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1.
四环素诱导表达系统（Tet-off／Tet-on系统）是比较成熟的真核生物基因诱导表达系统之一,具有高效、无毒、严密开／关功能的特点。猿猴病毒40T（SV40T）是一种病毒癌蛋白,其与肿瘤抑制蛋白p53和Rb结合,并使之失活,从而消除它们抑制细胞生长的功能,使细胞分裂加速,形成肿瘤。利用Tet-on系统首先稳定筛选获得了表达Tet-on系统调节元件rtTA的阳性细胞CHO-pTet-on,再通过稳定筛选又成功得到导入其反应元件的双阳性细胞CHO-pTet-on-pTRE2-SV40T-Hyg,经强力霉素诱导表达了目的基因SV40T,建立了Tet-on基因诱导表达系统的细胞诱导表达研究平台。 相似文献
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HTLV-I tax induces cellular proteins that activate the kappa B element in the IL-2 receptor alpha gene 总被引：91，自引：0，他引：91
D W Ballard E B?hnlein J W Lowenthal Y Wano B R Franza W C Greene 《Science (New York, N.Y.)》1988,241(4873):1652-1655
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J A Hoxie J D Alpers J L Rackowski K Huebner B S Haggarty A J Cedarbaum J C Reed 《Science (New York, N.Y.)》1986,234(4780):1123-1127
Cells infected with the human immunodeficiency virus (HIV) show decreased expression of the 58-kilodalton T4 (CD4) antigen on their surface. In this study, the effect of HIV infection on the synthesis of T4 messenger RNA (mRNA) and protein products was evaluated in T-cell lines. Metabolically labeled lysates from the T4+ cell line Sup-T1 were immunoprecipitated with monoclonal antibodies to T4. Compared with uninfected cells, HIV-infected Sup-T1 cells showed decreased amounts of T4 that coprecipitated with both the 120-kilodalton viral envelope and the 150-kilodalton envelope precursor molecules. In four of five HIV-producing T-cell lines studied, the steady-state levels of T4 mRNA were also reduced. Thus, the decreased T4 antigen on HIV-infected cells is due to at least three factors: reduced steady-state levels of T4-specific mRNA, reduced amounts of immunoprecipitable T4 antigen, and the complexing of available T4 antigen with viral envelope gene products. The data suggested that the T4 protein produced after infection may be complexed with viral envelope gene products within infected cells. Retroviral envelope-receptor complexes may thus participate in a general mechanism by which receptors for retroviruses are down-modulated and alterations in cellular function develop after infection. 相似文献
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The x gene is essential for HTLV replication 总被引：44，自引：0，他引：44
I S Chen D J Slamon J D Rosenblatt N P Shah S G Quan W Wachsman 《Science (New York, N.Y.)》1985,229(4708):54-58
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为了研究PtrGARP1与杨树木质化生长的相关性,明确木材发育及形成的分子机制,以毛果杨幼树为材料,提取各组织的cDNA进行PCR扩增,并构建植物表达载体在模式植物拟南芥中进行PtrGARP1组织表达分析。结果显示,PtrGARP1基因在毛果杨木质化组织内高丰度表达,且表达水平与幼茎木质化程度同步增加;用Gateway技术构建该基因启动子融合报告基因GUS的ProPtrGARP1::GUS植物表达载体,转化野生型拟南芥获得5个稳定表达的转基因株系;GUS活性染色分析显示,PtrGARP1基因启动子活性集中在转基因植株发达的维管组织内。这个结果暗示着PtrGARP1与杨树木质化生长相关,可能参与木材发育及形成。 相似文献
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Persistence of abnormal chloride conductance regulation in transformed cystic fibrosis epithelia 总被引：11，自引：0，他引：11
A M Jetten J R Yankaskas M J Stutts N J Willumsen R C Boucher 《Science (New York, N.Y.)》1989,244(4911):1472-1475
