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Sample records for recombinant adenovirus-mediated gene

  1. Evaluation of recombinant adenovirus-mediated gene delivery for expression of tracer genes in catecholaminergic neurons

    PubMed Central

    Kim, Mi-La; Han, Shengjun; Lee, Sat-Byol; Kim, Jung Hye; Ahn, Hee Kyung

    2010-01-01

    Selective labeling of small populations of neurons of a given phenotype for conventional neuronal tracing is difficult because tracers can be taken up by all neurons at the injection site, resulting in nonspecific labeling of unrelated pathways. To overcome these problems, genetic approaches have been developed that introduce tracer proteins as transgenes under the control of cell-type-specific promoter elements for visualization of specific neuronal pathways. The aim of this study was to explore the use of tracer gene expression for neuroanatomical tracing to chart the complex interconnections of the central nervous system. Genetic tracing methods allow for expression of tracer molecules using cell-type-specific promoters to facilitate neuronal tracing. In this study, the rat tyrosine hydroxylase (TH) promoter and an adenoviral delivery system were used to express tracers specifically in dopaminergic and noradrenergic neurons. Region-specific expression of the transgenes was then analyzed. Initially, we characterized cell-type-specific expression of GFP or RFP in cultured cell lines. We then injected an adenovirus carrying the tracer transgene into several brain regions using a stereotaxic apparatus. Three days after injection, strong GFP expression was observed in the injected site of the brain. RFP and WGA were expressed in a cell-type-specific manner in the cerebellum, locus coeruleus, and ventral tegmental regions. Our results demonstrate that selective tracing of catecholaminergic neuronal circuits is possible in the rat brain using the TH promoter and adenoviral expression. PMID:21189997

  2. Adenovirus-mediated gene transfer to tumor cells.

    PubMed

    Cascalló, Manel; Alemany, Ramon

    2004-01-01

    Cell transduction in vitro is only the first step toward proving that a genetherapy vector can be useful to treat tumors. However, tumor targeting in vivo is now the milestone for gene therapy to succeed against disseminated cancer. Therefore, most valuable information is obtained from studies of vector biodistribution. Owing to the hepatotropism of adenoviral vectors, a particularly important parameter is the tumor/liver ratio. This ratio can be given at the level of gene expression if the amount of transgene expression is measured. To optimize the targeting, however, the levels of viral particles that reach the tumor compared to other organs must be studied. Most of this chapter deals with methods to quantify the virus fate in tumor-bearing animals. We present a radioactive labeling method that can be used to study biodistribution. After a small section dealing with tumor models, we describe methods to quantify different parameters related to adenovirus-mediated tumor targeting. PMID:14970588

  3. Adenovirus-mediated gene transfer to ciliated airway epithelia requires prolonged incubation time.

    PubMed Central

    Zabner, J; Zeiher, B G; Friedman, E; Welsh, M J

    1996-01-01

    The efficiency of adenovirus-mediated gene transfer to airway epithelia will be an important factor in determining whether recombinant adenoviruses can be developed as vectors for transferring cystic fibrosis transmembrane conductance regulator (CFTR) cDNA to patients with cystic fibrosis. Current understanding of the biology of CF lung disease suggests that vectors should express transgene in mature, ciliated airway epithelia. We evaluated the efficiency of adenovirus-mediated gene transfer to primary cultures of normal and CF human airway epithelia. Our studies showed that the airway cells developed from an undifferentiated epithelium with markers characteristic of basal cells and a surface covered by short microvilli 3 days after seeding to a mature epithelium whose apical surface was covered with cilia by 10 to 14 days. The ability of adenovirus vectors to express a reporter gene and to correct defective cyclic AMP-stimulated Cl- transport in CF epithelia was correlated inversely with the state of differentiation. However, the inefficiency of adenovirus-mediated gene transfer could be partially corrected when the contact time between vector and epithelium was prolonged. After prolonged contact, we observed complete correction of the CF Cl- transport defect in differentiated CF airway epithelia in culture and of the Cl- transport defect in the nasal epithelia of mice homozygous for the deltaF508 mutation. The fact that gene transfer to airway epithelia required prolonged incubation with vector contrasts with the rapid infection observed in cell models such as 293 and HeLa cells, which are commonly used to study adenovirus infection. Gene transfer observed after prolonged incubation may result from mechanisms different from those that mediate infection of 293 cells. These observations suggest that interventions that either increase the contact time or alter the epithelium or the vector may be required to facilitate gene transfer to ciliated respiratory epithelia

  4. Adenovirus-Mediated Efficient Gene Transfer into Cultured Three-Dimensional Organoids

    PubMed Central

    Wang, Ning; Zhang, Hongyu; Zhang, Bing-Qiang; Liu, Wei; Zhang, Zhonglin; Qiao, Min; Zhang, Hongmei; Deng, Fang; Wu, Ningning; Chen, Xian; Wen, Sheng; Zhang, Junhui; Liao, Zhan; Zhang, Qian; Yan, Zhengjian; Yin, Liangjun; Ye, Jixing; Deng, Youlin; Luu, Hue H.; Haydon, Rex C.; Liang, Houjie; He, Tong-Chuan

    2014-01-01

    Three-dimensional organoids have been recently established from various tissue-specific progenitors (such as intestinal stem cells), induced pluripotent stem cells, or embryonic stem cells. These cultured self-sustaining stem cell–based organoids may become valuable systems to study the roles of tissue-specific stem cells in tissue genesis and disease development. It is thus conceivable that effective genetic manipulations in such organoids may allow us to reconstruct disease processes and/or develop novel therapeutics. Recombinant adenoviruses are one of the most commonly used viral vectors for in vitro and in vivo gene deliveries. In this study, we investigate if adenoviruses can be used to effectively deliver transgenes into the cultured “mini-gut” organoids derived from intestinal stem cells. Using adenoviral vectors that express fluorescent proteins, we demonstrate that adenoviruses can effectively deliver transgenes into the cultured 3-D “mini-gut” organoids. The transgene expression can last at least 10 days in the cultured organoids. As a proof-of-principle experiment, we demonstrate that adenovirus-mediated noggin expression effectively support the survival and self-renewal of mini-gut organoids, while adenovirus-mediated expression of BMP4 inhibits the self-sustainability and proliferation of the organoids. Thus, our results strongly suggest that adenovirus vectors can be explored as effective gene delivery vehicles to introduce genetic manipulations in 3-D organoids. PMID:24695466

  5. Adenovirus-mediated efficient gene transfer into cultured three-dimensional organoids.

    PubMed

    Wang, Ning; Zhang, Hongyu; Zhang, Bing-Qiang; Liu, Wei; Zhang, Zhonglin; Qiao, Min; Zhang, Hongmei; Deng, Fang; Wu, Ningning; Chen, Xian; Wen, Sheng; Zhang, Junhui; Liao, Zhan; Zhang, Qian; Yan, Zhengjian; Yin, Liangjun; Ye, Jixing; Deng, Youlin; Luu, Hue H; Haydon, Rex C; Liang, Houjie; He, Tong-Chuan

    2014-01-01

    Three-dimensional organoids have been recently established from various tissue-specific progenitors (such as intestinal stem cells), induced pluripotent stem cells, or embryonic stem cells. These cultured self-sustaining stem cell-based organoids may become valuable systems to study the roles of tissue-specific stem cells in tissue genesis and disease development. It is thus conceivable that effective genetic manipulations in such organoids may allow us to reconstruct disease processes and/or develop novel therapeutics. Recombinant adenoviruses are one of the most commonly used viral vectors for in vitro and in vivo gene deliveries. In this study, we investigate if adenoviruses can be used to effectively deliver transgenes into the cultured "mini-gut" organoids derived from intestinal stem cells. Using adenoviral vectors that express fluorescent proteins, we demonstrate that adenoviruses can effectively deliver transgenes into the cultured 3-D "mini-gut" organoids. The transgene expression can last at least 10 days in the cultured organoids. As a proof-of-principle experiment, we demonstrate that adenovirus-mediated noggin expression effectively support the survival and self-renewal of mini-gut organoids, while adenovirus-mediated expression of BMP4 inhibits the self-sustainability and proliferation of the organoids. Thus, our results strongly suggest that adenovirus vectors can be explored as effective gene delivery vehicles to introduce genetic manipulations in 3-D organoids. PMID:24695466

  6. A novel combination of promoter and enhancers increases transgene expression in vascular smooth muscle cells in vitro and coronary arteries in vivo after adenovirus-mediated gene transfer

    PubMed Central

    Appleby, CE; Kingston, PA; David, A; Gerdes, CA; Umaña, P; Castro, MG; Lowenstein, PR; Heagerty, AM

    2010-01-01

    Recombinant adenoviruses are employed widely for vascular gene transfer. Vascular smooth muscle cells (SMCs) are a relatively poor target for transgene expression after adenovirus-mediated gene delivery, however, even when expression is regulated by powerful, constitutive viral promoters. The major immediate-early murine cytomegalovirus enhancer/promoter (MIEmCMV) elicits substantially greater transgene expression than the human cytomegalovirus promoter (MIEhCMV) in all cell types in which they have been compared. The Woodchuck hepatitis virus post-transcriptional regulatory element (WPRE) increases transgene expression in numerous cell lines, and fragments of the smooth muscle myosin heavy chain (SMMHC) promoter increase expression within SMC from heterologous promoters. We therefore, compared the expression of β-galactosidase after adenovirus-mediated gene transfer of lacZ under the transcriptional regulation of a variety of combinations of the promoters and enhancers described, in vitro and in porcine coronary arteries. We demonstrate that inclusion of WPRE and a fragment of the rabbit SMMHC promoter along with MIEmCMV increases β-galactosidase expression 90-fold in SMC in vitro and ≈40-fold in coronary arteries, compared with vectors in which expression is regulated by MIEhCMV alone. Expression cassette modification represents a simple method of improving adenovirus-mediated vascular gene transfer efficiency and has important implications for the development of efficient cardiovascular gene therapy strategies. PMID:12907954

  7. Mechanism by which calcium phosphate coprecipitation enhances adenovirus-mediated gene transfer.

    PubMed

    Walters, R; Welsh, M

    1999-11-01

    Delivery of a normal copy of CFTR cDNA to airway epithelia may provide a novel treatment for cystic fibrosis lung disease. Unfortunately, current vectors are inefficient because of limited binding to the apical surface of airway epithelia. We recently reported that incorporation of adenovirus in a calcium phosphate coprecipitate (Ad:CaPi) improves adenovirus-mediated gene transfer to airway epithelia in vitro and in vivo. To understand better how coprecipitation improves gene transfer, we tested the hypothesis that incorporation in a CaPi coprecipitate increases the binding of adenovirus to the apical surface of differentiated human airway epithelia. When a Cy3-labelled adenovirus was delivered in a coprecipitate, binding increased 54-fold as compared with adenovirus alone. Moreover, infection by Ad:CaPi was independent of fiber knob-CAR and penton base-integrin interactions. After binding to the cell surface, the virus must enter the cell in order to infect. We hypothesized that Ad:CaPi may stimulate fluid phase endocytosis, thereby facilitating entry. However, we found that neither adenovirus nor Ad:CaPi coprecipitates altered fluid phase endocytosis. Nevertheless, Ad:CaPi preferentially infected cells showing endocytosis. Thus, CaPi coprecipitation improves adenovirus-mediated gene transfer by coating the epithelial surface with a layer of virus which enters cells during the normal process of endocytosis. PMID:10602380

  8. Adenovirus-Mediated Gene Transfer in Mesenchymal Stem Cells Can Be Significantly Enhanced by the Cationic Polymer Polybrene

    PubMed Central

    Zhao, Chen; Wu, Ningning; Deng, Fang; Zhang, Hongmei; Wang, Ning; Zhang, Wenwen; Chen, Xian; Wen, Sheng; Zhang, Junhui; Yin, Liangjun; Liao, Zhan; Zhang, Zhonglin; Zhang, Qian; Yan, Zhengjian; Liu, Wei; Wu, Di; Ye, Jixing; Deng, Youlin; Zhou, Guolin; Luu, Hue H.; Haydon, Rex C.; Si, Weike; He, Tong-Chuan

    2014-01-01

    Mesenchymal stem cells (MSCs) are multipotent progenitors, which can undergo self-renewal and give rise to multi-lineages. A great deal of attentions have been paid to their potential use in regenerative medicine as potential therapeutic genes can be introduced into MSCs. Genetic manipulations in MSCs requires effective gene deliveries. Recombinant adenoviruses are widely used gene transfer vectors. We have found that although MSCs can be infected in vitro by adenoviruses, high virus titers are needed to achieve high efficiency. Here, we investigate if the commonly-used cationic polymer Polybrene can potentiate adenovirus-mediated transgene delivery into MSCs, such as C2C12 cells and iMEFs. Using the AdRFP adenovirus, we find that AdRFP transduction efficiency is significantly increased by Polybrene in a dose-dependent fashion peaking at 8 μg/ml in C2C12 and iMEFs cells. Quantitative luciferase assay reveals that Polybrene significantly enhances AdFLuc-mediated luciferase activity in C2C12 and iMEFs at as low as 4 μg/ml and 2 μg/ml, respectively. FACS analysis indicates that Polybrene (at 4 μg/ml) increases the percentage of RFP-positive cells by approximately 430 folds in AdRFP-transduced iMEFs, suggesting Polybrene may increase adenovirus infection efficiency. Furthermore, Polybrene can enhance AdBMP9-induced osteogenic differentiation of MSCs as early osteogenic marker alkaline phosphatase activity can be increased more than 73 folds by Polybrene (4 μg/ml) in AdBMP9-transduced iMEFs. No cytotoxicity was observed in C2C12 and iMEFs at Polybrene up to 40 μg/ml, which is about 10-fold higher than the effective concentration required to enhance adenovirus transduction in MSCs. Taken together, our results demonstrate that Polybrene should be routinely used as a safe, effective and inexpensive augmenting agent for adenovirus-mediated gene transfer in MSCs, as well as other types of mammalian cells. PMID:24658746

  9. Prevention of bleomycin-induced pulmonary fibrosis after adenovirus-mediated transfer of the bacterial bleomycin resistance gene.

    PubMed Central

    Tran, P L; Weinbach, J; Opolon, P; Linares-Cruz, G; Reynes, J P; Grégoire, A; Kremer, E; Durand, H; Perricaudet, M

    1997-01-01

    A serious limitation in the use of the DNA-cleaving, antitumoral-antibiotic, bleomycin during chemotherapy is pulmonary toxicity. Lung injury induced by bleomycin is characterized by an increased deposition of interstitial extracellular matrix proteins in the alveolar wall that compromises respiratory function. Several drugs have been tested in animal models to prevent the pulmonary toxicity of bleomycin, but have not led to a useful clinical treatment because of their adverse effects on other tissues. We have shown that transgenic mice expressing Streptoalloteichus hindustanus (Sh) ble bleomycin resistance protein in pulmonary epithelial cells in the lungs are protected against bleomycin-induced toxicity in lungs. In the present study, we used intranasal administration by adenovirus-mediated gene transfer of the bleomycin resistance Sh ble gene to mouse lung for prevention of bleomycin-induced pulmonary fibrosis. We constructed recombinant adenoviruses Ad.CMVble and Ad.RSVble harboring the bleomycin resistance Sh ble gene under the control of the cytomegalovirus early promoter and the Rous sarcoma virus early promoter, respectively. Transgene expression was detected in epithelia of conducting airways and alveolar septa by immunostaining with a rabbit polyclonal antibody directed against the bleomycin resistance protein and persisted for the duration of drug treatment; i.e., up to 17 d. No toxic effect was seen in adenovirus-treated mice. Pretreatment of mice with Ad.CMVble or Ad.RSVble completely prevented collagen deposition 42-133 d after bleomycin treatment, as measured by lung OH-proline content. Histologic studies indicated that there was little or no lung injury in the adenovirus/bleomycin-treated mice compared with the bleomycin-treated mice. These observations may lead to new approaches for the prevention of bleomycin-induced pulmonary fibrosis. PMID:9045862

  10. Adenovirus-mediated Cre deletion of floxed sequences in primary mouse cells is an efficient alternative for studies of gene deletion

    PubMed Central

    Prost, Sandrine; Sheahan, Sharon; Rannie, Dominic; Harrison, David J.

    2001-01-01

    This study evaluates the utility of Cre-expressing adenovirus for deletion of floxed genes in primary cells using primary murine hepatocytes. Adenovirus infection was very efficient, even at very low MOI (>95% infection at a MOI of 6) and did not reduce viability. High level LacZ expression was cytotoxic to hepatocytes but Cre expression had no effect on viability. Cre-mediated recombination was completed within a timespan that permits experimentation during primary culture (>95% recombination after 24 h), independently of the number of floxed alleles per cell. Recombination did not induce p53 or produce cytological nuclear abnormalities (even in polyploid cells). Contrary to expectation, deletion of DNA ligase 1 did not alter cell cycle progression, although Cre expression hastens entry to S phase from G1, independently of the presence of floxed sequences. We conclude that adenovirus-mediated deletion of floxed alleles in primary cells is a straightforward and highly efficient tool for conducting preliminary studies of conditional gene targeting. Primary cells have advantages of differentiation, relative purity and ease of experimentation within controlled conditions, while avoiding confounding problems encountered in vivo (i.e. target cell specificity, kinetics and level of recombination, and elicitation of inflammatory and immune responses). This system could help identify important phenotypic effects and design and interpret in vivo studies. PMID:11504888

  11. The Effect of Adenovirus-Mediated Gene Expression of FHIT in Small Cell Lung Cancer Cells

    PubMed Central

    Zandi, Roza; Xu, Kai; Poulsen, Hans S.; Roth, Jack A.; Ji, Lin

    2012-01-01

    The candidate tumor suppressor fragile histidine traid (FHIT) is frequently inactivated in small cell lung cancer (SCLC). Mutations in the p53 gene also occur in the majority of SCLC leading to the accumulation of the mutant protein. Here we evaluated the effect of FHIT gene therapy alone or in combination with the mutant p53-reactivating molecule, PRIMA-1Met/APR-246, in SCLC. Overexpression of FHIT by recombinant adenoviral vector (Ad-FHIT)-mediated gene transfer in SCLC cells inhibited their growth by inducing apoptosis and when combined with PRIMA-1Met/APR-246, a synergistic cell growth inhibition was achieved. PMID:22085272

  12. Efficient adenovirus-mediated transfer of a human minidystrophin gene to skeletal muscle of mdx mice.

    PubMed

    Ragot, T; Vincent, N; Chafey, P; Vigne, E; Gilgenkrantz, H; Couton, D; Cartaud, J; Briand, P; Kaplan, J C; Perricaudet, M

    1993-02-18

    Duchenne progressive muscular dystrophy is a lethal and common X-linked genetic disease caused by the absence of dystrophin, a 427K protein encoded by a 14 kilobase transcript. Two approaches have been proposed to correct the dystrophin deficiency in muscle. The first, myoblast transfer therapy, uses cells from normal donors, whereas the second involves direct intramuscular injection of recombinant plasmids expressing dystrophin. Adenovirus is an efficient vector for in vivo expression of various foreign genes. It has recently been demonstrated that a recombinant adenovirus expressing the lac-Z reporter gene can infect stably many mouse tissues, particularly muscle and heart. We have tested the ability of a recombinant adenovirus, containing a 6.3 kilobase pair Becker-like dystrophin complementary DNA driven by the Rous sarcoma virus promoter to direct the expression of a 'minidystrophin' in infected 293 cells and C2 myoblasts, and in the mdx mouse, after intramuscular injection. We report here that in vivo, we have obtained a sarcolemmal immunostaining in up to 50% of fibres of the injected muscle. PMID:8437625

  13. In vivo expression of adenovirus-mediated lacZ gene in murine nasal mucosa.

    PubMed

    Arimoto, Yukiko; Nagata, Hiroshi; Isegawa, Naohisa; Kumahara, Keiichiro; Isoyama, Kyoko; Konno, Akiyoshi; Shirasawa, Hiroshi

    2002-09-01

    Adenovirus is a good tool for transferring exogenous genes into various organs because the virus has a wide spectrum of infection. In this report, we demonstrate that a recombinant adenovirus, Ax1CAlacZ, can transfer an exogenous lacZ gene into murine nasal mucosa in vivo. The efficiency of the exogenous gene expression varied for different cell types and was improved by optimizing the method of administration. In the olfactory region, the olfactory epithelia, sustentacular cells and olfactory nerve efficiently expressed lacZ gene transferred by Ax1CAlacZ using either of two administration methods, dripping or injecting. In contrast, in the respiratory region, the respiratory epithelia but not the subepithelial tissues expressed lacZ gene transferred by Ax1CAlacZ, and the efficiency of the gene transfer, which was low when the virus was administered by nasal drops, was improved when the virus was administered by injection. Our study demonstrated that gene transfer mediated by adenovirus is more efficient in the olfactory epithelia than in the respiratory epithelia, and may be applicable to nasal or paranasal diseases such as olfactory epithelial disturbances. PMID:12403125

  14. Adenovirus-mediated interleukin-12 gene therapy for metastatic colon carcinoma.

    PubMed Central

    Caruso, M; Pham-Nguyen, K; Kwong, Y L; Xu, B; Kosai, K I; Finegold, M; Woo, S L; Chen, S H

    1996-01-01

    Recombinant adenoviral mediated delivery of suicide and cytokine genes has been investigated as a treatment for hepatic metastases of colon carcinoma in mice. Liver tumors were established by intrahepatic implantation of a poorly immunogenic colon carcinoma cell line (MCA-26), which is syngeneic in BALB/c mice. Intratumoral transfer of the herpes simplex virus type 1 thymidine kinase (HSV-tk) and the murine interleukin (mIL)-2 genes resulted in substantial hepatic tumor regression, induced an effective systemic antitumoral immunity in the host and prolonged the median survival time of the treated animals from 22 to 35 days. The antitumoral immunity declined gradually, which led to tumor recurrence over time. A recombinant adenovirus expressing the mIL-12 gene was constructed and tested in the MCA-26 tumor model. Intratumoral administration of this cytokine vector alone increased significantly survival time of the animals with 25% of the treated animals still living over 70 days. These data indicate that local expression of IL-12 may also be an attractive treatment strategy for metastatic colon carcinoma. Images Fig. 5 PMID:8876130

  15. Suppression of proliferative cholangitis in a rat model with direct adenovirus-mediated retinoblastoma gene transfer to the biliary tract.

    PubMed

    Terao, R; Honda, K; Hatano, E; Uehara, T; Yamamoto, M; Yamaoka, Y

    1998-09-01

    Proliferative cholangitis (PC) associated with hepatolithiasis develops the stricture of main bile ducts, and is the main cause of residual and/or recurrent stones after repeated treatments for hepatolithiasis. The aim of this study was to inhibit PC using the cytostatic gene therapy with direct adenovirus-mediated retinoblastoma (Rb) gene transfer to the biliary tract. PC was induced by introducing a fine nylon thread into the bile duct in a rat model. The adenovirus vector encoding a nonphosphorylatable, constitutively active form of retinoblastoma gene product (AdRb) was administered directly into the biliary tract. The adenovirus vector encoding beta-galactosidase (AdlacZ) was also given as a control. The bile duct wall thickness and 5'-bromodeoxyuridine (BrdU) labeling index were compared among uninfected, AdlacZ-infected, and AdRb-infected PC rats. The Rb expression in the bile duct was detected using reverse-transcription polymerase chain reaction (RT-PCR) and immunohistochemical study. AdRb-infected bile ducts showed inhibition of the epithelial and fibrous tissue proliferation and the peribiliary gland hyperplasia, resulting in a significant reduction of wall thickness compared with uninfected and AdlacZ-infected ones. The BrdU labeling index was 4.87% +/- 3.06% in the AdRb-infected bile ducts, while those of uninfected and AdlacZ-infected ones were 15.48% +/- 4.61% and 11.72% +/- 1.23%, respectively (P < .05). In conclusion, our cytostatic gene therapy approach using direct Rb gene transfer into the biliary tract suppressed PC in a rat model and may offer an effective therapeutic option for reducing recurrences following treatments against hepatolithiasis. PMID:9731547

  16. Replication-competent adenovirus-mediated suicide gene therapy with radiation in a preclinical model of pancreatic cancer.

    PubMed

    Freytag, Svend O; Barton, Kenneth N; Brown, Stephen L; Narra, Vinod; Zhang, Yingshu; Tyson, Don; Nall, Colleen; Lu, Mei; Ajlouni, Munther; Movsas, Benjamin; Kim, Jae Ho

    2007-09-01

    In preparation for a Phase I trial, we evaluated the efficacy and toxicity of replication-competent adenovirus-mediated suicide gene therapy in combination with radiation in a preclinical model of pancreatic cancer. Human MiaPaCa-2 and PANC-1 pancreatic adenocarcinoma cells were found to be sensitive to the oncolytic effects of the Ad5-yCD/mutTK(SR39)rep-ADP adenovirus and also to the cytotoxic effects of the yeast cytosine deaminase (yCD) and herpes simplex virus thymidine kinase (HSV-1 TK(SR39)) genes in vitro. Combining Ad5-yCD/mutTK(SR39)rep-ADP-mediated suicide gene therapy with radiation significantly increased tumor control beyond that of either modality alone. Injection of Ad5-yCD/mutTK(SR39)rep-ADP in the dog pancreas at doses (10(12) virus particle (vp)) to be used in humans resulted in mild pancreatitis but not peritonitis or hepatotoxicity. Following administration of 9-(4-[(18)F]-fluoro-3-hydroxymethylbutyl)guanine ([(18)F]-FHBG), a positron-emitting substrate of HSV-1 TK, Ad5-yCD/mutTK(SR39)rep-ADP activity could be monitored non-invasively by positron emission tomography (PET). [(18)F]-FHBG uptake was readily detected in the pancreas but not in other major abdominal organs, indicating that little of the injected adenovirus disseminates to collateral tissues. These results demonstrate that Ad5-yCD/mutTK(SR39)rep-ADP-mediated suicide gene therapy has the potential to augment the effectiveness of pancreatic radiotherapy without resulting in excessive toxicity. Hence they provide the scientific basis for an ongoing Phase I trial in pancreatic cancer. PMID:17551507

  17. Effects of Adenovirus-Mediated Delivery of the Human Hepatocyte Growth Factor Gene in Experimental Radiation-Induced Heart Disease

    SciTech Connect

    Hu Shunying; Chen Yundai; Li Libing; Chen Jinlong; Wu Bin; Zhou, Xiao; Zhi Guang; Li Qingfang; Wang Rongliang; Duan Haifeng; Guo Zikuan; Yang Yuefeng; Xiao Fengjun; Wang Hua; Wang Lisheng

    2009-12-01

    Purpose: Irradiation to the heart may lead to late cardiovascular complications. The purpose of this study was to investigate whether adenovirus-mediated delivery of the human hepatocyte growth factor gene could reduce post-irradiation damage of the rat heart and improve heart function. Methods and Materials: Twenty rats received single-dose irradiation of 20 Gy gamma ray locally to the heart and were randomized into two groups. Two weeks after irradiation, these two groups of rats received Ad-HGF or mock adenovirus vector intramyocardial injection, respectively. Another 10 rats served as sham-irradiated controls. At post-irradiation Day 120, myocardial perfusion was tested by myocardial contrast echocardiography with contrast agent injected intravenously. At post-irradiation Day 180, cardiac function was assessed using the Langendorff technique with an isolated working heart model, after which heart samples were collected for histological evaluation. Results: Myocardial blood flow was significantly improved in HGF-treated animals as measured by myocardial contrast echocardiography at post-irradiation Day 120 . At post-irradiation Day 180, cardiac function was significantly improved in the HGF group compared with mock vector group, as measured by left ventricular peak systolic pressure (58.80 +- 9.01 vs. 41.94 +- 6.65 mm Hg, p < 0.05), the maximum dP/dt (5634 +- 1303 vs. 1667 +- 304 mm Hg/s, p < 0.01), and the minimum dP/dt (3477 +- 1084 vs. 1566 +- 499 mm Hg/s, p < 0.05). Picrosirius red staining analysis also revealed a significant reduction of fibrosis in the HGF group. Conclusion: Based on the study findings, hepatocyte growth factor gene transfer can attenuate radiation-induced cardiac injury and can preserve cardiac function.

  18. Adenovirus-mediated gene delivery to hypothalamic magnocellular neurons in mice

    NASA Technical Reports Server (NTRS)

    Vasquez, E. C.; Beltz, T. G.; Meyrelles, S. S.; Johnson, A. K.

    1999-01-01

    Vasopressin is synthesized by magnocellular neurons in supraoptic (SON) and paraventricular (PVN) hypothalamic nuclei and released by their axon terminals in the neurohypophysis (NH). With its actions as an antidiuretic hormone and vasoactive agent, vasopressin plays a pivotal role in the control of body fluids and cardiovascular homeostasis. Because of its well-defined neurobiology and functional importance, the SON/PVN-NH system is ideal to establish methods for gene transfer of genetic material into specific pathways in the mouse central nervous system. In these studies, we compared the efficiency of transferring the gene lacZ, encoding for beta-galactosidase (beta-gal), versus a gene encoding for green fluorescent protein by using replication-deficient adenovirus (Ad) vectors in adult mice. Transfection with viral concentrations up to 2 x 10(7) plaque-forming units per coverslip of NH, PVN, and SON in dissociated, cultured cells caused efficient transfection without cytotoxicity. However, over an extended period of time, higher levels (50% to 75% of the cells) of beta-gal expression were detected in comparison with green fluorescent protein (5% to 50% of the cells). With the use of a stereotaxic approach, the pituitary glands of mice were injected with Ad (4 x 10(6) plaque-forming units). In material from these animals, we were able to visualize the expression of the beta-gal gene in the NH and in magnocellular neurons of both the PVN and SON. The results of these experiments indicate that Ad-Rous sarcoma virus promoter-beta-gal is taken up by nerve terminals at the injection site (NH) and retrogradely transported to the soma of the neurons projecting to the NH. We conclude that the application of these experimental approaches will provide powerful tools for physiological studies and potential approaches to deliver therapeutic genes to treat diseases.

  19. Adenovirus-mediated WGA gene delivery for transsynaptic labeling of mouse olfactory pathways.

    PubMed

    Kinoshita, Nanako; Mizuno, Takeo; Yoshihara, Yoshihiro

    2002-03-01

    Detailed knowledge of neuronal connectivity patterns is indispensable for studies of various aspects of brain functions. We previously established a genetic strategy for visualization of multisynaptic neural pathways by expressing wheat germ agglutinin (WGA) transgene under the control of neuron type-specific promoter elements in transgenic mice and Drosophila. In this paper, we have developed a WGA-expressing recombinant adenoviral vector system and applied it for analysis of the olfactory system. When the WGA-expressing adenovirus was infused into a mouse nostril, various types of cells throughout the olfactory epithelium were infected and expressed WGA protein robustly. WGA transgene products in the olfactory sensory neurons were anterogradely transported along their axons to the olfactory bulb and transsynaptically transferred in glomeruli to dendrites of the second-order neurons, mitral and tufted cells. WGA protein was further conveyed via the lateral olfactory tract to the olfactory cortical areas including the anterior olfactory nucleus, olfactory tubercle, piriform cortex and lateral entorhinal cortex. In addition, transsynaptic retrograde labeling was observed in cholinergic neurons in the horizontal limb of diagonal band, serotonergic neurons in the median raphe nucleus, and noradrenergic neurons in the locus coeruleus, all of which project centrifugal fibers to the olfactory bulb. Thus, the WGA-expressing adenovirus is a useful and powerful tool for tracing neural pathways and could be used in animals that are not amenable to the transgenic technology. PMID:11923184

  20. Adenovirus-mediated gene delivery to cells of the magnocellular hypothalamo-neurohypophyseal system

    NASA Technical Reports Server (NTRS)

    Vasquez, E. C.; Beltz, T. G.; Haskell, R. E.; Johnson, R. F.; Meyrelles, S. S.; Davidson, B. L.; Johnson, A. K.

    2001-01-01

    The objective of the present study was to define the optimum conditions for using replication-defective adenovirus (Ad) to transfer the gene for the green fluorescent protein (GFP) to the hypothalamic paraventricular (PVN) and supraoptic (SON) nuclei and cells of the neurohypophysis (NH). As indicated by characterizing cell survival over 15 days in culture and in electrophysiological whole cell patch-clamp studies, viral concentrations up to 2 x 10(7) pfu/coverslip did not affect viability of transfected PVN and NH cultured cells from preweanling rats. At 2 x 10(7) pfu, GFP gene expression was higher (40% of GFP-positive cells) and more sustained (up to 15 days). Using a stereotaxic approach in adult rats, we were able to directly transduce the PVN, SON, and NH and visualize gene expression in coronal brain slices and in the pituitary 4 days after injection of Ad. In animals receiving NH injections of Ad, the virus was retrogradely transported to PVN and SON neurons as indicated by the appearance of GFP-positive neurons in cultures of dissociated cells from those brain nuclei and by polymerase chain reaction and Western blot analyses of PVN and SON tissues. Adenoviral concentrations of up to 8 x 10(6) pfu injected into the NH did not affect cell viability and did not cause inflammatory responses. Adenoviral injection into the pituitary enabled the selective delivery of genes to the soma of magnocellular neurons. The experimental approaches described here provide potentially useful strategies for the treatment of disordered expression of the hormones vasopressin or oxytocin. Copyright 2000 Academic Press.

  1. Adenovirus-mediated delivery of interferon-γ gene inhibits the growth of nasopharyngeal carcinoma

    PubMed Central

    2012-01-01

    Background Interferon-γ (IFN-γ) is regarded as a potent antitumor agent, but its clinical application is limited by its short half-life and significant side effects. In this paper, we tried to develop IFN-γ gene therapy by a replication defective adenovirus encoding the human IFN-γ (Ad-IFNγ), and evaluate the antitumoral effects of Ad-IFNγ on nasopharyngeal carcinoma (NPC) cell lines in vitro and in xenografts model. Methods The mRNA levels of human IFN-γ in Ad-IFNγ-infected NPC cells were detected by reverse transcription-polymerase chain reaction (RT-PCR), and IFN-γ protein concentrations were measured by enzyme-linked immunosorbent assay (ELISA) in the culture supernatants of NPC cells and tumor tissues and bloods of nude mice treated with Ad-IFNγ. The effects of Ad-IFNγ on NPC cell proliferation was determined using MTT assay, cell cycle distribution was determined by flow cytometry analysis for DNA content, and cells apoptosis were analyzed by Annexin V-FITC/7-AAD binding assay and hoechst 33342/PI double staining. The anti-tumor effects and toxicity of Ad-IFNγ were evaluated in BALB/c nude mice carrying NPC xenografts. Results The results demonstrated that Ad-IFNγ efficiently expressed human IFN-γ protein in NPC cell lines in vitro and in vivo. Ad-IFNγ infection resulted in antiproliferative effects on NPC cells by inducing G1 phase arrest and cell apoptosis. Intratumoral administration of Ad-IFNγ significantly inhibited the growth of CNE-2 and C666-1 cell xenografts in nude mice, while no significant toxicity was observed. Conclusions These findings indicate IFN-γ gene therapy mediated by replication defective adenoviral vector is likely a promising approach in the treatment of nasopharyngeal carcinoma. PMID:23272637

  2. Prevention of autoimmune recurrence and rejection by adenovirus-mediated CTLA4Ig gene transfer to the pancreatic graft in BB rat.

    PubMed

    Uchikoshi, F; Yang, Z D; Rostami, S; Yokoi, Y; Capocci, P; Barker, C F; Naji, A

    1999-03-01

    Type 1 diabetes is the result of a selective destruction of pancreatic islets by autoreactive T-cells. Therefore, in the context of islet or pancreas transplantation, newly transplanted beta-cells are threatened by both recurrent autoimmune and alloimmune responses in recipients with type 1 diabetes. In the present study, using spontaneously diabetic BB rats, we demonstrate that whereas isolated islets are susceptible to autoimmune recurrence and rejection, pancreaticoduodenal grafts are resistant to these biological processes. This resistance is mediated by lymphohematopoietic cells transplanted with the graft, since inactivation of these passenger cells by irradiation uniformly rendered the pancreaticoduodenal grafts susceptible to recurrent autoimmunity. We further studied the impact of local immunomodulation on autoimmune recurrence and rejection by ex vivo adenovirus-mediated CTLA4Ig gene transfer to pancreaticoduodenal grafts. Syngeneic DR-BB pancreaticoduodenal grafts transduced with AdmCTLA4Ig were rescued from recurrent autoimmunity. In fully histoincompatible LEW-->BB transplants, in which rejection and recurrence should be able to act synergistically, AdmCTLA4Ig transduced LEW-pancreaticoduodenal allografts enjoyed markedly prolonged survival in diabetic BB recipients. In situ reverse transcription-polymerase chain reaction revealed that transferred CTLA4Ig gene was strongly expressed in both endocrine and exocrine tissues on day 3. These results indicate the potential utility of local CD28-B7 costimulatory blockade for prevention of alloimmune and autoimmune destruction of pancreatic grafts in type 1 diabetic hosts. PMID:10078573

  3. Prospective Randomized Phase 2 Trial of Intensity Modulated Radiation Therapy With or Without Oncolytic Adenovirus-Mediated Cytotoxic Gene Therapy in Intermediate-Risk Prostate Cancer

    SciTech Connect

    Freytag, Svend O.; Stricker, Hans; Lu, Mei; Elshaikh, Mohamed; Aref, Ibrahim; Pradhan, Deepak; Levin, Kenneth; Kim, Jae Ho; Peabody, James; Siddiqui, Farzan; Barton, Kenneth; Pegg, Jan; Zhang, Yingshu; Cheng, Jingfang; Oja-Tebbe, Nancy; Bourgeois, Renee; Gupta, Nilesh; Lane, Zhaoli; Rodriguez, Ron; DeWeese, Theodore; and others

    2014-06-01

    Purpose: To assess the safety and efficacy of combining oncolytic adenovirus-mediated cytotoxic gene therapy (OAMCGT) with intensity modulated radiation therapy (IMRT) in intermediate-risk prostate cancer. Methods and Materials: Forty-four men with intermediate-risk prostate cancer were randomly assigned to receive either OAMCGT plus IMRT (arm 1; n=21) or IMRT only (arm 2; n=23). The primary phase 2 endpoint was acute (≤90 days) toxicity. Secondary endpoints included quality of life (QOL), prostate biopsy (12-core) positivity at 2 years, freedom from biochemical/clinical failure (FFF), freedom from metastases, and survival. Results: Men in arm 1 exhibited a greater incidence of low-grade influenza-like symptoms, transaminitis, neutropenia, and thrombocytopenia than men in arm 2. There were no significant differences in gastrointestinal or genitourinary events or QOL between the 2 arms. Two-year prostate biopsies were obtained from 37 men (84%). Thirty-three percent of men in arm 1 were biopsy-positive versus 58% in arm 2, representing a 42% relative reduction in biopsy positivity in the investigational arm (P=.13). There was a 60% relative reduction in biopsy positivity in the investigational arm in men with <50% positive biopsy cores at baseline (P=.07). To date, 1 patient in each arm exhibited biochemical failure (arm 1, 4.8%; arm 2, 4.3%). No patient developed hormone-refractory or metastatic disease, and none has died from prostate cancer. Conclusions: Combining OAMCGT with IMRT does not exacerbate the most common side effects of prostate radiation therapy and suggests a clinically meaningful reduction in positive biopsy results at 2 years in men with intermediate-risk prostate cancer.

