl sulfate (SDS), facilitates digestion 2. Nucleic acids are purified from the tissue lysate using buffer-saturated phenol and high speed centrifugation which generates a biphasic solution. DNA and RNA remain in the upper aqueous phase, while proteins, lipids and polysaccharides are sequestered in the inter- and organic-phases respectively. Retention of the aqueous phase and repeated phenol extractions generates a clean sample. Following phenol extractions, RNase A is added to eliminate contaminating RNA. Additional phenol extractions following incubation with RNase A are used to remove any remaining enzyme. The addition of sodium acetate and isopropanol precipitates DNA, and high speed centrifugation is used to pellet the DNA and facilitate isopropanol removal. Excess salts carried over from precipitation can interfere with subsequent enzymatic assays, but can be removed from the DNA by washing with 70% ethanol, followed by centrifugation to re-pellet the DNA 3. DNA is re-suspended in distilled water or the buffer of choice, quantified and stored at -20&deg;C. Purified DNA can subsequently be used in downstream applications which include, but are not limited to, PCR, array comparative genomic hybridization 4 (array CGH), methylated DNA Immunoprecipitation (MeDIP) and sequencing, allowing for an integrative analysis of tissue/tumor samples.

This video demonstrates the protocol for DNA extraction from formalin-fixed paraffin-embedded material. This is a multi-day procedure in which tissue sections are deparaffinized with xylene, rehydrated with ethanol and treated with proteinase K to purify and isolate DNA for subsequent gene-specific or genome-wide analysis.

从石蜡包埋材料的遗传和表观遗传分析的DNA提取

Disease development and progression are characterized by frequent genetic and epigenetic aberrations including chromosomal rearrangements, copy number ...

Transduction of Human Cells with Polymer-complexed Ecotropic Lentivirus for Enhanced Biosafety

Stem and tumor cell biology studies often require viral transduction of human cells with known or suspected oncogenes, raising major safety issues for laboratory personnel. Pantropic lentiviruses, such as the commonly used VSV-G pseudotype, are a valuable tool for studying gene function because they can transduce many cell types, including non-dividing cells. However, researchers may wish to avoid production and centrifugation of pantropic viruses encoding oncogenes due to higher biosafety level handling requirements and safety issues. Several potent oncogenes, including c-Myc and SV40 large T antigen, are known to enhance production of induced pluripotent stem cells (iPSC). All other known iPSC-inducing genetic changes (OCT4, SOX2, KLF4, NANOG, LIN28, and p53 loss of function) also have links to cancer, making them of relatively high safety concern as well. 
While these cancer-related viruses are useful in studying cellular reprogramming and pluripotency, they must be used safely. To address these biosafety issues, we demonstrate a method for transduction of human cells with ecotropic lentivirus, with additional emphasis on reduced cost and convenient handling. We have produced ecotropic lentivirus with sufficiently high titer to transduce greater than 90% of receptor-expressing human cells exposed to the virus, validating the efficacy of this approach. 
Lentivirus is often concentrated by ultracentrifugation; however, this process takes several hours and can produce aerosols infectious to human biomedical researchers. As an alternative, viral particles can be more safely sedimented onto cells by complexation with chondroitin sulfate and polybrene (CS/PB). This technique increases the functional viral titer up to 3-fold in cells stably expressing murine retrovirus receptor, with negligible added time and cost. Transduction of human dermal fibroblasts (HDFs) is maximally enhanced using CS/PB concentrations approximately 4-fold lower than the optimal value previously reported for cancer cell lines, suggesting that polymer concentration should be titrated for the target cell type of interest. We therefore describe the use of methylthiazolyldiphenyl-tetrazolium bromide (MTT) to assay for polymer toxicity in a new cell type. We observe equivalent viability of HDFs after viral transduction using either polymer complexation or the standard dose of polybrene (PB, 6 &mu;g/ml), indicating minimal acute toxicity.
In this protocol, we describe the use of ecotropic lentivirus for overexpression of oncogenes in human cells, reducing biosafety risks and increasing the transduction rate. We also demonstrate the use of polymer complexation to enhance transduction while avoiding aerosol-forming centrifugation of viral particles.

Lentiviruses are a valuable research tool for exploring gene function; however, researchers may wish to avoid production of pantropic lentivirus encoding known or suspected oncogenes. As an alternative, we present a safer protocol for use of ecotropic lentivirus on human cells modified to express the ecotropic receptor mSlc7a1.

增强生物安全与聚合物复合物Ecotropic慢病毒的人体细胞的转导

Stem and tumor cell biology studies often require viral transduction of human cells with known or suspected oncogenes, raising major safety issues for ...

The MultiBac Protein Complex Production Platform at the EMBL

Proteomics research revealed the impressive complexity of eukaryotic proteomes in unprecedented detail. It is now a commonly accepted notion that proteins in cells mostly exist not as isolated entities but exert their biological activity in association with many other proteins, in humans ten or more, forming assembly lines in the cell for most if not all vital functions.1,2 Knowledge of the function and architecture of these multiprotein assemblies requires their provision in superior quality and sufficient quantity for detailed analysis. The paucity of many protein complexes in cells, in particular in eukaryotes, prohibits their extraction from native sources, and necessitates recombinant production. The baculovirus expression vector system (BEVS) has proven to be particularly useful for producing eukaryotic proteins, the activity of which often relies on post-translational processing that other commonly used expression systems often cannot support.3 BEVS use a recombinant baculovirus into which the gene of interest was inserted to infect insect cell cultures which in turn produce the protein of choice. MultiBac is a BEVS that has been particularly tailored for the production of eukaryotic protein complexes that contain many subunits.4 A vital prerequisite for efficient production of proteins and their complexes are robust protocols for all steps involved in an expression experiment that ideally can be implemented as standard operating procedures (SOPs) and followed also by non-specialist users with comparative ease. The MultiBac platform at the European Molecular Biology Laboratory (EMBL) uses SOPs for all steps involved in a multiprotein complex expression experiment, starting from insertion of the genes into an engineered baculoviral genome optimized for heterologous protein production properties to small-scale analysis of the protein specimens produced.5-8 The platform is installed in an open-access mode at EMBL Grenoble and has supported many scientists from academia and industry to accelerate protein complex research projects.

Protein complexes catalyze key cellular functions. Detailed functional and structural characterization of many essential complexes requires recombinant production. MultiBac is a baculovirus/insect cell system particularly tailored for expressing eukaryotic proteins and their complexes. MultiBac was implemented as an open-access platform, and standard operating procedures developed to maximize its utility.

在EMBL的MultiBac蛋白质复杂的生产平台

Proteomics  research revealed the impressive complexity of eukaryotic proteomes in  unprecedented detail. It is now a commonly accepted notion that ...

Production of Haploid Zebrafish Embryos by In Vitro Fertilization

The zebrafish has become a mainstream vertebrate model that is relevant for many disciplines of scientific study. Zebrafish are especially well suited for forward genetic analysis of developmental processes due to their external fertilization, embryonic size, rapid ontogeny, and optical clarity &#8211; a constellation of traits that enable the direct observation of events ranging from gastrulation to organogenesis with a basic stereomicroscope. Further, zebrafish embryos can survive for several days in the haploid state. The production of haploid embryos in vitro is a powerful tool for mutational analysis, as it enables the identification of recessive mutant alleles present in first generation (F1) female carriers following mutagenesis in the parental (P) generation. This approach eliminates the necessity to raise multiple generations (F2, F3, etc.) which involves breeding of mutant families, thus saving the researcher time along with reducing the needs for zebrafish colony space, labor, and the husbandry costs. Although zebrafish have been used to conduct forward screens for the past several decades, there has been a steady expansion of transgenic and genome editing tools. These tools now offer a plethora of ways to create nuanced assays for next generation screens that can be used to further dissect the gene regulatory networks that drive vertebrate ontogeny. Here, we describe how to prepare haploid zebrafish embryos. This protocol can be implemented for novel future haploid screens, such as in enhancer and suppressor screens, to address the mechanisms of development for a broad number of processes and tissues that form during early embryonic stages.

Production of Haploid Zebrafish Embryos by In Vitro Fertilization

The zebrafish is a powerful model system for developmental biology and human disease research due to their genetic similarity with higher vertebrates. This protocol describes a methodology to create haploid zebrafish embryos that can be utilized for forward screen strategies to identify recessive mutations in genes essential for early embryogenesis.

生产单倍体斑马鱼的胚胎通过<em&gt;体外</em&gt;施肥

The zebrafish has become a mainstream vertebrate model that is relevant for many disciplines of scientific study. Zebrafish are especially well suited for ...

Green Fluorescent Protein-based Expression Screening of Membrane Proteins in Escherichia coli

The production of recombinant membrane proteins for structural and functional studies remains technically challenging due to low levels of expression and the inherent instability of many membrane proteins once solubilized in detergents. A protocol is described that combines ligation independent cloning of membrane proteins as GFP fusions with expression in Escherichia coli detected by GFP fluorescence. This enables the construction and expression screening of multiple membrane protein/variants to identify candidates suitable for further investment of time and effort. The GFP reporter is used in a primary screen of expression by visualizing GFP fluorescence following SDS polyacrylamide gel electrophoresis (SDS-PAGE). Membrane proteins that show both a high expression level with minimum degradation as indicated by the absence of free GFP, are selected for a secondary screen. These constructs are scaled and a total membrane fraction prepared and solubilized in four different detergents. Following ultracentrifugation to remove detergent-insoluble material, lysates are analyzed by fluorescence detection size exclusion chromatography (FSEC). Monitoring the size exclusion profile by GFP fluorescence provides information about the mono-dispersity and integrity of the membrane proteins in different detergents. Protein: detergent combinations that elute with a symmetrical peak with little or no free GFP and minimum aggregation are candidates for subsequent purification. Using the above methodology, the heterologous expression in E. coli of SED (shape, elongation, division, and sporulation) proteins from 47 different species of bacteria was analyzed. These proteins typically have ten transmembrane domains and are essential for cell division. The results show that the production of the SEDs orthologues in E. coli was highly variable with respect to the expression levels and integrity of the GFP fusion proteins. The experiment identified a subset for further investigation.

Green Fluorescent Protein-based Expression Screening of Membrane Proteins in Escherichia coli

A streamlined approach to screening for the expression of recombinant membrane proteins in Escherichia coli based on fusion to green fluorescent protein is presented.

膜蛋白的绿色荧光蛋白为基础的表达筛选<em&gt;大肠杆菌</em

The production of recombinant membrane proteins for structural and functional studies remains technically challenging due to low levels of expression and ...

Production of Double-stranded DNA Ministrings

We constructed linear covalently closed (LCC) DNA minivectors as a non-viral gene-delivery vector alternative produced via a simple platform in vivo. DNA ministrings possess a heightened safety profile and also efficiently deliver DNA cargo to targeted cells. Conventional DNA vectors carry undesirable prokaryotic sequences, including antibiotic resistance genes, CpG motifs, and bacterial origins of replication, which may lead to the stimulation of host immunological responses. The bioavailability of conventional DNA vectors is also compromised due to their larger molecular size. Their circular nature may also impart chromosomal integration, leading to insertional mutagenesis.
Bacterial sequences are excised from DNA minivectors, leaving only the gene of interest (GOI) and necessary eukaryotic expression elements. Our LCC DNA minivectors, or DNA ministrings, are devoid of immunogenic bacterial sequences; therefore improving their bioavailability and GOI expression. In the event of vector integration into the chromosome, the LCC DNA ministring will lethally disrupt the host chromosome, thereby removing the potentially dangerous mutant from the proliferating cell population. Consequently, DNA ministrings offer the benefits of &#39;minicircle&#39; DNA while eliminating the potential for undesirable vector integration events. In comparison to conventional plasmids and their isogenic circular covalently closed (CCC) counterparts, DNA ministrings demonstrate superior bioavailability, transfection efficiency, and cytoplasmic kinetics - they thus require lower amounts of cationic surfactants for effective transfection of target cells.
We have constructed a one-step inducible in vivo system for the production of DNA ministrings in Escherichia coli that is simple to use, rapid, and scalable.

The linear covalently closed (LCC) DNA minivector (DNA ministring) is a non-viral gene delivery vector offering high transfection efficiency and is relevant to any DNA delivery application. The production system is simple, rapid, and scalable in vivo. The following protocol provides visual step-by-step instructions for the production of DNA ministrings.

双链DNA Ministrings的生产

We constructed linear covalently closed (LCC) DNA minivectors as a non-viral gene-delivery vector alternative produced via a simple platform in vivo. DNA ...