An airway epithelial cell line (CF/T43) was developed by infecting cultured airway epithelial cells from patients with cystic fibrosis (CF) with the pZIPneoSV(X)1/SV40T retrovirus and selecting for G418 resistance and ion transport properties. The distinctive chloride secretory phenotypes of the CF cell line CF/T43 and a normal cell line (NL/T4) were not perturbed by SV40T-induced cell transformation. Epithelial cell lines generated from CF cells with the SV40T gene can be used to test candidate CF genes and to evaluate the molecular mechanisms responsible for the CF phenotype. 相似文献
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ras-transformed cells: altered levels of phosphatidylinositol-4,5-bisphosphate and catabolites 总被引：65，自引：0，他引：65
Steady-state cellular levels of phosphatidylinositol-4,5-bisphosphate (PIP2), 1,2-diacylglycerol (DAG), and inositol phosphates have been measured in two different fibroblast cell lines (NIH 3T3 and NRK cells) before and after transformation with three different ras genes. At high cell density the ratio of DAG to PIP2 was 2.5- to 3-fold higher in the ras-transformed cells than in their untransformed counterparts. The sum of the water-soluble breakdown products of the polyphosphoinositides, inositol-1,4-bisphosphate and inositol-1,4,5-trisphosphate, was also elevated in ras-transformed NRK cells compared with nontransformed NRK cells. These findings suggest that the ras (p21) protein may act by affecting these levels, possibly as a regulatory element in the PIP2 breakdown pathway. 相似文献
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Specific expression of a tyrosine kinase gene, blk, in B lymphoid cells 总被引：36，自引：0，他引：36
Several pathways of transmembrane signaling in lymphocytes involve protein-tyrosine phosphorylation. With the exception of p56lck, a tyrosine kinase specific to T lymphoid cells that associates with the T cell transmembrane proteins CD4 and CD8, the kinases that function in these pathways are unknown. A murine lymphocyte complementary DNA that represents a new member of the src family has now been isolated and characterized. This complementary DNA, termed blk (for B lymphoid kinase), specifies a polypeptide of 55 kilodaltons that is related to, but distinct from, previously identified retroviral or cellular tyrosine kinases. The protein encoded by blk exhibits tyrosine kinase activity when expressed in bacterial cells. In the mouse and among cell lines, blk is specifically expressed in the B cell lineage. The tyrosine kinase encoded by blk may function in a signal transduction pathway that is restricted to B lymphoid cells. 相似文献
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Li B Yu H Zheng W Voll R Na S Roberts AW Williams DA Davis RJ Ghosh S Flavell RA 《Science (New York, N.Y.)》2000,288(5474):2219-2222
T helper 1 (TH1) cells mediate cellular immunity, whereas TH2 cells potentiate antiparasite and humoral immunity. We used a complementary DNA subtraction method, representational display analysis, to show that the small guanosine triphosphatase Rac2 is expressed selectively in murine TH1 cells. Rac induces the interferon-gamma (IFN-gamma) promoter through cooperative activation of the nuclear factor kappa B and p38 mitogen-activated protein kinase pathways. Tetracycline-regulated transgenic mice expressing constitutively active Rac2 in T cells exhibited enhanced IFN-gamma production. Dominant-negative Rac inhibited IFN-gamma production in murine T cells. Moreover, T cells from Rac2-/- mice showed decreased IFN-gamma production under TH1 conditions in vitro. Thus, Rac2 activates TH1-specific signaling and IFN-gamma gene expression. 相似文献