  4. Chimeric smooth muscle-specific enhancer/promoters: valuable tools for adenovirus-mediated cardiovascular gene therapy.

    PubMed

    Ribault, S; Neuville, P; Méchine-Neuville, A; Augé, F; Parlakian, A; Gabbiani, G; Paulin, D; Calenda, V

    2001-03-16

    Gene transfer with adenoviral vectors is an attractive approach for the treatment of atherosclerosis and restenosis. However, because expression of a therapeutic gene in nontarget tissues may have deleterious effects, artery-specific expression is desirable. Although expression vectors containing transcriptional regulatory elements of genes expressed solely in smooth muscle cells (SMCs) have proved efficient to restrict expression of the transgene, their use in the clinical setting can be limited by their reduced strength. In the present study, we show that low levels of transgene expression are obtained with the smooth muscle (SM)-specific SM22alpha promoter compared with the viral cytomegalovirus (CMV) enhancer/promoter. We have generated chimeric transcriptional cassettes containing either a SM (SM-myosin heavy chain) or a skeletal muscle (creatine kinase) enhancer combined with the SM22alpha promoter. With both constructs we observed significantly stronger expression that remains SM-specific. In vivo, reporter gene expression was restricted to arterial SMCs with no detectable signal at remote sites. Moreover, when interferon-gamma expression was driven by one of these two chimeras, SMC growth was inhibited as efficiently as with the CMV promoter. Finally, we demonstrate that neointima formation in the rat carotid balloon injury model was reduced to the same extent by adenoviral gene transfer of interferon-gamma driven either by the SM-myosin heavy chain enhancer/SM22alpha promoter or the CMV promoter. These results indicate that such vectors can be useful for the treatment of hyperproliferative vascular disorders. PMID:11249869

  5. Comparative Proteomics Study of Streptozotocin-induced Diabetic Nephropathy in Rats Kidneys Transfected with Adenovirus-mediated Fibromodulin Gene

    PubMed Central

    Maleki, Akram; Ramazani, Ali; Foroutan, Maryam; Biglari, Alireza; Ranjzad, Parisa; Mellati, Ali Awsat

    2014-01-01

    Background Transforming Growth Factor-beta (TGF-β) activation appears to be crucial for tissue injury in Diabetic Nephropathy (DN). Fibromodulin, the small leucine-rich proteoglycan, has been proposed to be the potent TGF-β modulator. In this study, the therapeutic effects of fibromodulin in the kidneys of streptozotocin (STZ)-induced diabetic rats were investigated. Methods Diabetic rats received intraperitoneal (IP) injections of recombinant adenovirus expression vectors (RAd5) containing fibromodulin (RAd-FMOD) and were killed after 10 weeks. Proteins were isolated from the rat kidney and separated using two-dimensional gel electrophoresis. The differentially expressed proteins were analyzed using Matrix-assisted laser desorption/ ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Results Ten spots were identified using MALDI-TOF-MS. The identified proteins were primarily responsible for cell metabolism, cytoskeleton formation, and oxidative stress. RAd-FMOD treatment markedly attenuated the albuminuria in diabetic rats. Conclusion Taken together, these results provide a valuable clue in exploring the mechanism underlying the therapeutic effects of fibromodulin in diabetic nephropathy suggesting that it can be a potential agent in the treatment of this disease. PMID:24834312

  6. Inhibition of experimental autoimmune uveoretinitis by systemic and subconjunctival adenovirus-mediated transfer of the viral IL-10 gene

    PubMed Central

    De Kozak, Y; Thillaye-Goldenberg, B; Naud, M -C; Viana Da Costa, A; Auriault, C; Verwaerde, C

    2002-01-01

    Pathological ocular manifestations result from a dysregulation in the balance between proinflammatory type 1 cytokines and regulatory type 2 cytokines. Interleukin-10 (IL-10) is an anti-inflammatory cytokine with potent immunosuppressive effects. We have examined the efficiency of viral IL-10 adenovirus (Ad-vIL-10)-mediated gene transfer on experimental autoimmune uveoretinitis (EAU) induced in mice and rats by purified retinal autoantigens, respectively, interphotoreceptor binding protein (IRBP) and S-antigen (S-Ag). B10-A mice that received a single unilateral injection of Ad-vIL-10 in the retro-orbital sinus venosus performed 1 day before immunization with IRBP in the footpads showed high levels of circulating vIL-10 in their sera and a significant reduction in pathological ocular manifestations. Lower levels of IFN-γ and IL-2 were found in cellular supernatants from IRBP-stimulated splenic cells in these treated mice. The local effect on ocular disease of vIL-10 was neutralized completely by injection of a monoclonal anti-vIL-10 antibody, demonstrating the specificity of the treatment. To determine whether the transfer of the vIL-10 gene within the periocular tissues of the eye could prevent acute EAU, a subconjunctival injection of Ad-vIL-10 was performed in Lewis rats simultaneously with S-antigen in the footpads. This injection determined in situ vIL-10 expression with very low circulating vIL-10 and led to a significant reduction of EAU without affecting the systemic immune response. The present results suggest that Ad-mediated gene transfer resulting in systemic and local expression of vIL-10 provide a promising approach for the treatment of uveitis. PMID:12390308

  7. Methylation of PLCD1 and adenovirus-mediated PLCD1 overexpression elicits a gene therapy effect on human breast cancer

    SciTech Connect

    Mu, Haixi; Wang, Na; Zhao, Lijuan; Li, Shuman; Li, Qianqian; Chen, Ling; Luo, Xinrong; Qiu, Zhu; Li, Lili; Ren, Guosheng; Xu, Yongzhu; Zhou, Xiangyang; Xiang, Tingxiu

    2015-03-15

    Our previous study showed that PLCD1 significantly decreases cell proliferation and affects cell cycle progression in breast cancer cells. In the present study, we aimed to investigate its functional and molecular mechanisms, and whether or not can become a new target for gene therapies. We found reduced PLCD1 protein expression in breast tumor tissues compared with paired surgical margin tissues. PLCD1 promoter CpG methylation was detected in 55 of 96 (57%) primary breast tumors, but not in surgical-margin tissues and normal breast tissues. Ectopic expression of PLCD1 inhibited breast tumor cell proliferation in vivo by inducing apoptosis and suppressed tumor cell migration by regulating cytoskeletal reorganization proteins including RhoA and phospho-cofilin. Furthermore, we found that PLCD1 induced p53 accumulation, increased p27 and p21 protein levels, and cleaved PARP. Finally, we constructed an adenoviral vector expressing PLCD1 (AdH5-PLCD1), which exhibited strong cytotoxicity in breast cancer cells. Our findings provide insights into the development of PLCD1 gene therapies for breast cancer and perhaps, other human cancers. - Highlights: • PLCD1 is downregulated via hypermethylation in breast cancer. • PLCD1 suppressed cell migration by regulating cytoskeletal reorganization proteins. • Adenovirus AdHu5-PLCD1 may be a novel therapeutic option for breast cancer.

  8. Adenovirus-mediated artificial MicroRNAs targeting matrix or nucleoprotein genes protect mice against lethal influenza virus challenge.

    PubMed

    Zhang, H; Tang, X; Zhu, C; Song, Y; Yin, J; Xu, J; Ertl, H C J; Zhou, D

    2015-08-01

    Influenza virus (IV) infection is a major public health problem, causing millions of cases of severe illness and as many as 500 000 deaths each year worldwide. Given the limitations of current prevention or treatment of acute influenza, novel therapies are needed. RNA interference (RNAi) through microRNAs (miRNA) is an emerging technology that can suppress virus replication in vitro and in vivo. Here, we describe a novel strategy for the treatment of infuenza based on RNAi delivered by a replication-defective adenovirus (Ad) vector, derived from chimpanzee serotype 68 (AdC68). Our results showed that artificial miRNAs (amiRNAs) specifically targeting conserved regions of the IV genome could effectively inhibit virus replication in human embryonic kidney 293 cells. Moreover, our results demonstrated that prophylactic treatment with AdC68 expressing amiRNAs directed against M1, M2 or nucleoprotein genes of IV completely protected mice from homologous A/PR8 virus challenge and partially protected the mice from heterologous influenza A virus strains such as H9N2 and H5N1. Collectively, our data demonstrate that amiRNAs targeting the conserved regions of influenza A virus delivered by Ad vectors should be pursued as a novel strategy for prophylaxis of IV infection in humans and animals. PMID:25835311

  9. Adenovirus-mediated transfer of the PTEN gene inhibits human colorectal cancer growth in vitro and in vivo.

    PubMed

    Saito, Y; Swanson, X; Mhashilkar, A M; Oida, Y; Schrock, R; Branch, C D; Chada, S; Zumstein, L; Ramesh, R

    2003-11-01

    The tumor-suppressor gene PTEN encodes a multifunctional phosphatase that is mutated in a variety of human cancers. PTEN inhibits the phosphatidylinositol 3-kinase pathway and downstream functions, including activation of Akt/protein kinase B (PKB), cell survival, and cell proliferation in tumor cells carrying mutant- or deletion-type PTEN. In such tumor cells, enforced expression of PTEN decreases cell proliferation through cell-cycle arrest at G1 phase accompanied, in some cases, by induction of apoptosis. More recently, the tumor-suppressive effect of PTEN has been reported in ovarian and thyroid tumors that are wild type for PTEN. In the present study, we examined the tumor-suppressive effect of PTEN in human colorectal cancer cells that are wild type for PTEN. Adenoviral-mediated transfer of PTEN (Ad-PTEN) suppressed cell growth and induced apoptosis significantly in colorectal cancer cells (DLD-1, HT29, and SW480) carrying wtPTEN than in normal colon fibroblast cells (CCD-18Co) carrying wtPTEN. This suppression was induced through downregulation of the Akt/PKB pathway, dephosphorylation of focal adhesion kinase (FAK) and mitogen-activated protein kinase (MAPK) and cell-cycle arrest at the G2/M phase, but not the G1 phase. Furthermore, treatment of human colorectal tumor xenografts (HT-29, and SW480) with Ad-PTEN resulted in significant (P=0.01) suppression of tumor growth. These results indicate that Ad-PTEN exerts its tumor-suppressive effect on colorectal cancer cells through inhibition of cell-cycle progression and induction of cell death. Thus Ad-PTEN may be a potential therapeutic for treatment of colorectal cancers. PMID:14528320

  10. Adenovirus-mediated gene transfer of endostatin in vivo results in high level of transgene expression and inhibition of tumor growth and metastases

    NASA Astrophysics Data System (ADS)

    Sauter, Bernhard V.; Martinet, Olivier; Zhang, Wei-Jian; Mandeli, John; Woo, Savio L. C.

    2000-04-01

    Inhibition of angiogenesis has been shown to be an effective strategy in cancer therapy in mice. However, its widespread application has been hampered by difficulties in the large-scale production of the antiangiogenic proteins. This limitation may be resolved by in vivo delivery and expression of the antiangiogenic genes. We have constructed a recombinant adenovirus that expresses murine endostatin that is biologically active both in vitro, as determined in endothelial cell proliferation assays, and in vivo, by suppression of angiogenesis induced by vascular endothelial growth factor 165. Persistent high serum levels of endostatin (605-1740 ng/ml; mean, 936 ng/ml) were achieved after systemic administration of the vector to nude mice, which resulted in significant reduction of the growth rates and the volumes of JC breast carcinoma and Lewis lung carcinoma (P < 0.001 and P < 0.05, respectively). In addition, the endostatin vector treatment completely prevented the formation of pulmonary micrometastases in Lewis lung carcinoma (P = 0.0001). Immunohistochemical staining of the tumors demonstrated a decreased number of blood vessels in the treatment group versus the controls. In conclusion, the present study clearly demonstrates the potential of vector-mediated antiangiogenic gene therapy as a component in cancer therapy.

  11. Effect of adenovirus-mediated RNA interference on endogenous microRNAs in a mouse model of multidrug resistance protein 2 gene silencing.

    PubMed

    Narvaiza, Iñigo; Aparicio, Oscar; Vera, María; Razquin, Nerea; Bortolanza, Sergia; Prieto, Jesús; Fortes, Puri

    2006-12-01

    RNA interference with viral vectors that express short hairpin RNAs (shRNAs) has emerged as a powerful tool for functional genomics and therapeutic purposes. However, little is known about shRNA in vivo processing, accumulation, functional kinetics, and side effects related to shRNA saturation of the cellular gene silencing machinery. Therefore, we constructed first-generation recombinant adenoviruses encoding different shRNAs against murine ATP-binding cassette multidrug resistance protein 2 (Abcc2), which is involved in liver transport of bilirubin to bile, and analyzed Abcc2 silencing kinetics. C57/BL6 mice injected with these viruses showed significant impairment of Abcc2 function for up to 3 weeks, as reflected by increased serum bilirubin levels. The lack of Abcc2 function correlated with a specific reduction of Abcc2 mRNA and with high levels of processed shRNAs targeting Abcc2. Inhibition was lost at longer times postinfection, correlating with a decrease in the accumulation of processed shRNAs. This finding suggests that a minimal amount of processed shRNAs is required for efficient silencing in vivo. This system was also used to evaluate the effect of shRNA expression on the saturation of silencing factors. Saturation of the cellular silencing processing machinery alters the accumulation and functionality of endogenous microRNAs (miRNAs) and pre-miRNAs. However, expression of functional exogenous shRNAs did not change the levels of endogenous miRNAs or their precursors. In summary, this work shows that adenoviral vectors can deliver sufficient shRNAs to mediate inhibition of gene expression without saturating the silencing machinery. PMID:17020948

  12. Retrograde Ductal Administration of the Adenovirus-mediated NDRG2 Gene Leads to Improved Sialaden Hypofunction in Estrogen-deficient Rats

    PubMed Central

    Li, Yan; Liu, Changhao; Hou, Wugang; Li, Yang; Ma, Ji; Lin, Kaifeng; Situ, Zhenqiang; Xiong, Lize; Li, Shaoqing; Yao, Libo

    2014-01-01

    One of the most common oral manifestations of menopause is xerostomia. Oral dryness can profoundly affect quality of life and interfere with basic daily functions, such as chewing, deglutition, and speaking. Although the feeling of oral dryness can be ameliorated after estrogen supplementation, the side effects of estrogen greatly restrict its application. We previously found that N-myc downstream-regulated gene 2 (NDRG2) is involved in estrogen-mediated ion and fluid transport in a cell-based model. In the present study, we used an ovariectomized rat model to mimic xerostomia in menopausal women and constructed two adenovirus vectors bearing NDRG2 to validate their therapeutic potential. Ovariectomized rats exhibited severe sialaden hypofunction, including decreased saliva secretion and ion reabsorption as well as increased water intake. Immunohistochemistry revealed that the expression of NDRG2 and Na+ reabsorption-related Na+/K+-ATPase and epithelial sodium channels (EnaC) decreased in ovariectomized rat salivary glands. We further showed that the localized delivery of NDRG2 improved the dysfunction of Na+ and Cl− reabsorption. In addition, the saliva flow rate and water drinking recovered to normal. This study elucidates the mechanism of estrogen deficiency-mediated xerostomia or sialaden hypofunction and provides a promising strategy for therapeutic intervention. PMID:24343104

  13. Construction and characterization of recombinant adenovirus carrying a mouse TIGIT-GFP gene.

    PubMed

    Zheng, J M; Cui, J L; He, W T; Yu, D W; Gao, Y; Wang, L; Chen, Z K; Zhou, H M

    2015-01-01

    Recombinant adenovirus vector systems have been used extensively in protein research and gene therapy. However, the construction and characterization of recombinant adenovirus is a tedious and time-consuming process. TIGIT is a recently discovered immunosuppressive molecule that plays an important role in maintaining immunological balance. The construction of recombinant adenovirus mediating TIGIT expression must be simplified to facilitate its use in the study of TIGIT. In this study, the TIGIT gene was combined with green fluorescent protein (GFP); the TIGIT-GFP gene was inserted into a gateway plasmid to construct a TIGIT-GFP adenovirus. HEK 293A cells were infected with the adenovirus, which was then purified and subjected to virus titering. TIGIT-GFP adenovirus was characterized by flow cytometry and immunofluorescence, and its expression in mouse liver was detected by infection through caudal vein injection. The results showed the successful construction of the TIGIT-GFP adenovirus (5 x 10(10) PFU/mL). Co-expression of TIGIT and GFP was identified in 293A and liver cells; synthesis and positioning of TIGIT-GFP was viewed under a fluorescence microscope. TIGIT-GFP was highly expressed on liver cells 1 day (25.53%) after infection and faded 3 days (11.36%) after injection. In conclusion, the fusion of TIGIT with GFP allows easy, rapid, and uncomplicated detection of TIGIT translation. The construction of a TIGIT-GFP adenovirus, mediating TIGIT expression in vitro and in vivo, lays the foundation for further research into TIGIT function and gene therapy. Moreover, the TIGIT-GFP adenovirus is a helpful tool for studying other proteins (which could replace the TIGIT gene). PMID:26782515

  14. Adenovirus-mediated wild-type p53 gene transfer in combination with bronchial arterial infusion for treatment of advanced non-small-cell lung cancer, one year follow-up

    PubMed Central

    Guan, Yong-song; Liu, Yuan; Zou, Qing; He, Qing; La, Zi; Yang, Lin; Hu, Ying

    2009-01-01

    Objective: In the present study, we have examined the safety and efficacy of recombinant adenovirus encoding human p53 tumor suppressor gene (rAd-p53) injection in patients with advanced non-small-cell lung cancer (NSCLC) in the combination with the therapy of bronchial arterial infusion (BAI). Methods: A total of 58 patients with advanced NSCLC were enrolled in a non-randomized, two-armed clinical trial. Of which, 19 received a combination treatment of BAI and rAd-p53 (the combo group), while the remaining 39 were treated with only BAI (the control group). Patients were followed up for 12 months, with safety and local response evaluated by the National Cancer Institute’s Common Toxicity Criteria and response evaluation criteria in solid tumor (RECIST), respectively. Time to progression (TTP) and survival rates were also analyzed by Kaplan-Meier method. Results: In the combo group, 19 patients received a total of 49 injections of rAd-p53 and 46 times of BAI, respectively, while 39 patients in the control group received a total of 113 times of BAI. The combination treatment was found to have less adverse events such as anorexia, nausea and emesis, pain, and leucopenia (P<0.05) but more arthralgia, fever, influenza-like symptom, and myalgia (P<0.05), compared with the control group. The overall response rates (complete response (CR)+partial response (PR)) were 47.3% and 38.4% for the combo group and the control group, respectively (P>0.05). Patients in the combo group had a longer TTP than those in the control group (a median 7.75 vs 5.5 months, P=0.018). However, the combination treatment did not lead to better survival, with survival rates at 3, 6, and 12 months in the combo group being 94.74%, 89.47%, and 52.63%, respectively, compared with 92.31%, 69.23%, and 38.83% in the control group (P=0.224). Conclusion: Our results show that the combination of rAd-p53 and BAI was well tolerated in patients with NSCLC and may have improved the quality of life and delayed

  15. Adenovirus-mediated expression of BmK CT suppresses growth and invasion of rat C6 glioma cells.

    PubMed

    Du, Jun; Fu, Yuejun; Wang, Jianing; Liang, Aihua

    2013-06-01

    BmK CT, one of the key toxins in the venom of the scorpion, Buthus martensii Karsch, can interact specifically with glioma cells as a chloride channel blocker and inhibit the invasion and migration of those cells via MMP-2. A recombinant adenovirus, Ad-BmK CT, was constructed and characterized by in vitro and in vivo studies, using MTT cytotoxicity assay and the glioma C6/RFP (red fluorescence protein)/BALB/c allogeneic athymic nude mice model, respectively. The adenovirus-mediated expression of BmK CT displayed a high activity in suppressing rat C6 glioma cells growth and invasion thereby suggesting that this recombinant adenovirus may be a powerful method for treating glioblastoma. PMID:23443213

  16. Apical localization of the coxsackie-adenovirus receptor by glycosyl-phosphatidylinositol modification is sufficient for adenovirus-mediated gene transfer through the apical surface of human airway epithelia.

    PubMed

    Walters, R W; van't Hof, W; Yi, S M; Schroth, M K; Zabner, J; Crystal, R G; Welsh, M J

    2001-08-01

    In well-differentiated human airway epithelia, the coxsackie B and adenovirus type 2 and 5 receptor (CAR) resides primarily on the basolateral membrane. This location may explain the observation that gene transfer is inefficient when adenovirus vectors are applied to the apical surface. To further test this hypothesis and to investigate requirements and barriers to apical gene transfer to differentiated human airway epithelia, we expressed CAR in which the transmembrane and cytoplasmic tail were replaced by a glycosyl-phosphatidylinositol (GPI) anchor (GPI-CAR). As controls, we expressed wild-type CAR and CAR lacking the cytoplasmic domain (Tailless-CAR). All three constructs enhanced gene transfer with similar efficiencies in fibroblasts. In airway epithelia, GPI-CAR localized specifically to the apical membrane, where it bound adenovirus and enhanced gene transfer to levels obtained when vector was applied to the basolateral membrane. Moreover, GPI-CAR facilitated gene transfer of the cystic fibrosis transmembrane conductance regulator to cystic fibrosis airway epithelia, correcting the Cl(-) transport defect. In contrast, when we expressed wild-type CAR it localized to the basolateral membrane and failed to increase apical gene transfer. Only a small amount of Tailless-CAR resided in the apical membrane, and the effects on apical virus binding and gene transfer were minimal. These data indicate that binding of adenovirus to an apical membrane receptor is sufficient to mediate effective gene transfer to human airway epithelia and that the cytoplasmic domain of CAR is not required for this process. The results suggest that targeting apical receptors in differentiated airway epithelia may be sufficient for gene transfer in the genetic disease cystic fibrosis. PMID:11462042

  17. Apical Localization of the Coxsackie-Adenovirus Receptor by Glycosyl-Phosphatidylinositol Modification Is Sufficient for Adenovirus-Mediated Gene Transfer through the Apical Surface of Human Airway Epithelia

    PubMed Central

    Walters, Robert W.; van't Hof, Wouter; Yi, Su Min P.; Schroth, Mary K.; Zabner, Joseph; Crystal, Ronald G.; Welsh, Michael J.

    2001-01-01

    In well-differentiated human airway epithelia, the coxsackie B and adenovirus type 2 and 5 receptor (CAR) resides primarily on the basolateral membrane. This location may explain the observation that gene transfer is inefficient when adenovirus vectors are applied to the apical surface. To further test this hypothesis and to investigate requirements and barriers to apical gene transfer to differentiated human airway epithelia, we expressed CAR in which the transmembrane and cytoplasmic tail were replaced by a glycosyl-phosphatidylinositol (GPI) anchor (GPI-CAR). As controls, we expressed wild-type CAR and CAR lacking the cytoplasmic domain (Tailless-CAR). All three constructs enhanced gene transfer with similar efficiencies in fibroblasts. In airway epithelia, GPI-CAR localized specifically to the apical membrane, where it bound adenovirus and enhanced gene transfer to levels obtained when vector was applied to the basolateral membrane. Moreover, GPI-CAR facilitated gene transfer of the cystic fibrosis transmembrane conductance regulator to cystic fibrosis airway epithelia, correcting the Cl− transport defect. In contrast, when we expressed wild-type CAR it localized to the basolateral membrane and failed to increase apical gene transfer. Only a small amount of Tailless-CAR resided in the apical membrane, and the effects on apical virus binding and gene transfer were minimal. These data indicate that binding of adenovirus to an apical membrane receptor is sufficient to mediate effective gene transfer to human airway epithelia and that the cytoplasmic domain of CAR is not required for this process. The results suggest that targeting apical receptors in differentiated airway epithelia may be sufficient for gene transfer in the genetic disease cystic fibrosis. PMID:11462042

  18. Adenovirus-mediated expression of an elastase-specific inhibitor (elafin): a comparison of different promoters.

    PubMed

    Sallenave, J M; Xing, Z; Simpson, A J; Graham, F L; Gauldie, J

    1998-03-01

    This report describes the design and construction of three recombinant adenoviruses of serotype 5 (Ad5) expressing elafin (EL), also called elastase-specific inhibitor. Three promoters were chosen to drive the synthesis of elafin: the small (380 bp) human cytomegalovirus promoter (HCMV), the Ad2 major late promoter (MLP) and the mouse cytomegalovirus (MCMV) promoter. Human alveolar epithelial cells (A549), as well as rat and human primary pulmonary fibroblasts were infected with Ad5-HCMV-EL, Ad5-MLP-EL, Ad5-MCMV-EL and with the control Ad5-dl70/3. The MCMV promoter was the most efficient promoter in all cells studied. MLP was the least efficient promoter Intermediate between MCMV and MLP was HCMV which was able to induce significant amounts of elafin, particularly in human A549 cells. When compared in vivo in rat lungs, results were similar; MCMV was the only promoter which induced significant amounts of elafin as assessed by Northern blot analysis and ELISA, even with a low dose of virus (3 x 10(8) p.f.u.). Our data indicate that the MCMV promoter is the promoter of choice for the strong induction of adenovirus-mediated transgenes in the lung and suggest its suitability both in rodent experimental models and in humans for investigative and therapeutic purposes. PMID:9614555

  19. Cellular and humoral immune responses to viral antigens create barriers to lung-directed gene therapy with recombinant adenoviruses.

    PubMed Central

    Yang, Y; Li, Q; Ertl, H C; Wilson, J M

    1995-01-01

    Recombinant adenoviruses are an attractive vehicle for gene therapy to the lung in the treatment of cystic fibrosis (CF). First-generation viruses deleted of E1a and E1b transduce genes into airway epithelial cells in vivo; however, expression of the transgene is transient and associated with substantial inflammatory responses, and gene transfer is significantly reduced following a second administration of the virus. In this study, we have used mice deficient in immunological effector functions in combination with adoptive and passive transfer techniques to define antigen-specific cellular and humoral immune responses that underlie these important limitations. Our studies indicate that major histocompatibility complex class I-restricted CD8+ cytotoxic T lymphocytes are activated in response to newly synthesized antigens, leading to destruction of virus infected cells and loss of transgene expression. Major histocompatibility complex class II-associated presentation of exogenous viral antigens activates CD4+ T-helper (TH) cells of the TH1 subset and, to a lesser extent, of the TH2 subset. CD4+ cell-mediated responses are insufficient in the absence of cytotoxic T cells to completely eliminate transgene containing cells; however, they contribute to the formation of neutralizing antibodies in the airway which block subsequent adenovirus-mediated gene transfer. Definition of immunological barriers to gene therapy of cystic fibrosis should facilitate the design of rational strategies to overcome them. PMID:7884845

  20. The antitumor efficacy of a novel adenovirus-mediated anti-p21Ras single chain fragment variable antibody on human cancers in vitro and in vivo.

    PubMed

    Yang, Ju-Lun; Pan, Xin-Yan; Zhao, Wen-Xing; Hu, Qi-Chan; Ding, Feng; Feng, Qiang; Li, Gui-Yun; Luo, Ying

    2016-03-01

    Activated ras genes are found in a large number of human tumors, and therefore are one of important targets for cancer therapy. This study investigated the antitumor effects of a novel single chain fragment variable antibody (scFv) against ras protein, p21Ras. The anti-p21Ras scFv gene was constructed by phage display library from hybridoma KGHR1, and then subcloned into replication-defective adenovirus vector to obtain recombinant adenovirus KGHV100. Human tumor cell lines with high expression of p21Ras SW480, MDA-MB‑231, OVCAR-3, BEL-7402, as well as tumor cell line with low expression of p21Ras, SKOV3, were employed to investigate antitumor effects in vitro and in vivo. Fluorescence microscopy demonstrated that KGHV100 was able to express intracellularly anti-p21Ras scFv antibody in cultured tumor cells and in transplantation tumor cells. MTT, Transwell, colony formation, and flow cytometry analysis showed that KGHV100 led to significant growth arrest in tumor cells with high p21Ras expression, and induced G0/G1 cell cycle arrest in the studied tumor cell lines. In vivo, KGHV100 significantly inhibited tumor growth following intratumoral injection, and the survival rates of the mice were higher than the control group. These results indicate that the adenovirus-mediated intracellular expression of the novel anti-p21Ras scFv exerted strong antitumoral effects, and may be a potential method for therapy of cancers with p21Ras overexpression. PMID:26780944

  1. Adenovirus-mediated downregulation of the ubiquitin ligase RNF8 sensitizes bladder cancer to radiotherapy

    PubMed Central

    Yang, Xu-Guang; Xie, Kun; Jing, Yu-Hong; Wang, De-Gui

    2016-01-01

    The ubiquitin ligase RNF8 promotes the DNA damage response (DDR). We observed that the expression of RNF8 was increased in bladder cancer cells and that this change in RNF8 expression could be reversed by adenovirus-mediated shRNA treatment. Moreover, we found that RNF8 knockdown sensitized bladder cancer cells to radiotherapy, as demonstrated by reduced cell survival. Additionally, the absence of RNF8 induced a high rate of apoptosis and impaired double-strand break repair signaling after radiotherapy. Furthermore, experiments on nude mice showed that combining shRNF8 treatment with radiotherapy suppressed implanted bladder tumor growth and enhanced apoptotic cell death in vivo. Altogether, our results indicated that RNF8 might be a novel target for bladder cancer treatment. PMID:26788910

  2. Inhibitory effect of recombinant adenovirus carrying immunocaspase-3 on hepatocellular carcinoma

    SciTech Connect

    Li, Xiaohua; Fan, Rui; Zou, Xue; Gao, Lin; Jin, Haifeng; Du, Rui; Xia, Lin; Fan, Daiming . E-mail: fandaim@yahoo.com.cn

    2007-06-29

    Previously, Srinivasula devised a contiguous molecule (C-cp-3 or immunocaspase-3) containing the small and large subunits similar to that in the active form of caspas-3 and found C-cp-3 had similar cleavage activity to the active form of caspase-3. To search for a new clinical application of C-cp-3 to treat hepatocellular carcinoma, recombinant adenoviruses carrying the C-cp-3 and a-fetoprotein (AFP) promoter (Ad-rAFP-C-cp-3) were constructed through a bacterial homologous recombinant system. The efficiency of adenovirus-mediated gene transfer and the inhibitory effect of Ad-rAFP-C-cp-3 on the proliferation of hepatocarcinoma cells were determined by X-gal stain and MTT assay, respectively. The tumorigenicity of hepatocarcinoma cells transfected by Ad-rAFP-C-cp-3 and the antitumor effect of Ad-rAFP-C-cp-3 on transplanted tumor in nude mice were detected in vivo. The results suggested that Ad-rAFP-C-cp-3 can inhibit specifically proliferation of AFP-producing human hepatocarcinoma cells in vitro and in vivo and adenovirus-mediated C-cp-3 transfer could be used as a new method to treat human hepatocarcinoma.

  3. HSV Recombinant Vectors for Gene Therapy

    PubMed Central

    Manservigi, Roberto; Argnani, Rafaela; Marconi, Peggy

    2010-01-01

    The very deep knowledge acquired on the genetics and molecular biology of herpes simplex virus (HSV), has allowed the development of potential replication-competent and replication-defective vectors for several applications in human healthcare. These include delivery and expression of human genes to cells of the nervous systems, selective destruction of cancer cells, prophylaxis against infection with HSV or other infectious diseases, and targeted infection to specific tissues or organs. Replication-defective recombinant vectors are non-toxic gene transfer tools that preserve most of the neurotropic features of wild type HSV-1, particularly the ability to express genes after having established latent infections, and are thus proficient candidates for therapeutic gene transfer settings in neurons. A replication-defective HSV vector for the treatment of pain has recently entered in phase 1 clinical trial. Replication-competent (oncolytic) vectors are becoming a suitable and powerful tool to eradicate brain tumours due to their ability to replicate and spread only within the tumour mass, and have reached phase II/III clinical trials in some cases. The progress in understanding the host immune response induced by the vector is also improving the use of HSV as a vaccine vector against both HSV infection and other pathogens. This review briefly summarizes the obstacle encountered in the delivery of HSV vectors and examines the various strategies developed or proposed to overcome such challenges. PMID:20835362

  4. Mechanism of adenovirus-mediated endosome lysis: role of the intact adenovirus capsid structure.

    PubMed

    Seth, P

    1994-12-15

    Adenoviruses have been previously shown to enhance the delivery of many ligands including proteins and plasmid DNAs to the cells. The key biochemical step during this process is the ability of adenovirus to disrupt (lyse) the endosome membrane releasing the co-internalized virus and the other ligands into the cytosol (Seth et al, 1986, In: Adenovirus attachment and entry into cells, pp 191-195, American Society for Microbiology, Washington, D.C.). To understand the role of the adenovirus proteins involved in the endosome lysis, it is further shown here that empty capsids of adenovirus also possess this membrane vesicle lytic activity; though the activity is about 5-times lower than the adenovirus. Incubation of adenovirus with low concentration of ionic detergent or brief exposure to 45 degrees C destroyed this lytic activity without affecting the adenovirus binding to cell surface receptor, suggesting the lytic activity of adenovirus to be of enzymatic nature. However, exposing adenovirus to conditions that can disrupt adenovirus capsid structure such as heating at 65 degrees C, treating with 0.5% SDS, treating with different proteases, dialyzing against no glycerol buffer, treating with 6 M urea or with 10% pyridine, and sonication destroyed the adenovirus-associated lytic activity. Results suggest the requirement of an intact capsid structure for adenovirus-mediated lysis of the endosome. PMID:7802664

  5. Functional divergence of gene duplicates through ectopic recombination

    PubMed Central

    Christiaens, Joaquin F; Van Mulders, Sebastiaan E; Duitama, Jorge; Brown, Chris A; Ghequire, Maarten G; De Meester, Luc; Michiels, Jan; Wenseleers, Tom; Voordeckers, Karin; Verstrepen, Kevin J

    2012-01-01

    Gene duplication stimulates evolutionary innovation as the resulting paralogs acquire mutations that lead to sub- or neofunctionalization. A comprehensive in silico analysis of paralogs in Saccharomyces cerevisiae reveals that duplicates of cell-surface and subtelomeric genes also undergo ectopic recombination, which leads to new chimaeric alleles. Mimicking such intergenic recombination events in the FLO (flocculation) family of cell-surface genes shows that chimaeric FLO alleles confer different adhesion phenotypes than the parental genes. Our results indicate that intergenic recombination between paralogs can generate a large set of new alleles, thereby providing the raw material for evolutionary adaptation and innovation. PMID:23070367

  6. Recombinant Rp1 genes confer necrotic or nonspecific resistance phenotypes.

    PubMed

    Smith, Shavannor M; Steinau, Martin; Trick, Harold N; Hulbert, Scot H

    2010-06-01

    Genes at the Rp1 rust resistance locus of maize confer race-specific resistance to the common rust fungus Puccinia sorghi. Three variant genes with nonspecific effects (HRp1 -Kr1N, -D*21 and -MD*19) were found to be generated by intragenic crossing over within the LRR region. The LRR region of most NBS-LRR encoding genes is quite variable and codes for one of the regions in resistance gene proteins that controls specificity. Sequence comparisons demonstrated that the Rp1-Kr1N recombinant gene was identical to the N-terminus of the rp1-kp2 gene and C-terminus of another gene from its HRp1-K grandparent. The Rp1-D*21 recombinant gene consists of the N-terminus of the rp1-dp2 gene and C-terminus of the Rp1-D gene from the parental haplotype. Similarly, a recombinant gene from the Rp1-MD*19 haplotype has the N-terminus of an rp1 gene from the HRp1-M parent and C-terminus of the rp1-D19 gene from the HRp1-D parent. The recombinant Rp1 -Kr1N, -D*21 and -MD*19 genes activated defense responses in the absence of their AVR proteins triggering HR (hypersensitive response) in the absence of the pathogen. The results indicate that the frequent intragenic recombination events that occur in the Rp1 gene cluster not only recombine the genes into novel haplotypes, but also create genes with nonspecific effects. Some of these may contribute to nonspecific quantitative resistance but others have severe consequences for the fitness of the plant. PMID:20443026

  7. Recombination Rate Heterogeneity within Arabidopsis Disease Resistance Genes.

    PubMed

    Choi, Kyuha; Reinhard, Carsten; Serra, Heïdi; Ziolkowski, Piotr A; Underwood, Charles J; Zhao, Xiaohui; Hardcastle, Thomas J; Yelina, Nataliya E; Griffin, Catherine; Jackson, Matthew; Mézard, Christine; McVean, Gil; Copenhaver, Gregory P; Henderson, Ian R

    2016-07-01

    Meiotic crossover frequency varies extensively along chromosomes and is typically concentrated in hotspots. As recombination increases genetic diversity, hotspots are predicted to occur at immunity genes, where variation may be beneficial. A major component of plant immunity is recognition of pathogen Avirulence (Avr) effectors by resistance (R) genes that encode NBS-LRR domain proteins. Therefore, we sought to test whether NBS-LRR genes would overlap with meiotic crossover hotspots using experimental genetics in Arabidopsis thaliana. NBS-LRR genes tend to physically cluster in plant genomes; for example, in Arabidopsis most are located in large clusters on the south arms of chromosomes 1 and 5. We experimentally mapped 1,439 crossovers within these clusters and observed NBS-LRR gene associated hotspots, which were also detected as historical hotspots via analysis of linkage disequilibrium. However, we also observed NBS-LRR gene coldspots, which in some cases correlate with structural heterozygosity. To study recombination at the fine-scale we used high-throughput sequencing to analyze ~1,000 crossovers within the RESISTANCE TO ALBUGO CANDIDA1 (RAC1) R gene hotspot. This revealed elevated intragenic crossovers, overlapping nucleosome-occupied exons that encode the TIR, NBS and LRR domains. The highest RAC1 recombination frequency was promoter-proximal and overlapped CTT-repeat DNA sequence motifs, which have previously been associated with plant crossover hotspots. Additionally, we show a significant influence of natural genetic variation on NBS-LRR cluster recombination rates, using crosses between Arabidopsis ecotypes. In conclusion, we show that a subset of NBS-LRR genes are strong hotspots, whereas others are coldspots. This reveals a complex recombination landscape in Arabidopsis NBS-LRR genes, which we propose results from varying coevolutionary pressures exerted by host-pathogen relationships, and is influenced by structural heterozygosity. PMID:27415776

  8. Recombination Rate Heterogeneity within Arabidopsis Disease Resistance Genes

    PubMed Central

    Serra, Heïdi; Ziolkowski, Piotr A.; Yelina, Nataliya E.; Jackson, Matthew; Mézard, Christine; McVean, Gil; Henderson, Ian R.

    2016-01-01

    Meiotic crossover frequency varies extensively along chromosomes and is typically concentrated in hotspots. As recombination increases genetic diversity, hotspots are predicted to occur at immunity genes, where variation may be beneficial. A major component of plant immunity is recognition of pathogen Avirulence (Avr) effectors by resistance (R) genes that encode NBS-LRR domain proteins. Therefore, we sought to test whether NBS-LRR genes would overlap with meiotic crossover hotspots using experimental genetics in Arabidopsis thaliana. NBS-LRR genes tend to physically cluster in plant genomes; for example, in Arabidopsis most are located in large clusters on the south arms of chromosomes 1 and 5. We experimentally mapped 1,439 crossovers within these clusters and observed NBS-LRR gene associated hotspots, which were also detected as historical hotspots via analysis of linkage disequilibrium. However, we also observed NBS-LRR gene coldspots, which in some cases correlate with structural heterozygosity. To study recombination at the fine-scale we used high-throughput sequencing to analyze ~1,000 crossovers within the RESISTANCE TO ALBUGO CANDIDA1 (RAC1) R gene hotspot. This revealed elevated intragenic crossovers, overlapping nucleosome-occupied exons that encode the TIR, NBS and LRR domains. The highest RAC1 recombination frequency was promoter-proximal and overlapped CTT-repeat DNA sequence motifs, which have previously been associated with plant crossover hotspots. Additionally, we show a significant influence of natural genetic variation on NBS-LRR cluster recombination rates, using crosses between Arabidopsis ecotypes. In conclusion, we show that a subset of NBS-LRR genes are strong hotspots, whereas others are coldspots. This reveals a complex recombination landscape in Arabidopsis NBS-LRR genes, which we propose results from varying coevolutionary pressures exerted by host-pathogen relationships, and is influenced by structural heterozygosity. PMID:27415776

  9. Human DNA repair and recombination genes

    SciTech Connect

    Thompson, L.H.; Weber, C.A.; Jones, N.J.

    1988-09-01

    Several genes involved in mammalian DNA repair pathways were identified by complementation analysis and chromosomal mapping based on hybrid cells. Eight complementation groups of rodent mutants defective in the repair of uv radiation damage are now identified. At least seven of these genes are probably essential for repair and at least six of them control the incision step. The many genes required for repair of DNA cross-linking damage show overlap with those involved in the repair of uv damage, but some of these genes appear to be unique for cross-link repair. Two genes residing on human chromosome 19 were cloned from genomic transformants using a cosmid vector, and near full-length cDNA clones of each gene were isolated and sequenced. Gene ERCC2 efficiently corrects the defect in CHO UV5, a nucleotide excision repair mutant. Gene XRCC1 normalizes repair of strand breaks and the excessive sister chromatid exchange in CHO mutant EM9. ERCC2 shows a remarkable /approximately/52% overall homology at both the amino acid and nucleotide levels with the yeast RAD3 gene. Evidence based on mutation induction frequencies suggests that ERCC2, like RAD3, might also be an essential gene for viability. 100 refs., 4 tabs.

  10. A recombineering-based gene tagging system for Arabidopsis.

    PubMed

    Alonso, Jose M; Stepanova, Anna N

    2015-01-01

    Many of the experimental approaches aimed at studying gene function heavily rely on the ability to make precise modifications in the gene's DNA sequence. Homologous recombination (HR)-based strategies provide a convenient way to create such types of modifications. HR-based DNA sequence manipulations can be enormously facilitated by expressing in E. coli a small set of bacteriophage proteins that make the exchange of DNA between a linear donor and the target DNA molecules extremely efficient. These in vivo recombineering techniques have been incorporated as essential components of the molecular toolbox in many model organisms. In this chapter, we describe the experimental procedures involved in recombineering-based tagging of an Arabidopsis gene contained in a plant transformation-ready bacterial artificial chromosome (TAC). PMID:25239749

  11. A Network Approach to Analyzing Highly Recombinant Malaria Parasite Genes

    PubMed Central

    Larremore, Daniel B.; Clauset, Aaron; Buckee, Caroline O.

    2013-01-01

    The var genes of the human malaria parasite Plasmodium falciparum present a challenge to population geneticists due to their extreme diversity, which is generated by high rates of recombination. These genes encode a primary antigen protein called PfEMP1, which is expressed on the surface of infected red blood cells and elicits protective immune responses. Var gene sequences are characterized by pronounced mosaicism, precluding the use of traditional phylogenetic tools that require bifurcating tree-like evolutionary relationships. We present a new method that identifies highly variable regions (HVRs), and then maps each HVR to a complex network in which each sequence is a node and two nodes are linked if they share an exact match of significant length. Here, networks of var genes that recombine freely are expected to have a uniformly random structure, but constraints on recombination will produce network communities that we identify using a stochastic block model. We validate this method on synthetic data, showing that it correctly recovers populations of constrained recombination, before applying it to the Duffy Binding Like-α (DBLα) domain of var genes. We find nine HVRs whose network communities map in distinctive ways to known DBLα classifications and clinical phenotypes. We show that the recombinational constraints of some HVRs are correlated, while others are independent. These findings suggest that this micromodular structuring facilitates independent evolutionary trajectories of neighboring mosaic regions, allowing the parasite to retain protein function while generating enormous sequence diversity. Our approach therefore offers a rigorous method for analyzing evolutionary constraints in var genes, and is also flexible enough to be easily applied more generally to any highly recombinant sequences. PMID:24130474

  12. Recombination facilitates neofunctionalization of duplicate genes via originalization

    PubMed Central

    2010-01-01

    Background Recently originalization was proposed to be an effective way of duplicate-gene preservation, in which recombination provokes the high frequency of original (or wild-type) allele on both duplicated loci. Because the high frequency of wild-type allele might drive the arising and accumulating of advantageous mutation, it is hypothesized that recombination might enlarge the probability of neofunctionalization (Pneo) of duplicate genes. In this article this hypothesis has been tested theoretically. Results Results show that through originalization recombination might not only shorten mean time to neofunctionalizaiton, but also enlarge Pneo. Conclusions Therefore, recombination might facilitate neofunctionalization via originalization. Several extensive applications of these results on genomic evolution have been discussed: 1. Time to nonfunctionalization can be much longer than a few million generations expected before; 2. Homogenization on duplicated loci results from not only gene conversion, but also originalization; 3. Although the rate of advantageous mutation is much small compared with that of degenerative mutation, Pneo cannot be expected to be small. PMID:20534125

  13. Identification of Recombination and Positively Selected Genes in Brucella.

    PubMed

    Vishnu, Udayakumar S; Sankarasubramanian, Jagadesan; Sridhar, Jayavel; Gunasekaran, Paramasamy; Rajendhran, Jeyaprakash

    2015-12-01

    Brucella is a facultative intracellular bacterium belongs to the class alpha proteobacteria. It causes zoonotic disease brucellosis to wide range of animals. Brucella species are highly conserved in nucleotide level. Here, we employed a comparative genomics approach to examine the role of homologous recombination and positive selection in the evolution of Brucella. For the analysis, we have selected 19 complete genomes from 8 species of Brucella. Among the 1599 core genome predicted, 24 genes were showing signals of recombination but no significant breakpoint was found. The analysis revealed that recombination events are less frequent and the impact of recombination occurred is negligible on the evolution of Brucella. This leads to the view that Brucella is clonally evolved. On other hand, 56 genes (3.5 % of core genome) were showing signals of positive selection. Results suggest that natural selection plays an important role in the evolution of Brucella. Some of the genes that are responsible for the pathogenesis of Brucella were found positively selected, presumably due to their role in avoidance of the host immune system. PMID:26543263

  14. Selection and recombination in populations containing tandem multiplet genes.

    PubMed

    Koch, A L

    1979-12-01

    Computer simulation for selective conditions that may apply in nature yielded three generalizations for prokaryotic organisms with recombinant mechanisms. (1) Selective forces can suffice to maintain a tandem gene family with the nearly optimum number of genes with little variance within the population. (2) Tandem genes will occur within the population unless the population is frequently cloned or unless the function due to a single copy is capable of over-providing the needs of the organism. (3) Even when there is no selective advantage or disadvantage due to extra gene copies, the population distribution becomes more skewed with time; and organisms with only single copies of the gene comprise a progressively larger fraction of the total. This may be the case with genes that function under strong cellular regulation. Evolutionary implications of these calculations are that the occurrence of unequal recombination of tandem genes would greatly slow evolution via duplication of genetic material. This difficulty and its possible resolutions are discussed. PMID:537107

  15. Genetically Engineered Poxviruses for Recombinant Gene Expression, Vaccination, and Safety

    NASA Astrophysics Data System (ADS)

    Moss, Bernard

    1996-10-01

    Vaccinia virus, no longer required for immunization against smallpox, now serves as a unique vector for expressing genes within the cytoplasm of mammalian cells. As a research tool, recombinant vaccinia viruses are used to synthesize and analyze the structure--function relationships of proteins, determine the targets of humoral and cell-mediated immunity, and investigate the types of immune response needed for protection against specific infectious diseases and cancer. The vaccine potential of recombinant vaccinia virus has been realized in the form of an effective oral wild-life rabies vaccine, although no product for humans has been licensed. A genetically altered vaccinia virus that is unable to replicate in mammalian cells and produces diminished cytopathic effects retains the capacity for high-level gene expression and immunogenicity while promising exceptional safety for laboratory workers and potential vaccine recipients.

  16. Detecting Key Structural Features within Highly Recombined Genes

    PubMed Central

    Wertz, John E; McGregor, Karen F; Bessen, Debra E

    2007-01-01

    Many microorganisms exhibit high levels of intragenic recombination following horizontal gene transfer events. Furthermore, many microbial genes are subject to strong diversifying selection as part of the pathogenic process. A multiple sequence alignment is an essential starting point for many of the tools that provide fundamental insights on gene structure and evolution, such as phylogenetics; however, an accurate alignment is not always possible to attain. In this study, a new analytic approach was developed in order to better quantify the genetic organization of highly diversified genes whose alleles do not align. This BLAST-based method, denoted BLAST Miner, employs an iterative process that places short segments of highly similar sequence into discrete datasets that are designated “modules.” The relative positions of modules along the length of the genes, and their frequency of occurrence, are used to identify sequence duplications, insertions, and rearrangements. Partial alleles of sof from Streptococcus pyogenes, encoding a surface protein under host immune selection, were analyzed for module content. High-frequency Modules 6 and 13 were identified and examined in depth. Nucleotide sequences corresponding to both modules contain numerous duplications and inverted repeats, whereby many codons form palindromic pairs. Combined with evidence for a strong codon usage bias, data suggest that Module 6 and 13 sequences are under selection to preserve their nucleic acid secondary structure. The concentration of overlapping tandem and inverted repeats within a small region of DNA is highly suggestive of a mechanistic role for Module 6 and 13 sequences in promoting aberrant recombination. Analysis of pbp2X alleles from Streptococcus pneumoniae, encoding cell wall enzymes that confer antibiotic resistance, supports the broad applicability of this tool in deciphering the genetic organization of highly recombined genes. BLAST Miner shares with phylogenetics the

  17. Homologous recombination is required for AAV-mediated gene targeting

    PubMed Central

    Vasileva, Ana; Linden, R. Michael; Jessberger, Rolf

    2006-01-01

    High frequencies of gene targeting can be achieved by infection of mammalian cells with recombinant adeno-associated virus (rAAV) vectors [D. W. Russell and R. K. Hirata (1998) Nature Genet., 18, 325–330; D. W. Russell and R. K. Hirata (2000) J. Virol., 74, 4612–4620; R. Hirata et al. (2002) Nat. Biotechnol., 20, 735–738], but the mechanism of targeting is unclear and random integration often occurs in parallel. We assessed the role of specific DNA repair and recombination pathways in rAAV gene targeting by measuring correction of a mutated enhanced green fluorescent protein (EGFP) gene in cells where homologous recombination (HR) or non-homologous end-joining (NHEJ) had been suppressed by RNAi. EGFP-negative cells were transduced with rAAV vectors carrying a different inactivating deletion in the EGFP, and in parallel with rAAV vectors carrying red fluorescent protein (RFP). Expression of RFP accounted for viral transduction efficiency and long-term random integration. Approximately 0.02% of the infected GFP-negative cells were stably converted to GFP positive cells. Silencing of the essential NHEJ component DNA-PK had no significant effect on the frequency of targeting at any time point examined. Silencing of the SNF2/SWI2 family members RAD54L or RAD54B, which are important for HR, reduced the rate of stable rAAV gene targeting ∼5-fold. Further, partial silencing of the Rad51 paralogue XRCC3 completely abolished stable long-term EGFP expression. These results show that rAAV gene targeting requires the Rad51/Rad54 pathway of HR. PMID:16822856

  18. Gene delivery into plant cells for recombinant protein production.

    PubMed

    Chen, Qiang; Lai, Huafang

    2015-01-01

    Recombinant proteins are primarily produced from cultures of mammalian, insect, and bacteria cells. In recent years, the development of deconstructed virus-based vectors has allowed plants to become a viable platform for recombinant protein production, with advantages in versatility, speed, cost, scalability, and safety over the current production paradigms. In this paper, we review the recent progress in the methodology of agroinfiltration, a solution to overcome the challenge of transgene delivery into plant cells for large-scale manufacturing of recombinant proteins. General gene delivery methodologies in plants are first summarized, followed by extensive discussion on the application and scalability of each agroinfiltration method. New development of a spray-based agroinfiltration and its application on field-grown plants is highlighted. The discussion of agroinfiltration vectors focuses on their applications for producing complex and heteromultimeric proteins and is updated with the development of bridge vectors. Progress on agroinfiltration in Nicotiana and non-Nicotiana plant hosts is subsequently showcased in context of their applications for producing high-value human biologics and low-cost and high-volume industrial enzymes. These new advancements in agroinfiltration greatly enhance the robustness and scalability of transgene delivery in plants, facilitating the adoption of plant transient expression systems for manufacturing recombinant proteins with a broad range of applications. PMID:26075275

  19. Gene Delivery into Plant Cells for Recombinant Protein Production

    PubMed Central

    Chen, Qiang

    2015-01-01

    Recombinant proteins are primarily produced from cultures of mammalian, insect, and bacteria cells. In recent years, the development of deconstructed virus-based vectors has allowed plants to become a viable platform for recombinant protein production, with advantages in versatility, speed, cost, scalability, and safety over the current production paradigms. In this paper, we review the recent progress in the methodology of agroinfiltration, a solution to overcome the challenge of transgene delivery into plant cells for large-scale manufacturing of recombinant proteins. General gene delivery methodologies in plants are first summarized, followed by extensive discussion on the application and scalability of each agroinfiltration method. New development of a spray-based agroinfiltration and its application on field-grown plants is highlighted. The discussion of agroinfiltration vectors focuses on their applications for producing complex and heteromultimeric proteins and is updated with the development of bridge vectors. Progress on agroinfiltration in Nicotiana and non-Nicotiana plant hosts is subsequently showcased in context of their applications for producing high-value human biologics and low-cost and high-volume industrial enzymes. These new advancements in agroinfiltration greatly enhance the robustness and scalability of transgene delivery in plants, facilitating the adoption of plant transient expression systems for manufacturing recombinant proteins with a broad range of applications. PMID:26075275

  20. Adenovirus-Mediated siRNA Targeting CXCR2 Attenuates Titanium Particle-Induced Osteolysis by Suppressing Osteoclast Formation

    PubMed Central

    Wang, Chen; Liu, Yang; Wang, Yang; Li, Hao; Zhang, Ran-Xi; He, Mi-Si; Chen, Liang; Wu, Ning-Ning; Liao, Yong; Deng, Zhong-Liang

    2016-01-01

    Background Wear particle-induced peri-implant loosening is the most common complication affecting long-term outcomes in patients who undergo total joint arthroplasty. Wear particles and by-products from joint replacements may cause chronic local inflammation and foreign body reactions, which can in turn lead to osteolysis. Thus, inhibiting the formation and activity of osteoclasts may improve the functionality and long-term success of total joint arthroplasty. The aim of this study was to interfere with CXC chemokine receptor type 2 (CXCR2) to explore its role in wear particle-induced osteolysis. Material/Methods Morphological and biochemical assays were used to assess osteoclastogenesis in vivo and in vitro. CXCR2 was upregulated in osteoclast formation. Results Local injection with adenovirus-mediated siRNA targeting CXCR2 inhibited titanium-induced osteolysis in a mouse calvarial model in vivo. Furthermore, siCXCR2 suppressed osteoclast formation both directly by acting on osteoclasts themselves and indirectly by altering RANKL and OPG expression in osteoblasts in vitro. Conclusions CXCR2 plays a critical role in particle-induced osteolysis, and siCXCR2 may be a novel treatment for aseptic loosening. PMID:26939934

  1. Adenovirus-mediated siRNA targeting CXCR2 attenuates titanium particle-induced osteolysis by suppressing osteoclast formation.

    PubMed

    Wang, Chen; Liu, Yang; Wang, Yang; Li, Hao; Zhang, Ran-Xi; He, Mi-Si; Chen, Liang; Wu, Ning-Ning; Liao, Yong; Deng, Zhong-Liang

    2016-01-01

    BACKGROUND Wear particle-induced peri-implant loosening is the most common complication affecting long-term outcomes in patients who undergo total joint arthroplasty. Wear particles and by-products from joint replacements may cause chronic local inflammation and foreign body reactions, which can in turn lead to osteolysis. Thus, inhibiting the formation and activity of osteoclasts may improve the functionality and long-term success of total joint arthroplasty. The aim of this study was to interfere with CXC chemokine receptor type 2 (CXCR2) to explore its role in wear particle-induced osteolysis. MATERIAL AND METHODS Morphological and biochemical assays were used to assess osteoclastogenesis in vivo and in vitro. CXCR2 was upregulated in osteoclast formation. RESULTS Local injection with adenovirus-mediated siRNA targeting CXCR2 inhibited titanium-induced osteolysis in a mouse calvarial model in vivo. Furthermore, siCXCR2 suppressed osteoclast formation both directly by acting on osteoclasts themselves and indirectly by altering RANKL and OPG expression in osteoblasts in vitro. CONCLUSIONS CXCR2 plays a critical role in particle-induced osteolysis, and siCXCR2 may be a novel treatment for aseptic loosening. PMID:26939934

  2. Recombinant cells that highly express chromosomally-integrated heterologous genes

    DOEpatents

    Ingram, L.O.; Ohta, Kazuyoshi; Wood, B.E.

    1998-10-13

    Recombinant host cells are obtained that comprise (A) a heterologous, polypeptide-encoding polynucleotide segment, stably integrated into a chromosome, which is under transcriptional control of an endogenous promoter and (B) a mutation that effects increased expression of the heterologous segment, resulting in enhanced production by the host cells of each polypeptide encoded by that segment, relative to production of each polypeptide by the host cells in the absence of the mutation. The increased expression thus achieved is retained in the absence of conditions that select for cells displaying such increased expression. When the integrated segment comprises, for example, ethanol-production genes from an efficient ethanol producer like Zymomonas mobilis, recombinant Escherichia coli and other enteric bacterial cells within the present invention are capable of converting a wide range of biomass-derived sugars efficiently to ethanol. 13 figs.

  3. Recombinant cells that highly express chromosomally-integrated heterologous gene

    DOEpatents

    Ingram, Lonnie O.; Ohta, Kazuyoshi; Wood, Brent E.

    2007-03-20

    Recombinant host cells are obtained that comprise (A) a heterologous, polypeptide-encoding polynucleotide segment, stably integrated into a chromosome, which is under transcriptional control of an endogenous promoter and (B) a mutation that effects increased expression of the heterologous segment, resulting in enhanced production by the host cells of each polypeptide encoded by that segment, relative to production of each polypeptide by the host cells in the absence of the mutation. The increased expression thus achieved is retained in the absence of conditions that select for cells displaying such increased expression. When the integrated segment comprises, for example, ethanol-production genes from an efficient ethanol producer like Zymomonas mobilis, recombinant Escherichia coli and other enteric bacterial cells within the present invention are capable of converting a wide range of biomass-derived sugars efficiently to ethanol.

  4. Recombinant cells that highly express chromosomally-integrated heterologous genes

    DOEpatents

    Ingram, Lonnie O.; Ohta, Kazuyoshi; Wood, Brent E.

    1998-01-01

    Recombinant host cells are obtained that comprise (A) a heterologous, polypeptide-encoding polynucleotide segment, stably integrated into a chromosome, which is under transcriptional control of an endogenous promoter and (B) a mutation that effects increased expression of the heterologous segment, resulting in enhanced production by the host cells of each polypeptide encoded by that segment, relative to production of each polypeptide by the host cells in the absence of the mutation. The increased expression thus achieved is retained in the absence of conditions that select for cells displaying such increased expression. When the integrated segment comprises, for example, ethanol-production genes from an efficient ethanol producer like Zymomonas mobilis, recombinant Escherichia coli and other enteric bacterial cells within the present invention are capable of converting a wide range of biomass-derived sugars efficiently to ethanol.

  5. Recombinant cells that highly express chromosomally-integrated heterologous genes

    DOEpatents

    Ingram, Lonnie O.; Ohta, Kazuyoshi; Wood, Brent E.

    2000-08-22

    Recombinant host cells are obtained that comprise (A) a heterologous, polypeptide-encoding polynucleotide segment, stably integrated into a chromosome, which is under transcriptional control of an endogenous promoter and (B) a mutation that effects increased expression of the heterologous segment, resulting in enhanced production by the host cells of each polypeptide encoded by that segment, relative to production of each polypeptide by the host cells in the absence of the mutation. The increased expression thus achieved is retained in the absence of conditions that select for cells displaying such increased expression. When the integrated segment comprises, for example, ethanol-production genes from an efficient ethanol producer like Zymomonas mobilis, recombinant Escherichia coli and other enteric bacterial cells within the present invention are capable of converting a wide range of biomass-derived sugars efficiently to ethanol.

  6. Gene knockout of the intracellular amylase gene by homologous recombination in Streptococcus bovis.

    PubMed

    Brooker, J D; McCarthy, J M

    1997-09-01

    Streptococcus bovis expresses two different amylases, one intracellular and the other secreted. A suicide vector containing part of the intracellular alpha-amylase gene from Streptococcus bovis WI-1 was recombined into the S. bovis WI-1 chromosome to disrupt the endogenous gene. Recombination was demonstrated by Southern blot, and zymogram analysis confirmed the loss of the intracellular amylase. Amylase activity in cell-free extracts of the recombinant grown in the presence of 1% starch was only 7% of wild type. The rate of logarithmic growth of the recombinant was 15-20% of the wild type in medium containing either 1% glucose, starch, or cellobiose. Revertants and non-amylase control recombinants had logarithmic growth rates that were the same as wild type. Plasmid transformants containing multiple copies of the cloned gene expressed up to threefold higher levels of intracellular amylase activity than wild type but did not demonstrate elevated growth rates. These results suggest that a critical level of expression of the intracellular amylase gene may be important for rapid growth of the bacterium. PMID:9236293

  7. Characterization of recombinant bacteriophages containing mosquito ribosomal RNA genes

    SciTech Connect

    Park, Y.J.

    1988-01-01

    A family of nine recombinant bacteriophages containing rRNA genes from cultured cells of the mosquito, Aedes albopictus, has been isolated by screening two different genomic DNA libraries - Charon 30 and EMBL 3 using {sup 32}P-labeled 18S and 28S rRNA as probes. These nine recombinant bacteriophages were characterized by restriction mapping, Southern blotting, and S1 nuclease analysis. The 18S rRNA coding region contains an evolutionarily conserved EcoRI site near the 3{prime}-end, and measures 1800 bp. The 28S rRNA genes were divided into {alpha} and {beta} coding regions measuring 1750 bp and 2000 bp, respectively. The gap between these two regions measures about 340 bp. No insertion sequences were found in the rRNA coding regions. The entire rDNA repeat unit had a minimum length of 15.6 kb, including a nontranscribed spacer region. The non-transcribed spacer region of cloned A. albopictus rDNA contained a common series of seven PvuI sites within a 1250 bp region upstream of the 18S rRNA coding region, and a proportion of this region also showed heterogeneity both in the length and in the restriction sites.

  8. Three faces of recombination activating gene 1 (RAG1) mutations.

    PubMed

    Patiroglu, Turkan; Akar, Himmet Haluk; Van Der Burg, Mirjam

    2015-12-01

    Severe combined immune deficiency (SCID) is a group of genetic disorder associated with development of T- and/or B-lymphocytes. Recombination-activating genes (RAG1/2) play a critical role on VDJ recombination process that leads to the production of a broad T-cell receptor (TCR) and B-cell receptor (BCR) repertoire in the development of T and B cells. RAG1/2 genes mutations result in various forms of primary immunodeficiency, ranging from classic SCID to Omenn syndrome (OS) to atypical SCID with such as granuloma formation and autoimmunity. Herein, we reported 4 patients with RAG1 deficiency: classic SCID was seen in two patients who presented with recurrent pneumonia and chronic diarrhoea, and failure to thrive. OS was observed in one patient who presented with chronic diarrhoea, skin rash, recurrent lower respiratory infections, and atypical SCID was seen in one patient who presented with Pyoderma gangrenosum (PG) and had novel RAG1 mutation. PMID:26689875

  9. Adenovirus-mediated ING4 expression reduces multidrug resistance of human gastric carcinoma cells in vitro and in vivo.

    PubMed

    Mao, Zong-Lei; He, Song-Bing; Sheng, Wei-Hua; Dong, Xiao-Qiang; Yang, Ji-Cheng

    2013-11-01

    Chemotherapy is the primary treatment for both resectable and advanced gastric carcinoma, yet multiple drug resistance (MDR) of gastric carcinoma remains a significant therapeutic obstacle. The development of novel strategies to reduce MDR in gastric carcinoma would yield a better outcome following chemotherapy. ING4, a member of the inhibitor of growth (ING) tumor-suppressor family, possesses antitumor and radiosensitization or chemosensitization effects in a variety of human cancers. The present study investigated the effects and possible mechanisms of action of adenovirus-mediated ING4 (AdVING4) on the reversion of human gastric carcinoma cell MDR in vitro and in vivo in nude mouse xenografts. The data showed that the expression of ING4 mRNA and protein was dramatically downregulated (or lost) in gastric carcinoma SGC7901/CDDP cells after CDDP-induced MDR phenotype and in the parental SGC7901 cells. AdVING4‑induced ING4 expression reversed MDR and induced apoptosis of SGC7901/CDDP cells in vitro and in vivo in the SGC7901/CDDP xenograft tumors. Furthermore, AdVING4 substantially downregulated the expression of MDR-related proteins P-gp and MRP1 and apoptosis‑related proteins Bcl-2 and survivin, but upregulated the expression of apoptosis-related protein Bax in the SGC7901/CDDP xenograft tissues. The reversion effects elicited by AdVING4 on gastric cancer cell MDR were closely associated with the downregulation of ATP-binding cassette transporters and activation of apoptotic pathways. Thus, these findings suggest that AdVING4 may be a feasible modulator for the MDR phenotype of gastric carcinoma cells. PMID:23969950

  10. SITE-SPECIFIC RECOMBINATION FOR PLANT GENETIC ENGINEERING: STRATEGY FOR AGRO-MEDIATED GENE STACKING

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The precise rearrangement of DNA in planta can be achieved through site-specific recombination. For the past decade and a half, laboratory experiments have shown that site-specific recombination can delete genomic DNA, regulate gene expression, recombine chromosomes, and target new DNA into designat...

  11. Adenovirus mediated homozygous endometrial epithelial Pten deletion results in aggressive endometrial carcinoma

    SciTech Connect

    Joshi, Ayesha; Ellenson, Lora Hedrick

    2011-07-01

    Pten is the most frequently mutated gene in uterine endometriod carcinoma (UEC) and its precursor complex atypical hyperplasia (CAH). Because the mutation frequency is similar in CAH and UEC, Pten mutations are thought to occur relatively early in endometrial tumorigenesis. Previous work from our laboratory using the Pten{sup +/-} mouse model has demonstrated somatic inactivation of the wild type allele of Pten in both CAH and UEC. In the present study, we injected adenoviruses expressing Cre into the uterine lumen of adult Pten floxed mice in an attempt to somatically delete both alleles of Pten specifically in the endometrium. Our results demonstrate that biallelic inactivation of Pten results in an increased incidence of carcinoma as compared to the Pten{sup +/-} mouse model. In addition, the carcinomas were more aggressive with extension beyond the uterus into adjacent tissues and were associated with decreased expression of nuclear ER{alpha} as compared to associated CAH. Primary cultures of epithelial and stromal cells were prepared from uteri of Pten floxed mice and Pten was deleted in vitro using Cre expressing adenovirus. Pten deletion was evident in both the epithelial and stromal cells and the treatment of the primary cultures with estrogen had different effects on Akt activation as well as Cyclin D3 expression in the two purified components. This study demonstrates that somatic biallelic inactivation of Pten in endometrial epithelium in vivo results in an increased incidence and aggressiveness of endometrial carcinoma compared to mice carrying a germline deletion of one allele and provides an important in vivo and in vitro model system for understanding the genetic underpinnings of endometrial carcinoma.

  12. The haemagglutinin gene, but not the neuraminidase gene, of 'Spanish flu' was a recombinant.

    PubMed Central

    Gibbs, M J; Armstrong, J S; Gibbs, A J

    2001-01-01

    Published analyses of the sequences of three genes from the 1918 Spanish influenza virus have cast doubt on the theory that it came from birds immediately before the pandemic. They showed that the virus was of the H1N1 subtype lineage but more closely related to mammal-infecting strains than any known bird-infecting strain. They provided no evidence that the virus originated by gene reassortment nor that the virus was the direct ancestor of the two lineages of H1N1 viruses currently found in mammals; one that mostly infects human beings, the other pigs. The unusual virulence of the virus and why it produced a pandemic have remained unsolved. We have reanalysed the sequences of the three 1918 genes and found conflicting patterns of relatedness in all three. Various tests showed that the patterns in its haemagglutinin (HA) gene were produced by true recombination between two different parental HA H1 subtype genes, but that the conflicting patterns in its neuraminidase and non-structural-nuclear export proteins genes resulted from selection. The recombination event that produced the 1918 HA gene probably coincided with the start of the pandemic, and may have triggered it. PMID:11779383

  13. Divergence of human [alpha]-chain constant region gene sequences: A novel recombinant [alpha]2 gene

    SciTech Connect

    Chintalacharuvu, K. R.; Morrison, S.L. ); Raines, M. )

    1994-06-01

    IgA is the major Ig synthesized in humans and provides the first line of defense at the mucosal surfaces. The constant region of IgA heavy chain is encoded by the [alpha] gene on chromosome 14. Previous studies have indicated the presence of two [alpha] genes, [alpha]1 and [alpha]2 existing in two allotypic forms, [alpha]2 m(1) and [alpha]2 m(2). Here the authors report the cloning and complete nucleotide sequence determination of a novel human [alpha] gene. Nucleotide sequence comparison with the published [alpha] sequences suggests that the gene arose as a consequence of recombination or gene conversion between the two [alpha]2 alleles. The authors have expressed the gene as a chimeric protein in myeloma cells indicating that it encodes a functional protein. The novel IgA resembles IgA2 m(2) in that disulfide bonds link H and L chains. This novel recombinant gene provides insights into the mechanisms of generation of different constant regions and suggests that within human populations, multiple alleles of [alpha] may be present providing IgAs of different structures.

  14. Identification of recombination in the NS1 and VPs genes of parvovirus B19.

    PubMed

    Shen, Hongxing; Zhang, Wen; Wang, Hua; Shao, Shihe

    2016-08-01

    Human parvovirus B19 (B19V), a member of the genus Erythrovirus of the family Parvoviridae, is a pathogenic virus distributed worldwide in the human population. In this study, we performed phylogenetic and recombination analysis of B19V based on the available nonstructural gene (NS1) and capsid proteins (VPs) genes in GenBank. Results indicated that recombination occurred between genotypes 3 and 1, leading to the recombinant cluster genotype 2. Other three inter-genotype recombination events were also discovered. Moreover, our results showed that among the four recombinant events in the present study, all of the major parents belonged to genotype 1, the minor parents were from genotypes 3 or 2, and all of the recombinants belonged to genotype 2. These recombinant events were confirmed by SimPlot Program and phylogenetic analysis. J. Med. Virol. 88:1457-1461, 2016. © 2016 Wiley Periodicals, Inc. PMID:26756922

  15. Pangenome Analysis of Burkholderia pseudomallei: Genome Evolution Preserves Gene Order despite High Recombination Rates

    PubMed Central

    Spring-Pearson, Senanu M.; Stone, Joshua K.; Doyle, Adina; Allender, Christopher J.; Okinaka, Richard T.; Mayo, Mark; Broomall, Stacey M.; Hill, Jessica M.; Karavis, Mark A.; Hubbard, Kyle S.; Insalaco, Joseph M.; McNew, Lauren A.; Rosenzweig, C. Nicole; Gibbons, Henry S.; Currie, Bart J.; Wagner, David M.; Keim, Paul; Tuanyok, Apichai

    2015-01-01

    The pangenomic diversity in Burkholderia pseudomallei is high, with approximately 5.8% of the genome consisting of genomic islands. Genomic islands are known hotspots for recombination driven primarily by site-specific recombination associated with tRNAs. However, recombination rates in other portions of the genome are also high, a feature we expected to disrupt gene order. We analyzed the pangenome of 37 isolates of B. pseudomallei and demonstrate that the pangenome is ‘open’, with approximately 136 new genes identified with each new genome sequenced, and that the global core genome consists of 4568±16 homologs. Genes associated with metabolism were statistically overrepresented in the core genome, and genes associated with mobile elements, disease, and motility were primarily associated with accessory portions of the pangenome. The frequency distribution of genes present in between 1 and 37 of the genomes analyzed matches well with a model of genome evolution in which 96% of the genome has very low recombination rates but 4% of the genome recombines readily. Using homologous genes among pairs of genomes, we found that gene order was highly conserved among strains, despite the high recombination rates previously observed. High rates of gene transfer and recombination are incompatible with retaining gene order unless these processes are either highly localized to specific sites within the genome, or are characterized by symmetrical gene gain and loss. Our results demonstrate that both processes occur: localized recombination introduces many new genes at relatively few sites, and recombination throughout the genome generates the novel multi-locus sequence types previously observed while preserving gene order. PMID:26484663

  16. Saturation mapping of a gene-rich recombination hot spot region in wheat.

    PubMed Central

    Faris, J D; Haen, K M; Gill, B S

    2000-01-01

    Physical mapping of wheat chromosomes has revealed small chromosome segments of high gene density and frequent recombination interspersed with relatively large regions of low gene density and infrequent recombination. We constructed a detailed genetic and physical map of one highly recombinant region on the long arm of chromosome 5B. This distally located region accounts for 4% of the physical size of the long arm and at least 30% of the recombination along the entire chromosome. Multiple crossovers occurred within this region, and the degree of recombination is at least 11-fold greater than the genomic average. Characteristics of the region such as gene order and frequency of recombination appear to be conserved throughout the evolution of the Triticeae. The region is more prone to chromosome breakage by gametocidal gene action than gene-poor regions, and evidence for genomic instability was implied by loss of gene collinearity for six loci among the homeologous regions. These data suggest that a unique level of chromatin organization exists within gene-rich recombination hot spots. The many agronomically important genes in this region should be accessible by positional cloning. PMID:10655233

  17. Targeted DNA recombination in vivo using an adenovirus carrying the cre recombinase gene.

    PubMed Central

    Wang, Y; Krushel, L A; Edelman, G M

    1996-01-01

    Conditional gene expression and gene deletion are important experimental approaches for examining the functions of particular gene products in development and disease. The cre-loxP system from bacteriophage P1 has been used in transgenic animals to induce site-specific DNA recombination leading to gene activation or deletion. To regulate the recombination in a spatiotemporally controlled manner, we constructed a recombinant adenoviral vector, Adv/cre, that contained the cre recombinase gene under regulation of the herpes simplex virus thymidine kinase promoter. The efficacy and target specificity of this vector in mediating loxP-dependent recombination were analyzed in mice that had been genetically engineered to contain loxP sites in their genome. After intravenous injection of the Adv/cre vector into adult animals, the liver and spleen showed the highest infectivity of the adenovirus as well as the highest levels of recombination, whereas other tissues such as kidney, lung, and heart had lower levels of infection and recombination. Only trace levels of recombination were detected in the brain. However, when the Adv/cre vector was injected directly into specific regions of the adult brain, including the cerebral cortex, hippocampus, and cerebellum, recombination was detectable at the injection site. Furthermore, when the Adv/cre vector was injected into the forebrains of neonatal mice, the rearranged toxP locus from recombination could be detected in the injected regions for at least 8 weeks. Taken together, these results demonstrate that the Adv/cre vector expressing a functional cre protein is capable of mediating loxP-dependent recombination in various tissues and the recombined gene locus may in some cases be maintained for an extended period. The use of the adenovirus vector expressing cre combined with localized delivery to specific tissues may provide an efficient means to achieve conditional gene expression or knockout with precise spatiotemporal control

  18. Positive genetic selection for gene disruption in mammalian cells by homologous recombination.

    PubMed Central

    Sedivy, J M; Sharp, P A

    1989-01-01

    Efficient modification of genes in mammalian cells by homologous recombination has not been possible because of the high frequency of nonhomologous recombination. An efficient method for targeted gene disruption has been developed. Cells with substitution of exogenous sequences into a chromosomal locus were enriched, by a factor of 100, using a positive genetic selection that specifically selects for homologous recombination at the targeted site. The selection is based on the conditional expression of a dominant selectable marker by virtue of in-frame gene fusion with the target gene. The dominant selectable marker was derived by modification of the Escherichia coli neo gene so that it retains significant activity in mammalian cells after in-frame fusion with heterologous coding sequences. In the example presented here, homologous recombinants were efficiently recovered from a pool in which the targeted gene was disrupted in 1 per 10,000 cells incorporating exogenous DNA. Images PMID:2536156

  19. Inhibition of breast cancer growth in vivo by antiangiogenesis gene therapy with adenovirus-mediated antisense-VEGF

    PubMed Central

    Im, S-A; Kim, J-S; Gomez-Manzano, C; Fueyo, J; Liu, T-J; Cho, M-S; Seong, C-M; Lee, S N; Hong, Y-K; Yung, W K A

    2001-01-01

    Increased expression of VEGF in several types of tumours has been shown to correlate with poor prognosis. We used a replication-deficient adenoviral vector containing antisense VEGF cDNA (Ad5CMV-αVEGF) to down-regulate VEGF expression and increase the efficiency of delivery of the antisense sequence in the human breast cancer cell line MDA231-MB. Transfection of these cells with Ad5CMV-αVEGF in vitro reduced secreted levels of VEGF protein without affecting cell growth. Moreover, injection of the Ad5CMV-αVEGF vector into intramammary xenografts of these cells established in nude mice inhibited tumour growth and reduced the amount of VEGF protein and the density of microvessels in those tumours relative to tumours treated with the control vector Ad5(dl312). Our results showed that antisense VEGF 165 cDNA was efficiently delivered in vivo via an adenoviral vector and that this treatment significantly inhibited the growth of established experimental breast tumours. The Ad5CMV-αVEGF vector may be useful in targeting the tumour vasculature in the treatment of breast cancer. © 2001 Cancer Research Campaign http://www.bjcancer.com PMID:11336478

  20. Adenovirus-mediated HIF-1α gene transfer promotes repair of mouse airway allograft microvasculature and attenuates chronic rejection.

    PubMed

    Jiang, Xinguo; Khan, Mohammad A; Tian, Wen; Beilke, Joshua; Natarajan, Ramesh; Kosek, Jon; Yoder, Mervin C; Semenza, Gregg L; Nicolls, Mark R

    2011-06-01

    Chronic rejection, manifested as small airway fibrosis (obliterative bronchiolitis [OB]), is the main obstacle to long-term survival in lung transplantation. Recent studies demonstrate that the airways involved in a lung transplant are relatively hypoxic at baseline and that OB pathogenesis may be linked to ischemia induced by a transient loss of airway microvasculature. Here, we show that HIF-1α mediates airway microvascular repair in a model of orthotopic tracheal transplantation. Grafts with a conditional knockout of Hif1a demonstrated diminished recruitment of recipient-derived Tie2⁺ angiogenic cells to the allograft, impaired repair of damaged microvasculature, accelerated loss of microvascular perfusion, and hastened denudation of epithelial cells. In contrast, graft HIF-1α overexpression induced via an adenoviral vector prolonged airway microvascular perfusion, preserved epithelial integrity, extended the time window for the graft to be rescued from chronic rejection, and attenuated airway fibrotic remodeling. HIF-1α overexpression induced the expression of proangiogenic factors such as Sdf1, Plgf, and Vegf, and promoted the recruitment of vasoreparative Tie2⁺ cells. This study demonstrates that a therapy that enhances vascular integrity during acute rejection may promote graft health and prevent chronic rejection. PMID:21606594

  1. Recombinant HT.sub.m4 gene, protein and assays

    DOEpatents

    Lim, Bing; Adra, Chaker N.; Lelias, Jean-Michel

    1996-01-01

    The invention relates to a recombinant DNA molecule which encodes a HT.sub.m4 protein, a transformed host cell which has been stably transfected with a DNA molecule which encodes a HT.sub.m4 protein and a recombinant HT.sub.m4 protein. The invention also relates to a method for detecting the presence of a hereditary atopy.

  2. Generation of Recombinant Capripoxvirus Vectors for Vaccines and Gene Knockout Function Studies.

    PubMed

    Boshra, Hani; Cao, Jingxin; Babiuk, Shawn

    2016-01-01

    The ability to manipulate capripoxvirus through gene knockouts and gene insertions has become an increasingly valuable research tool in elucidating the function of individual genes of capripoxvirus, as well as in the development of capripoxvirus-based recombinant vaccines. The homologous recombination technique is used to generate capripoxvirus knockout viruses (KO), and is based on the targeting a particular viral gene of interest. This technique can also be used to insert a gene of interest. A protocol for the generation of a viral gene knockout is described. This technique involves the use of a plasmid which encodes the flanking sequences of the regions where the homologous recombination will occur, and will result in the insertion of an EGFP reporter gene for visualization of recombinant virus, as well as the E. coli gpt gene as a positive selection marker. If an additional gene is to be incorporated, this can be achieved by inserting a gene of interest for expression under a poxvirus promoter into the plasmid between the flanking regions for insertion. This chapter describes a protocol for generating such recombinant capripoxviruses. PMID:26458835

  3. A systematic analysis of recombination activity and genotype-phenotype correlation in human recombination-activating gene 1 deficiency

    PubMed Central

    Lee, Yu Nee; Frugoni, Francesco; Dobbs, Kerry; Walter, Jolan E.; Giliani, Silvia; Gennery, Andrew R.; Al-Herz, Waleed; Haddad, Elie; LeDeist, Francoise; Bleesing, Jack H.; Henderson, Lauren A.; Pai, Sung-Yun; Nelson, Robert P.; El-Ghoneimy, Dalia H.; El-Feky, Reem A.; Reda, Shereen M.; Hossny, Elham; Soler-Palacin, Pere; Fuleihan, Ramsay L.; Patel, Niraj C.; Massaad, Michel J.; Geha, Raif S.; Puck, Jennifer M.; Palma, Paolo; Cancrini, Caterina; Chen, Karin; Vihinen, Mauno; Alt, Frederick W.; Notarangelo, Luigi D.

    2014-01-01

    Background The recombination-activating gene (RAG) 1/2 proteins play a critical role in the development of T and B cells by initiating the VDJ recombination process that leads to generation of a broad T-cell receptor (TCR) and B-cell receptor repertoire. Pathogenic mutations in the RAG1/2 genes result in various forms of primary immunodeficiency, ranging from T−B− severe combined immune deficiency to delayed-onset disease with granuloma formation, autoimmunity, or both. It is not clear what contributes to such heterogeneity of phenotypes. Objective We sought to investigate the molecular basis for phenotypic diversity presented in patients with various RAG1 mutations. Methods We have developed a flow cytometry–based assay that allows analysis of RAG recombination activity based on green fluorescent protein expression and have assessed the induction of the Ighc locus rearrangements in mouse Rag1−/− pro-B cells reconstituted with wild-type or mutant human RAG1 (hRAG1) using deep sequencing technology. Results Here we demonstrate correlation between defective recombination activity of hRAG1 mutant proteins and severity of the clinical and immunologic phenotype and provide insights on the molecular mechanisms accounting for such phenotypic diversity. Conclusions Using a sensitive assay to measure the RAG1 activity level of 79 mutations in a physiologic setting, we demonstrate correlation between recombination activity of RAG1 mutants and the severity of clinical presentation and show that RAG1 mutants can induce specific abnormalities of the VDJ recombination process. PMID:24290284

  4. Recombination within and between the human insulin and beta-globin gene loci.

    PubMed Central

    Lebo, R V; Chakravarti, A; Buetow, K H; Cheung, M C; Cann, H; Cordell, B; Goodman, H

    1983-01-01

    We detected a large number of polymorphic insulin restriction fragments in black Americans. These different size fragments were probably generated by unequal recombination on both sides of the human insulin gene. Population genetic analysis indicates that recombination occurred 33 times more frequently than expected to generate this large number of polymorphic fragments. Specific properties of the unique repeated 14- to 16-base-pair sequences 5' to the insulin gene suggest that this sequence would promote increased unequal recombination. Additional pedigree analysis showed that the recombination rate between the structural insulin and beta-globin gene loci was 14% with strong evidence for linkage. Since both insulin and beta-globin have been mapped to the short arm of human chromosome 11, this study establishes that the genetic map distance between these genes is 14.2 centimorgans. PMID:6348773

  5. Effects of the rad52 gene on recombination in Saccharomyces cerevisiae

    SciTech Connect

    Prakash, S.; Prakash, L.; Burke, W.; Montelone, B.A.

    1980-01-01

    Effects of the rad 52 mutation in Saccharomyces cerevisiae on meiotic, ..gamma..-ray-induced, uv-induced and spontaneous mitotic recombination were studied. The rad52/rad52 diploids undergo premeiotic DNA synthesis; sporulation occurs but inviable spores are produced. Both intra and intergenic recombination during meiosis were examined in cells transferred from sporulation medium to vegetative medium at different time intervals. No intragenic recombination was observed at the his1-1/his1-315 and trp-5-2/trp5-48 heteroalleles. Gene-centromere recombination also was not observed in rad/52/rad52 diploids. No ..gamma..-ray- or uv-induced intragenic mitotic recombination is seen in rad52/rad52 diploids. The rate of spontaneous mitotic recombination is lowered five-fold at the his1-1/his1-315 and leu1-c/leu1-12 heteroalleles. Spontaneous reversion rates of both his1-1 and his1-315 were elevated 10 to 20 fold in rad52/rad52 diploids. The RAD52 gene function is required for spontaneous mitotic recombination, uv- and ..gamma..-ray-induced mitotic recombination and mitotic recombination.

  6. Recombinant HT{sub m4} gene, protein and assays

    DOEpatents

    Lim, B.; Adra, C.N.; Lelias, J.M.

    1996-09-03

    The invention relates to a recombinant DNA molecule which encodes a HT{sub m4} protein, a transformed host cell which has been stably transfected with a DNA molecule which encodes a HT{sub m4} protein and a recombinant HT{sub m4} protein. The invention also relates to a method for detecting the presence of a hereditary atopy. 2 figs.

  7. Radiosensitization of head/neck sqaumous cell carcinoma by adenovirus-mediated expression of the Nbs1 protein

    SciTech Connect

    Rhee, Juong G.; Li, Daqing; Suntharalingam, Mohan; Guo Chuanfa; O'Malley, Bert W.; Carney, James P. . E-mail: jcarney@som.umaryland.edu

    2007-01-01

    Purpose: Local failure and toxicity to adjacent critical structures is a significant problem in radiation therapy of cancers of the head and neck. We are developing a gene therapy based method of sensitizing head/neck squamous cell carcinoma (HNSCC) to radiation treatment. As patients with the rare hereditary disorder, Nijmegen breakage syndrome, show radiation sensitivity we hypothesized that tumor-specific disruption of the function of the Nbs1 protein would lead to enhanced cellular sensitivity to ionizing radiation. Experimental Procedures: We constructed two recombinant adenoviruses by cloning the full-length Nbs1 cDNA as well as the C-terminal 300 amino acids of Nbs1 into an adenovirus backbone under the control of a CMV promoter. The resulting adenoviruses were used to infect HNSCC cell line JHU011. These cells were evaluated for expression of the viral based constructs and assayed for clonogenic survival following radiation exposure. Results: Exposure of cells expressing Nbs1-300 to ionizing radiation resulted in a small reduction in survival relative to cells infected with control virus. Surprisingly, expression of full-length Nbs1 protein resulted in markedly enhanced sensitivity to ionizing radiation. Furthermore, the use of a fractionated radiation scheme following virus infection demonstrates that expression of full-length Nbs1 protein results in significant reduction in cell survival. Conclusions: These results provide a proof of principle that disruption of Nbs1 function may provide a means of enhancing the radiosensitivity of head and neck tumors. Additionally, this work highlights the Mre11 complex as an attractive target for development of radiation sensitizers.

  8. A method to generate recombinant Salmonella typhi Ty21a strains expressing multiple heterologous genes using an improved recombineering strategy.

    PubMed

    Yu, Bin; Yang, Mei; Wong, Ho Yin Bosco; Watt, Rory M; Song, Erwei; Zheng, Bo-Jian; Yuen, Kwok-Yung; Huang, Jian-Dong

    2011-07-01

    Live attenuated Salmonella enterica serovar Typhi Ty21a (Ty21a) is an important vaccine strain used in clinical studies for typhoid fever and as a vaccine vector for the expression of heterologous antigens. To facilitate the use of Ty21a in such studies, it is desirable to develop improved strategies that enable the stable chromosomal integration and expression of multiple heterologous antigens. The phage λ Red homologous recombination system has previously been used in various gram-negative bacteria species to mediate the accurate replacement of regions of chromosomal DNA with PCR-generated 'targeting cassettes' that contain flanking regions of shared homologous DNA sequence. However, the efficiency of λ Red-mediated recombineering in Ty21a is far lower than in Escherichia coli and other Salmonella typhimurium strains. Here, we describe an improved strategy for recombineering-based methods in Ty21a. Our reliable and efficient method involves the use of linear DNA-targeting cassettes that contain relatively long flanking 'arms' of sequence (ca. 1,000 bp) homologous to the chromosomal target. This enables multiple gene-targeting procedures to be performed on a single Ty21a chromosome in a straightforward, sequential manner. Using this strategy, we inserted three different influenza antigen expression cassettes as well as a green fluorescent protein gene reporter into four different loci on the Ty21a chromosome, with high efficiency and accuracy. Fluorescent microscopy and Western blotting analysis confirmed that strong inducible expression of all four heterologous genes could be achieved. In summary, we have developed an efficient, robust, and versatile method that may be used to construct recombinant Ty21a antigen-expressing strains. PMID:21611798

  9. Quantitative analysis of recombination between YFP and CFP genes of FRET biosensors introduced by lentiviral or retroviral gene transfer.

    PubMed

    Komatsubara, Akira T; Matsuda, Michiyuki; Aoki, Kazuhiro

    2015-01-01

    Biosensors based on the principle of Förster (or fluorescence) resonance energy transfer (FRET) have been developed to visualize spatio-temporal dynamics of signalling molecules in living cells. Many of them adopt a backbone of intramolecular FRET biosensor with a cyan fluorescent protein (CFP) and yellow fluorescent protein (YFP) as donor and acceptor, respectively. However, there remains the difficulty of establishing cells stably expressing FRET biosensors with a YFP and CFP pair by lentiviral or retroviral gene transfer, due to the high incidence of recombination between YFP and CFP genes. To address this, we examined the effects of codon-diversification of YFP on the recombination of FRET biosensors introduced by lentivirus or retrovirus. The YFP gene that was fully codon-optimized to E.coli evaded the recombination in lentiviral or retroviral gene transfer, but the partially codon-diversified YFP did not. Further, the length of spacer between YFP and CFP genes clearly affected recombination efficiency, suggesting that the intramolecular template switching occurred in the reverse-transcription process. The simple mathematical model reproduced the experimental data sufficiently, yielding a recombination rate of 0.002-0.005 per base. Together, these results show that the codon-diversified YFP is a useful tool for expressing FRET biosensors by lentiviral or retroviral gene transfer. PMID:26290434

  10. Oral Administration of Recombinant Lactococcus lactis Expressing the Cellulase Gene Increases Digestibility of Fiber in Geese.

    PubMed

    Zhou, Haizhu; Gao, Yunhang; Gao, Guang; Lou, Yujie

    2015-12-01

    Enhancing cellulose digestibility in animals is important for improving the utilization of forage, which can decrease the amount of food used in animal production. The aim of the present study was to achieve recombinant expression of the cellulase gene in Lactococcus lactis and evaluate the effects of oral administration of the recombinant L. lactis on fiber digestibility in geese. Cellulase (Cell) and green fluorescent protein (GFP) genes were cloned into a L. lactis expression vector (pNZ8149) to construct the recombinant expression plasmid (pNZ8149-GFP-Cell). Then, the recombinant expression plasmid was transformed into L. lactis (NZ3900) competent cells by electroporation to obtain recombinant L. lactis (pNZ8149-GFP-Cell/NZ3900) in which protein expression was induced by Nisin. Expression of GFP and Cell by the recombinant L. lactis was confirmed using SDS-PAGE, fluorescence detection, and Congo red assays. A feeding experiment showed that oral administration of pNZ8149-GFP-Cell/NZ3900 significantly increased the digestibility of dietary fiber in geese fed either a maize stalk diet or a rice chaff diet. Therefore, oral administration of recombinant L. lactis cells expressing the cellulase gene increases fiber digestibility in geese, offering a way to increase the utilization of dietary fiber in geese. PMID:26341925

  11. DNA secondary structures are associated with recombination in major Plasmodium falciparum variable surface antigen gene families

    PubMed Central

    Sander, Adam F.; Lavstsen, Thomas; Rask, Thomas S.; Lisby, Michael; Salanti, Ali; Fordyce, Sarah L.; Jespersen, Jakob S.; Carter, Richard; Deitsch, Kirk W.; Theander, Thor G.; Pedersen, Anders Gorm; Arnot, David E.

    2014-01-01

    Many bacterial, viral and parasitic pathogens undergo antigenic variation to counter host immune defense mechanisms. In Plasmodium falciparum, the most lethal of human malaria parasites, switching of var gene expression results in alternating expression of the adhesion proteins of the Plasmodium falciparum-erythrocyte membrane protein 1 class on the infected erythrocyte surface. Recombination clearly generates var diversity, but the nature and control of the genetic exchanges involved remain unclear. By experimental and bioinformatic identification of recombination events and genome-wide recombination hotspots in var genes, we show that during the parasite’s sexual stages, ectopic recombination between isogenous var paralogs occurs near low folding free energy DNA 50-mers and that these sequences are heavily concentrated at the boundaries of regions encoding individual Plasmodium falciparum-erythrocyte membrane protein 1 structural domains. The recombinogenic potential of these 50-mers is not parasite-specific because these sequences also induce recombination when transferred to the yeast Saccharomyces cerevisiae. Genetic cross data suggest that DNA secondary structures (DSS) act as inducers of recombination during DNA replication in P. falciparum sexual stages, and that these DSS-regulated genetic exchanges generate functional and diverse P. falciparum adhesion antigens. DSS-induced recombination may represent a common mechanism for optimizing the evolvability of virulence gene families in pathogens. PMID:24253306

  12. A protocol for construction of gene targeting vectors and generation of homologous recombinant ES cells

    PubMed Central

    Bouabe, Hicham; Okkenhaug, Klaus

    2015-01-01

    Summary The completion of human and mouse genome sequencing has confronted us with huge amount of data sequences that certainly need decades and many generations of scientists to be reasonably interpreted and assigned to physiological functions, and subsequently fruitfully translated into medical application. A means to assess the function of genes provides gene targeting in mouse embryonic stem (ES) cells that enables to introduce site-specific modifications in the mouse genome, and analyze their physiological consequences. Gene targeting enables almost any type of genetic modifications of interest, ranging from gene insertion (e.g. insertion of human-specific genes or reporter genes), gene disruption, point mutations, short and long range deletions, inversions. Site-specific modification into the genome of ES cells can be reached by homologous recombination using targeting vectors. Here, we describe a protocol to generate targeting constructs and homologous recombinant ES cells. PMID:23996269

  13. Chromosomal integration of recombinant alpha-amylase and glucoamylase genes in saccharomyces cerevisiae for starch conversion

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Recombinant constructs of barley '-amylase and Lentinula edodes glucoamylase genes were integrated into the chromosomes of Saccharomyces cerevisiae. The insertion was confirmed by PCR amplification of the gene sequence in the chromosomes. The expression was analyzed by SDS-PAGE of the enzymes puri...

  14. Recombinant Gene Expression in vivo within Endothelial Cells of the Arterial Wall

    NASA Astrophysics Data System (ADS)

    Nabel, Elizabeth G.; Plautz, Gregory; Boyce, Frederick M.; Stanley, James C.; Nabel, Gary J.

    1989-06-01

    A technique for the transfer of endothelial cells and expression of recombinant genes in vivo could allow the introduction of proteins of therapeutic value in the management of cardiovascular diseases. Porcine endothelial cells expressing recombinant β -galactosidase from a murine amphotropic retroviral vector were introduced with a catheter into denuded iliofemoral arteries of syngeneic animals. Arterial segments explanted 2 to 4 weeks later contained endothelial cells expressing β -galactosidase, an indication that they were successfully implanted on the vessel wall.

  15. Analysis of putative recombination hot sites in the S gene of canine coronaviruses.

    PubMed

    Wang, Y Y; Lu, C P

    2009-01-01

    The S gene sequence of Canine coronavirus strain 1-71 (CCoV 1-71) was cloned, sequenced, and compared to those of other CCoVs, Transmissible gastroenteritis virus (TGEV), and Feline coronavirus (FCoV). The sequence analysis showed that CCoV 1-71 displayed a 98.8-99.8% identity with CCoVs strains V1, K378, and GP. Four putative recombination sites were found at the 5'-end of the S gene, namely at nt 53, 75, 425, 991. Both sequences flanking each site were significantly different. Three recombination hot regions were found on the S gene, namely at nt 337-437, 1545-3405, and 4203-4356, which shared a common recombination signal with Group 2 coronaviruses. The G/CTAAAAA/GT sequence downstream of the recombination site may represent a specific recombination signal in CCoVs. The CCoV 1-71 S protein sequence was found to be similar to those of other CCoVs except for several N-glycosylation sites at the N-terminus of the S protein, which could be related to the differences in virulence and cell tropism in individual CCoVs. This study indicated that the similarity of CCoVs in virulence and tropism was mostly acquired by the homologous RNA recombination and not only by simple mutation and selection. PMID:19537912

  16. Extensive Recombination Due to Heteroduplexes Generates Large Amounts of Artificial Gene Fragments during PCR

    PubMed Central

    Liu, Jia; Song, Hongshuo; Liu, Donglai; Zuo, Tao; Lu, Fengmin; Zhuang, Hui; Gao, Feng

    2014-01-01

    Artificial recombinants can be generated during PCR when more than two genetically distinct templates coexist in a single PCR reaction. These recombinant amplicons can lead to the false interpretation of genetic diversity and incorrect identification of biological phenotypes that do not exist in vivo. We investigated how recombination between 2 or 35 genetically distinct HIV-1 genomes was affected by different PCR conditions using the parallel allele-specific sequencing (PASS) assay and the next generation sequencing method. In a standard PCR condition, about 40% of amplicons in a PCR reaction were recombinants. The high recombination frequency could be significantly reduced if the number of amplicons in a PCR reaction was below a threshold of 1013–1014 using low thermal cycles, fewer input templates, and longer extension time. Heteroduplexes (each DNA strand from a distinct template) were present at a large proportion in the PCR products when more thermal cycles, more templates, and shorter extension time were used. Importantly, the majority of recombinants were identified in heteroduplexes, indicating that the recombinants were mainly generated through heteroduplexes. Since prematurely terminated extension fragments can form heteroduplexes by annealing to different templates during PCR amplification, recombination has a better chance to occur with samples containing different genomes when the number of amplicons accumulate over the threshold. New technologies are warranted to accurately characterize complex quasispecies gene populations. PMID:25211143

  17. Recombination between elongation factor 1α genes from distantly related archaeal lineages

    PubMed Central

    Inagaki, Yuji; Susko, Edward; Roger, Andrew J.

    2006-01-01

    Homologous recombination (HR) and lateral gene transfer are major processes in genome evolution. The combination of the two processes, HR between genes in different species, has been documented but is thought to be restricted to very similar sequences in relatively closely related organisms. Here we report two cases of interspecific HR in the gene encoding the core translational protein translation elongation factor 1α (EF-1α) between distantly related archaeal groups. Maximum-likelihood sliding window analyses indicate that a fragment of the EF-1α gene from the archaeal lineage represented by Methanopyrus kandleri was recombined into the orthologous gene in a common ancestor of the Thermococcales. A second recombination event appears to have occurred between the EF-1α gene of the genus Methanothermobacter and its ortholog in a common ancestor of the Methanosarcinales, a distantly related euryarchaeal lineage. These findings suggest that HR occurs across a much larger evolutionary distance than generally accepted and affects highly conserved essential “informational” genes. Although difficult to detect by standard whole-gene phylogenetic analyses, interspecific HR in highly conserved genes may occur at an appreciable frequency, potentially confounding deep phylogenetic inference and hypothesis testing. PMID:16537397

  18. Molluscan mobile elements similar to the vertebrate recombination-activating genes

    PubMed Central

    Panchin, Yuri; Moroz, Leonid L.

    2009-01-01

    Animal genomes contain ~20,000 genes. Additionally millions of genes for antigen receptors are generated in cells of the immune system from the sets of separate gene segments by a mechanism known as the V(D)J somatic recombination. The components of the V(D)J recombination system, Recombination-Activating Gene proteins (RAG1 and RAG2) and recombination signal sequence (RSS), are thought to have “entered” the vertebrate genome as a hypothetical “RAG transposon”. Recently discovered mobile elements have terminal inverted repeats (TIRs) similar to RSS and may encode proteins with a different degree of similarity to RAG1. We describe a novel N-RAG-TP transposon identified from the sea slug Aplysia californica that encodes a protein similar to the N-terminal part of RAG1 in vertebrates. This refines the “RAG transposon” hypothesis and allows us to propose a scenario for V(D)J recombination machinery evolution from a relic transposon related to the existing mobile elements N-RAG-TP, Chapaev and Transib. PMID:18313399

  19. Construction of heterologous gene expression cassettes for the development of recombinant Clostridium beijerinckii.

    PubMed

    Oh, Young Hoon; Eom, Gyeong Tae; Kang, Kyoung Hee; Joo, Jeong Chan; Jang, Young-Ah; Choi, Jae Woo; Song, Bong Keun; Lee, Seung Hwan; Park, Si Jae

    2016-04-01

    Gene-expression cassettes for the construction of recombinant Clostridium beijerinckii were developed as potential tools for metabolic engineering of C. beijerinckii. Gene expression cassettes containing ColE1 origin and pAMB origin along with the erythromycin resistance gene were constructed, in which promoters from Escherichia coli, Lactococcus lactis, Ralstonia eutropha, C. acetobutylicum, and C. beijerinckii are examined as potential promoters in C. beijerinckii. Zymogram analysis of the cell extracts and comparison of lipase activities of the recombinant C. beijerinckii strains expressing Pseudomonas fluorescens tliA gene suggested that the tliA gene was functionally expressed by all the examined promoters with different expression level. Also, recombinant C. beijerinckii expressing C. beijerinckii secondary alcohol dehydrogenase by the constructed expression cassettes successfully produced 2-propanol from glucose. The best promoter for TliA expression was the R. eutropha phaP promoter while that for 2-propanol production was the putative C. beijerinckii pta promoter. Gene expression cassettes developed in this study may be useful tools for the construction of recombinant C. beijerinckii strains as host strains for the valuable chemicals and fuels from renewable resources. PMID:26780375

  20. Pathogen corruption and site-directed recombination at a plant disease resistance gene cluster

    PubMed Central

    Nagy, Ervin D.; Bennetzen, Jeffrey L.

    2008-01-01

    The Pc locus of sorghum (Sorghum bicolor) determines dominant sensitivity to a host-selective toxin produced by the fungal pathogen Periconia circinata. The Pc region was cloned by a map-based approach and found to contain three tandemly repeated genes with the structures of nucleotide binding site–leucine-rich repeat (NBS–LRR) disease resistance genes. Thirteen independent Pc-to-pc mutations were analyzed, and each was found to remove all or part of the central gene of the threesome. Hence, this central gene is Pc. Most Pc-to-pc mutations were associated with unequal recombination. Eight recombination events were localized to different sites in a 560-bp region within the ∼3.7-kb NBS–LRR genes. Because any unequal recombination located within the flanking NBS–LRR genes would have removed Pc, the clustering of cross-over events within a 560-bp segment indicates that a site-directed recombination process exists that specifically targets unequal events to generate LRR diversity in NBS–LRR loci. PMID:18719093

  1. A novel recombinant pseudorabies virus expressing parvovirus VP2 gene: Immunogenicity and protective efficacy in swine

    PubMed Central

    2011-01-01

    Background Porcine parvovirus (PPV) VP2 gene has been successfully expressed in many expression systems resulting in self-assembly of virus-like particles (VLPs) with similar morphology to the native capsid. Here, a pseudorabies virus (PRV) system was adopted to express the PPV VP2 gene. Methods A recombinant PRV SA215/VP2 was obtained by homologous recombination between the vector PRV viral DNA and a transfer plasmid. Then recombinant virus was purified with plaque purification, and its identity confirmed by PCR amplification, Western blot and indirect immunofluorescence (IFA) analyses. Electronic microscopy of PRV SA215/VP2 confirmed self-assembly of both pseudorabies virus and VLPs from VP2 protein. Results Immunization of piglets with recombinant virus elicited PRV-specific and PPV-specific humoral immune responses and provided complete protection against a lethal dose of PRV challenges. Gilts immunized with recombinant viruses induced PPV-specific antibodies, and significantly reduced the mortality rate of (1 of 28) following virulent PPV challenge compared with the control (7 of 31). Furthermore, PPV virus DNA was not detected in the fetuses of recombinant virus immunized gilts. Conclusions In this study, a recombinant PRV SA215/VP2 virus expressing PPV VP2 protein was constructed using PRV SA215 vector. The safety, immunogenicity, and protective efficacy of the recombinant virus were demonstrated in piglets and primiparous gilts. This recombinant PRV SA215/VP2 represents a suitable candidate for the development of a bivalent vaccine against both PRV and PPV infection. PMID:21679423

  2. Homologous Recombination in E3 Genes of Human Adenovirus Species D

    PubMed Central

    Singh, Gurdeep; Robinson, Christopher M.; Dehghan, Shoaleh; Jones, Morris S.; Dyer, David W.; Seto, Donald

    2013-01-01

    Genes within the E3 transcription unit of human adenoviruses modulate host immune responses to infection. A comprehensive genomics and bioinformatics analysis of the E3 transcription unit for 38 viruses within human adenovirus species D (HAdV-D) revealed distinct and surprising patterns of homologous recombination. Homologous recombination was identified in open reading frames for E3 CR1α, CR1β, and CR1γ, similar to that previously observed with genes encoding the three major structural capsid proteins, the penton base, hexon, and fiber. PMID:24027303

  3. Selection of recombinant MVA by rescue of the essential D4R gene

    PubMed Central

    2011-01-01

    Modified vaccinia virus Ankara (MVA) has become a promising vaccine vector due to its immunogenicity and its proven safety in humans. As a general approach for stringent and rapid selection of recombinant MVA, we assessed marker rescue of the essential viral D4R gene in an engineered deletion mutant that is fully replication defective in wild-type cells. Recombinant, replicating virus was obtained by re-introduction of the deleted viral gene as a dominant selection marker into the deletion mutant. PMID:22152060

  4. Genomic sequencing reveals gene content, genomic organization, and recombination relationships in barley.

    PubMed

    Rostoks, Nils; Park, Yong-Jin; Ramakrishna, Wusirika; Ma, Jianxin; Druka, Arnis; Shiloff, Bryan A; SanMiguel, Phillip J; Jiang, Zeyu; Brueggeman, Robert; Sandhu, Devinder; Gill, Kulvinder; Bennetzen, Jeffrey L; Kleinhofs, Andris

    2002-05-01

    Barley (Hordeum vulgare L.) is one of the most important large-genome cereals with extensive genetic resources available in the public sector. Studies of genome organization in barley have been limited primarily to genetic markers and sparse sequence data. Here we report sequence analysis of 417.5 kb DNA from four BAC clones from different genomic locations. Sequences were analyzed with respect to gene content, the arrangement of repetitive sequences and the relationship of gene density to recombination frequencies. Gene densities ranged from 1 gene per 12 kb to 1 gene per 103 kb with an average of 1 gene per 21 kb. In general, genes were organized into islands separated by large blocks of nested retrotransposons. Single genes in apparent isolation were also found. Genes occupied 11% of the total sequence, LTR retrotransposons and other repeated elements accounted for 51.9% and the remaining 37.1% could not be annotated. PMID:12021850

  5. Adenovirus-mediated expression of vascular endothelial growth factor-a potentiates bone morphogenetic protein9-induced osteogenic differentiation and bone formation.

    PubMed

    Pi, Chang-Jun; Liang, Kai-Lu; Ke, Zhen-Yong; Chen, Fu; Cheng, Yun; Yin, Liang-Jun; Deng, Zhong-Liang; He, Bai-Cheng; Chen, Liang

    2016-08-01

    Mesenchymal stem cells (MSCs) are suitable seed cells for bone tissue engineering because they can self-renew and undergo differentiation into osteogenic, adipogenic, chondrogenic, or myogenic lineages. Vascular endothelial growth factor-a (VEGF-a), an angiogenic factor, is also involved in osteogenesis and bone repair. However, the effects of VEGF-a on osteogenic MSCs differentiation remain unknown. It was previously reported that bone morphogenetic protein9 (BMP9) is one of the most important osteogenic BMPs. Here, we investigated the effects of VEGF-a on BMP9-induced osteogenesis with mouse embryo fibroblasts (MEFs). We found that endogenous VEGF-a expression was undetectable in MSCs. Adenovirus-mediated expression of VEGF-a in MEFs potentiated BMP9-induced early and late osteogenic markers, including alkaline phosphatase (ALP), osteocalcin (OCN), and osteopontin (OPN). In stem cell implantation assays, VEGF-a augmented BMP9-induced ectopic bone formation. VEGF-a in combination with BMP9 effectively increased the bone volume and osteogenic activity. However, the synergistic effect was efficiently abolished by the phosphoinositide 3-kinase (PI3K)/AKT inhibitor LY294002. These results demonstrated that BMP9 may crosstalk with VEGF-a through the PI3K/AKT signaling pathway to induce osteogenic differentiation in MEFs. Thus, our findings demonstrate the effects of VEGF-a on BMP9-induced bone formation and provide a new potential strategy for treating nonunion fractures, large segmental bony defects, and/or osteoporotic fractures. PMID:27003241

  6. Lovastatin enhances adenovirus-mediated TRAIL induced apoptosis by depleting cholesterol of lipid rafts and affecting CAR and death receptor expression of prostate cancer cells.

    PubMed

    Liu, Youhong; Chen, Lin; Gong, Zhicheng; Shen, Liangfang; Kao, Chinghai; Hock, Janet M; Sun, Lunquan; Li, Xiong

    2015-02-20

    Oncolytic adenovirus and apoptosis inducer TRAIL are promising cancer therapies. Their antitumor efficacy, when used as single agents, is limited. Oncolytic adenoviruses have low infection activity, and cancer cells develop resistance to TRAIL-induced apoptosis. Here, we explored combining prostate-restricted replication competent adenovirus-mediated TRAIL (PRRA-TRAIL) with lovastatin, a commonly used cholesterol-lowering drug, as a potential therapy for advanced prostate cancer (PCa). Lovastatin significantly enhanced the efficacy of PRRA-TRAIL by promoting the in vivo tumor suppression, and the in vitro cell killing and apoptosis induction, via integration of multiple molecular mechanisms. Lovastatin enhanced PRRA replication and virus-delivered transgene expression by increasing the expression levels of CAR and integrins, which are critical for adenovirus 5 binding and internalization. Lovastatin enhanced TRAIL-induced apoptosis by increasing death receptor DR4 expression. These multiple effects of lovastatin on CAR, integrins and DR4 expression were closely associated with cholesterol-depletion in lipid rafts. These studies, for the first time, show correlations between cholesterol/lipid rafts, oncolytic adenovirus infection efficiency and the antitumor efficacy of TRAIL at the cellular level. This work enhances our understanding of the molecular mechanisms that support use of lovastatin, in combination with PRRA-TRAIL, as a candidate strategy to treat human refractory prostate cancer in the future. PMID:25605010

  7. Gene doctoring: a method for recombineering in laboratory and pathogenic Escherichia coli strains

    PubMed Central

    2009-01-01

    Background Homologous recombination mediated by the λ-Red genes is a common method for making chromosomal modifications in Escherichia coli. Several protocols have been developed that differ in the mechanisms by which DNA, carrying regions homologous to the chromosome, are delivered into the cell. A common technique is to electroporate linear DNA fragments into cells. Alternatively, DNA fragments are generated in vivo by digestion of a donor plasmid with a nuclease that does not cleave the host genome. In both cases the λ-Red gene products recombine homologous regions carried on the linear DNA fragments with the chromosome. We have successfully used both techniques to generate chromosomal mutations in E. coli K-12 strains. However, we have had limited success with these λ-Red based recombination techniques in pathogenic E. coli strains, which has led us to develop an enhanced protocol for recombineering in such strains. Results Our goal was to develop a high-throughput recombineering system, primarily for the coupling of genes to epitope tags, which could also be used for deletion of genes in both pathogenic and K-12 E. coli strains. To that end we have designed a series of donor plasmids for use with the λ-Red recombination system, which when cleaved in vivo by the I-SceI meganuclease generate a discrete linear DNA fragment, allowing for C-terminal tagging of chromosomal genes with a 6 × His, 3 × FLAG, 4 × ProteinA or GFP tag or for the deletion of chromosomal regions. We have enhanced existing protocols and technologies by inclusion of a cassette conferring kanamycin resistance and, crucially, by including the sacB gene on the donor plasmid, so that all but true recombinants are counter-selected on kanamycin and sucrose containing media, thus eliminating the need for extensive screening. This method has the added advantage of limiting the exposure of cells to the potential damaging effects of the λ-Red system, which can lead to unwanted secondary

  8. [Construction of recombinant adenoviral vector expressing genes of the conservative influenza proteins M2 and nucleoprotein].

    PubMed

    Esmagambetov, I B; Sedova, E S; Shcherbinin, D N; Lysenko, A A; Garas, M N; Shmarov, M M; Logunov, D Iu

    2014-01-01

    Influenza is a highly contagious and one of the most massive infection diseases. General epidemiological significance has a strain, which belongs to subtype A. A high degree of genetic variety leads to the permanent changes in the antigenic structure of the influenza virus. Therefore, the current influenza vaccines require periodic updating of the composition of strains. Presently, it is important to develop a universal vaccine that can protect against different strains of influenza A virus at the same time and is based on the conserved antigens of the influenza virus. The recombinant adenovirus vectors expressing genes of conserved viral antigenes may be a promising candidate vaccine against influenza A. Using the method of the homologous recombination, we developed in this study recombinant adenovirus of fifth serotype that expresses genes of the ion channel M2 and nucleoprotein NP of the influenza virus A. Genes of the consensus protein M2 and NP of human influenza A virus were included into the structure of the viral genome. The expression of the antigens M2 and NP using recombinant adenovirus vector was detected by a Western blot assay. The immunogenicity of the developed recombinant adenovirus vector was demonstrated by the intranasal immunization of laboratory mice. PMID:25080815

  9. Normalization of raised sodium absorption and raised calcium-mediated chloride secretion by adenovirus-mediated expression of cystic fibrosis transmembrane conductance regulator in primary human cystic fibrosis airway epithelial cells.

    PubMed Central

    Johnson, L G; Boyles, S E; Wilson, J; Boucher, R C

    1995-01-01

    Cystic fibrosis airway epithelia exhibit a spectrum of ion transport properties that differ from normal, including not only defective cAMP-mediated Cl- secretion, but also increased Na+ absorption and increased Ca(2+)-mediated Cl- secretion. In the present study, we examined whether adenovirus-mediated (Ad5) transduction of CFTR can correct all of these CF ion transport abnormalities. Polarized primary cultures of human CF and normal nasal epithelial cells were infected with Ad5-CBCFTR at an moi (10(4)) which transduced virtually all cells or Ad5-CMV lacZ as a control. Consistent with previous reports, Ad5-CBCFTR, but not Ad5-CMV lacZ, corrected defective CF cAMP-mediated Cl- secretion. Basal Na+ transport rates (basal Ieq) in CF airway epithelial sheets (-78.5 +/- 9.8 microA/cm2) were reduced to levels measured in normal epithelial sheets (-30.0 +/- 2.0 microA/cm2) by Ad5-CBCFTR (-36.9 +/- 4.8 microA/cm2), but not Ad5-CMV lacZ (-65.8 +/- 6.1 microA/cm2). Surprisingly, a significant reduction in delta Ieq in response to ionomycin, a measure of Ca(2+)-mediated Cl- secretion, was observed in CFTR-expressing (corrected) CF epithelial sheets (-6.9 +/- 11.8 microA/cm2) when compared to uninfected CF epithelial sheets (-76.2 +/- 15.1 microA/cm2). Dose response effects of Ad5-CBCFTR on basal Na+ transport rates and Ca(2+)-mediated Cl- secretion suggest that the mechanism of regulation of these two ion transport functions by CFTR may be different. In conclusion, efficient transduction of CFTR corrects hyperabsorption of Na+ in primary CF airway epithelial cells and restores Ca(2+)-mediated Cl- secretion to levels observed in normal airway epithelial cells. Moreover, assessment of these ion transport abnormalities may represent important endpoints for testing the efficacy of gene therapy for cystic fibrosis. Images PMID:7533790

  10. Role of recombination activating genes in the generation of antigen receptor diversity and beyond.

    PubMed

    Nishana, Mayilaadumveettil; Raghavan, Sathees C

    2012-12-01

    V(D)J recombination is the process by which antibody and T-cell receptor diversity is attained. During this process, antigen receptor gene segments are cleaved and rejoined by non-homologous DNA end joining for the generation of combinatorial diversity. The major players of the initial process of cleavage are the proteins known as RAG1 (recombination activating gene 1) and RAG2. In this review, we discuss the physiological function of RAGs as a sequence-specific nuclease and its pathological role as a structure-specific nuclease. The first part of the review discusses the basic mechanism of V(D)J recombination, and the last part focuses on how the RAG complex functions as a sequence-specific and structure-specific nuclease. It also deals with the off-target cleavage of RAGs and its implications in genomic instability. PMID:23039142

  11. The origins of the Rag genes--from transposition to V(D)J recombination.

    PubMed

    Fugmann, Sebastian D

    2010-02-01

    The recombination activating genes 1 and 2 (Rag1 and Rag2) encode the key enzyme that is required for the generation of the highly diversified antigen receptor repertoire central to adaptive immunity. The longstanding model proposed that this gene pair was acquired by horizontal gene transfer to explain its abrupt appearance in the vertebrate lineage. The analyses of the enormous amount of sequence data created by many genome sequencing projects now provide the basis for a more refined model as to how this unique gene pair evolved from a selfish DNA transposon into a sophisticated DNA recombinase essential for immunity. PMID:20004590

  12. The origins of the RAG genes – from transposition to V(D)J recombination

    PubMed Central

    Fugmann, Sebastian D.

    2009-01-01

    The Recombination Activating Genes 1 and 2 (Rag1 and Rag2) encode the key enzyme that is required for the generation of the highly diversified antigen receptor repertoire central to adaptive immunity. The longstanding model proposed that this gene pair was acquired by horizontal gene transfer to explain its abrupt appearance in the vertebrate lineage. The analyses of the enormous amount of sequence data created by many genome sequencing projects now provides the basis for a more refined model as to how this unique gene pair evolved from a selfish DNA transposon into a sophisticated DNA recombinase essential for immunity. PMID:20004590

  13. Homologous recombination within the capsid gene of porcine circovirus type 2 subgroup viruses via natural co-infection

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Several studies had reported homologous recombination between porcine circovirus type 2 (PCV2)-group 1 (Gp1) and -group 2 (Gp2) viruses. Interestingly, the recombination events described thus far mapped either within the Rep gene sequences or the sequences flanking the Rep gene region. Previously, ...

  14. Problem-Solving Test: Conditional Gene Targeting Using the Cre/loxP Recombination System

    ERIC Educational Resources Information Center

    Szeberényi, József

    2013-01-01

    Terms to be familiar with before you start to solve the test: gene targeting, knock-out mutation, bacteriophage, complementary base-pairing, homologous recombination, deletion, transgenic organisms, promoter, polyadenylation element, transgene, DNA replication, RNA polymerase, Shine-Dalgarno sequence, restriction endonuclease, polymerase chain…

  15. Evolution and homologous recombination of the hemagglutinin-esterase gene sequences from porcine torovirus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of the present study was to gain new insights into the evolution, homologous recombination and selection pressures imposed on the porcine torovirus (PToV), by examining changes in the hemagglutinin-esterase (HE) gene. The most recent common ancestor of PToV was estimated to have emerge...

  16. Gene A protein cleavage of recombinant plasmids containing the phi X174 replication origin.

    PubMed Central

    Fluit, A C; Baas, P D; Van Boom, J H; Veeneman, G H; Jansz, H S

    1984-01-01

    Synthetic oligonucleotides, DNA ligase and DNA polymerase were used to construct double-stranded DNA fragments homologous to the first 25, 27 or 30 b.p. of the origin of replication of bacteriophage phi X174 (nucleotides 4299-4328 of the phi X174 DNA sequence). The double-stranded DNA fragments were cloned into the unique SmaI or HindIII restriction sites in the kanamycin-resistance gene of pACYC177 (AmpR, KmR). Recombinant plasmids were picked up by colony hybridization. DNA sequencing showed that not only recombinant plasmids with the expected insert were formed, but also recombinant plasmids with a shorter insert. Recombinant plasmids with an insert homologous to the first 24, 25, 26, 27, 28 or all 30 b.p. of the phi X174 origin region were thus obtained. Supercoiled plasmids containing a sequence homologous to the first 27, 28 or 30 b.p. of the phi X174 origin region are nicked by the phi X174 gene A protein. However, the other supercoiled plasmids are not nicked by the phi X174 gene A protein. These results show that the first 27 b.p. of the phi X174 origin region are sufficient as well as required for the initiation step in phi X174 RF DNA replication, i.e. the cleavage by gene A protein. Images PMID:6236428

  17. Recombinant Hendra viruses expressing a reporter gene retain pathogenicity in ferrets

    PubMed Central

    2013-01-01

    Background Hendra virus (HeV) is an Australian bat-borne zoonotic paramyxovirus that repeatedly spills-over to horses causing fatal disease. Human cases have all been associated with close contact with infected horses. Methods A full-length antigenome clone of HeV was assembled, a reporter gene (GFP or luciferase) inserted between the P and M genes and transfected to 293T cells to generate infectious reporter gene-encoding recombinant viruses. These viruses were then assessed in vitro for expression of the reporter genes. The GFP expressing recombinant HeV was used to challenge ferrets to assess the virulence and tissue distribution by monitoring GFP expression in infected cells. Results Three recombinant HeV constructs were successfully cloned and rescued; a wild-type virus, a GFP-expressing virus and a firefly luciferase-expressing virus. In vitro characterisation demonstrated expression of the reporter genes, with levels proportional to the initial inoculum levels. Challenge of ferrets with the GFP virus demonstrated maintenance of the fatal phenotype with disease progressing to death consistent with that observed previously with the parental wild-type isolate of HeV. GFP expression could be observed in infected tissues collected from animals at euthanasia. Conclusions Here, we report on the first successful rescue of recombinant HeV, including wild-type virus and viruses expressing two different reporter genes encoded as an additional gene cassette inserted between the P and M genes. We further demonstrate that the GFP virus retained the ability to cause fatal disease in a well-characterized ferret model of henipavirus infection despite the genome being an extra 1290 nucleotides in length. PMID:23521919

  18. A modified recombineering protocol for the genetic manipulation of gene clusters in Aspergillus fumigatus.

    PubMed

    Alcazar-Fuoli, Laura; Cairns, Timothy; Lopez, Jordi F; Zonja, Bozo; Pérez, Sandra; Barceló, Damià; Igarashi, Yasuhiro; Bowyer, Paul; Bignell, Elaine

    2014-01-01

    Genomic analyses of fungal genome structure have revealed the presence of physically-linked groups of genes, termed gene clusters, where collective functionality of encoded gene products serves a common biosynthetic purpose. In multiple fungal pathogens of humans and plants gene clusters have been shown to encode pathways for biosynthesis of secondary metabolites including metabolites required for pathogenicity. In the major mould pathogen of humans Aspergillus fumigatus, multiple clusters of co-ordinately upregulated genes were identified as having heightened transcript abundances, relative to laboratory cultured equivalents, during the early stages of murine infection. The aim of this study was to develop and optimise a methodology for manipulation of gene cluster architecture, thereby providing the means to assess their relevance to fungal pathogenicity. To this end we adapted a recombineering methodology which exploits lambda phage-mediated recombination of DNA in bacteria, for the generation of gene cluster deletion cassettes. By exploiting a pre-existing bacterial artificial chromosome (BAC) library of A. fumigatus genomic clones we were able to implement single or multiple intra-cluster gene replacement events at both subtelomeric and telomere distal chromosomal locations, in both wild type and highly recombinogenic A. fumigatus isolates. We then applied the methodology to address the boundaries of a gene cluster producing a nematocidal secondary metabolite, pseurotin A, and to address the role of this secondary metabolite in insect and mammalian responses to A. fumigatus challenge. PMID:25372385

  19. Role of RAD52 Epistasis Group Genes in Homologous Recombination and Double-Strand Break Repair

    PubMed Central

    Symington, Lorraine S.

    2002-01-01

    The process of homologous recombination is a major DNA repair pathway that operates on DNA double-strand breaks, and possibly other kinds of DNA lesions, to promote error-free repair. Central to the process of homologous recombination are the RAD52 group genes (RAD50, RAD51, RAD52, RAD54, RDH54/TID1, RAD55, RAD57, RAD59, MRE11, and XRS2), most of which were identified by their requirement for the repair of ionizing-radiation-induced DNA damage in Saccharomyces cerevisiae. The Rad52 group proteins are highly conserved among eukaryotes, and Rad51, Mre11, and Rad50 are also conserved in prokaryotes and archaea. Recent studies showing defects in homologous recombination and double-strand break repair in several human cancer-prone syndromes have emphasized the importance of this repair pathway in maintaining genome integrity. Although sensitivity to ionizing radiation is a universal feature of rad52 group mutants, the mutants show considerable heterogeneity in different assays for recombinational repair of double-strand breaks and spontaneous mitotic recombination. Herein, I provide an overview of recent biochemical and structural analyses of the Rad52 group proteins and discuss how this information can be incorporated into genetic studies of recombination. PMID:12456786

  20. Gene expression analysis in MCF-7 breast cancer cells treated with recombinant bromelain.

    PubMed

    Fouz, Nour; Amid, Azura; Hashim, Yumi Zuhanis Has-Yun

    2014-08-01

    The contributing molecular pathways underlying the pathogenesis of breast cancer need to be better characterized. The principle of our study was to better understand the genetic mechanism of oncogenesis for human breast cancer and to discover new possible tumor markers for use in clinical practice. We used complimentary DNA (cDNA) microarrays to compare gene expression profiles of treated Michigan Cancer Foundation-7 (MCF-7) with recombinant bromelain and untreated MCF-7. SpringGene analysis was carried out of differential expression followed by Ingenuity Pathway Analysis (IPA), to understand the underlying consequence in developing disease and disorders. We identified 1,102 known genes differentially expressed to a significant degree (p<0.001) changed between the treatment. Within this gene set, 20 genes were significantly changed between treated cells and the control cells with cutoff fold change of more than 1.5. These genes are RNA-binding motif, single-stranded interacting protein 1 (RBMS1), ribosomal protein L29 (RPL29), glutathione S-transferase mu 2 (GSTM2), C15orf32, Akt3, B cell translocation gene 1 (BTG1), C6orf62, C7orf60, kinesin-associated protein 3 (KIFAP3), FBXO11, AT-rich interactive domain 4A (ARID4A), COPS2, TBPL1|SLC2A12, TMEM59, SNORD46, glioma tumor suppressor candidate region gene 2 (GLTSCR2), and LRRFIP. Our observation on gene expression indicated that recombinant bromelain produces a unique signature affecting different pathways, specific for each congener. The microarray results give a molecular mechanistic insight and functional effects, following recombinant bromelain treatment. The extent of changes in genes is related to and involved significantly in gap junction signaling, amyloid processing, cell cycle regulation by BTG family proteins, and breast cancer regulation by stathmin1 that play major roles. PMID:24928548

  1. Adenovirus-mediated suppression of HMGI(Y) protein synthesis as potential therapy of human malignant neoplasias

    PubMed Central

    Scala, Stefania; Portella, Giuseppe; Fedele, Monica; Chiappetta, Gennaro; Fusco, Alfredo

    2000-01-01

    High mobility group I (HMGI) proteins are overexpressed in several human malignant tumors. We previously demonstrated that inhibition of HMGI synthesis prevents thyroid cell transformation. Here, we report that an adenovirus carrying the HMGI(Y) gene in an antisense orientation (Ad-Yas) induced programmed cell death of two human thyroid anaplastic carcinoma cell lines (ARO and FB-1), but not normal thyroid cells. The Ad-Yas virus led to death of lung, colon, and breast carcinoma cells. A control adenovirus carrying the lacZ gene did not inhibit the growth of either normal or neoplastic cells. Ad-Yas treatment of tumors induced in athymic mice by ARO cells caused a drastic reduction in tumor size. Therefore, suppression of HMGI(Y) protein synthesis by an HMGI(Y) antisense adenoviral vector may be a useful treatment strategy in a variety of human malignant neoplasias, in which HMGI(Y) gene overexpression is a general event. PMID:10759549

  2. Recombination-activating gene 1 and 2 (RAG1 and RAG2) in flounder (Paralichthys olivaceus).

    PubMed

    Wang, Xianlei; Tan, Xungang; Zhang, Pei-Jun; Zhang, Yuqing; Xu, Peng

    2014-12-01

    During the development of B and T lymphocytes, Ig and TCR variable region genes are assembled from germline V, D, and J gene segments by a site-specific recombination reaction known as V(D)J recombination. The process of somatic V(D)J recombination, mediated by the recombination-activating gene (RAG) products, is the most significant characteristic of adaptive immunity in jawed vertebrates. Flounder (Paralichthys olivaceus) RAG1 and RAG2 were isolated by Genome Walker and RT-PCR, and their expression patterns were analysed by RT-PCR and in situ hybridization on sections. RAG1 spans over 7.0 kb, containing 4 exons and 3 introns, and the full-length ORF is 3207 bp, encoding a peptide of 1068 amino acids. The first exon lies in the 5'-UTR, which is an alternative exon. RAG2 full-length ORF is 1062 bp, encodes a peptide of 533 amino acids, and lacks introns in the coding region. In 6-month old flounders, the expression of RAG1 and RAG2 was essentially restricted to the pronephros (head kidney) and mesonephros (truck kidney). Additionally, both of them were mainly expressed in the thymus. These results revealed that the thymus and kidney most likely serve as the primary lymphoid tissues in the flounder. PMID:25431413

  3. DNA shuffling method for generating highly recombined genes and evolved enzymes.

    PubMed

    Coco, W M; Levinson, W E; Crist, M J; Hektor, H J; Darzins, A; Pienkos, P T; Squires, C H; Monticello, D J

    2001-04-01

    We introduce a method of in vitro recombination or "DNA shuffling" to generate libraries of evolved enzymes. The approach relies on the ordering, trimming, and joining of randomly cleaved parental DNA fragments annealed to a transient polynucleotide scaffold. We generated chimeric libraries averaging 14.0 crossovers per gene, a several-fold higher level of recombination than observed for other methods. We also observed an unprecedented four crossovers per gene in regions of 10 or fewer bases of sequence identity. These properties allow generation of chimeras unavailable by other methods. We detected no unshuffled parental clones or duplicated "sibling" chimeras, and relatively few inactive clones. We demonstrated the method by molecular breeding of a monooxygenase for increased rate and extent of biodesulfurization on complex substrates, as well as for 20-fold faster conversion of a nonnatural substrate. This method represents a conceptually distinct and improved alternative to sexual PCR for gene family shuffling. PMID:11283594

  4. Adenovirus-Mediated Over-Expression of Nrf2 Within Mesenchymal Stem Cells (MSCs) Protected Rats Against Acute Kidney Injury

    PubMed Central

    Mohammadzadeh-Vardin, Mohammad; Habibi Roudkenar, Mehryar; Jahanian-Najafabadi, Ali

    2015-01-01

    Purpose: Recent developments in the field of cell therapy have led to a renewed interest in treatment of acute kidney injury (AKI). However, the early death of transplanted mesenchymal stem cells (MSCs) in stressful microenvironment of a recipient tissue is a major problem with this kind of treatment. The objective of this study was to determine whether overexpression of a cytoprotective factor, nuclear factor erythroid-2 related factor 2 (Nrf2), in MSCs could protect rats against AKI. Methods: The Nrf2 was overexpressed in MSCs by recombinant adenoviruses, and the MSCs were implanted to rats suffering from cisplatin-induced AKI. Results: The obtained results showed that transplantation with the engineered MSCs ameliorates cisplatin-induced AKI. Morphologic features of the investigated kidneys showed that transplantation with the MSCs in which Nrf2 had been overexpressed significantly improved the complications of AKI. Conclusion: These findings suggested that the engineered MSCs might be a good candidate to be further evaluated in clinical trials. However, detailed studies must be performed to investigate the possible carcinogenic effect of Nrf2 overexpression. PMID:26236658

  5. Gene Targeting Using Homologous Recombination in Embryonic Stem Cells: The Future for Behavior Genetics?

    PubMed Central

    Gerlai, Robert

    2016-01-01

    Gene targeting with homologous recombination in embryonic stem cells created a revolution in the analysis of the function of genes in behavioral brain research. The technology allowed unprecedented precision with which one could manipulate genes and study the effect of this manipulation on the central nervous system. With gene targeting, the uncertainty inherent in psychopharmacology regarding whether a particular compound would act only through a specific target was removed. Thus, gene targeting became highly popular. However, with this popularity came the realization that like other methods, gene targeting also suffered from some technical and principal problems. For example, two decades ago, issues about compensatory changes and about genetic linkage were raised. Since then, the technology developed, and its utility has been better delineated. This review will discuss the pros and cons of the technique along with these advancements from the perspective of the neuroscientist user. It will also compare and contrast methods that may represent novel alternatives to the homologous recombination based gene targeting approach, including the TALEN and the CRISPR/Cas9 systems. The goal of the review is not to provide detailed recipes, but to attempt to present a short summary of these approaches a behavioral geneticist or neuroscientist may consider for the analysis of brain function and behavior. PMID:27148349

  6. Rapid Engineering of the Geldanamycin Biosynthesis Pathway by Red/ET Recombination and Gene Complementation

    PubMed Central

    Vetcher, Leandro; Tian, Zong-Qiang; McDaniel, Robert; Rascher, Andreas; Revill, W. Peter; Hutchinson, C. Richard; Hu, Zhihao

    2005-01-01

    Genetic manipulation of antibiotic producers, such as Streptomyces species, is a rational approach to improve the properties of biologically active molecules. However, this can be a slow and sometimes problematic process. Red/ET recombination in an Escherichia coli host has permitted rapid and more versatile engineering of geldanamycin biosynthetic genes in a complementation plasmid, which can then be readily transferred into the Streptomyces host from which the corresponding wild type gene(s) has been removed. With this rapid Red/ET recombination and gene complementation approach, efficient gene disruptions and gene replacements in the geldanamycin biosynthetic gene cluster have been successfully achieved. As an example, we describe here the creation of a ketoreductase 6 null mutation in an E. coli high-copy-number plasmid carrying gdmA2A3 from Streptomyces hygroscopicus NRRL3602 and the subsequent complementation of a gdmA2A3 deletion host with this plasmid to generate a novel geldanamycin analog. PMID:15812008

  7. Efficient construction of recombinant adenovirus expression vector of the Qinchuan cattle LYRM1 gene.

    PubMed

    Li, Y K; Fu, C Z; Zhang, Y R; Zan, L S

    2015-01-01

    In this study, we cloned the coding DNA sequence (CDS) region of Qinchuan cattle LYR motif-containing 1 (LYRM1) and constructed a recombinant adenovirus expression vector to examine the function of LYRM1 on the cellular level. Total RNA was extracted from the adipose tissue of Qinchuan cattle, cDNA was obtained by reverse transcription, and polymerase chain reaction was used to amplify the CDS region of the LYRM1 gene. The CDS-containing fragment was inserted into the shuttle vector pAdTrack-CMV to construct pAdTrack-CMV-LYRM1 vector. After linearization of pAdTrack-CMV-LYRM1 and the negative control vector pAdTrack-CMV by restriction endonuclease PmeI, the vectors were transformed into Escherichia coli BJ5183 containing pAdEasy-1 to obtain the recombinant adenovirus vector pAd-LYRM1 and pAd-CMV through homologous recombination. pAd-LYRM1 and pAd-CMV were then digested by PacI and transfected into the 293A cell line. The recombinant adenovirus Ad-LYRM1 and Ad-CMV was obtained at a concentration of 7 x 108 and 1.3 x 109 green fluorescent units/mL, respectively. Preadipocytes derived from Qinchuan cattle were separately infected with Ad-LYRM1 and Ad- CMV. Quantitative real-time polymerase chain reaction demonstrated that the expression of LYRM1 was increased by approximate 28,000-folds after the infection with recombinant adenovirus for 48 h. In conclusion, we successfully cloned the CDS region of the Qinchuan cattle LYRM1 gene, constructed the recombinant adenovirus expression vector, and obtained the adenovirus with high titer, providing valuable materials for studying the function of LYRM1 at the cellular level. PMID:26345880

  8. Genetic diversity and recombination analysis in the coat protein gene of Banana bract mosaic virus.

    PubMed

    Balasubramanian, V; Selvarajan, R

    2014-06-01

    Banana bract mosaic virus (BBrMV), a member of the genus Potyvirus, family Potyviridae, is the causal agent of the bract mosaic disease (BBrMD) that causes serious yield losses in banana and plantain in India and the Philippines. In this study, global genetic diversity and molecular evolution of BBrMV based on the capsid protein (CP) gene were investigated. Multiple alignments of CP gene of 49 BBrMV isolates showed nucleotide (nt) and amino acid (aa) identity of 79-100 and 80-100 %, respectively. Phylogenetic analysis revealed that except two Indians isolates (TN14 and TN16), all isolates clustered together. Eleven recombination events were detected using Recombination Detection Program. Codon-based maximum-likelihood methods revealed that most of the codons in the CP gene were under negative or neutral selection except for codons 28, 43, and 92 which were under positive selection. Gene flow between BBrMV populations of banana and cardamom was relatively frequent but not between two different populations of banana infecting isolates identified in this study. This is the first report on genetic diversity, and evolution of BBrMV isolates based on recombination and phylogenetic analysis in India. PMID:24691817

  9. A system for assaying homologous recombination at the endogenous human thymidine kinase gene

    SciTech Connect

    Benjamin, M.B.; Little, J.B. ); Potter, H. ); Yandell, D.W. Massachusetts Eye and Ear Infirmary, Boston Harvard Medical School, Boston, MA )

    1991-08-01

    A system for assaying human interchromosomal recombination in vitro was developed, using a cell line containing two different mutant thymidine kinase genes (TK) on chromosomes 17. Heteroalleles were generated in the TK{sup +/+} parent B-lymphoblast cell line WIL-2 by repeated exposure to the alkylating nitrogen mustard ICR-191, which preferentially causes +1 or {minus}1 frameshifts. Resulting TK{sup {minus}/{minus}} mutants were selected in medium containing the toxic thymidine analog trifluorothymidine. In two lines, heterozygous frameshifts were located in exons 4 and 7 of the TK gene separated by {approx}8 kilobases. These lines undergo spontaneous reversion to TK{sup +} at a frequency of < 10{sup {minus}7}, and revertants can be selected in cytidine/hypoxanthine/aminopterin/thymidine medium. The nature and location of these heteroallelic mutations make large deletions, rearrangements, nondisjunction, and reduplication unlikely mechanisms for reversion to TK{sup +}. The mode of reversion to TK{sup +} was specifically assessed by DNA sequencing, use of single-strand conformation polymorphisms, and analysis of various restriction fragment length polymorphisms (RFLPs) linked to the TK gene on chromosome 17. The data suggest that a proportion of revertants has undergone recombination and gene conversion at the TK locus, with concomitant loss of frameshifts and allele loss at linked RFLPs. Models are presented for the origin of two recombinants.

  10. Crossovers are associated with mutation and biased gene conversion at recombination hotspots.

    PubMed

    Arbeithuber, Barbara; Betancourt, Andrea J; Ebner, Thomas; Tiemann-Boege, Irene

    2015-02-17

    Meiosis is a potentially important source of germline mutations, as sites of meiotic recombination experience recurrent double-strand breaks (DSBs). However, evidence for a local mutagenic effect of recombination from population sequence data has been equivocal, likely because mutation is only one of several forces shaping sequence variation. By sequencing large numbers of single crossover molecules obtained from human sperm for two recombination hotspots, we find direct evidence that recombination is mutagenic: Crossovers carry more de novo mutations than nonrecombinant DNA molecules analyzed for the same donors and hotspots. The observed mutations were primarily CG to TA transitions, with a higher frequency of transitions at CpG than non-CpGs sites. This enrichment of mutations at CpG sites at hotspots could predominate in methylated regions involving frequent single-stranded DNA processing as part of DSB repair. In addition, our data set provides evidence that GC alleles are preferentially transmitted during crossing over, opposing mutation, and shows that GC-biased gene conversion (gBGC) predominates over mutation in the sequence evolution of hotspots. These findings are consistent with the idea that gBGC could be an adaptation to counteract the mutational load of recombination. PMID:25646453

  11. Crossovers are associated with mutation and biased gene conversion at recombination hotspots

    PubMed Central

    Arbeithuber, Barbara; Betancourt, Andrea J.; Ebner, Thomas; Tiemann-Boege, Irene

    2015-01-01

    Meiosis is a potentially important source of germline mutations, as sites of meiotic recombination experience recurrent double-strand breaks (DSBs). However, evidence for a local mutagenic effect of recombination from population sequence data has been equivocal, likely because mutation is only one of several forces shaping sequence variation. By sequencing large numbers of single crossover molecules obtained from human sperm for two recombination hotspots, we find direct evidence that recombination is mutagenic: Crossovers carry more de novo mutations than nonrecombinant DNA molecules analyzed for the same donors and hotspots. The observed mutations were primarily CG to TA transitions, with a higher frequency of transitions at CpG than non-CpGs sites. This enrichment of mutations at CpG sites at hotspots could predominate in methylated regions involving frequent single-stranded DNA processing as part of DSB repair. In addition, our data set provides evidence that GC alleles are preferentially transmitted during crossing over, opposing mutation, and shows that GC-biased gene conversion (gBGC) predominates over mutation in the sequence evolution of hotspots. These findings are consistent with the idea that gBGC could be an adaptation to counteract the mutational load of recombination. PMID:25646453

  12. Construction and characterization of recombinant flaviviruses bearing insertions between E and NS1 genes

    PubMed Central

    Bonaldo, Myrna C; Mello, Samanta M; Trindade, Gisela F; Rangel, Aymara A; Duarte, Adriana S; Oliveira, Prisciliana J; Freire, Marcos S; Kubelka, Claire F; Galler, Ricardo

    2007-01-01

    Background The yellow fever virus, a member of the genus Flavivirus, is an arthropod-borne pathogen causing severe disease in humans. The attenuated yellow fever 17D virus strain has been used for human vaccination for 70 years and has several characteristics that are desirable for the development of new, live attenuated vaccines. We described here a methodology to construct a viable, and immunogenic recombinant yellow fever 17D virus expressing a green fluorescent protein variant (EGFP). This approach took into account the presence of functional motifs and amino acid sequence conservation flanking the E and NS1 intergenic region to duplicate and fuse them to the exogenous gene and thereby allow the correct processing of the viral polyprotein precursor. Results YF 17D EGFP recombinant virus was grew in Vero cells and reached a peak titer of approximately 6.45 ± 0.4 log10 PFU/mL at 96 hours post-infection. Immunoprecipitation and confocal laser scanning microscopy demonstrated the expression of the EGFP, which was retained in the endoplasmic reticulum and not secreted from infected cells. The association with the ER compartment did not interfere with YF assembly, since the recombinant virus was fully competent to replicate and exit the cell. This virus was genetically stable up to the tenth serial passage in Vero cells. The recombinant virus was capable to elicit a neutralizing antibody response to YF and antibodies to EGFP as evidenced by an ELISA test. The applicability of this cloning strategy to clone gene foreign sequences in other flavivirus genomes was demonstrated by the construction of a chimeric recombinant YF 17D/DEN4 virus. Conclusion This system is likely to be useful for a broader live attenuated YF 17D virus-based vaccine development for human diseases. Moreover, insertion of foreign genes into the flavivirus genome may also allow in vivo studies on flavivirus cell and tissue tropism as well as cellular processes related to flavivirus infection. PMID

  13. The Interaction between AID and CIB1 Is Nonessential for Antibody Gene Diversification by Gene Conversion or Class Switch Recombination

    PubMed Central

    Demorest, Zachary L.; MacDuff, Donna A.; Brown, William L.; Morham, Scott G.; Parise, Leslie V.; Harris, Reuben S.

    2010-01-01

    Activation-induced deaminase (AID) initiates somatic hypermutation, gene conversion and class switch recombination by deaminating variable and switch region DNA cytidines to uridines. AID is predominantly cytoplasmic and must enter the nuclear compartment to initiate these distinct antibody gene diversification reactions. Nuclear AID is relatively short-lived, as it is efficiently exported by a CRM1-dependent mechanism and it is susceptible to proteasome-dependent degradation. To help shed light on mechanisms of post-translational regulation, a yeast-based screen was performed to identify AID-interacting proteins. The calcium and integrin binding protein CIB1 was identified by sequencing and the interaction was confirmed by immunoprecipitation experiments. The AID/CIB1 resisted DNase and RNase treatment, and it is therefore unlikely to be mediated by nucleic acid. The requirement for CIB1 in AID-mediated antibody gene diversification reactions was assessed in CIB1-deficient DT40 cells and in knockout mice, but immunoglobulin gene conversion and class switch recombination appeared normal. The DT40 system was also used to show that CIB1 over-expression has no effect on gene conversion and that AID-EGFP subcellular localization is normal. These combined data demonstrate that CIB1 is not required for AID to mediate antibody gene diversification processes. It remains possible that CIB1 has an alternative, a redundant or a subtle non-limiting regulatory role in AID biology. PMID:20652029

  14. Adenovirus-mediated delivery of herpes simplex virus thymidine kinase administration improves outcome of recurrent high-grade glioma

    PubMed Central

    Liu, Cang; Gu, Zheng; Chen, Shizhang; Guo, Ying; Fan, Zhong; Wang, Xiao; Chen, Jianfei; Zhao, Yanyan; Zhou, Jianfeng; Wang, Jisheng; Ma, Ding; Li, Ning

    2016-01-01

    Background This randomized, open-label, multicenter, phase II clinical trial was conducted to assess the anti-tumor efficacy and safety of replication-deficient adenovirus mutant thymidine kinase (ADV-TK) in combination with ganciclovir administration in patients with recurrent high-grade glioma (HGG). Patients and Methods 53 patients with recurrent HGG were randomly allocated to receive intra-arterial cerebral infusion of ADV-TK or conventional treatments. The primary end point was 6-month progression-free survival (PFS-6). Secondary end points included progression-free survival (PFS), overall survival (OS), safety, and clinical benefit. This trial is registered with Clinicaltrials.gov, NCT00870181. Results In ADV-TK group, PFS-6 was 54.5%, the median PFS was 29.6 weeks, the median OS was 45.4 weeks, and better survivals were achieved when compared with control group. The one-year PFS and OS were 22.7% and 44.6% in ADV-TK group respectively, and clinical benefit was 68.2%. There are 2 patients alive for more than 4 years without progression in ADV-TK group. In the subgroup of glioblastoma received ADV-TK, PFS-6 was 71.4%, median PFS was 34.9 weeks, median OS was 45.7 weeks respectively, much better than those in control group. The one-year PFS and OS were 35.7% and 50.0% in ADV-TK group respectively. ADV-TK/ganciclovir gene therapy was well tolerated, and no treatment-related severe adverse events were noted. Conclusion Our study demonstrated a notable improvement of PFS-6, PFS and OS in ADV-TK treated group, and the efficacy and safety appear to be comparable to other reported treatments used for recurrent HGG. ADV-TK gene therapy is therefore a valuable therapeutic option for recurrent HGG. PMID:26716896

  15. Conserved cryptic recombination signals in Vκ gene segments are cleaved in small pre-B cells

    PubMed Central

    Lieberman, Anne E; Kuraoka, Masayuki; Davila, Marco; Kelsoe, Garnett; Cowell, Lindsay G

    2009-01-01

    Background The cleavage of recombination signals (RS) at the boundaries of immunoglobulin V, D, and J gene segments initiates the somatic generation of the antigen receptor genes expressed by B lymphocytes. RS contain a conserved heptamer and nonamer motif separated by non-conserved spacers of 12 or 23 nucleotides. Under physiologic conditions, V(D)J recombination follows the "12/23 rule" to assemble functional antigen-receptor genes, i.e., cleavage and recombination occur only between RS with dissimilar spacer types. Functional, cryptic RS (cRS) have been identified in VH gene segments; these VH cRS were hypothesized to facilitate self-tolerance by mediating VH → VHDJH replacements. At the Igκ locus, however, secondary, de novo rearrangements can delete autoreactive VκJκ joins. Thus, under the hypothesis that V-embedded cRS are conserved to facilitate self-tolerance by mediating V-replacement rearrangements, there would be little selection for Vκ cRS. Recent studies have demonstrated that VH cRS cleavage is only modestly more efficient than V(D)J recombination in violation of the 12/23 rule and first occurs in pro-B cells unable to interact with exogenous antigens. These results are inconsistent with a model of cRS cleavage during autoreactivity-induced VH gene replacement. Results To test the hypothesis that cRS are absent from Vκ gene segments, a corollary of the hypothesis that the need for tolerizing VH replacements is responsible for the selection pressure to maintain VH cRS, we searched for cRS in mouse Vκ gene segments using a statistical model of RS. Scans of 135 mouse Vκ gene segments revealed highly conserved cRS that were shown to be cleaved in the 103/BCL2 cell line and mouse bone marrow B cells. Analogous to results for VH cRS, we find that Vκ cRS are conserved at multiple locations in Vκ gene segments and are cleaved in pre-B cells. Conclusion Our results, together with those for VH cRS, support a model of cRS cleavage in which cleavage is

  16. Meiotic recombination generates rich diversity in NK cell receptor genes, alleles, and haplotypes.

    PubMed

    Norman, Paul J; Abi-Rached, Laurent; Gendzekhadze, Ketevan; Hammond, John A; Moesta, Achim K; Sharma, Deepti; Graef, Thorsten; McQueen, Karina L; Guethlein, Lisbeth A; Carrington, Christine V F; Chandanayingyong, Dasdayanee; Chang, Yih-Hsin; Crespí, Catalina; Saruhan-Direskeneli, Güher; Hameed, Kamran; Kamkamidze, Giorgi; Koram, Kwadwo A; Layrisse, Zulay; Matamoros, Nuria; Milà, Joan; Park, Myoung Hee; Pitchappan, Ramasamy M; Ramdath, D Dan; Shiau, Ming-Yuh; Stephens, Henry A F; Struik, Siske; Tyan, Dolly; Verity, David H; Vaughan, Robert W; Davis, Ronald W; Fraser, Patricia A; Riley, Eleanor M; Ronaghi, Mostafa; Parham, Peter

    2009-05-01

    Natural killer (NK) cells contribute to the essential functions of innate immunity and reproduction. Various genes encode NK cell receptors that recognize the major histocompatibility complex (MHC) Class I molecules expressed by other cells. For primate NK cells, the killer-cell immunoglobulin-like receptors (KIR) are a variable and rapidly evolving family of MHC Class I receptors. Studied here is KIR3DL1/S1, which encodes receptors for highly polymorphic human HLA-A and -B and comprises three ancient allelic lineages that have been preserved by balancing selection throughout human evolution. While the 3DS1 lineage of activating receptors has been conserved, the two 3DL1 lineages of inhibitory receptors were diversified through inter-lineage recombination with each other and with 3DS1. Prominent targets for recombination were D0-domain polymorphisms, which modulate enhancer function, and dimorphism at position 283 in the D2 domain, which influences inhibitory function. In African populations, unequal crossing over between the 3DL1 and 3DL2 genes produced a deleted KIR haplotype in which the telomeric "half" was reduced to a single fusion gene with functional properties distinct from its 3DL1 and 3DL2 parents. Conversely, in Eurasian populations, duplication of the KIR3DL1/S1 locus by unequal crossing over has enabled individuals to carry and express alleles of all three KIR3DL1/S1 lineages. These results demonstrate how meiotic recombination combines with an ancient, preserved diversity to create new KIR phenotypes upon which natural selection acts. A consequence of such recombination is to blur the distinction between alleles and loci in the rapidly evolving human KIR gene family. PMID:19411600

  17. Meiotic recombination generates rich diversity in NK cell receptor genes, alleles, and haplotypes

    PubMed Central

    Norman, Paul J.; Abi-Rached, Laurent; Gendzekhadze, Ketevan; Hammond, John A.; Moesta, Achim K.; Sharma, Deepti; Graef, Thorsten; McQueen, Karina L.; Guethlein, Lisbeth A.; Carrington, Christine V.F.; Chandanayingyong, Dasdayanee; Chang, Yih-Hsin; Crespí, Catalina; Saruhan-Direskeneli, Güher; Hameed, Kamran; Kamkamidze, Giorgi; Koram, Kwadwo A.; Layrisse, Zulay; Matamoros, Nuria; Milà, Joan; Park, Myoung Hee; Pitchappan, Ramasamy M.; Ramdath, D. Dan; Shiau, Ming-Yuh; Stephens, Henry A.F.; Struik, Siske; Tyan, Dolly; Verity, David H.; Vaughan, Robert W.; Davis, Ronald W.; Fraser, Patricia A.; Riley, Eleanor M.; Ronaghi, Mostafa; Parham, Peter

    2009-01-01

    Natural killer (NK) cells contribute to the essential functions of innate immunity and reproduction. Various genes encode NK cell receptors that recognize the major histocompatibility complex (MHC) Class I molecules expressed by other cells. For primate NK cells, the killer-cell immunoglobulin-like receptors (KIR) are a variable and rapidly evolving family of MHC Class I receptors. Studied here is KIR3DL1/S1, which encodes receptors for highly polymorphic human HLA-A and -B and comprises three ancient allelic lineages that have been preserved by balancing selection throughout human evolution. While the 3DS1 lineage of activating receptors has been conserved, the two 3DL1 lineages of inhibitory receptors were diversified through inter-lineage recombination with each other and with 3DS1. Prominent targets for recombination were D0-domain polymorphisms, which modulate enhancer function, and dimorphism at position 283 in the D2 domain, which influences inhibitory function. In African populations, unequal crossing over between the 3DL1 and 3DL2 genes produced a deleted KIR haplotype in which the telomeric “half” was reduced to a single fusion gene with functional properties distinct from its 3DL1 and 3DL2 parents. Conversely, in Eurasian populations, duplication of the KIR3DL1/S1 locus by unequal crossing over has enabled individuals to carry and express alleles of all three KIR3DL1/S1 lineages. These results demonstrate how meiotic recombination combines with an ancient, preserved diversity to create new KIR phenotypes upon which natural selection acts. A consequence of such recombination is to blur the distinction between alleles and loci in the rapidly evolving human KIR gene family. PMID:19411600

  18. A recombinant varicella vaccine harboring a respiratory syncytial virus gene induces humoral immunity.

    PubMed

    Murakami, Kouki; Matsuura, Masaaki; Ota, Megumi; Gomi, Yasuyuki; Yamanishi, Koichi; Mori, Yasuko

    2015-11-01

    The varicella-zoster virus (VZV) Oka vaccine strain (vOka) is highly efficient and causes few adverse events; therefore, it is used worldwide. We previously constructed recombinant vOka (rvOka) harboring the mumps virus gene. Immunizing guinea pigs with rvOka induced the production of neutralizing antibodies against the mumps virus and VZV. Here, we constructed recombinant vOka viruses containing either the respiratory syncytial virus (RSV) subgroup A fusion glycoprotein (RSV A-F) gene or RSV subgroup B fusion glycoprotein (RSV B-F) gene (rvOka-RSV A-F or rvOka-RSV B-F). Indirect immunofluorescence and Western blot analyses confirmed the expression of each recombinant RSV protein in virus-infected cells. Immunizing guinea pigs with rvOka-RSV A-F or rvOka-RSV B-F led to the induction of antibodies against RSV proteins. These results suggest that the current varicella vaccine genome can be used to generate custom-made vaccine vectors to develop the next generation of live vaccines. PMID:26116253

  19. Intensive Pharmacological Immunosuppression Allows for Repetitive Liver Gene Transfer With Recombinant Adenovirus in Nonhuman Primates

    PubMed Central

    Fontanellas, Antonio; Hervás-Stubbs, Sandra; Mauleón, Itsaso; Dubrot, Juan; Mancheño, Uxua; Collantes, María; Sampedro, Ana; Unzu, Carmen; Alfaro, Carlos; Palazón, Asis; Smerdou, Cristian; Benito, Alberto; Prieto, Jesús; Peñuelas, Iván; Melero, Ignacio

    2010-01-01

    Repeated administration of gene therapies is hampered by host immunity toward vectors and transgenes. Attempts to circumvent antivector immunity include pharmacological immunosuppression or alternating different vectors and vector serotypes with the same transgene. Our studies show that B-cell depletion with anti-CD20 monoclonal antibody and concomitant T-cell inhibition with clinically available drugs permits repeated liver gene transfer to a limited number of nonhuman primates with recombinant adenovirus. Adenoviral vector–mediated transfer of the herpes simplex virus type 1 thymidine kinase (HSV1-tk) reporter gene was visualized in vivo with a semiquantitative transgene-specific positron emission tomography (PET) technique, liver immunohistochemistry, and immunoblot for the reporter transgene in needle biopsies. Neutralizing antibody and T cell–mediated responses toward the viral capsids were sequentially monitored and found to be repressed by the drug combinations tested. Repeated liver transfer of the HSV1-tk reporter gene with the same recombinant adenoviral vector was achieved in macaques undergoing a clinically feasible immunosuppressive treatment that ablated humoral and cellular immune responses. This strategy allows measurable gene retransfer to the liver as late as 15 months following the first adenoviral exposure in a macaque, which has undergone a total of four treatments with the same adenoviral vector. PMID:20087317

  20. Intergeneric transfer and recombination of the 6-phosphogluconate dehydrogenase gene (gnd) in enteric bacteria.

    PubMed Central

    Nelson, K; Selander, R K

    1994-01-01

    The gnd gene, encoding 6-phosphogluconate dehydrogenase (EC 1.1.1.44), was sequenced in 87 strains of 15 species assigned to five nominal genera of the Enterobacteriaceae, including 36 isolates of Salmonella enterica and 32 strains of Escherichia coli. In S. enterica, the effective (realized) rate of recombination of horizontally transferred gnd sequences is only moderately higher than the rates for other chromosomal housekeeping genes. In contrast, recombination at gnd has occurred with such high frequency in Escherichia coli that the indicated evolutionary relationships among strains are not congruent with those estimated by sequence analysis of other genes and by multilocus enzyme electrophoresis. E. coli and S. enterica apparently have not exchanged gnd sequences, but those of several strains of E. coli have been imported from species of Citrobacter and Klebsiella. The relatively frequent exchange of gnd within and among taxonomic groups of the Enterobacteriaceae, compared with other housekeeping genes, apparently results from its close linkage with genes that are subject to diversifying selection, including those of the rfb region determining the structure of the O antigen polysaccharide. PMID:7937867

  1. Establishing targeted carp TLR22 gene disruption via homologous recombination using CRISPR/Cas9.

    PubMed

    Chakrapani, Vemulawada; Patra, Swagat Kumar; Panda, Rudra Prasanna; Rasal, Kiran Dashrath; Jayasankar, Pallipuram; Barman, Hirak Kumar

    2016-08-01

    Recent advances in gene editing techniques have not been exploited in farmed fishes. We established a gene targeting technique, using the CRISPR/Cas9 system in Labeo rohita, a farmed carp (known as rohu). We demonstrated that donor DNA was integrated via homologous recombination (HR) at the site of targeted double-stranded nicks created by CRISPR/Cas9 nuclease. This resulted in the successful disruption of rohu Toll-like receptor 22 (TLR22) gene, involved in innate immunity and exclusively present in teleost fishes and amphibians. The null mutant, thus, generated lacked TLR22 mRNA expression. Altogether, this is the first evidence that the CRISPR/Cas9 system is a highly efficient tool for targeted gene disruption via HR in teleosts for generating model large-bodied farmed fishes. PMID:27079451

  2. Mutations in homologous recombination genes rescue top3 slow growth in Saccharomyces cerevisiae.

    PubMed Central

    Shor, Erika; Gangloff, Serge; Wagner, Marisa; Weinstein, Justin; Price, Gavrielle; Rothstein, Rodney

    2002-01-01

    In budding yeast, loss of topoisomerase III, encoded by the TOP3 gene, leads to a genomic instability phenotype that includes slow growth, hyper-sensitivity to genotoxic agents, mitotic hyper-recombination, increased chromosome missegregation, and meiotic failure. Slow growth and other defects of top3 mutants are suppressed by mutation of SGS1, which encodes the only RecQ helicase in S. cerevisiae. sgs1 is epistatic to top3, suggesting that the two proteins act in the same pathway. To identify other factors that function in the Sgs1-Top3 pathway, we undertook a genetic screen for non-sgs1 suppressors of top3 defects. We found that slow growth and DNA damage sensitivity of top3 mutants are suppressed by mutations in RAD51, RAD54, RAD55, and RAD57. In contrast, top3 mutants show extreme synergistic growth defects with mutations in RAD50, MRE11, XRS2, RDH54, and RAD1. We also analyzed recombination at the SUP4-o region, showing that in a rad51, rad54, rad55, or rad57 background top3Delta does not increase recombination to the same degree as in a wild-type strain. These results suggest that the presence of the Rad51 homologous recombination complex in a top3 background facilitates creation of detrimental intermediates by Sgs1. We present a model wherein Rad51 helps recruit Sgs1-Top3 to sites of replicative damage. PMID:12399378

  3. Subcloning plus insertion (SPI)--a novel recombineering method for the rapid construction of gene targeting vectors.

    PubMed

    Reddy, Thimma R; Kelsall, Emma J; Fevat, Léna M S; Munson, Sarah E; Cowley, Shaun M

    2015-01-01

    Gene targeting refers to the precise modification of a genetic locus using homologous recombination. The generation of novel cell lines and transgenic mouse models using this method necessitates the construction of a 'targeting' vector, which contains homologous DNA sequences to the target gene, and has for many years been a limiting step in the process. Vector construction can be performed in vivo in Escherichia coli cells using homologous recombination mediated by phage recombinases using a technique termed recombineering. Recombineering is the preferred technique to subclone the long homology sequences (>4 kb) and various targeting elements including selection markers that are required to mediate efficient allelic exchange between a targeting vector and its cognate genomic locus. Typical recombineering protocols follow an iterative scheme of step-wise integration of the targeting elements and require intermediate purification and transformation steps. Here, we present a novel recombineering methodology of vector assembly using a multiplex approach. Plasmid gap repair is performed by the simultaneous capture of genomic sequence from mouse Bacterial Artificial Chromosome libraries and the insertion of dual bacterial and mammalian selection markers. This subcloning plus insertion method is highly efficient and yields a majority of correct recombinants. We present data for the construction of different types of conditional gene knockout, or knock-in, vectors and BAC reporter vectors that have been constructed using this method. SPI vector construction greatly extends the repertoire of the recombineering toolbox and provides a simple, rapid and cost-effective method of constructing these highly complex vectors. PMID:25590226

  4. Regulation of Recombination between gtfB/gtfC Genes in Streptococcus mutans by Recombinase A

    PubMed Central

    Inagaki, Satoko; Fujita, Kazuyo; Takashima, Yukiko; Nagayama, Kayoko; Ardin, Arifah C.; Matsumi, Yuki; Matsumoto-Nakano, Michiyo

    2013-01-01

    Streptococcus mutans produces 3 types of glucosyltransferases (GTFs), whose cooperative action is essential for cellular adhesion. The recombinase A (RecA) protein is required for homologous recombination. In our previous study, we isolated several strains with a smooth colony morphology and low GTF activity, characteristics speculated to be derived from the GTF fusions. The purpose of the present study was to investigate the mechanism of those fusions. S. mutans strain MT8148 was grown in the presence of recombinant RecA (rRecA) protein, after which smooth colonies were isolated. The biological functions and sequences of the gtfB and gtfC genes of this as well as other clinical strains were determined. The sucrose-dependent adherence rates of those strains were reduced as compared to that of MT8148. Determination of the sequences of the gtfB and gtfC genes showed that an approximately 3500 bp region was deleted from the area between them. Furthermore, expression of the recA gene was elevated in those strains as compared to MT8148. These results suggest that RecA has an important role in fusions of gtfB and gtfC genes, leading to alteration of colony morphology and reduction in sucrose-dependent adhesion. PMID:23476132

  5. Two recombination-dependent DNA replication pathways of bacteriophage T4, and their roles in mutagenesis and horizontal gene transfer

    PubMed Central

    Mosig, Gisela; Gewin, John; Luder, Andreas; Colowick, Nancy; Vo, Daniel

    2001-01-01

    Two major pathways of recombination-dependent DNA replication, “join-copy” and “join-cut-copy,” can be distinguished in phage T4: join-copy requires only early and middle genes, but two late proteins, endonuclease VII and terminase, are uniquely important in the join-cut-copy pathway. In wild-type T4, timing of these pathways is integrated with the developmental program and related to transcription and packaging of DNA. In primase mutants, which are defective in origin-dependent lagging-strand DNA synthesis, the late pathway can bypass the lack of primers for lagging-strand DNA synthesis. The exquisitely regulated synthesis of endo VII, and of two proteins from its gene, explains the delay of recombination-dependent DNA replication in primase (as well as topoisomerase) mutants, and the temperature-dependence of the delay. Other proteins (e.g., the single-stranded DNA binding protein and the products of genes 46 and 47) are important in all recombination pathways, but they interact differently with other proteins in different pathways. These homologous recombination pathways contribute to evolution because they facilitate acquisition of any foreign DNA with limited sequence homology during horizontal gene transfer, without requiring transposition or site-specific recombination functions. Partial heteroduplex repair can generate what appears to be multiple mutations from a single recombinational intermediate. The resulting sequence divergence generates barriers to formation of viable recombinants. The multiple sequence changes can also lead to erroneous estimates in phylogenetic analyses. PMID:11459968

  6. Gene CATCHR--gene cloning and tagging for Caenorhabditis elegans using yeast homologous recombination: a novel approach for the analysis of gene expression.

    PubMed

    Sassi, Holly E; Renihan, Stephanie; Spence, Andrew M; Cooperstock, Ramona L

    2005-01-01

    Expression patterns of gene products provide important insights into gene function. Reporter constructs are frequently used to analyze gene expression in Caenorhabditis elegans, but the sequence context of a given gene is inevitably altered in such constructs. As a result, these transgenes may lack regulatory elements required for proper gene expression. We developed Gene Catchr, a novel method of generating reporter constructs that exploits yeast homologous recombination (YHR) to subclone and tag worm genes while preserving their local sequence context. YHR facilitates the cloning of large genomic regions, allowing the isolation of regulatory sequences in promoters, introns, untranslated regions and flanking DNA. The endogenous regulatory context of a given gene is thus preserved, producing expression patterns that are as accurate as possible. Gene Catchr is flexible: any tag can be inserted at any position without introducing extra sequence. Each step is simple and can be adapted to process multiple genes in parallel. We show that expression patterns derived from Gene Catchr transgenes are consistent with previous reports and also describe novel expression data. Mutant rescue assays demonstrate that Gene Catchr-generated transgenes are functional. Our results validate the use of Gene Catchr as a valuable tool to study spatiotemporal gene expression. PMID:16254074

  7. [Estimation of the recombination fraction by the maximum likelihood method in mapping interacting genes relative to marker loci].

    PubMed

    Priiatkina, S N

    2002-05-01

    For mapping nonlinked interacting genes relative to marker loci, the recombination fractions can be calculated by using the log-likelihood functions were derived that permit estimation of recombinant fractions by solving the ML equations on the basis of F2 data at various types of interaction. In some cases, the recombinant fraction estimates are obtained in the analytical form while in others they are numerically calculated from concrete experimental data. With the same type of epistasis the log-functions were shown to differ depending on the functional role (suppression or epistasis) of the mapped gene. Methods for testing the correspondence of the model and the recombination fraction estimates to the experimental data are discussed. In ambiguous cases, analysis of the linked marker behavior makes it possible to differentiate gene interaction from distorted single-locus segregation, which at some forms of interaction imitate phenotypic ratios. PMID:12068553

  8. Coevolution between Nuclear-Encoded DNA Replication, Recombination, and Repair Genes and Plastid Genome Complexity

    PubMed Central

    Zhang, Jin; Ruhlman, Tracey A.; Sabir, Jamal S. M.; Blazier, John Chris; Weng, Mao-Lun; Park, Seongjun; Jansen, Robert K.

    2016-01-01

    Disruption of DNA replication, recombination, and repair (DNA-RRR) systems has been hypothesized to cause highly elevated nucleotide substitution rates and genome rearrangements in the plastids of angiosperms, but this theory remains untested. To investigate nuclear–plastid genome (plastome) coevolution in Geraniaceae, four different measures of plastome complexity (rearrangements, repeats, nucleotide insertions/deletions, and substitution rates) were evaluated along with substitution rates of 12 nuclear-encoded, plastid-targeted DNA-RRR genes from 27 Geraniales species. Significant correlations were detected for nonsynonymous (dN) but not synonymous (dS) substitution rates for three DNA-RRR genes (uvrB/C, why1, and gyrA) supporting a role for these genes in accelerated plastid genome evolution in Geraniaceae. Furthermore, correlation between dN of uvrB/C and plastome complexity suggests the presence of nucleotide excision repair system in plastids. Significant correlations were also detected between plastome complexity and 13 of the 90 nuclear-encoded organelle-targeted genes investigated. Comparisons revealed significant acceleration of dN in plastid-targeted genes of Geraniales relative to Brassicales suggesting this correlation may be an artifact of elevated rates in this gene set in Geraniaceae. Correlation between dN of plastid-targeted DNA-RRR genes and plastome complexity supports the hypothesis that the aberrant patterns in angiosperm plastome evolution could be caused by dysfunction in DNA-RRR systems. PMID:26893456

  9. Coevolution between Nuclear-Encoded DNA Replication, Recombination, and Repair Genes and Plastid Genome Complexity.

    PubMed

    Zhang, Jin; Ruhlman, Tracey A; Sabir, Jamal S M; Blazier, John Chris; Weng, Mao-Lun; Park, Seongjun; Jansen, Robert K

    2016-01-01

    Disruption of DNA replication, recombination, and repair (DNA-RRR) systems has been hypothesized to cause highly elevated nucleotide substitution rates and genome rearrangements in the plastids of angiosperms, but this theory remains untested. To investigate nuclear-plastid genome (plastome) coevolution in Geraniaceae, four different measures of plastome complexity (rearrangements, repeats, nucleotide insertions/deletions, and substitution rates) were evaluated along with substitution rates of 12 nuclear-encoded, plastid-targeted DNA-RRR genes from 27 Geraniales species. Significant correlations were detected for nonsynonymous (dN) but not synonymous (dS) substitution rates for three DNA-RRR genes (uvrB/C, why1, and gyrA) supporting a role for these genes in accelerated plastid genome evolution in Geraniaceae. Furthermore, correlation between dN of uvrB/C and plastome complexity suggests the presence of nucleotide excision repair system in plastids. Significant correlations were also detected between plastome complexity and 13 of the 90 nuclear-encoded organelle-targeted genes investigated. Comparisons revealed significant acceleration of dN in plastid-targeted genes of Geraniales relative to Brassicales suggesting this correlation may be an artifact of elevated rates in this gene set in Geraniaceae. Correlation between dN of plastid-targeted DNA-RRR genes and plastome complexity supports the hypothesis that the aberrant patterns in angiosperm plastome evolution could be caused by dysfunction in DNA-RRR systems. PMID:26893456

  10. Gene transfer in the liver using recombinant adeno-associated virus

    PubMed Central

    Ahmed, Seemin Seher; Li, Jia; Godwin, Jonathan; Gao, Guangping; Zhong, Li

    2013-01-01

    Liver-directed gene transfer and gene therapy are rapidly gaining attention primarily because the liver is centrally involved in a variety of metabolic functions that are affected in various inherited disorders. Recombinant adeno-associated virus (rAAV) is a popular gene delivery vehicle for gene therapy and intravenous delivery of some rAAV serotypes results in very efficient transduction of the liver. rAAV-mediated and liver-directed gene transfer can help in creating somatic transgenic animals or disease models and studying the function of various genes and miRNAs. The liver is the target tissue for gene therapy of many inborn metabolic diseases and may also be exploited as a “bio-factory” for the production of coagulation factors, insulin and growth hormones and other non-hepatic proteins. Hence efficient delivery of transgenes and small RNAs to the liver by rAAV vectors has been of long-standing interest to research scientists and clinicians alike. PMID:23686826

  11. Divergent genes in potential inoculant Sinorhizobium strains are related to DNA replication, recombination, and repair.

    PubMed

    Penttinen, Petri; Greco, Dario; Muntyan, Victoria; Terefework, Zewdu; De Lajudie, Philippe; Roumiantseva, Marina; Becker, Anke; Auvinen, Petri; Lindström, Kristina

    2016-06-01

    To serve as inoculants of legumes, nitrogen-fixing rhizobium strains should be competitive and tolerant of diverse environments. We hybridized the genomes of symbiotically efficient and salt tolerant Sinorhizobium inoculant strains onto the Sinorhizobium meliloti Rm1021 microarray. The number of variable genes, that is, divergent or putatively multiplied genes, ranged from 503 to 1556 for S. meliloti AK23, S. meliloti STM 1064 and S. arboris HAMBI 1552. The numbers of divergent genes affiliated with the symbiosis plasmid pSymA and related to DNA replication, recombination and repair were significantly higher than expected. The variation was mainly in the accessory genome, implying that it was important in shaping the adaptability of the strains. PMID:26879331

  12. Ectopic recombination within homologous immunoglobulin mu gene constant regions in a mouse hybridoma cell line.

    PubMed Central

    Baker, M D; Read, L R

    1992-01-01

    We have transferred a pSV2neo vector containing the wild-type constant region of the immunoglobulin mu gene (C mu) into the mutant hybridoma igm482, which bears a 2-bp deletion in the third constant-region exon of its haploid chromosomal mu gene (C mu 3). Independent igm482 transformants contain the wild-type immunoglobulin C mu region stably integrated in ectopic chromosomal positions. We report here that the wild-type immunoglobulin C mu region can function as the donor sequence in a gene conversion event which corrects the 2-bp deletion in the mutant igm482 chromosomal C mu 3 exon. The homologous recombination event restores normal immunoglobulin M production in the mutant cell. Images PMID:1406631

  13. Recombinant adeno-associated virus targets passenger gene expression to cones in primate retina

    NASA Astrophysics Data System (ADS)

    Mancuso, Katherine; Hendrickson, Anita E.; Connor, Thomas B., Jr.; Mauck, Matthew C.; Kinsella, James J.; Hauswirth, William W.; Neitz, Jay; Neitz, Maureen

    2007-05-01

    Recombinant adeno-associated virus (rAAV) is a promising vector for gene therapy of photoreceptor-based diseases. Previous studies have demonstrated that rAAV serotypes 2 and 5 can transduce both rod and cone photoreceptors in rodents and dogs, and it can target rods, but not cones in primates. Here we report that using a human cone-specific enhancer and promoter to regulate expression of a green fluorescent protein (GFP) reporter gene in an rAAV-5 vector successfully targeted expression of the reporter gene to primate cones, and the time course of GFP expression was able to be monitored in a living animal using the RetCam II digital imaging system.

  14. Novel Recombinant Hepatitis B Virus Vectors Efficiently Deliver Protein and RNA Encoding Genes into Primary Hepatocytes

    PubMed Central

    Hong, Ran; Bai, Weiya; Zhai, Jianwei; Liu, Wei; Li, Xinyan; Zhang, Jiming; Cui, Xiaoxian; Zhao, Xue; Ye, Xiaoli; Deng, Qiang; Tiollais, Pierre; Wen, Yumei

    2013-01-01

    Hepatitis B virus (HBV) has extremely restricted host and hepatocyte tropism. HBV-based vectors could form the basis of novel therapies for chronic hepatitis B and other liver diseases and would also be invaluable for the study of HBV infection. Previous attempts at developing HBV-based vectors encountered low yields of recombinant viruses and/or lack of sufficient infectivity/cargo gene expression in primary hepatocytes, which hampered follow-up applications. In this work, we constructed a novel vector based on a naturally occurring, highly replicative HBV mutant with a 207-bp deletion in the preS1/polymerase spacer region. By applying a novel insertion strategy that preserves the continuity of the polymerase open reading frame (ORF), recombinant HBV (rHBV) carrying protein or small interfering RNA (siRNA) genes were obtained that replicated and were packaged efficiently in cultured hepatocytes. We demonstrated that rHBV expressing a fluorescent reporter (DsRed) is highly infective in primary tree shrew hepatocytes, and rHBV expressing HBV-targeting siRNA successfully inhibited antigen expression from coinfected wild-type HBV. This novel HBV vector will be a powerful tool for hepatocyte-targeting gene delivery, as well as the study of HBV infection. PMID:23552416

  15. Mutation analysis of mycobacterial rpoB genes and rifampin resistance using recombinant Mycobacterium smegmatis.

    PubMed

    Nakata, Noboru; Kai, Masanori; Makino, Masahiko

    2012-04-01

    Rifampin is a major drug used to treat leprosy and tuberculosis. The rifampin resistance of Mycobacterium leprae and Mycobacterium tuberculosis results from a mutation in the rpoB gene, encoding the β subunit of RNA polymerase. A method for the molecular determination of rifampin resistance in these two mycobacteria would be clinically valuable, but the relationship between the mutations and susceptibility to rifampin must be clarified before its use. Analyses of mutations responsible for rifampin resistance using clinical isolates present some limitations. Each clinical isolate has its own genetic variations in some loci other than rpoB, which might affect rifampin susceptibility. For this study, we constructed recombinant strains of Mycobacterium smegmatis carrying the M. leprae or M. tuberculosis rpoB gene with or without mutation and disrupted their own rpoB genes on the chromosome. The rifampin and rifabutin susceptibilities of the recombinant bacteria were measured to examine the influence of the mutations. The results confirmed that several mutations detected in clinical isolates of these two pathogenic mycobacteria can confer rifampin resistance, but they also suggested that some mutations detected in M. leprae isolates or rifampin-resistant M. tuberculosis isolates are not involved in rifampin resistance. PMID:22252831

  16. Diversity and Recombination of Dispersed Ribosomal DNA and Protein Coding Genes in Microsporidia

    PubMed Central

    Ironside, Joseph Edward

    2013-01-01

    Microsporidian strains are usually classified on the basis of their ribosomal DNA (rDNA) sequences. Although rDNA occurs as multiple copies, in most non-microsporidian species copies within a genome occur as tandem arrays and are homogenised by concerted evolution. In contrast, microsporidian rDNA units are dispersed throughout the genome in some species, and on this basis are predicted to undergo reduced concerted evolution. Furthermore many microsporidian species appear to be asexual and should therefore exhibit reduced genetic diversity due to a lack of recombination. Here, DNA sequences are compared between microsporidia with different life cycles in order to determine the effects of concerted evolution and sexual reproduction upon the diversity of rDNA and protein coding genes. Comparisons of cloned rDNA sequences between microsporidia of the genus Nosema with different life cycles provide evidence of intragenomic variability coupled with strong purifying selection. This suggests a birth and death process of evolution. However, some concerted evolution is suggested by clustering of rDNA sequences within species. Variability of protein-coding sequences indicates that considerable intergenomic variation also occurs between microsporidian cells within a single host. Patterns of variation in microsporidian DNA sequences indicate that additional diversity is generated by intragenomic and/or intergenomic recombination between sequence variants. The discovery of intragenomic variability coupled with strong purifying selection in microsporidian rRNA sequences supports the hypothesis that concerted evolution is reduced when copies of a gene are dispersed rather than repeated tandemly. The presence of intragenomic variability also renders the use of rDNA sequences for barcoding microsporidia questionable. Evidence of recombination in the single-copy genes of putatively asexual microsporidia suggests that these species may undergo cryptic sexual reproduction, a

  17. Use of Bacteriophage λ Recombination Functions To Promote Gene Replacement in Escherichia coli

    PubMed Central

    Murphy, Kenan C.

    1998-01-01

    Replacement of Escherichia coli’s RecBCD function with phage λ’s Red function generates a strain whose chromosome recombines with short linear DNA fragments at a greatly elevated rate. The rate is at least 70-fold higher than that exhibited by a recBC sbcBC or recD strain. The value of the system is highlighted by gene replacement with a PCR-generated DNA fragment. The ΔrecBCD::Plac-red kan replacement allele can be P1 transduced to other E. coli strains, making the hyper-Rec phenotype easily transferable. PMID:9555887

  18. Ethanol production by recombinant Escherichia coli carrying genes from Zymomonas mobilis

    SciTech Connect

    Lawford, H.G.; Rousseau, J.D.

    1991-12-31

    Efficient utilization of lignocellulosic feedstocks offers an opportunity to reduce the cost of producing fuel ethanol. The fermentation performance characteristics of recombinant Escherichia coli ATCC 11303 carrying the {open_quotes}PET plasmid{close_quotes} (pLO1297) with the lac operon controlling the expression of pyruvate decarboxylase (pdc) and alcohol dehydrogenase 11 (adhB) genes cloned from Zymomonas mobilis CP4 were assessed in batch and continuous processes with sugar mixtures designed to mimic process streams from lignocellulosic hydrolysis systems.

  19. Recombinant AAV-directed gene therapy for type I glycogen storage diseases

    PubMed Central

    Chou, JY; Mansfield, BC

    2011-01-01

    Introduction Glycogen storage disease (GSD) type Ia and Ib are disorders of impaired glucose homeostasis affecting the liver and kidney. GSD-Ib also affects neutrophils. Current dietary therapies cannot prevent long-term complications. In animal studies, recombinant adeno-associated virus (rAAV) vector-mediated gene therapy can correct or minimize multiple aspects of the disorders, offering hope for human gene therapy. Areas covered A summary of recent progress in rAAV-mediated gene therapy for GSD-I; strategies to improve rAAV-mediated gene delivery, transduction efficiency and immune avoidance; and vector refinements that improve expression. Expert opinion rAAV-mediated gene delivery to the liver can restore glucose homeostasis in preclinical models of GSD-I, but some long-term complications of the liver and kidney remain. Gene therapy for GSD-Ib is less advanced than for GSD-Ia and only transient correction of myeloid dysfunction has been achieved. A question remains whether a single rAAV vector can meet the expression efficiency and tropism required to treat all aspects of GSD-I, or if a multi-prong approach is needed. An understanding of the strengths and weaknesses of rAAV vectors in the context of strategies to achieve efficient transduction of the liver, kidney, and hematopoietic stem cells is required for treating GSD-I. PMID:21504389

  20. Multi-Homologous Recombination-Based Gene Manipulation in the Rice Pathogen Fusarium fujikuroi.

    PubMed

    Hwang, In Sun; Ahn, Il-Pyung

    2016-06-01

    Gene disruption by homologous recombination is widely used to investigate and analyze the function of genes in Fusarium fujikuroi, a fungus that causes bakanae disease and root rot symptoms in rice. To generate gene deletion constructs, the use of conventional cloning methods, which rely on restriction enzymes and ligases, has had limited success due to a lack of unique restriction enzyme sites. Although strategies that avoid the use of restriction enzymes have been employed to overcome this issue, these methods require complicated PCR steps or are frequently inefficient. Here, we introduce a cloning system that utilizes multi-fragment assembly by In-Fusion to generate a gene disruption construct. This method utilizes DNA fragment fusion and requires only one PCR step and one reaction for construction. Using this strategy, a gene disruption construct for Fusarium cyclin C1 (FCC1 ), which is associated with fumonisin B1 biosynthesis, was successfully created and used for fungal transformation. In vivo and in vitro experiments using confirmed fcc1 mutants suggest that fumonisin production is closely related to disease symptoms exhibited by F. fujikuroi strain B14. Taken together, this multi-fragment assembly method represents a simpler and a more convenient process for targeted gene disruption in fungi. PMID:27298592

  1. Multi-Homologous Recombination-Based Gene Manipulation in the Rice Pathogen Fusarium fujikuroi

    PubMed Central

    Hwang, In Sun; Ahn, Il-Pyung

    2016-01-01

    Gene disruption by homologous recombination is widely used to investigate and analyze the function of genes in Fusarium fujikuroi, a fungus that causes bakanae disease and root rot symptoms in rice. To generate gene deletion constructs, the use of conventional cloning methods, which rely on restriction enzymes and ligases, has had limited success due to a lack of unique restriction enzyme sites. Although strategies that avoid the use of restriction enzymes have been employed to overcome this issue, these methods require complicated PCR steps or are frequently inefficient. Here, we introduce a cloning system that utilizes multi-fragment assembly by In-Fusion to generate a gene disruption construct. This method utilizes DNA fragment fusion and requires only one PCR step and one reaction for construction. Using this strategy, a gene disruption construct for Fusarium cyclin C1 (FCC1 ), which is associated with fumonisin B1 biosynthesis, was successfully created and used for fungal transformation. In vivo and in vitro experiments using confirmed fcc1 mutants suggest that fumonisin production is closely related to disease symptoms exhibited by F. fujikuroi strain B14. Taken together, this multi-fragment assembly method represents a simpler and a more convenient process for targeted gene disruption in fungi. PMID:27298592

  2. Inducible and Reversible Lentiviral and Recombination Mediated Cassette Exchange (RMCE) Systems for Controlling Gene Expression

    PubMed Central

    Bersten, David C.; Sullivan, Adrienne E.; Li, Dian; Bhakti, Veronica; Bent, Stephen J.; Whitelaw, Murray L.

    2015-01-01

    Manipulation of gene expression to invoke loss of function (LoF) or gain of function (GoF) phenotypes is important for interrogating complex biological questions both in vitro and in vivo. Doxycycline (Dox)-inducible gene expression systems are commonly used although success is often limited by high background and insufficient sensitivity to Dox. Here we develop broadly applicable platforms for reliable, tightly controlled and reversible Dox-inducible systems for lentiviral mediated generation of cell lines or FLP Recombination-Mediated Cassette Exchange (RMCE) into the Collagen 1a1 (Col1a1) locus (FLP-In Col1a1) in mouse embryonic stem cells. We significantly improve the flexibility, usefulness and robustness of the Dox-inducible system by using Tetracycline (Tet) activator (Tet-On) variants which are more sensitive to Dox, have no background activity and are expressed from single Gateway-compatible constructs. We demonstrate the usefulness of these platforms in ectopic gene expression or gene knockdown in multiple cell lines, primary neurons and in FLP-In Col1a1 mouse embryonic stem cells. We also improve the flexibility of RMCE Dox-inducible systems by generating constructs that allow for tissue or cell type-specific Dox-inducible expression and generate a shRNA selection algorithm that can effectively predict potent shRNA sequences able to knockdown gene expression from single integrant constructs. These platforms provide flexible, reliable and broadly applicable inducible expression systems for studying gene function. PMID:25768837

  3. Optimal gene expression and amplification strategies for batch and continuous recombinant cultures

    SciTech Connect

    Seressiotis, A.; Bailey, J.E.

    1987-02-20

    Maximizing the amount of protein produced from a cloned gene in a recombinant organism requires careful consideration of the trade-offs involved between cloned gene expression and host cell growth and biosythetic activity. Numerous experimental studies of recombinant Escherichia coli and Saccharomyces cerevisiae have shown that the presence of plasmids reduces host cell growth rate and, overall protein synthesis activity. Reduction host cell growth rates and biosynthetic activity in the presence of plasmid-directed macromolecular synthesis presumably occurs because of competition between plasmid-directed and host-cell-directed activity for common pools of precursors, chemical energy and electrons, activator species, repressor molecules, transport apparatus, and enzymes and other catalytic assemblies. The use of regulated promoters and plasmid replication controls amenable to environmental manipulation offers the opportunity of reconciling the opposing effects of cloned-gene content and expression level on process productivity. Several promoters are available for E. coli, S. cerevisiae, and other hosts that allow the expression level of the cloned gene to be switched from a relatively low to a relatively high level by a change in the organism environment. Similarly, in a plasmid replicon repressed by a temperature-sensitive molecule, such as the ColE1 origin of replication for E. coli plasmids with a mutant RNA I gene providing temperature-sensitive replication repressor activity, cellular plasmid content can be altered from around 25 to 700 or more copies per cell by increasing the medium temperature. Similar temperature-sensitive replication regulators are known for R1 plasmids.

  4. Immunogenicity of recombinant BCGs expressing predicted antigenic epitopes of bovine viral diarrhea virus E2 gene.

    PubMed

    Liu, Dongxu; Lu, Huijun; Shi, Kun; Su, Fengyan; Li, Jianming; Du, Rui

    2014-10-01

    To develop a vaccine to prevent diseases caused by Mycobacterium tuberculosis and bovine viral diarrhea virus (BVDV) simultaneously, recombinant Bacillus Calmette-Guerin (rBCG) vaccines expressing different regions of the BVDV E2 gene were constructed. Using DNASTAR 6.0 software, potential antigenic epitopes were predicted, and six regions were chosen to generate recombinant plasmids with the pMV361 vector (pMV361-E2-1, pMV361-E2-2, pMV361-E2-3, pMV361-E2-4, pMV361-E2-5 and pMV361-E2-6, respectively). The recombinant plasmids were transformed into BCG, and protein expression was thermally induced at 45 °C. Mice were immunized with 5 × 10(6) CFU/200 µL of each rBCG strain. Compared with other groups, BVDV E2 specific antibody titers were higher in mice immunized with rBCG-E2-6. Ratios and numbers of CD4+, CD8+ and IL-12 expressing spleen lymphocytes of the rBCG-E2-6 group also were higher than those of other groups. Thus, the rBCG-E2-6 vaccine showed the highest immunogenicity of all groups based on the humoral and cellular responses to vaccination. PMID:25135492

  5. RecET direct cloning and Redαβ recombineering of biosynthetic gene clusters, large operons or single genes for heterologous expression.

    PubMed

    Wang, Hailong; Li, Zhen; Jia, Ruonan; Hou, Yu; Yin, Jia; Bian, Xiaoying; Li, Aiying; Müller, Rolf; Stewart, A Francis; Fu, Jun; Zhang, Youming

    2016-07-01

    Full-length RecE and RecT from Rac prophage mediate highly efficient linear-linear homologous recombination that can be used to clone large DNA regions directly from genomic DNA into expression vectors, bypassing library construction and screening. Homologous recombination mediated by Redαβ from lambda phage has been widely used for recombinant DNA engineering. Here we present a protocol for direct cloning and engineering of biosynthetic gene clusters, large operons or single genes from genomic DNA using one Escherichia coli host that harbors both RecET and Redαβ systems. The pipeline uses standardized cassettes for horizontal gene transfer options, as well as vectors with different replication origins configured to minimize recombineering background through the use of selectively replicating templates or CcdB counterselection. These optimized reagents and protocols facilitate fast acquisition of transgenes from genomic DNA preparations, which are ready for heterologous expression within 1 week. PMID:27254463

  6. Evidence of Localized Prophage-Host Recombination in the lytA Gene, Encoding the Major Pneumococcal Autolysin ▿

    PubMed Central

    Morales, María; García, Pedro; de la Campa, Adela G.; Liñares, Josefina; Ardanuy, Carmen; García, Ernesto

    2010-01-01

    According to a highly polymorphic region in the lytA gene, encoding the major autolysin of Streptococcus pneumoniae, two different families of alleles can be differentiated by PCR and restriction digestion. Here, we provide evidence that this polymorphic region arose from recombination events with homologous genes of pneumococcal temperate phages. PMID:20304992

  7. BTK gene targeting by homologous recombination using a helper-dependent adenovirus/adeno-associated virus hybrid vector.

    PubMed

    Yamamoto, H; Ishimura, M; Ochiai, M; Takada, H; Kusuhara, K; Nakatsu, Y; Tsuzuki, T; Mitani, K; Hara, T

    2016-02-01

    X-linked agammaglobulinemia (XLA) is one of the most common humoral immunodeficiencies, which is caused by mutations in Bruton's tyrosine kinase (BTK) gene. To examine the possibility of using gene therapy for XLA, we constructed a helper-dependent adenovirus/adeno-associated virus BTK targeting vector (HD-Ad.AAV BTK vector) composed of a genomic sequence containing BTK exons 6-19 and a green fluorescence protein-hygromycin cassette driven by a cytomegalovirus promoter. We first used NALM-6, a human male pre-B acute lymphoblastic leukemia cell line, as a recipient to measure the efficiency of gene targeting by homologous recombination. We identified 10 clones with the homologous recombination of the BTK gene among 107 hygromycin-resistant stable clones isolated from two independent experiments. We next used cord blood CD34⁺ cells as the recipient cells for the gene targeting. We isolated colonies grown in medium containing cytokines and hygromycin. We found that the targeting of the BTK gene occurred in four of the 755 hygromycin-resistant colonies. Importantly, the gene targeting was also observed in CD19⁺ lymphoid progenitor cells that were differentiated from the homologous recombinant CD34⁺ cells during growth in selection media. Our study shows the potential for the BTK gene therapy using the HD-Ad.AAV BTK vector via homologous recombination in hematopoietic stem cells. PMID:26280081

  8. Cloning of a copper resistance gene cluster from the cyanobacterium Synechocystis sp. PCC 6803 by recombineering recovery.

    PubMed

    Gittins, John R

    2015-07-01

    A copper resistance gene cluster (6 genes, ∼8.2 kb) was isolated from the cyanobacterium Synechocystis sp. PCC 6803 by recombineering recovery (RR). Following integration of a narrow-host-range plasmid vector adjacent to the target region in the Synechocystis genome (pSYSX), DNA was isolated from transformed cells and the plasmid plus flanking sequence circularized by recombineering to precisely clone the gene cluster. Complementation of a copper-sensitive Escherichia coli mutant demonstrated the functionality of the pcopM gene encoding a copper-binding protein. RR provides a novel alternative method for cloning large DNA fragments from species that can be transformed by homologous recombination. PMID:25980606

  9. Expression of essential B cell genes and immunoglobulin isotypes suggests active development and gene recombination during equine gestation.

    PubMed

    Tallmadge, Rebecca L; McLaughlin, Kristin; Secor, Erica; Ruano, Diana; Matychak, Mary Beth; Flaminio, M Julia B F

    2009-09-01

    Many features of the equine immune system develop during fetal life, yet the naïve or immature immune state of the neonate renders the foal uniquely susceptible to particular pathogens. RT-PCR and immunohistochemical experiments investigated the progressive expression of developmental B cell markers and immunoglobulins in lymphoid tissues from equine fetus, pre-suckle neonate, foal, and adult horses. Serum IgM, IgG isotype, and IgA concentrations were also quantified in pre-suckle foals and adult horses. The expression of essential B cell genes suggests active development and gene recombination during equine gestation, including immunoglobulin isotype switching. The corresponding production of IgM and IgG proteins is detectable in a limited scale at birth. Although the equine neonate humoral response seems competent, B cell activation factors derived from antigen presenting cells and T cells may control critical developmental regulation and immunoglobulin production during the initial months of life. PMID:19442687

  10. Homologous recombination-mediated gene targeting in the liverwort Marchantia polymorpha L.

    PubMed Central

    Ishizaki, Kimitsune; Johzuka-Hisatomi, Yasuyo; Ishida, Sakiko; Iida, Shigeru; Kohchi, Takayuki

    2013-01-01

    The liverwort Marchantia polymorpha is an emerging model organism on account of its ideal characteristics for molecular genetics in addition to occupying a crucial position in the evolution of land plants. Here we describe a method for gene targeting by applying a positive/negative selection system for reduction of non-homologous random integration to an efficient Agrobacterium-mediated transformation system using M. polymorpha sporelings. The targeting efficiency was evaluated by knocking out the NOP1 gene, which impaired air-chamber formation. Homologous recombination was observed in about 2% of the thalli that passed the positive/negative selection. With the advantage of utilizing the haploid gametophytic generation, this strategy should facilitate further molecular genetic analysis of M. polymorpha, in which many of the mechanisms found in land plants are conserved, yet in a less complex form. PMID:23524944

  11. Recombinations between Alu repeat sequences that result in partial deletions within the C1 inhibitor gene.

    PubMed

    Ariga, T; Carter, P E; Davis, A E

    1990-12-01

    Genomic DNA sequence analysis was used to define the extent of deletions within the C1 inhibitor gene in two families with type I hereditary angioneurotic edema. Southern blot analysis initially indicated the presence of the partial deletions. One deletion was approximately 2 kb and included exon VII, whereas the other was approximately 8.5 kb and included exons IV-VI. Genomic libraries from an affected member of each family were constructed and clones containing the deletions were analyzed. Sequence analysis of the deletion joints of the mutants and corresponding regions of the normal gene in the two families demonstrated that both deletion joints resulted from recombination of two Alu repetitive DNA elements. Alu repeat sequences from introns VI and VII combined to make a novel Alu in family A, and Alu sequences in introns III and VI were spliced to make a new Alu in family B. The splice sites in the Alu sequences of both mutants were located in the left arm of the Alu element, and both recombination joints overlapped one of the RNA polymerase III promoter sequences. Because the involved Alu sequences, in both instances, were oriented in the same direction, unequal crossingover is the most likely mechanism to account for these mutations. PMID:2276734

  12. The Joint Effects of Background Selection and Genetic Recombination on Local Gene Genealogies

    PubMed Central

    Zeng, Kai; Charlesworth, Brian

    2011-01-01

    Background selection, the effects of the continual removal of deleterious mutations by natural selection on variability at linked sites, is potentially a major determinant of DNA sequence variability. However, the joint effects of background selection and genetic recombination on the shape of the neutral gene genealogy have proved hard to study analytically. The only existing formula concerns the mean coalescent time for a pair of alleles, making it difficult to assess the importance of background selection from genome-wide data on sequence polymorphism. Here we develop a structured coalescent model of background selection with recombination and implement it in a computer program that efficiently generates neutral gene genealogies for an arbitrary sample size. We check the validity of the structured coalescent model against forward-in-time simulations and show that it accurately captures the effects of background selection. The model produces more accurate predictions of the mean coalescent time than the existing formula and supports the conclusion that the effect of background selection is greater in the interior of a deleterious region than at its boundaries. The level of linkage disequilibrium between sites is elevated by background selection, to an extent that is well summarized by a change in effective population size. The structured coalescent model is readily extendable to more realistic situations and should prove useful for analyzing genome-wide polymorphism data. PMID:21705759

  13. Joint effects of natural selection and recombination on gene flow between Drosophila ananassae populations.

    PubMed

    Chen, Y; Marsh, B J; Stephan, W

    2000-07-01

    We estimated DNA sequence variation in a 5.7-kb fragment of the furrowed (fw) gene region within and between four populations of Drosophila ananassae; fw is located in a chromosomal region of very low recombination. We analyzed gene flow between these four populations along a latitudinal transect on the Indian subcontinent: two populations from southern, subtropical areas (Hyderabad, India, and Sri Lanka) and two from more temperate zones in the north (Nepal and Burma). Furthermore, we compared the pattern of differentiation at fw with published data from Om(1D), a gene located in a region of normal recombination. While differentiation at Om(1D) shows an isolation-by-distance effect, at fw the pattern of differentiation is quite different such that the frequencies of single nucleotide polymorphisms are homogenized over extended geographic regions (i.e., among the two populations of the northern species range from Burma and Nepal as well as among the two southern populations from India and Sri Lanka), but strongly differentiated between the northern and southern populations. To examine these differences in the patterns of variation and differentiation between the Om(1D) and fw gene regions, we determine the critical values of our previously proposed test of the background selection hypothesis (henceforth called F(ST) test). Using these results, we show that the pattern of differentiation at fw may be inconsistent with the background selection model. The data depart from this model in a direction that is compatible with the occurrence of recent selective sweeps in the northern as well as southern populations. PMID:10880480

  14. Adenovirus-mediated delivery into myocytes of muscle glycogen phosphorylase, the enzyme deficient in patients with glycogen-storage disease type V.

    PubMed Central

    Baqué, S; Newgard, C B; Gerard, R D; Guinovart, J J; Gómez-Foix, A M

    1994-01-01

    The feasibility of using adenovirus as a vector for the introduction of glycogen phosphorylase activity into myocytes has been examined. We used the C2C12 myoblast cell line to assay the impact of phosphorylase gene transfer on myocyte glycogen metabolism and to reproduce in vitro the two strategies proposed for the treatment of muscle genetic diseases, myoblast transplantation and direct DNA delivery. In this study, a recombinant adenovirus containing the muscle glycogen phosphorylase cDNA transcribed from the cytomegalovirus promoter (AdCMV-MGP) was used to transduce both differentiating myoblasts and nondividing mature myotube cells. Muscle glycogen phosphorylase mRNA levels and total phosphorylase activity were increased in both cell types after viral treatment although more efficiently in the differentiated myotubes. The increase in phosphorylase activity was transient (15 days) in myoblasts whereas in myotubes higher levels of phosphorylase gene expression and activity were reached, which remained above control levels for the duration of the study (20 days). The introduction of muscle phosphorylase into myotubes enhanced their glycogenolytic capacity. AdCMV MGP-transduced myotubes had lower glycogen levels under basal conditions. In addition, these engineered cells showed more extensive glycogenolysis in response to both adrenaline, which stimulates glycogen phosphorylase phosphorylation, and carbonyl cyanide m-chlorophenylhydrazone, a metabolic uncoupler. In conclusion, transfer of the muscle glycogen phosphorylase cDNA into myotubes confers an enhanced and regulatable glycogenolytic capacity. Thus this system might be useful for delivery of muscle glycogen phosphorylase and restoration of glycogenolysis in muscle cells from patients with muscle phosphorylase deficiency (McArdle's disease). Images Figure 1 Figure 2 Figure 5 PMID:7818463

  15. BF integrase genes of HIV-1 circulating in São Paulo, Brazil, with a recurrent recombination region.

    PubMed

    Iamarino, Atila; de Melo, Fernando Lucas; Braconi, Carla Torres; Zanotto, Paolo Marinho de Andrade

    2012-01-01

    Although some studies have shown diversity in HIV integrase (IN) genes, none has focused particularly on the gene evolving in epidemics in the context of recombination. The IN gene in 157 HIV-1 integrase inhibitor-naïve patients from the São Paulo State, Brazil, were sequenced tallying 128 of subtype B (23 of which were found in non-B genomes), 17 of subtype F (8 of which were found in recombinant genomes), 11 integrases were BF recombinants, and 1 from subtype C. Crucially, we found that 4 BF recombinant viruses shared a recurrent recombination breakpoint region between positions 4900 and 4924 (relative to the HXB2) that includes 2 gRNA loops, where the RT may stutter. Since these recombinants had independent phylogenetic origin, we argue that these results suggest a possible recombination hotspot not observed so far in BF CRF in particular, or in any other HIV-1 CRF in general. Additionally, 40% of the drug-naïve and 45% of the drug-treated patients had at least 1 raltegravir (RAL) or elvitegravir (EVG) resistance-associated amino acid change, but no major resistance mutations were found, in line with other studies. Importantly, V151I was the most common minor resistance mutation among B, F, and BF IN genes. Most codon sites of the IN genes had higher rates of synonymous substitutions (dS) indicative of a strong negative selection. Nevertheless, several codon sites mainly in the subtype B were found under positive selection. Consequently, we observed a higher genetic diversity in the B portions of the mosaics, possibly due to the more recent introduction of subtype F on top of an ongoing subtype B epidemics and a fast spread of subtype F alleles among the B population. PMID:22485165

  16. BF Integrase Genes of HIV-1 Circulating in São Paulo, Brazil, with a Recurrent Recombination Region

    PubMed Central

    Iamarino, Atila; de Melo, Fernando Lucas; Braconi, Carla Torres; Zanotto, Paolo Marinho de Andrade

    2012-01-01

    Although some studies have shown diversity in HIV integrase (IN) genes, none has focused particularly on the gene evolving in epidemics in the context of recombination. The IN gene in 157 HIV-1 integrase inhibitor-naïve patients from the São Paulo State, Brazil, were sequenced tallying 128 of subtype B (23 of which were found in non-B genomes), 17 of subtype F (8 of which were found in recombinant genomes), 11 integrases were BF recombinants, and 1 from subtype C. Crucially, we found that 4 BF recombinant viruses shared a recurrent recombination breakpoint region between positions 4900 and 4924 (relative to the HXB2) that includes 2 gRNA loops, where the RT may stutter. Since these recombinants had independent phylogenetic origin, we argue that these results suggest a possible recombination hotspot not observed so far in BF CRF in particular, or in any other HIV-1 CRF in general. Additionally, 40% of the drug-naïve and 45% of the drug-treated patients had at least 1 raltegravir (RAL) or elvitegravir (EVG) resistance-associated amino acid change, but no major resistance mutations were found, in line with other studies. Importantly, V151I was the most common minor resistance mutation among B, F, and BF IN genes. Most codon sites of the IN genes had higher rates of synonymous substitutions (dS) indicative of a strong negative selection. Nevertheless, several codon sites mainly in the subtype B were found under positive selection. Consequently, we observed a higher genetic diversity in the B portions of the mosaics, possibly due to the more recent introduction of subtype F on top of an ongoing subtype B epidemics and a fast spread of subtype F alleles among the B population. PMID:22485165

  17. Pseudomonas putida KT2440 markerless gene deletion using a combination of λ Red recombineering and Cre/loxP site-specific recombination.

    PubMed

    Luo, Xi; Yang, Yunwen; Ling, Wen; Zhuang, Hao; Li, Qin; Shang, Guangdong

    2016-02-01

    Pseudomonas putida KT2440 is a saprophytic, environmental microorganism that plays important roles in the biodegradation of environmental toxic compounds and production of polymers, chemicals and secondary metabolites. Gene deletion of KT2440 usually involves cloning of the flanking homologous fragments of the gene of interest into a suicide vector followed by transferring into KT2440 via triparental conjugation. Selection and counterselection steps are then employed to generate gene deletion mutant. However, these methods are tedious and are not suitable for the manipulation of multiple genes simultaneously. Herein, a two-step, markerless gene deletion method is presented. First, homologous armsflanked loxP-neo-loxP was knocked-in to replace the gene of interest, then the kanamycin resistance marker is removed by Cre recombinase catalyzed site-specific recombination. Both two-plasmid and one-plasmid gene systems were established. MekR/PmekA regulated gene expression system was found to be suitable for tight Cre expression in one-plasmid deletion system. The straightforward, time saving and highly efficient markerless gene deletion strategy has the potential to facilitate the genetics and functional genomics study of P. putida KT2440. PMID:26802072

  18. [Construction of Bacillus thuringiensis labeled recombinant strain and horizontal transfer of its cry1Ac10 gene].

    PubMed

    Zhou, Qin; Sun, Ming; Li, Lin; Yang, Zaiqing; Yu, Ziniu

    2005-01-01

    A recombinant plasmid pBMBZGC10 was obtained by the ligation of gfp-cry1Ac10 fusion gene and vector plasmid pAD4412, which was then introduced by gene pulser into acrystalliferous strain CryB, and a recombinant strain CryB(pBMBZGC10) was obtained. Different fermentative solutions of recombinant strain were used for multi-spraying on Brassica pekinesis, Ipomoea aquatica and Lycopersicon esculentum leaves. The results of fluorescent detection and PCR amplification revealed that cry1Ac10 gene did not transfer into indigenous bacteria, actinomyces and fungi in test soil, and could not be detected in roots, stems and leaves of test plants. PMID:15852975

  19. Evidence for increased recombination near the human insulin gene: implication for disease association studies

    SciTech Connect

    Chakravarti, A.; Elbein, S.C.; Permutt, M.A.

    1986-02-01

    Haplotypes for four new restriction site polymorphisms (detected by Rsa I, Taq I, HincII, and Sac I) and a previously identified DNA length polymorphism (5'FP), all at the insulin locus, have been studied in US Blacks, African Blacks, Caucasians, and Pima Indians. Black populations are polymorphic for all five markers, whereas the other groups are polymorphic for Rsa I, Taq I, and 5'FP only. The data suggest that approx. = 1 in 550 base pairs is variant in this region. The polymorphisms, even though located within 20 kilobases, display low levels of nonrandom association. Population genetic analysis suggests that recombination within this 20-kilobase segment occurs 24 times more frequently than expected if crossing-over occurred uniformly throughout the human genome. These findings suggest that population association between DNA polymorphisms and disease susceptibility genes near the insulin gene or structural mutations in the insulin gene will be weak. Thus, population studies would probably require large sample sizes to detect association. However, the low levels of nonrandom association increase the information content of the locus for linkage studies, which is the best alternative for discovering disease susceptibility genes.

  20. A conditional mouse model for measuring the frequency of homologous recombination events in vivo in the absence of essential genes.

    PubMed

    Brown, Adam D; Claybon, Alison B; Bishop, Alexander J R

    2011-09-01

    The ability to detect and repair DNA damage is crucial to the prevention of various diseases. Loss of function of genes involved in these processes is known to result in significant developmental defects and/or predisposition to cancer. One such DNA repair mechanism, homologous recombination, has the capacity to repair a wide variety of lesions. Knockout mouse models of genes thought to be involved in DNA repair processes are frequently lethal, making in vivo studies very difficult, if not impossible. Therefore, we set out to develop an in vivo conditional mouse model system to facilitate investigations into the involvement of essential genes in homologous recombination. To test our model, we measured the frequency of spontaneous homologous recombination using the pink-eyed unstable mouse model, in which we conditionally excised either Blm or full-length Brca1 (breast cancer 1, early onset). These two genes are hypothesized to have opposing roles in homologous recombination. In summary, our in vivo data supports in vitro studies suggesting that BLM suppresses homologous recombination, while full-length BRCA1 promotes this process. PMID:21709021

  1. Temperature influences β-carotene production in recombinant Saccharomyces cerevisiae expressing carotenogenic genes from Phaffia rhodozyma.

    PubMed

    Shi, Feng; Zhan, Wubing; Li, Yongfu; Wang, Xiaoyuan

    2014-01-01

    Red yeast Phaffia rhodozyma is a prominent microorganism able to synthesize carotenoid. Here, three carotenogenic cDNAs of P. rhodozyma CGMCC 2.1557, crtE, crtYB and crtI, were cloned and introduced into Saccharomyces cerevisiae INVSc1. The recombinant Sc-EYBI cells could synthesize 258.8 ± 43.8 μg g(-1) dry cell weight (DCW) of β-carotene when growing at 20 °C, about 59-fold higher than in those growing at 30 °C. Additional expression of the catalytic domain of 3-hydroxy-3-methylglutaryl-coenzyme A reductase from S. cerevisiae (Sc-EYBIH) increased the β-carotene level to 528.8 ± 13.3 μg g(-1) DCW as cells growing at 20 °C, 27-fold higher than cells growing at 30 °C, although cells grew faster at 30 °C than at 20 °C. Consistent with the much higher β-carotene level in cells growing at 20 °C, transcription level of three crt genes and cHMG1 gene in cells growing at 20 °C was a little higher than in those growing at 30 °C. Meanwhile, expression of three carotenogenic genes and accumulation of β-carotene promoted cell growth. These results reveal the influence of temperature on β-carotene biosynthesis and may be helpful for improving β-carotene production in recombinant S. cerevisiae. PMID:23861041

  2. Design and characterization of novel recombinant listeriolysin O-protamine fusion proteins for enhanced gene delivery.

    PubMed

    Kim, Na Hyung; Provoda, Chester; Lee, Kyung-Dall

    2015-02-01

    To improve the efficiency of gene delivery for effective gene therapy, it is essential that the vector carries functional components that can promote overcoming barriers in various steps leading to the transport of DNA from extracellular to ultimately nuclear compartment. In this study, we designed genetically engineered fusion proteins as a platform to incorporate multiple functionalities in one chimeric protein. Prototypes of such a chimera tested here contain two domains: one that binds to DNA; the other that can facilitate endosomal escape of DNA. The fusion proteins are composed of listeriolysin O (LLO), the endosomolytic pore-forming protein from Listeria monocytogenes, and a 22 amino acid sequence of the DNA-condensing polypeptide protamine (PN), singly or as a pair: LLO-PN and LLO-PNPN. We demonstrate dramatic enhancement of the gene delivery efficiency of protamine-condensed DNA upon incorporation of a small amount of LLO-PN fusion protein and further improvement with LLO-PNPN in vitro using cultured cells. Additionally, the association of anionic liposomes with cationic LLO-PNPN/protamine/DNA complexes, yielding a net negative surface charge, resulted in better in vitro transfection efficiency in the presence of serum. An initial, small set of data in mice indicated that the observed enhancement in gene expression could also be applicable to in vivo gene delivery. This study suggests that incorporation of a recombinant fusion protein with multiple functional components, such as LLO-protamine fusion protein, in a nonviral vector is a promising strategy for various nonviral gene delivery systems. PMID:25521817

  3. Two DNA repair and recombination genes in Saccharomyces cerevisiae, RAD52 and RAD54, are induced during meiosis

    SciTech Connect

    Cole, G.M.; Mortimer, R.K. ); Schild, D. )

    1989-07-01

    The DNA repair and recombination genes of Saccharomyces cerevisiae, RAD52 and RAD54, were transcriptionally induced approximately 10- to 15-fold in sporulating MATa/{alpha} cells. Congenic MATa/a cells, which did not sporulate, did not show similar increases. Assays of {beta}-galactosidase activity in strains harboring either a RAD52- or RAD54-lacZ gene fusion indicated that this induction occurred at a time concomitant with a commitment to meiotic recombination, as measured by prototroph formation from his1 heteroalleles.

  4. Strain variation, based on the hemagglutinin gene, in Norwegian ISA virus isolates collected from 1987 to 2001: indications of recombination.

    PubMed

    Devold, M; Falk, K; Dale, B; Krossøy, B; Biering, E; Aspehaug, V; Nilsen, F; Nylund, A

    2001-11-01

    Infectious salmon anemia (ISA) is caused by a virus that probably belongs to the Orthomyxoviridae and was first recorded in Norway in 1984. The disease has since spread along the Norwegian coast and has later been found in Canada, Scotland, the Faroe Islands, Chile, and the USA. This study presents sequence variation of the hemagglutinin gene from 37 ISA virus isolates, viz. one isolate from Scotland, one from Canada and 35 from Norway. The hemagglutinin gene contains a highly polymorphic region (HPR), which together with the rest of the gene sequence provides a good tool for studies of epizootics. The gene shows temporal and geographical sequence variation, where certain areas are dominated by distinct groups of isolates. Evidence of transmission of ISA virus isolates within and between regions is given. It is suggested that the hemagglutinin gene from different isolates may recombine. Possible recombination sites are found within the HPR and in the 5'-end flanking region close to the HPR. PMID:11775793

  5. Loss of coxsackie and adenovirus receptor expression in human colorectal cancer: A potential impact on the efficacy of adenovirus-mediated gene therapy in Chinese Han population.

    PubMed

    Ma, Ying-Yu; Wang, Xiao-Jun; Han, Yong; Li, Gang; Wang, Hui-Ju; Wang, Shi-Bing; Chen, Xiao-Yi; Liu, Fan-Long; He, Xiang-Lei; Tong, Xiang-Min; Mou, Xiao-Zhou

    2016-09-01

    The coxsackie and adenovirus receptor (CAR) is considered a tumor suppressor and critical factor for the efficacy of therapeutic strategies that employ the adenovirus. However, data on CAR expression levels in colorectal cancer are conflicting and its clinical relevance remains to be elucidated. Immunohistochemistry was performed on tissue microarrays containing 251 pairs of colon cancer and adjacent normal tissue samples from Chinese Han patients to assess the expression levels of CAR. Compared with healthy mucosa, decreased CAR expression (40.6% vs. 95.6%; P<0.001) was observed in colorectal cancer samples. The CAR immunopositivity in tumor tissues was not significantly associated with gender, age, tumor size, differentiation, TNM stage, lymph node metastasis or distant metastasis in patients with colon cancer. However, expression of CAR is present in 83.3% of the tumor tissues from patient with colorectal liver metastasis, which was significantly higher than those without liver metastasis (39.6%; P=0.042). At the plasma membrane, CAR was observed in 29.5% normal mucosa samples, which was significantly higher than in colorectal cancer samples (4.0%; P<0.001). In addition, the survival analysis demonstrated that the expression level of CAR has no association with the prognosis of colorectal cancer. CAR expression was observed to be downregulated in colorectal cancer, and it exerts complex effects during colorectal carcinogenesis, potentially depending on the stage of the cancer development and progression. High CAR expression may promote liver metastasis. With regard to oncolytic therapy, CAR expression analysis should be performed prior to adenoviral oncolytic treatment to stratify Chinese Han patients for treatment. PMID:27485384

  6. Loss of coxsackie and adenovirus receptor expression in human colorectal cancer: A potential impact on the efficacy of adenovirus-mediated gene therapy in Chinese Han population

    PubMed Central

    Ma, Ying-Yu; Wang, Xiao-Jun; Han, Yong; Li, Gang; Wang, Hui-Ju; Wang, Shi-Bing; Chen, Xiao-Yi; Liu, Fan-Long; He, Xiang-Lei; Tong, Xiang-Min; Mou, Xiao-Zhou

    2016-01-01

    The coxsackie and adenovirus receptor (CAR) is considered a tumor suppressor and critical factor for the efficacy of therapeutic strategies that employ the adenovirus. However, data on CAR expression levels in colorectal cancer are conflicting and its clinical relevance remains to be elucidated. Immunohistochemistry was performed on tissue microarrays containing 251 pairs of colon cancer and adjacent normal tissue samples from Chinese Han patients to assess the expression levels of CAR. Compared with healthy mucosa, decreased CAR expression (40.6% vs. 95.6%; P<0.001) was observed in colorectal cancer samples. The CAR immunopositivity in tumor tissues was not significantly associated with gender, age, tumor size, differentiation, TNM stage, lymph node metastasis or distant metastasis in patients with colon cancer. However, expression of CAR is present in 83.3% of the tumor tissues from patient with colorectal liver metastasis, which was significantly higher than those without liver metastasis (39.6%; P=0.042). At the plasma membrane, CAR was observed in 29.5% normal mucosa samples, which was significantly higher than in colorectal cancer samples (4.0%; P<0.001). In addition, the survival analysis demonstrated that the expression level of CAR has no association with the prognosis of colorectal cancer. CAR expression was observed to be downregulated in colorectal cancer, and it exerts complex effects during colorectal carcinogenesis, potentially depending on the stage of the cancer development and progression. High CAR expression may promote liver metastasis. With regard to oncolytic therapy, CAR expression analysis should be performed prior to adenoviral oncolytic treatment to stratify Chinese Han patients for treatment. PMID:27485384

  7. Analysis of the CYP21A2 gene with intergenic recombination and multiple gene deletions in the RCCX module.

    PubMed

    Chang, Shwu-Fen; Lee, Hsien-Hsiung

    2011-01-01

    The most frequent bimodular RCCX module of the RP1-C4A-CYP21A1P-TNXA-RP2-C4B-CYP21A2-TNXB gene sequence is located on chromosome 6p21.3. To determine RCCX alterations, we used the polymerase chain reaction (PCR) product containing the tenascin B (TNXB) and CYP21A2 genes with TaqI digestion and Southern blot analysis with AseI and NdeI endonuclease digestion of genomic DNA from congenital adrenal hyperplasia patients with common mutations resulting from an intergenic conversion of CYP21A1P, such as an I2 splice, I172N, V281L, F306-L307insT, Q318X, and R356W, and dual mutations of I236N/V237E in the CYP21A2 gene. The results showed that a 3.7-kb fragment of the CYP21A2 gene was detected in each case, and 21.6- and 11.3-kb DNA fragments were found in the RCCX region by a Southern blot analysis with these corresponding mutations. However, the IVS2-12A/C- > G (I2 splice) haplotype in combination with the 707-714delGAGACTAC (without the P30L mutation) mutation produced a 3.2-kb TaqI fragment in the PCR product analysis and a specific 9.3-kb fragment by the Southern blot method. Therefore, we concluded that the rearrangement in the RCCX region resulting from processing of either an intergenic recombination or multiple gene deletions can be identified by the PCR analysis and Southern blot method based on a fragment-distinguishing configuration without a family study. PMID:21117955

  8. Production of L-DOPA and dopamine in recombinant bacteria bearing the Vitreoscilla hemoglobin gene.

    PubMed

    Kurt, Asli Giray; Aytan, Emel; Ozer, Ufuk; Ates, Burhan; Geckil, Hikmet

    2009-07-01

    Given the well-established beneficial effects of Vitreoscilla hemoglobin (VHb) on heterologous organisms, the potential of this protein for the production of L-DOPA and dopamine in two bacteria, Citrobacter freundii and Erwinia herbicola, was investigated. The constructed recombinants bearing the VHb gene (vgb(+)) had substantially higher levels of cytoplasmic L-DOPA (112 mg/L for C. freundii and 97 mg/L for E. herbicola) than their respective hosts (30.4 and 33.8 mg/L) and the vgb(-) control strains (35.6 and 35.8 mg/L). Further, the vgb(+) recombinants of C. freundii and E. herbicola had 20-fold and about two orders of magnitude higher dopamine levels than their hosts, repectively. The activity of tyrosine phenol-lyase, the enzyme converting L-tyrosine to L-DOPA, was well-correlated to cytoplasmic L-DOPA levels. As cultures aged, higher tyrosine phenol-lyase activity of the vgb(+) strains was more apparent. PMID:19585534

  9. Intragenic recombination of a single plant pathogen gene provides a mechanism for the evolution of new host specificities.

    PubMed Central

    Yang, Y; Gabriel, D W

    1995-01-01

    Gene pthA is required for virulence of Xanthomonas citri on citrus plants and has pleiotropic pathogenicity and avirulence functions when transferred to many different xanthomonads. DNA sequencing revealed that pthA belongs to a family of Xanthomonas avirulence/pathogenicity genes characterized by nearly identical 102-bp tandem repeats in the central region. By inserting an nptI-sac cartridge into the tandemly repeated region of pthA as a selective marker, intragenic recombination among homologous repeats was observed in both Xanthomonas spp. and Escherichia coli. Intragenic recombination within pthA created new genes with novel host specificities and altered pathogenicity and/or avirulence phenotypes. Many pthA recombinants gained or lost avirulence function in pathogenicity assays on bean, citrus, and cotton cultivars. Although the ability to induce cell division (hyperplastic cankers) on citrus could be lost, this ability was not acquired on cotton or bean plants. Intragenic recombination therefore provides a genetic mechanism for the generation of multiple, different, and gratuitous avirulence genes from a single, required, host-specific pathogenicity gene. PMID:7665472

  10. [Construction of recombinant adenovirus co-expressing M1 and HA genes of influenza virus type A].

    PubMed

    Guo, Jian-Qiang; Yao, Li-Hong; Chen, Ai-Jun; Xu, Yi; Jia, Run-Qing; Bo, Hong; Dong, Jie; Zhou, Jian-Fang; Shu, Yue-Long; Zhang, Zhi-Qing

    2009-03-01

    Based on the human H5N1 influenza virus strain A/Anhui/1/2005, recombinant adenovirus co-expressing M1 and HA genes of H5N1 influenza virus was constructed using an internal ribosome entry site (IRES) sequence to link the two genes. The M1 and HA genes of H5N1 influenza virus were amplified by PCR and subcloned into pStar vector separately. Then the M1-IRES-HA fragment was amplified and subcloned into pShuttle-CMV vector, the shuttle plasmid was then linearized and transformed into BJ5183 bacteria which contained backbone vector pAd-Easy. The recombinant vector pAd-Easy was packaged in 293 cells to get recombinant adenovirus Ad-M1/HA. CPE was observed after 293 cells were transfected by Ad-M1/HA. The co-expression of M1 and HA genes was confirmed by Western-blot and IFA (immunofluorescence assay). The IRES containing recombinant adenovirus allowed functional co-expression of M1 and HA genes and provided the foundation for developing new influenza vaccines with adenoviral vector. PMID:19678564

  11. Clinical trial design issues raised during recombinant DNA advisory committee review of gene transfer protocols.

    PubMed

    Scharschmidt, Tiffany; Lo, Bernard

    2006-04-01

    Gene transfer clinical trial protocols are reviewed by the Recombinant DNA Advisory Committee (RAC). Identifying the design concerns and suggestions commonly raised during RAC review may help investigators and sponsors shorten the process of protocol development and improve the quality of gene transfer trials. We therefore examined 53 full public reviews of gene transfer clinical trial protocols performed by the RAC between December 2000 and June 2004 to determine what trial design concerns or suggestions RAC members raised during written review or public discussion or in the formal letter to investigators after the review was completed. We also determined how frequently these concerns were raised. We found that RAC members raised issues regarding selection of subjects in 89% of reviews, dose escalation in 77%, selection of safety end points in 76%, biological activity measures in 66%, and overall design in 60% of reviews. The most common issue raised by RAC reviewers was the need to exclude subjects at increased risk for adverse events. Furthermore, in 89% of reviews, at least one design issue pertaining to safety of participants was raised. In 91% of reviews, at least one design concern was presented as a written RAC recommendation or concern to the investigator after the public review. When submitting protocols for RAC review, investigators and sponsors might devote more attention to issues that RAC reviewers commonly raise. Such attention might help strengthen clinical trial protocols, shorten the protocol development process, and enhance the protection of research participants. PMID:16610932

  12. Expression of a foreign gene by recombinant canine distemper virus recovered from cloned DNAs.

    PubMed

    Parks, Christopher L; Wang, Hai-Ping; Kovacs, Gerald R; Vasilakis, Nikos; Kowalski, Jacek; Nowak, Rebecca M; Lerch, Robert A; Walpita, Pramila; Sidhu, Mohinderjit S; Udem, Stephen A

    2002-02-26

    A canine distemper virus (CDV) genomic cDNA clone and expression plasmids required to establish a CDV rescue system were generated from a laboratory-adapted strain of the Onderstepoort vaccine virus. In addition, a CDV minireplicon was prepared and used in transient expression studies performed to identify optimal virus rescue conditions. Results from the transient expression experiments indicated that minireplicon-encoded reporter gene activity was increased when transfected cell cultures were maintained at 32 rather than 37 degrees C, and when the cellular stress response was induced by heat shock. Applying these findings to rescue of recombinant CDV (rCDV) resulted in efficient recovery of virus after transfected HEp2 or A549 cells were co-cultured with Vero cell monolayers. Nucleotide sequence determination and analysis of restriction site polymorphisms confirmed that rescued virus was rCDV. A rCDV strain also was engineered that contained the luciferase gene inserted between the P and M genes; this virus directed high levels of luciferase expression in infected cells. PMID:11864746

  13. Genetic engineering and heterologous expression of the disorazol biosynthetic gene cluster via Red/ET recombineering.

    PubMed

    Tu, Qiang; Herrmann, Jennifer; Hu, Shengbiao; Raju, Ritesh; Bian, Xiaoying; Zhang, Youming; Müller, Rolf

    2016-01-01

    Disorazol, a macrocyclic polykitide produced by the myxobacterium Sorangium cellulosum So ce12 and it is reported to have potential cytotoxic activity towards several cancer cell lines, including multi-drug resistant cells. The disorazol biosynthetic gene cluster (dis) from Sorangium cellulosum (So ce12) was identified by transposon mutagenesis and cloned in a bacterial artificial chromosome (BAC) library. The 58-kb dis core gene cluster was reconstituted from BACs via Red/ET recombineering and expressed in Myxococcus xanthus DK1622. For the first time ever, a myxobacterial trans-AT polyketide synthase has been expressed heterologously in this study. Expression in M. xanthus allowed us to optimize the yield of several biosynthetic products using promoter engineering. The insertion of an artificial synthetic promoter upstream of the disD gene encoding a discrete acyl transferase (AT), together with an oxidoreductase (Or), resulted in 7-fold increase in disorazol production. The successful reconstitution and expression of the genetic sequences encoding for these promising cytotoxic compounds will allow combinatorial biosynthesis to generate novel disorazol derivatives for further bioactivity evaluation. PMID:26875499

  14. Genetic engineering and heterologous expression of the disorazol biosynthetic gene cluster via Red/ET recombineering

    PubMed Central

    Tu, Qiang; Herrmann, Jennifer; Hu, Shengbiao; Raju, Ritesh; Bian, Xiaoying; Zhang, Youming; Müller, Rolf

    2016-01-01

    Disorazol, a macrocyclic polykitide produced by the myxobacterium Sorangium cellulosum So ce12 and it is reported to have potential cytotoxic activity towards several cancer cell lines, including multi-drug resistant cells. The disorazol biosynthetic gene cluster (dis) from Sorangium cellulosum (So ce12) was identified by transposon mutagenesis and cloned in a bacterial artificial chromosome (BAC) library. The 58-kb dis core gene cluster was reconstituted from BACs via Red/ET recombineering and expressed in Myxococcus xanthus DK1622. For the first time ever, a myxobacterial trans-AT polyketide synthase has been expressed heterologously in this study. Expression in M. xanthus allowed us to optimize the yield of several biosynthetic products using promoter engineering. The insertion of an artificial synthetic promoter upstream of the disD gene encoding a discrete acyl transferase (AT), together with an oxidoreductase (Or), resulted in 7-fold increase in disorazol production. The successful reconstitution and expression of the genetic sequences encoding for these promising cytotoxic compounds will allow combinatorial biosynthesis to generate novel disorazol derivatives for further bioactivity evaluation. PMID:26875499

  15. Role of Schizosaccharomyces pombe RecQ homolog, recombination, and checkpoint genes in UV damage tolerance.

    PubMed Central

    Murray, J M; Lindsay, H D; Munday, C A; Carr, A M

    1997-01-01

    The cellular responses to DNA damage are complex and include direct DNA repair pathways that remove the damage and indirect damage responses which allow cells to survive DNA damage that has not been, or cannot be, removed. We have identified the gene mutated in the rad12.502 strain as a Schizosaccharomyces pombe recQ homolog. The same gene (designated rqh1) is also mutated in the hus2.22 mutant. We show that Rqhl is involved in a DNA damage survival mechanism which prevents cell death when UV-induced DNA damage cannot be removed. This pathway also requires the correct functioning of the recombination machinery and the six checkpoint rad gene products plus the Cdsl kinase. Our data suggest that Rqh1 operates during S phase as part of a mechanism which prevents DNA damage causing cell lethality. This process may involve the bypass of DNA damage sites by the replication fork. Finally, in contrast with the reported literature, we do not find that rqh1 (rad12) mutant cells are defective in UV dimer endonuclease activity. PMID:9372918

  16. Intrinsic biocontainment: Multiplex genome safeguards combine transcriptional and recombinational control of essential yeast genes

    PubMed Central

    Cai, Yizhi; Agmon, Neta; Choi, Woo Jin; Ubide, Alba; Stracquadanio, Giovanni; Caravelli, Katrina; Hao, Haiping; Bader, Joel S.; Boeke, Jef D.

    2015-01-01

    Biocontainment may be required in a wide variety of situations such as work with pathogens, field release applications of engineered organisms, and protection of intellectual properties. Here, we describe the control of growth of the brewer’s yeast, Saccharomyces cerevisiae, using both transcriptional and recombinational “safeguard” control of essential gene function. Practical biocontainment strategies dependent on the presence of small molecules require them to be active at very low concentrations, rendering them inexpensive and difficult to detect. Histone genes were controlled by an inducible promoter and controlled by 30 nM estradiol. The stability of the engineered genes was separately regulated by the expression of a site-specific recombinase. The combined frequency of generating viable derivatives when both systems were active was below detection (<10−10), consistent with their orthogonal nature and the individual escape frequencies of <10−6. Evaluation of escaper mutants suggests strategies for reducing their emergence. Transcript profiling and growth test suggest high fitness of safeguarded strains, an important characteristic for wide acceptance. PMID:25624482

  17. Coupling the CRISPR/Cas9 System with Lambda Red Recombineering Enables Simplified Chromosomal Gene Replacement in Escherichia coli.

    PubMed

    Pyne, Michael E; Moo-Young, Murray; Chung, Duane A; Chou, C Perry

    2015-08-01

    To date, most genetic engineering approaches coupling the type II Streptococcus pyogenes clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9 system to lambda Red recombineering have involved minor single nucleotide mutations. Here we show that procedures for carrying out more complex chromosomal gene replacements in Escherichia coli can be substantially enhanced through implementation of CRISPR/Cas9 genome editing. We developed a three-plasmid approach that allows not only highly efficient recombination of short single-stranded oligonucleotides but also replacement of multigene chromosomal stretches of DNA with large PCR products. By systematically challenging the proposed system with respect to the magnitude of chromosomal deletion and size of DNA insertion, we demonstrated DNA deletions of up to 19.4 kb, encompassing 19 nonessential chromosomal genes, and insertion of up to 3 kb of heterologous DNA with recombination efficiencies permitting mutant detection by colony PCR screening. Since CRISPR/Cas9-coupled recombineering does not rely on the use of chromosome-encoded antibiotic resistance, or flippase recombination for antibiotic marker recycling, our approach is simpler, less labor-intensive, and allows efficient production of gene replacement mutants that are both markerless and "scar"-less. PMID:26002895

  18. Overproduction of polygalacturonase by Penicillium griseoroseum recombinant strains and functional analysis by targeted disruption of the pgg2 gene.

    PubMed

    Teixeira, Janaina Aparecida; Ribeiro, João Batista; Gonçalves, Daniel Bonoto; de Queiroz, Marisa Vieira; de Araújo, Elza Fernandes

    2013-03-01

    Inactivation of the pgg2 gene, a polygalacturonase-encoding gene from Penicillium griseoroseum, reduced the total activity of polygalacturonase (PG) by 90 % in wild-type P. griseoroseum, which indicates that the pgg2 gene is the major gene responsible for PG production in this species. To increase PG production, the coding region of the pgg2 gene was cloned under the control of the glyceraldehyde 3-phosphate dehydrogenase (gpd) promoter and the terminator region of the tryptophan synthase (trpC) gene from Aspergillus nidulans (pAN52pgg2 vector). This vector was then used to transform P. griseoroseum. The transformed strains were characterized according to PG production using glucose, sucrose, or sugar cane juice as the carbon sources. The recombinant P. griseoroseum T146 strain contained an additional copy of the pgg2 gene, which resulted in a 12-fold increase in PG activity when compared with that detected in the supernatant of the control PG63 strain. The proteins secreted by the recombinant strain T146 showed a strong band at 38 kDa, which corresponds to the molecular weight of PG of the P. griseoroseum. The results demonstrate the significant biotechnological potential of recombinant P. griseoroseum T146 for use in PG production. PMID:23354503

  19. High recombination between two physically close human basement membrane collagen genes at the distal end of chromosome 13q.

    PubMed Central

    Bowcock, A M; Hebert, J M; Wijsman, E; Gadi, I; Cavalli-Sforza, L L; Boyd, C D

    1988-01-01

    Two basement membrane collagen genes coding for the pro alpha 1 chain and pro alpha 2 chain of type IV collagen map to 13q34 and are linked with a maximum likelihood estimate of recombination of 0.028 at a logarithm of odds (lod) score of 19.98. The single-copy sequence that identifies the locus D13S3 is also closely linked to both collagen genes. Four enzymes reveal polymorphisms with COL4A1, and 10 haplotypes have been observed in Caucasoids. Within COL4A1 a nonrandom association of alleles exists only between alleles defined by Hae III and those defined by the other three enzymes. A random association of alleles of COL4A1 and COL4A2 is observed. Between the two collagen genes were detected three meiotic recombination events that contributed to the estimate of 2.8% recombination. This is higher than expected for two genes that lie within 650 kilobases of each other. The lack of linkage disequilibrium between COL4A1 and COL4A2 is in agreement with the relatively high recombination that is observed. Images PMID:2895928

  20. Molecular mapping of four blast resistance genes using recombinant inbred lines of 93-11 and nipponbare

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Molecular mapping of new blast resistance genes is important for developing resistant rice cultivars using marker-assisted selection. In this study, 259 recombinant inbred lines (RILs) were developed from a cross between Nipponbare and 93-11, and were used to construct a 1165.8-cM linkage map with 1...

  1. Recombinative events of the T cell antigen receptor delta gene in peripheral T cell lymphomas.

    PubMed Central

    Kanavaros, P; Farcet, J P; Gaulard, P; Haioun, C; Divine, M; Le Couedic, J P; Lefranc, M P; Reyes, F

    1991-01-01

    Recombinative events of the T cell antigen receptor (TCR) delta-chain gene were studied in 37 cases of peripheral T cell lymphoma (PTCL) and related to their clinical presentation and the expression of the alpha beta or gamma delta heterodimers as determined by immunostaining of frozen tissue samples. There were 22 cases of alpha beta, 5 cases of gamma delta, and 10 cases of silent TCR expressing neither the alpha beta nor gamma delta TCR. 5 different probes were used to examine the delta locus. The 22 cases of alpha beta PTCL displayed biallelic and monoallelic deletions; a monoallelic V delta 1 J delta 1 rearrangement was observed in 1 case and a monoallelic germ line configuration in 7 cases. The 5 cases of gamma delta PTCL displayed biallelic rearrangements: the productive rearrangements could be ascribed to V delta 1J delta 1 joining in 3 cases and VJ delta 1 joining in 2 cases according to the combined pattern of DNA hybridization with the appropriate probes and of cell reactivity with the TCR delta-1, delta TCS-1, and anti-V delta 2 monoclonal antibodies. In the VJ delta 1 joining, the rearranged V segments were located between V delta 1 and V delta 2. Interestingly, in the third group of 10 cases of silent PTCL, 5 cases were found to have a TCR gene configuration identical to that in the TCR alpha beta PTCL, as demonstrated by biallelic delta gene deletion. These 5 cases were CD3 positive. The 5 remaining cases showed a monoallelic delta gene rearrangement with a monoallelic germ line configuration in 4 and a monoallelic deletion in 1. Four of these cases were CD3 negative, which was consistent with an immature genotype the TCR commitent of which could not be ascertained. Finally, TCR gamma delta PTCL consisted of a distinct clinical morphological and molecular entity whereas TCR alpha beta and silent PTCL had a similar presentation. Images PMID:1991851

  2. Analysis of Two Lysozyme Genes and Antimicrobial Functions of Their Recombinant Proteins in Asian Seabass

    PubMed Central

    Fu, Gui Hong; Bai, Zhi Yi; Xia, Jun Hong; Liu, Feng; Liu, Peng; Yue, Gen Hua

    2013-01-01

    Lysozymes are important proteins of the innate immune system for the defense against bacterial infection. We cloned and analyzed chicken-type (c-type) and goose-type (g-type) lysozymes from Asian seabass (Lates calcarifer). The deduced amino acid sequence of the c-type lysozyme contained 144 residues and possessed typical structure residues, conserved catalytic residues (Glu50 and Asp67) and a “GSTDYGIFQINS” motif. The deduced g-type lysozyme contained 187 residues and possessed a goose egg white lysozyme (GEWL) domain containing three conserved catalytic residues (Glu71, Asp84, Asp95) essential for catalytic activity. Real time quantitative PCR (qRT-PCR) revealed that the two lysozyme genes were constitutively expressed in all the examined tissues. The c-type lysozyme was most abundant in liver, while the g-type lysozyme was predominantly expressed in intestine and weakly expressed in muscle. The c-type and g-type transcripts were up-regulated in the kidney, spleen and liver in response to a challenge with Vibrio harveyi. The up-regulation of the c-type lysozyme was much stronger than that of the g-type lysozyme in kidney and spleen. The recombinant proteins of the c-type and g-type lysozymes showed lytic activities against the bacterial pathogens Vibrio harveyi and Photobacterium damselae in a dosage-dependent manner. We identified single nucleotide polymorphisms (SNPs) in the two lysozyme genes. There were significant associations of these polymorphisms with resistance to the big belly disease. These results suggest that the c- and g-type genes play an important role in resistance to bacterial pathogens in fish. The SNP markers in the two genes associated with the resistance to bacterial pathogens may facilitate the selection of Asian seabass resistant to bacterial diseases. PMID:24244553

  3. Recent stable insertion of mitochondrial DNA into an Arabidopsis polyubiquitin gene by nonhomologous recombination.

    PubMed

    Sun, C W; Callis, J

    1993-01-01

    Sequence analysis of a newly identified polyubiquitin gene (UBQ13) from the Columbia ecotype of Arabidopsis thaliana revealed that the gene contained a 3.9-kb insertion in the coding region. All subclones of the 3.9-kb insert hybridized to isolated mitochondrial DNA. The insert was found to consist of at least two, possibly three, distinct DNA segments from the mitochondrial genome. A 590-bp region of the insert is nearly identical to the Arabidopsis mitochondrial nad1 gene. UBQ13 restriction fragments in total cellular DNA from ecotypes Ler, No-0, Be-0, WS, and RLD were identified and, with the exception of Be-0, their sizes were equivalent to that predicted from the corresponding ecotype Columbia UBQ13 restriction fragment without the mitochondrial insert. Isolation by polymerase chain reaction and sequence determination of UBQ13 sequences from the other ecotypes showed that all lacked the mitochondrial insert. All ecotypes examined, except Columbia, contain intact open reading frames in the region of the insert, including four ubiquitin codons which Columbia lacks. This indicates that the mitochondrial DNA in UBQ13 in ecotype Columbia is the result of an integration event that occurred after speciation of Arabidopsis rather than a deletion event that occurred in all ecotypes except Columbia. This stable movement of mitochondrial DNA to the nucleus is so recent that there are few nucleotide changes subsequent to the transfer event. This allows for precise analysis of the sequences involved and elucidation of the possible mechanism. The presence of intron sequences in the transferred nucleic acid indicates that DNA was the transfer intermediate. The lack of sequence identity between the integrating sequence and the target site, represented by the other Arabidopsis ecotypes, suggests that integration occurred via nonhomologus recombination. This nuclear/organellar gene transfer event is strikingly similar to the experimentally accessible process of nuclear

  4. Genealogy-Based Methods for Inference of Historical Recombination and Gene Flow and Their Application in Saccharomyces cerevisiae

    PubMed Central

    Jenkins, Paul A.; Song, Yun S.; Brem, Rachel B.

    2012-01-01

    Genetic exchange between isolated populations, or introgression between species, serves as a key source of novel genetic material on which natural selection can act. While detecting historical gene flow from DNA sequence data is of much interest, many existing methods can be limited by requirements for deep population genomic sampling. In this paper, we develop a scalable genealogy-based method to detect candidate signatures of gene flow into a given population when the source of the alleles is unknown. Our method does not require sequenced samples from the source population, provided that the alleles have not reached fixation in the sampled recipient population. The method utilizes recent advances in algorithms for the efficient reconstruction of ancestral recombination graphs, which encode genealogical histories of DNA sequence data at each site, and is capable of detecting the signatures of gene flow whose footprints are of length up to single genes. Further, we employ a theoretical framework based on coalescent theory to test for statistical significance of certain recombination patterns consistent with gene flow from divergent sources. Implementing these methods for application to whole-genome sequences of environmental yeast isolates, we illustrate the power of our approach to highlight loci with unusual recombination histories. By developing innovative theory and methods to analyze signatures of gene flow from population sequence data, our work establishes a foundation for the continued study of introgression and its evolutionary relevance. PMID:23226196

  5. Efficient gene delivery to the inflamed colon by local administration of recombinant adenoviruses with normal or modified fibre structure

    PubMed Central

    Wirtz, S; Galle, P; Neurath, M

    1999-01-01

    BACKGROUND/AIMS—Replication deficient recombinant adenoviruses represent an efficient means of transferring genes in vivo into a wide variety of dividing and quiescent cells from many different organs. Although the gastrointestinal tract is a potentially attractive target for gene therapy approaches, only a few studies on the use of viral gene transfer vehicles in the gut have been reported. The prospects of using recombinant adenoviruses for gene delivery into epithelial and subepithelial cells of the normal and inflamed colon are here analysed.
METHODS—An E1/E3 deleted recombinant adenovirus (denoted AdCMVβGal) and an adenovirus with modified fibre structure (denoted AdZ.F(pk7)) both expressing the bacterial lacZ gene under the control of a human cytomegalovirus promoter were used for reporter gene expression in vitro and in vivo. β-Galactosidase activity was determined by specific chemiluminescent reporter gene assay.
RESULTS—Intravenous or intraperitoneal injection of AdCMVβGal into healthy Balb/c mice caused strong reporter gene expression in the liver and spleen but not in the colon. In contrast, local administration of AdCMVβGal resulted in high reporter gene expression in colonic epithelial cells and lamina propria mononuclear cells. A local route of adenovirus administration in mice with experimental colitis induced by the hapten reagent trinitrobenzenesulphonic acid was next evaluated. Interestingly, rectal administration of AdCMVβGal caused a higher β-galactosidase activity in isolated lamina propria cells from infected mice with experimental colitis than in those from controls. Furthermore, isolated lamina propria cells from mice with colitis infected in vitro showed a significant increase in reporter gene activity compared with controls. Finally, AdZ.F(pk7) adenoviruses with modified fibre structure produced 10- to 40-fold higher reporter gene activity in spleen T cells and lamina propria mononuclear cells of colitic mice compared with

  6. Inhibition of tumor angiogenesis by angiostatin: from recombinant protein to gene therapy.

    PubMed

    Dell'Eva, Raffaella; Pfeffer, Ulrich; Indraccolo, S; Albini, Adriana; Noonan, Douglas

    2002-01-01

    Tumor growth, local invasion, and metastatic dissemination are dependent on the formation of new microvessels. The process of angiogenesis is regulated by a balance between pro-angiogenic and anti-angiogenic factors, and the shift to an angiogenic phenotype (the "angiogenic switch") is a key event in tumor progression. The use of anti-angiogenic agents to restore this balance represents a promising approach to cancer treatment. Known physiological inhibitors include trombospondin, several interleukins, and the proteolytic break-down products of several proteins. Angiostatin, an internal fragment of plasminogen, is one of the more potent of this latter class of angiogenesis inhibitors. Like endostatin, another anti-angiogenic peptide derived from collagen XVIII, angiostatin can induce tumor vasculature regression, leading to a complete cessation of tumor growth. Inhibitors of angiogenesis target normal endothelial cells, therefore the development of resistance to these drugs is unlikely. The efficacy of angiostatin has been demonstrated in animal models for many different types of solid tumors. Anti-angiogenic cancer therapy with angiostatin requires prolonged administration of the peptide. The production of the functional polypeptides is expensive and technical problems related to physical properties and purity are frequently encountered. Gene transfer represents an alternative method to deliver angiostatin. Gene therapy has the potential to produce the therapeutic agent in high concentrations in a local area for a sustained period, thereby avoiding the problems encountered with long-term administration of recombinant proteins, monoclonal antibodies, or anti-angiogenic drugs. In this review we compare the different gene therapy strategies that have been applied to angiostatin, with special regard to their ability to provide sufficient angiostatin at the target site. PMID:12901356

  7. Genetic analysis of a novel human adenovirus with a serologically unique hexon and a recombinant fiber gene.

    PubMed

    Liu, Elizabeth B; Ferreyra, Leonardo; Fischer, Stephen L; Pavan, Jorge V; Nates, Silvia V; Hudson, Nolan Ryan; Tirado, Damaris; Dyer, David W; Chodosh, James; Seto, Donald; Jones, Morris S

    2011-01-01

    In February of 1996 a human adenovirus (formerly known as Ad-Cor-96-487) was isolated from the stool of an AIDS patient who presented with severe chronic diarrhea. To characterize this apparently novel pathogen of potential public health significance, the complete genome of this adenovirus was sequenced to elucidate its origin. Bioinformatic and phylogenetic analyses of this genome demonstrate that this virus, heretofore referred to as HAdV-D58, contains a novel hexon gene as well as a recombinant fiber gene. In addition, serological analysis demonstrated that HAdV-D58 has a different neutralization profile than all previously characterized HAdVs. Bootscan analysis of the HAdV-D58 fiber gene strongly suggests one recombination event. PMID:21915339

  8. Method for concentrating and purifying recombinant autonomous parvovirus vectors designed for tumour-cell-targeted gene therapy.

    PubMed

    Avalosse, B; Dupont, F; Spegelaere, P; Mine, N; Burny, A

    1996-12-01

    Recent work has highlighted the use of parvoviruses as potential vectors for tumour-cell-targeted gene therapy. The oncotropic properties of the prototype strain of minute virus of mice (MVMp) suggest that this virus might be a useful vehicle for introducing selectively therapeutic genes, e.g. lymphokine or suicide genes, into tumour cells and preferentially expressing them. But the low titre of recombinant virus stocks (10(5)-10(6) infectious units per ml) and their high level of contamination by cell proteins make it practically impossible to evaluate their efficacy in in vivo systems. A technique is described for producing cellular contaminant-free stocks of recombinant virus particles, with titres up to 5 x 10(8) IU/ml. PMID:9002076

  9. Chloroplast-targeted expression of recombinant crystal-protein gene in cotton: an unconventional combat with resistant pests.

    PubMed

    Kiani, Sarfraz; Mohamed, Bahaeldeen Babiker; Shehzad, Kamran; Jamal, Adil; Shahid, Muhammad Naveed; Shahid, Ahmad Ali; Husnain, Tayyab

    2013-07-10

    Plants transformed with single Bt gene are liable to develop insect resistance and this has already been reported in a number of studies carried out around the world where Bt cotton was cultivated on commercial scale. Later, it was envisaged to transform plants with more than one Bt genes in order to combat with resistant larvae. This approach seems valid as various Bt genes possess different binding domains which could delay the likely hazards of insect resistance against a particular Bt toxin. But it is difficult under field conditions to develop homozygous plants expressing all Bt genes equally after many generations without undergoing recombination effects. A number of researches claiming to transform plants from three to seven transgenes in a single plant were reported during the last decade but none has yet applied for patent of homozygous transgenic lines. A better strategy might be to use hybrid-Bt gene(s) modified for improved lectin-binding domains to boost Bt receptor sites in insect midgut. These recombinant-Bt gene(s) would express different lectin domains in a single polypeptide and it is relatively easy to develop homozygous transgenic lines under field conditions. Enhanced chloroplast-localized expression of hybrid-Bt gene would leave no room for insects to develop resistance. We devised and successfully applied this strategy in cotton (Gossypium hirsutum) and data up to T3 generation showed that our transgenic cotton plants were displaying enhanced chloroplast-targeted Cry1Ac-RB expression. Laboratory and field bioassays gave promising results against American bollworm (Heliothis armigera), pink bollworm (Pictinophora scutigera) and fall armyworm (Spodoptera frugiperda) that otherwise, were reported to have evolved resistance against Cry1Ac toxin. Elevated levels of hybrid-Bt toxin were confirmed by ELISA of chloroplast-enriched protein samples extracted from leaves of transgenic cotton lines. While, localization of recombinant Cry1Ac-RB protein in

  10. A homologue of the recombination-dependent growth gene, rdgC, is involved in gonococcal pilin antigenic variation.

    PubMed Central

    Mehr, I J; Long, C D; Serkin, C D; Seifert, H S

    2000-01-01

    Neisseria gonorrhoeae pilin undergoes high-frequency changes in primary amino acid sequence that aid in the avoidance of the host immune response and alter pilus expression. The pilin amino acid changes reflect nucleotide changes in the expressed gene, pilE, which result from nonreciprocal recombination reactions with numerous silent loci, pilS. A series of mini-transposon insertions affecting pilin antigenic variation were localized to three genes in one region of the Gc chromosome. Mutational analysis with complementation showed that a Gc gene with sequence similarity to the Escherichia coli rdgC gene is involved in pilus-dependent colony phase variation and in pilin antigenic variation. Furthermore, we show that the Gc rdgC homologue is transcriptionally linked in an operon with a gene encoding a predicted GTPase. The inability to disrupt expression of this gene suggests it is an essential gene (engA, essential neisserial GTPase). While some of the transposon mutations in rdgC and insertions in the 5'-untranslated portion of engA showed a growth defect, all transposon insertions investigated conferred an aberrant cellular morphology. Complementation analysis showed that the growth deficiencies are due to the interruption of RdgC expression and not that of EngA. The requirement of RdgC for efficient pilin variation suggests a role for this protein in specialized DNA recombination reactions. PMID:10655208

  11. A single Argonaute gene is required for induction of RNA silencing antiviral defense and promotes viral RNA recombination.

    PubMed

    Sun, Qihong; Choi, Gil H; Nuss, Donald L

    2009-10-20

    Dicer gene dcl2, required for the RNA silencing antiviral defense response in the chestnut blight fungus Cryphonectria parasitica, is inducible upon mycovirus infection and promotes viral RNA recombination. We now report that the antiviral defense response requires only one of the four C. parasitica Argonaute-like protein genes, agl2. The agl2 gene is required for the virus-induced increase in dcl2 transcript accumulation. Agl2 and dcl2 transcripts accumulated to much higher levels in response to hairpin RNA production or infection by a mutant CHV1-EP713 hypovirus lacking the suppressor of RNA silencing p29 than to wild-type CHV1-EP713. Similar results were obtained for an agl2-promoter/EGFP-reporter construct, indicating that p29-mediated repression of agl2 transcript accumulation is promoter-dependent. Significantly, the agl2 deletion mutant exhibited stable maintenance of non-viral sequences in recombinant hypovirus RNA virus vectors and the absence of hypovirus-defective interfering (DI) RNA production. These results establish a key role for an Argonaute gene in the induction of an RNA silencing antiviral defense response and the promotion of viral RNA recombination. They also provide evidence for a mechanism by which a virus-encoded RNA silencing suppressor represses the transcriptional induction of an RNA silencing component. PMID:19822766

  12. Irradiated esophageal cells are protected from radiation-induced recombination by MnSOD gene therapy.

    PubMed

    Niu, Yunyun; Wang, Hong; Wiktor-Brown, Dominika; Rugo, Rebecca; Shen, Hongmei; Huq, M Saiful; Engelward, Bevin; Epperly, Michael; Greenberger, Joel S

    2010-04-01

    Radiation-induced DNA damage is a precursor to mutagenesis and cytotoxicity. During radiotherapy, exposure of healthy tissues can lead to severe side effects. We explored the potential of mitochondrial SOD (MnSOD) gene therapy to protect esophageal, pancreatic and bone marrow cells from radiation-induced genomic instability. Specifically, we measured the frequency of homologous recombination (HR) at an integrated transgene in the Fluorescent Yellow Direct Repeat (FYDR) mice, in which an HR event can give rise to a fluorescent signal. Mitochondrial SOD plasmid/liposome complex (MnSOD-PL) was administered to esophageal cells 24 h prior to 29 Gy upper-body irradiation. Single cell suspensions from FYDR, positive control FYDR-REC, and negative control C57BL/6NHsd (wild-type) mouse esophagus, pancreas and bone marrow were evaluated by flow cytometry. Radiation induced a statistically significant increase in HR 7 days after irradiation compared to unirradiated FYDR mice. MnSOD-PL significantly reduced the induction of HR by radiation at day 7 and also reduced the level of HR in the pancreas. Irradiation of the femur and tibial marrow with 8 Gy also induced a significant increase in HR at 7 days. Radioprotection by intraesophageal administration of MnSOD-PL was correlated with a reduced level of radiation-induced HR in esophageal cells. These results demonstrate the efficacy of MnSOD-PL for suppressing radiation-induced HR in vivo. PMID:20334517

  13. Precision control of recombinant gene transcription for CHO cell synthetic biology.

    PubMed

    Brown, Adam J; James, David C

    2016-01-01

    The next generation of mammalian cell factories for biopharmaceutical production will be genetically engineered to possess both generic and product-specific manufacturing capabilities that may not exist naturally. Introduction of entirely new combinations of synthetic functions (e.g. novel metabolic or stress-response pathways), and retro-engineering of existing functional cell modules will drive disruptive change in cellular manufacturing performance. However, before we can apply the core concepts underpinning synthetic biology (design, build, test) to CHO cell engineering we must first develop practical and robust enabling technologies. Fundamentally, we will require the ability to precisely control the relative stoichiometry of numerous functional components we simultaneously introduce into the host cell factory. In this review we discuss how this can be achieved by design of engineered promoters that enable concerted control of recombinant gene transcription. We describe the specific mechanisms of transcriptional regulation that affect promoter function during bioproduction processes, and detail the highly-specific promoter design criteria that are required in the context of CHO cell engineering. The relative applicability of diverse promoter development strategies are discussed, including re-engineering of natural sequences, design of synthetic transcription factor-based systems, and construction of synthetic promoters. This review highlights the potential of promoter engineering to achieve precision transcriptional control for CHO cell synthetic biology. PMID:26721629

  14. Tissue-engineered human bioartificial muscles expressing a foreign recombinant protein for gene therapy

    NASA Technical Reports Server (NTRS)

    Powell, C.; Shansky, J.; Del Tatto, M.; Forman, D. E.; Hennessey, J.; Sullivan, K.; Zielinski, B. A.; Vandenburgh, H. H.

    1999-01-01

    Murine skeletal muscle cells transduced with foreign genes and tissue engineered in vitro into bioartificial muscles (BAMs) are capable of long-term delivery of soluble growth factors when implanted into syngeneic mice (Vandenburgh et al., 1996b). With the goal of developing a therapeutic cell-based protein delivery system for humans, similar genetic tissue-engineering techniques were designed for human skeletal muscle stem cells. Stem cell myoblasts were isolated, cloned, and expanded in vitro from biopsied healthy adult (mean age, 42 +/- 2 years), and elderly congestive heart failure patient (mean age, 76 +/- 1 years) skeletal muscle. Total cell yield varied widely between biopsies (50 to 672 per 100 mg of tissue, N = 10), but was not significantly different between the two patient groups. Percent myoblasts per biopsy (73 +/- 6%), number of myoblast doublings prior to senescence in vitro (37 +/- 2), and myoblast doubling time (27 +/- 1 hr) were also not significantly different between the two patient groups. Fusion kinetics of the myoblasts were similar for the two groups after 20-22 doublings (74 +/- 2% myoblast fusion) when the biopsy samples had been expanded to 1 to 2 billion muscle cells, a number acceptable for human gene therapy use. The myoblasts from the two groups could be equally transduced ex vivo with replication-deficient retroviral expression vectors to secrete 0.5 to 2 microg of a foreign protein (recombinant human growth hormone, rhGH)/10(6) cells/day, and tissue engineered into human BAMs containing parallel arrays of differentiated, postmitotic myofibers. This work suggests that autologous human skeletal myoblasts from a potential patient population can be isolated, genetically modified to secrete foreign proteins, and tissue engineered into implantable living protein secretory devices for therapeutic use.

  15. Biased Gene Conversion in Rhizobium etli Is Caused by Preferential Double-Strand Breaks on One of the Recombining Homologs

    PubMed Central

    Yáñez-Cuna, Fares Osam; Castellanos, Mildred

    2015-01-01

    ABSTRACT Gene conversion, the nonreciprocal transfer of information during homologous recombination, is the main process that maintains identity between members of multigene families. Gene conversion in the nitrogenase (nifH) multigene family of Rhizobium etli was analyzed by using a two-plasmid system, where each plasmid carried a copy of nifH. One of the nifH copies was modified, creating restriction fragment length polymorphisms (RFLPs) spaced along the gene. Once the modified plasmid was introduced into R. etli, selection was done for cointegration with a resident plasmid lacking the RFLPs. Most of the cointegrate molecules harbor gene conversion events, biased toward a gain of RFLPs. This bias may be explained under the double-strand break repair model by proposing that the nifH gene lacking the RFLPs suffers a DNA double-strand break, so the incoming plasmid functions as a template for repairing the homolog on the resident plasmid. To support this proposal, we cloned an SceI site into the nifH homolog that had the RFLPs used for scoring gene conversion. In vivo expression of the meganuclease I-SceI allowed the generation of a double-strand break on this homolog. Upon introduction of this modified plasmid into an R. etli strain lacking I-SceI, biased gene conversion still favored the retention of markers on the incoming plasmid. In contrast, when the recipient strain ectopically expressed I-SceI, a dramatic reversal in gene conversion bias was seen, favoring the preservation of resident sequences. These results show that biased gene conversion is caused by preferential double-strand breaks on one of the recombining homologs. IMPORTANCE In this work, we analyzed gene conversion by using a system that entails horizontal gene transfer followed by homologous recombination in the recipient cell. Most gene conversion events are biased toward the acquisition of the incoming sequences, ranging in size from 120 bp to 800 bp. This bias is due to preferential cutting of

  16. In vivo and in vitro genetic recombination between conventional and gene-deleted vaccine strains of pseudorabies virus.

    PubMed

    Henderson, L M; Katz, J B; Erickson, G A; Mayfield, J E

    1990-10-01

    Pseudorabies virus (PRV), an alpha-herpesvirus, causes substantial economic losses in the swine industry and is currently the focus of eradication and control programs. Some of these programs rely on the ability of veterinarians to differentiate animals exposed to virulent strains of PRV from animals exposed to avirulent vaccine strains of PRV on the basis of a serologic response to nonessential glycoproteins that are deleted in some vaccine strains of PRV. Genetic recombination resulting in the creation of virulent strains of PRV with the same negative immunologic markers as vaccine strains could disrupt these programs. Two strains of PRV were coinoculated either into tissue culture or into sheep to facilitate recombination. Progeny viruses were selected to detect a specific recombinant phenotype. We were able to detect genetic recombination between vaccine strains of PRV following in vitro or in vivo coinoculation of 2 strains of PRV. The selected recombinants had marker-deleted phenotypes in strains with restored virulence genes. Increased virulence was observed in sheep after coinoculation of 2 avirulent vaccine strains of PRV. PMID:2173449

  17. Construction and characterization of the recombinant Moloney murine leukemia viruses bearing the mouse Fv-4 env gene.

    PubMed Central

    Masuda, M; Yoshikura, H

    1990-01-01

    A nucleotide sequence of the mouse Fv-4 env gene was completed. Structural comparison revealed a close relationship of Fv-4 to the ecotropic Cas-Br-E murine leukemia virus isolated from a wild mouse in southern California. Various portions of the env gene of Moloney murine leukemia virus were replaced by the corresponding Fv-4 env sequence to construct recombinant murine leukemia virus clones. Infectivity of these recombinants was checked by the S+L- cell focus induction assay and the XC cell syncytium formation assay. Recombinants bearing the following Fv-4 env sequence retained ecotropic infectivity; the AccI-BamHI and BamHI-BalI regions coding for the N- and C-terminal halves of Fv-4 gp70SU, respectively; and the BalI-NcoI region encoding the cleavage site between gp70SU and p15(E)TM of the Fv-4 env. However, when the Fv-4 sequence was substituted for the p15(E)TM-coding NcoI-EcoRV region or the AccI-EcoRV region covering almost the entire env gene, infectivity was undetectable in our assays. The recombinant clone containing the Fv-4 AccI-EcoRV region, i.e., almost the entire Fv-4 env sequence, was introduced with pSV2neo into NIH 3T3 cells, and a G418r cell line named NIH(Fv4)-2 was isolated. The NIH(Fv4)-2 cell released viral particles that contained reverse transcriptase, Fv-4 env molecules as well as the other viral proteins, and viral genomic RNA. However, proviral DNA synthesis was not detected upon inoculation of this virus in NIH 3T3 cells. The loss of infectivity of the recombinant virus bearing the Fv-4 AccI-EcoRV region appeared to be caused by failure in an early step of replication. Images PMID:2304138

  18. Identification, Characterization and Down-Regulation of Cysteine Protease Genes in Tobacco for Use in Recombinant Protein Production

    PubMed Central

    Duwadi, Kishor; Chen, Ling; Menassa, Rima; Dhaubhadel, Sangeeta

    2015-01-01

    Plants are an attractive host system for pharmaceutical protein production. Many therapeutic proteins have been produced and scaled up in plants at a low cost compared to the conventional microbial and animal-based systems. The main technical challenge during this process is to produce sufficient levels of recombinant proteins in plants. Low yield is generally caused by proteolytic degradation during expression and downstream processing of recombinant proteins. The yield of human therapeutic interleukin (IL)-10 produced in transgenic tobacco leaves was found to be below the critical level, and may be due to degradation by tobacco proteases. Here, we identified a total of 60 putative cysteine protease genes (CysP) in tobacco. Based on their predicted expression in leaf tissue, 10 candidate CysPs (CysP1-CysP10) were selected for further characterization. The effect of CysP gene silencing on IL-10 accumulation was examined in tobacco. It was found that the recombinant protein yield in tobacco could be increased by silencing CysP6. Transient expression of CysP6 silencing construct also showed an increase in IL-10 accumulation in comparison to the control. Moreover, CysP6 localizes to the endoplasmic reticulum (ER), suggesting that ER may be the site of IL-10 degradation. Overall results suggest that CysP6 is important in determining the yield of recombinant IL-10 in tobacco leaves. PMID:26148064

  19. A recombinant rabies virus encoding two copies of the glycoprotein gene confers protection in dogs against a virulent challenge.

    PubMed

    Liu, Xiaohui; Yang, Youtian; Sun, Zhaojin; Chen, Jing; Ai, Jun; