草鱼肾细胞电转条件的优化及草鱼呼肠孤病毒NS26蛋白的瞬时表达

本研究先以pEGFP-N1载体质粒中的绿色荧光蛋白基因为报道基因进行电转实验,优化电压、脉冲时间、质粒添加量和电击次数等电转条件,确立最佳条件。实验表明,细胞密度为1.5×107/mL时,取200μl在0.2cm电击杯中进行电击转染,电压为200V,脉冲时间为45ms,添加质粒30μg,电击1次时,转染效果最佳。提取草鱼呼肠孤病毒基因组总RNA,以其逆转录的cDNA作为扩增模板,设计特异引物扩增出GCRV非结构蛋白NS26的基因片段,重组到pEGFP-N1载体上得到重组质粒pEGFP-NS26,将其导入CIK细胞中用电转法高效表达了EGFPNS26融合蛋白。本研究为进一步研究NS26的功能奠定了基础。     

急性早幼粒白血病HL60细胞电转染条件的优化

目的：比较不同电转染条件下,真核表达载体转染HL60细胞的效率,筛选得到针对HL60细胞最佳的电转染条件。方法：采用pDsRED-C1真核表达载体,分别在2mm和4mm电转杯中依照不同电转条件对HL60细胞进行转染,根据存活细胞所占比例确定电转参数;在转染48h后,比较不同质粒加入量及二甲基亚砜（dimethyl sulfoxide,DMSO）加入电转体系前后的细胞转染阳性率。调整G418筛选浓度,在选定转染条件下进行HL60细胞电转,采用流式细胞技术,细胞化学染色及超微结构观察,分析电转前后HL60细胞的生物学性状。应用相同条件再转染eYFP-C1质粒于HL60细胞,G418筛选后观察荧光表达情况。结果：HL60细胞在2mm和4mm电转杯中的死亡数量随电击强度和脉冲次数的增加而升高,且方形波较回旋波有更强的击穿细胞膜的能力;固定电转参数下,2mm和4mm电转杯中的HL60细胞电转阳性细胞数随加入质粒量的增加呈先升高后下降的趋势,且在相同质粒加入量,2mm电转杯比4mm电转杯有更高的转染效率;在相同电转参数和相同电转杯中,预冷条件下加入DMSO电转时阳性率比不加入DMSO进行电转的阳性率高近13倍;400μg/ml G418是最佳筛选浓度;选定最佳电转条件进行电转,通过筛选,没有发现细胞表面分化抗原CD11b和CD14的表达,细胞形态原始,未见凋亡现象发生。相同条件电转eYFP-C1空载质粒于HL60细胞仍然可以获得很好的转染效果。结论：HL60细胞电转染条件的改良,可以有效提高HL60细胞的电转阳性率,为后续细胞真核表达载体的转染及基因功能研究奠定基础。     

融合蛋白基因与抗体基因电转染CHO-S细胞的条件摸索优化

旨在对编码融合蛋白和抗体的重组质粒转染CHO-S细胞的转染条件进行摸索优化,提高外源基因的转染效率,从而增加外源蛋白的表达。应用Amaxa Nucleofector-II电转仪,从电转染程序、质粒用量及细胞用量三方面着手,最终发现编码融合蛋白的重组质粒的最佳电转条件为:电转程序U-030,质粒用量20μg/孔,细胞用量1×10~7个/孔;编码抗体的重组质粒的最佳电转条件为:电转程序U-024,质粒用量15μg/孔,细胞用量1×10~7个/孔;实验结果进一步显示抗体重组质粒电转染CHO-S细胞的效果要优于融合蛋白重组质粒,利用高通量细胞筛选仪Clone Pix对转染后重组细胞的阳性克隆数进行统计,证实了该抗体重组质粒的转染效率更高。这为以后的抗体及融合蛋白重组质粒电转染CHO-S细胞提供了一定的数据支持,同时提示不同类型的细胞及外源基因,都需要设计相应的电转染实验进行条件优化,进而为获得高产稳定的生产用细胞株奠定基础。     

树突状细胞电穿孔法转染条件的优化

目的将带有EGFP的质粒电转入树突状细胞,探讨不同电转条件对树突状细胞的电转率和存活率影响。方法分离人外周血单核细胞加入刺激因子将其诱导为成熟DC,设置不同电转参数将质粒转入树突状细胞,荧光显微镜检测转染效率及细胞存活率。结果电转48小时后,镜下观察在电转条件为300V,20ms时,细胞存活率及表达率最高,结论选择适当的电转参数及细胞浓度,可明显提高转染效率同时降低细胞死亡率。     

电穿孔介导小干扰RNA高效转染小鼠附植前胚胎

使用Cy3标记的阴性对照小干扰RNA(siRNA)转染小鼠附植前胚胎,建立向小鼠附植前胚胎导入siRNA的电穿孔方法。通过控制透明带弱化程度、电压、脉冲时间和脉冲次数等条件,采用不同参数组合并结合使用不同介质作为电转缓冲液将Cy3标记的阴性对照siRNA转染小鼠附植前胚胎。在荧光倒置显微镜下,观察胚胎的存活率、siRNA转染率以及阳性转染存活胚胎的囊胚发育率。结果显示小鼠附植前胚胎在使用台氏液消化胚胎透明带10 s后,以opti-MEM作为电转缓冲液,电穿孔参数设置为30 V,1 ms,3次的条件下取得最佳转染效果。总之,电穿孔方法可实现siRNA简便、高效地转染小鼠附植前胚胎。     

优化脂质体对肝癌细胞株HepG2细胞转染效率

摸索用Lipofectamine 2000(Lipo)转染质粒pEGFP-C1到肝癌细胞HepG2较为合适的转染条件。以HepG2细胞为研究对象,采用脂质体Lipofectamine 2000转染pEGFP-C1质粒,在24孔板先按每孔0.5μg固定pEGFP-C1质粒用量,摸索Lipo在1μL、1.5μL、2μL、2.5μL量上较为合适的用量,确定Lipo用量后,然后固定Lipo为1μL,摸索质粒用量0.5μg、1μg,确定脂质体与质粒的最佳比例。此外,对转染中培养基是否含血清,Lipofectamine 2000与pEGFP-C1质粒比例为1:0.5的基础上,扩大用量,即Lipofectamine 2000 2μL和pEGFP-C1质粒1μg,以及脂质体复合物孵育细胞时间进行优化。最后,采用荧光倒置显微镜观察细胞转染效率和方差分析及秩和检验的统计学方法进行统计分析。结果显示,pEGFP-C1质粒固定为0.5μg时,Lipo用量在1μL及1.5μL用量组转染效率最好,之后随着Lipo用量加大,转染效率下降;固定Lipo用量1μL,pEGFP-C1质粒0.5μg时转染效率最好(p0.05),比例不变,扩大Lipo和质粒用量,并不增加转染效率。转染后于3 h、6 h、8 h、12 h、24 h换成正常培养基培养,转染6 h后换液较好。此外,研究发现培养基是否含血清不影响转染效率。本研究表明在24孔板板中用Lipofectamine 2000转染HepG2细胞时较为合适的转染条件为每孔1μL Lipofectamine 2000和0.5μg质粒,脂质体与质粒的最佳比例为2:1,血清不影响转染效率,用含血清培养基转染后6 h换液培养。     

不同质粒电转三种乳酸菌的比较研究

为比较研究不同质粒针对不同乳酸茵的电转效率的差异,分别以乳酸乳球菌NZ9000、干酪乳杆菌LC2W和植物乳杆菌WCFS1三种乳酸菌为受体,以七种不同质粒为载体,进行电转实验.结果表明在乳酸乳球菌NZ9000中,转化效率最高的是pIB 184质粒,达到了1.53×107 cfg/μgDNA,在干酪乳杆菌LC2W中,pSIP403质粒的电转化效率最高,达到了6.42×105 cfg/μgDNA,在植物乳杆菌WCFS1的电转化中,是pNZ44质粒达到8.68×105 cfg/μgDNA的最高转化效率.其中质粒pIB184和pNZ44在三种菌株中均有较高的电转化效率,超过了103 cfg/μgDNA,另一方面T-pAMS100、pSIP403、pSIP409三个质粒在干酪乳杆菌与植物乳杆菌中的电转化效率明显高于乳酸乳球菌.不同质粒针对不同乳酸茵的转化效率为乳酸茵的高效电转和表达栽体的选择与构建提供了可行依据.     

电穿孔法转染293T细胞条件的优化

为筛选电穿孔转染人胚肾293T细胞的最优条件,将增强型绿色荧光蛋白(EGFP)基因克隆至启动子p CMV前,获得的重组质粒在不同电压、质粒浓度和电击次数条件下电穿孔转染293T细胞,继而在倒置荧光显微镜下观察转染细胞,根据EGFP表达情况评价转染效率。结果表明400 V电压、45 mg质粒电穿孔转染293T细胞2次时转染效率达到44%,与脂质体转染效率(51%)无统计学差异。     

宫颈细胞系化学转染与电穿孔转染效率的比较与优化

目的 定量比较4种化学转染试剂在五株常用的宫颈(癌)细胞系中的DNA转染效率,以助于针对不同细胞系选择合适的转染试剂;同时探索电穿孔转染法在难转细胞系Ect1/E6E7、CaSki中的应用,选择最佳转染条件。方法 以pcDNA3.1-EGFP为报告载体,采用FuGENE HD、jetPRIME、Lipofectamine 2000和Lipofectamine 3000四种转染试剂分别转染常用宫颈(癌)细胞系HeLa、SiHa、CaSki、C33A和Ect1/E6E7,转染24h后用倒置荧光显微镜观察记录,并采用Cellometer K2对转染效率进行定量分析。针对化学转染法难转细胞系Ect1/E6E7、CaSki,采用电穿孔转染法进行转染,优化转染条件,并对转染效率进行定量比较。结果 jetPRIME和Lipofectamine 3000转染试剂在HeLa细胞中的转染效果很好,而对SiHa、C33A细胞转染效率相对较低,在CaSki、E6E7细胞中的转染效果很差。FuGENE HD转染试剂除了对HeLa、SiHa细胞转染效果较好之外,在其他3株细胞中的转染效果均不理想。Lipofectamine 2000在5株细胞中的转染效果也不理想。在穿孔电压170V、脉冲波长7ms、脉冲间隙10ms和驱动电压20V的条件下电穿孔转染法在Ect1/E6E7、CaSki细胞中的转染效率最佳且均高于化学转染法。结论 针对不同的宫颈(癌)细胞系选择合适的转染方式和转染试剂可达到更高的转染效率。相对电转染,化学转染细胞存活率高,电转染更适用于难转细胞的稳定转染。     

小鼠雌性生殖系统电穿孔与微泡增强超声波转EG即基因的研究（简报）

非病毒载体转基因法。如注射裸DNA或脂质体转染,不产生细胞毒性。但除了肌肉组织外其他组织的转导效率均不高。电脉冲可使细胞膜产生临时的微孔允许一些分子通过。因此应用此方法可将药物或基因转人动物组织。电穿孔常用于培养的细胞转基因,理论上,低强度、长脉冲。或高强度、短脉冲有利于电转导。选择适合的参数是电转导的关键。本实验比较了不同电压和脉冲时间对小鼠卵巢在体转入绿色荧光蛋白基因的效果．确定了最适的电转导参数。为卵巢疾病的药物、基因治疗和研究卵泡发育中的基因调控提供了实验手段。     

Effects of WT1 gene downregulation on apoptosis in porcine fetal fibroblasts

Wilms’ tumor gene 1 (WT1) is located on chromosome 11p13. Besides a role in the development of Wilms’ tumor, specific mutations in the Zn finger region are found in Denys-Drash syndrome and Frasier syndrome, both characterized by urogenital abnormalities, sometimes in combination with Wilms’ tumor. Our past study shows that WT1 is expressed in porcine kidney fibroblasts (PKFs) and swine testis cells (ST cells) and is essential for the maintenance of the development and survival of PKFs and ST cells. But we do not know whether WT1 gene was expressed in porcine fetal fibroblasts or not. To further explore whether WT1 was expressed in porcine fetal fibroblasts (PFFs) and its contribution to cell apoptosis, RT-PCR, immunocytochemical staining, and Western blot were used to detect the expression of WT1, the recombinant plasmids of pLV3-WT1 short hairpin ribonucleic acid (shRNA) were used to downregulate the WT1 gene in porcine fetal fibroblasts, and the role of WT1 in cell proliferation was examined by apoptosis analysis also. Our results indicated that WT1 was expressed in PFFs, the pLV3-WT1 shRNA dramatically reduced the expression of WT1, and downregulation of WT1 directly led to early cell apoptosis by downregulating the expression of antiapoptotic gene Bcl-2 and upregulating the expression of proapoptotic gene Bax in PFFs. Our results demonstrate that WT1 is also essential for the maintenance of the survival of PFFs.     

Efficient transfection of primarily cultured porcine embryonic fibroblasts using the Amaxa Nucleofection system

Porcine embryonic fibroblasts (PEF) are important as donor cells for nuclear transfer for generation of genetically modified pigs. In this study, we determined an optimal protocol for transfection of PEF with the Amaxa Nucleofection system, which directly transfers DNA into the nucleus of cells, and compared its efficiency with conventional lipofection and electroporation. Cell survival and transfection efficiency were assessed using dye-exclusion assay and a green fluorescent protein (GFP) reporter construct, respectively. Our optimized nucleofection parameters yielded survival rates above 60%. Under these conditions, FACS analysis demonstrated that 79% of surviving cells exhibited transgene expression 48 h after nucleofection when program U23 was used. This efficiency was higher than that of transfection of PEFs with electroporation (ca. 3-53%) or lipofection (ca. 3-8%). Transfected cells could be expanded as stably transgene-expressing clones over a month. When porcine nuclear transfer (NT) was performed using stable transformant expressing GFP as a donor cell, 5-6% of reconstituted embryos developed to blastocysts, from which 30-50% of embryos exhibited NT-embryo-derived green fluorescence. Under the conditions evaluated, nucleofection exhibited higher efficiency than conventional electroporation and lipofection, and may be a useful alternative for generation of genetically engineered pigs through nuclear transfer.     

Electroporation of human embryonic stem cells: Small and macromolecule loading and DNA transfection

Cryopreservation, directed differentiation, and genetic manipulation of human embryonic stem cells (hESCs) all require the transport of exogenous small molecules, proteins, or DNA into the cell. The absence of standard small and macromolecule loading techniques in hESCs as well as the inadequacies of current DNA transfection techniques have led us to develop electroporation as an efficient loading and transfection methodology. The electroporation parameters of pulse voltage, duration, and number have been explored and evaluated in terms of cell viability, molecular loading, and transfection efficiency on a per cell basis. Small molecule loading was assessed using propidium iodide (PI) and the disaccharide trehalose. Additionally, protein loading was investigated using a glutathione-S-transferase green fluorescent protein (GST-GFP) conjugate, and DNA transfection optimization was performed by constitutive expression of GFP from a plasmid. The optimum pulse voltage must balance cell viability, which decreases as voltage increases, and loading efficiency, which increases at higher voltages. Short pulse times of 0.05 ms facilitated PI and trehalose loading, whereas 0.5 ms or more was required for GST-GFP loading and DNA transfection. Multiple pulses increased per cell loading of all molecules, though there was a dramatic loss of viability with GST-GFP loading and DNA transfection, likely resulting from the longer pulse duration required to load these molecules.     

The cellular location and effect on nisin immunity of the NisI protein from Lactococcus lactis N8 expressed in Escherichia coli and L. lactis

Abstract Vibrio anguillarum and Pasteurella piscicida are Gram-negative bacteria which are pathogenic for marine fish and we report here the first successful transformation of these two bacteria by electroporation. The optimal conditions for electroporation included a field strength of 12.5 kV cm^t-1 and a time constant of 5 ms using 0.2-cm cuvettes. With these parameters, three plasmids (pSU2718, pCML, pEV3) with molecular sizes of 2.6, 5 and 13.7 kb, respectively were successfully transformed into both pathogens. V. anguillarum isolates belonging to serotypes O1 and O2 were transformed with greatest efficiency, 2.5 × 10³ transformants per μg DNA, being achieved in the serotype O2 strains using plasmid pCML. Strains of serotype O3 were not transformed. In the case of P. piscicida the maximum efficiency achieved was 9.8 × 10² transformants per μg pCML plasmid DNA. This optimized system will allow development of procedures for the genetic manipulation of these pathogens.     

Chemical and electroporated transformation of Edwardsiella ictaluri using three different plasmids

Transfer of DNA by conjugation has been the method generally used for genetic manipulation of Edwardsiella ictaluri because, previously, attempts to transform E. ictaluri by the uptake of naked DNA have apparently failed. We report here the successful transformation of seven strains of E. ictaluri using electroporation and two different chemical procedures [conventional calcium chloride (CaCl₂) and 'one-step' (polyethylene glycol, dimethyl sulfoxide and MgSO₄) protocols]. Seven strains of E. ictaluri were transformed using three different plasmids [pZsGreen, pUC18 and pET-30a(+)]. The highest transformation efficiency was achieved by electroporation (5.5±0.2 × 10⁴ transformants ng⁻¹ plasmid DNA) than with the CaCl₂ (8.1±6.1 × 10⁻¹ transformants ng⁻¹ plasmid) and the 'one-step transformation' protocol (2.5±2.7 transformants ng⁻¹ plasmid). An efficient transformation by electroporation required only 0.2 ng of plasmid compared with 200 ng required for the CaCl₂ and one-step protocols. The plasmids were stably maintained in E. ictaluri grown in the presence of antibiotic for 12 or more passages. The results of this study show that transformation of E. ictaluri by electroporation can be routinely used for the molecular genetic manipulation of this organism, and is a quicker and easier method than transformation performed by conjugation.     

Electroporation optimization to deliver plasmid DNA into dental follicle cells

Electroporation is a simple and versatile approach for DNA transfer but needs to be optimized for specific cells. We conducted square wave electroporation experiments for rat dental follicle cells under various conditions. These experiments indicated that the optimal electroporation electric field strength was 375 V/cm, and that plasmid concentrations greater than 0.18 μg/μL were required to achieve high transfection efficiency. BSA or fetal bovine serum in the pulsing buffer significantly improved cell survival and increased the number of transfected cells. The optimal pulsing duration was in the range of 45–120 ms at 375 V/cm. This electroporation protocol can be used to deliver DNA into dental follicle cells to study the roles of candidate genes in regulating tooth eruption. This is the first report showing the transfection of dental follicle cells using electroporation. The parameters determined in this study are likely to be applied to transfection of other fibroblast cells.     

RNA干扰猪NHEJ通路修复因子对HR效率的影响

非同源末端连接(nonhomologous end joining, NHEJ)是动物基因组DNA双链断裂(double-strand break, DSB)修复的优选途径,通过与同源重组(homologous recombination, HR)竞争DSB靶点,进而抑制HR的效率。为提高HR效率,本研究针对猪NHEJ通路修复关键因子PNKP、LIG4和NHEJ1的编码序列,设计并合成相应的靶向小干扰RNA (small interfering RNA, siRNA),组成若干对RNAi (RNA interference)系统,将RNAi系统与报告质粒SSA-GFP reporter、HDR -GFP system和ssODN-GFP system共转染至猪胎儿成纤维细胞(porcine fetal fibroblasts, PFFs),检测敲低上述NHEJ关键修复因子后对HR的影响。RNAi结果显示,针对PNKP、LIG4和NHEJ1设计的siRNA均可显著敲低PNKP、LIG4和NHEJ1基因的表达(P<0.05)。选择干扰效果最好的siRNA与报告载体共转染PFFs,结果表明干扰PNKP基因表达后可显著提高单链退火(single strand annealing, SSA)修复效率、双链或单链DNA介导的同源重组定向修复(homology-directed repair, HDR)效率分别为55.7%、37.4%和73.1% (P<0.05),而干扰LIG4和NHEJ1分别提高双链和单链介导的HDR效率为37.5% 和 76.9% (P<0.05)。     

Optimization of Electrotransfection Conditions of Mammalian Cells with Different Biological Features

We introduced eukaryotic expression plasmid pEGFP-N1 encoding green fluorescent protein (GFP) genes into cells with different biological features through electroporation. The effects of conditions, including voltage, capacitor flow, pulse cycle, DNA dosage and buffer, on transfection efficiency were investigated based on fluorescent microscopy and posttransfection survival rate of cells by staining with trypan blue. Better electrotransfection outcomes were achieved in the following epithelial cells: Vero cells at 300?V/850???F, PK15 cells at 300?V/500???F, MDCK cells at 200?V/600???F, F81 cells at 200?V/500???F, cancer cells MB49 at 300?V/400???F, Hela cells at 200?V/450???F, HF-29 cells at 300?V/800???F and B16F1 cells at 200?V/650???F. Among fibroblast cells, better electrotransfection was achieved in BHK21 cells at 300?V/600???F and ST cells at 200?V/750???F. RPMI-1640 medium without antibiotics and serum demonstrated higher electrotransfection efficiency and cell survival rate than other cell culture media as electroporation buffer. Our findings further prove that electroporation transfection is an effective method for genetic transfection. Cells with different biological features require varying transfection conditions to obtain higher transfection efficiency of target genes.     

Enhanced transfection efficiency and improved cell survival after electroporation of G2/M-synchronized cells and treatment with sodium butyrate.

To achieve high transfection efficiency in human fibroblasts with good preservation of proliferative capacity we developed an electroporation procedure that combines two distinct modalities: use of recipient cells synchronized in the late G2/mitotic phase of the cell cycle and treatment of cells post-electroporation with 5 mM butyrate. This combination enabled reduction of plasmid DNA concentration and electroporation voltage, both associated with cytotoxicity, while greatly enhancing transfection efficiencies. Although the method was primarily developed for transient expression it was also found to improve stable expression. This procedure should have wide applicability, particularly in studies seeking to identify DNA sequences that lead to inhibition of DNA synthesis and proliferation in human fibroblasts and other cells refractory to transfection.     

Optimization of transfection methods for Huh-7 and Vero cells: A comparative study

Availability of an efficient transfection protocol is the first determinant in success of gene transferring studies in mammalian cells which is accomplished experimentally for every single cell type. Herein, we provide data of a comparative study on optimization of transfection condition by electroporation and chemical methods for Huh-7 and Vero cells. Different cell confluencies, DNA/reagent ratios and total transfection volumes were optimized for two chemical reagents including jetPEI? and Lipofectamine? 2000. Besides, the effects of electric field strength and pulse length were investigated to improve electroporation efficiency. Transfection of cells by pEGFP-N1 vector and tracking the expression of GFP by FACS and Fluorescence Microscopy analysis were the employed methods to evaluate transfection efficiencies. Optimized electroporation protocols yielded 63.73 ± 2.36 and 73.9 ± 1.6% of transfection in Huh-7 and Vero cells respectively, while maximum achieved level of transfection by jetPEI? was 14.2 ± 0.69 and 28 ± 1.11% Huh-7 and Vero cells, respectively. Post transfectional chilling of the cells did not improve electrotransfection efficiency of Huh-7 cells. Compared to chemical based reagents, electroporation showed superior levels of transfection in both cell lines. The presented protocols should satisfy most of the experimental applications requiring high transfection efficiencies of these two cell lines.