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Repression of rearranged mu gene and translocated c-myc in mouse 3T3 cells X Burkitt lymphoma cell hybrids 总被引：18，自引：0，他引：18
K Nishikura A ar-Rushdi J Erikson E DeJesus D Dugan C M Croce 《Science (New York, N.Y.)》1984,224(4647):399-402
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东莞大蕉超表达拟南芥CBF1基因及其抗寒性检测 总被引：2，自引：1，他引：1
【目的】研究超表达拟南芥CBF1基因（AtCBF1）对大蕉抗寒性的影响,为从大蕉克隆抗寒相关基因奠定基础。【方法】采用农杆菌介导法转化东莞大蕉的胚性细胞悬浮系,获得转AtCBF1基因的大蕉植株;利用GUS组织染色、PCR、RT-PCR以及RT-qPCR对转基因植株进行鉴定;比较低温处理后的转基因株系和对照的冷害特征以及超氧化物歧化酶（SOD）活性和丙二醛（MDA）含量等生理生化指标,鉴定转基因大蕉植株的抗寒能力。【结果】试验共获得6个抗性再生转化系。GUS组织染色结果表明,除T1外,其余均为阳性;PCR鉴定结果表明,AtCBF1在6个抗性再生转化系均为阳性,而GUS基因在T1转化系中没有检测出;RT-PCR结果表明,AtCBF1在6个转化系均得到表达,对T1、T2和T3 3个转化系进行RT-qPCR检测发现,AtCBF1基因在3个转基因株系表达水平存在差异;在低温处理下,转基因植株的叶片相对电导率、MDA的累积都低于非转基因植株,而SOD总活性高于对照;低温处理条件下,转基因植株叶片的冷害症状明显轻于对照。【结论】AtCBF1在大蕉中超表达,具有增强大蕉SOD活性,降低因低温导致的MDA含量和离子渗漏率,缓解质膜过氧程度,进而改善大蕉植株抗低温胁迫的能力。 相似文献
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Knockdown of the Meq gene in Marek's disease tumor cell line MSB1 might induce cell apoptosis and inhibit cell proliferation and invasion 
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下载免费PDF全文 ZHAO Chun-fang LI Xin HAN Bo QU Lu-jiang LIU Chang-jun Jiu Zhou SONG YANG Ning LIAN Ling 《农业科学学报》2020,19(11):2767-2774
Marek's disease (MD), a highly cell-associated and contagious disease of chickens caused by Marek's disease virus (MDV) can result in neural lesions, immunosuppression and neoplasia in chicken. The Meq gene is an important oncogene in the MDV genome, and it is expressed highly in MD tumor tissues and MD T-lymphoblastoid cell lines. An experiment was conducted to elucidate the role of Meq in MD tumor transformation. RNA interference technology was used to block its expression, and then analyzed the biological effects of Meq knockdown on the MD tumor cell line MSB1. A small interfering RNA with an interference efficiency of 70% (P<0.01) was transfected into MSB1 cells to knock down the expression of Meq gene. The cell proliferation, cycle and apoptosis were detected post-Meq knockdown. The results showed that MSB1 cell proliferation was downregulated remarkably at 48 h (P<0.01), 60 h (P<0.05) and 72 h (P<0.01) post-Meq knockdown. The cell cycle was unaffected (P>0.05). B-cell lymphoma 2 gene (BCL2) was anti-apoptotic and caspase-6 was the effector in the apoptosis pathway. The activity of caspase-6 was upregulated (P<0.05) significantly and BCL2 gene expression was downregulated (P<0.05) significantly post-Meq knockdown, suggesting cell apoptosis might be induced. MSB1 cell migration did not exhibit any obvious change (P>0.05) post-Meq knockdown, but the expression of two genes (matrix metalloproteinase 2 (MMP2) and MMP9) that are correlated closely to cell invasion was downregulated (P<0.05) remarkably post-Meq knockdown. The Meq knockdown might affect the main features of tumorous cells, including proliferation, apoptosis, and invasion, suggesting that the Meq gene might play a crucial role in interfering with lymphomatous cell transformation. 相似文献
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Sequence-specific binding of human Ets-1 to the T cell receptor alpha gene enhancer 总被引：48，自引：0，他引：48
I C Ho N K Bhat L R Gottschalk T Lindsten C B Thompson T S Papas J M Leiden 《Science (New York, N.Y.)》1990,250(4982):814-818
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Induction of self-tolerance in T cells but not B cells of transgenic mice expressing little self antigen 总被引：28，自引：0，他引：28
S Adelstein H Pritchard-Briscoe T A Anderson J Crosbie G Gammon R H Loblay A Basten C C Goodnow 《Science (New York, N.Y.)》1991,251(4998):1223-1225
Self-tolerance to a transgene-encoded protein, hen egg lysozyme, was examined in the T and B cell repertoires of a series of lines of transgenic mice that expressed different serum concentrations of soluble lysozyme. T cells were tolerant in all lines in which lysozyme was expressed irrespective of the antigen concentration, whereas B cell tolerance did not occur when the serum lysozyme concentration was less than 1.5 nanograms per milliliter (0.1 nM). Induction of elevated transgene expression could restore B cell tolerance. These findings support the hypothesis that autoimmune disease may in some instances arise through a bypass of T cell tolerance. 相似文献
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试验尝试建立稳定表达外源基因的人成纤维细胞系。取成年男性包皮皮肤的皮下组织,分离培养人皮肤成纤维细胞,分别采用脂质体和慢病毒载体介导转染人皮肤成纤维细胞表达绿色荧光蛋白。结果显示,来自成年人包皮皮下组织的成纤维细胞呈梭形,具有快速的增殖和稳定的生长性能。脂质体介导转染的人皮肤成纤维细胞绿色荧光蛋白表达不稳定,阳性细胞表达率低,转染后的人成纤维细胞变得更为细长,细胞生长速度降低。慢病毒载体介导人皮肤成纤维细胞高效稳定表达绿色荧光蛋白,转染后细胞生长性能和形态没有变化,经过多次传代和冻存复苏对人皮肤成纤维细胞绿色荧光蛋白的表达没有影响,通过流式细胞仪对慢病毒介导表达绿色荧光蛋白的人皮肤成纤维细胞检测显示,绿色荧光蛋白表达阳性率为99.85%,并且表达绿色荧光蛋白的人皮肤成纤维细胞细胞均一程度为76.05%。试验证实了慢病毒载体能够高效稳定介导人皮肤成纤维细胞表达绿色荧光蛋白。 相似文献
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Microinjected c-myc as a competence factor 总被引：54，自引：0，他引：54
L Kaczmarek J K Hyland R Watt M Rosenberg R Baserga 《Science (New York, N.Y.)》1985,228(4705):1313-1315
While a number of oncogenes are expressed in a cell cycle-dependent manner, their role in the control of cell proliferation can only be established by a direct functional assay. The c-myc protein, upon microinjection into nuclei of quiescent Swiss 3T3 cells, cooperated with platelet-poor plasma in the stimulation of cellular DNA synthesis. This suggests that c-myc protein, like platelet-derived growth factor (PDGF), may act as a competence factor in the cell cycle to promote the progression of cells to S phase. The presence in the medium of an antibody against PDGF abolished DNA synthesis induced by microinjected PDGF; however, the microinjected c-myc protein stimulated DNA synthesis even when its own antibody was present in the medium. The c-myc protein may act as an intracellular competence factor, while PDGF expresses its biological activity only from outside the cells. 相似文献
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[目的]建立具有绿色荧光标记的表达T7RNA聚合酶的稳定细胞系。[方法]从BL21（DE3）大肠杆菌中克隆出T7RNAP基因,定向克隆进质粒FG12后,构建了表达T7RNA聚合酶基因（T7）的Lenti-virus重组质粒FG12-T7RNAP。用此重组质粒转染293T细胞,WB可检测出瞬时表达的T7RNAP蛋白;利用辅助质粒对表达T7的非复制型Lenti-virus病毒进行体外包装,所获得的非复制型Lenti-virus病毒感染BHK-21细胞,利用GFP通过流式细胞分选仪筛选表达T7的细胞系,并利用WB检测基因的表达。[结果]通过WB检测出不同代次的阳性细胞中均能稳定表达目的基因T7RNA聚合酶。[结论]T7RNA聚合酶能顺利在真核细胞内表达,并在此基础上建立的稳定细胞系为RNA病毒体内拯救技术平台的建立奠定了基础。 相似文献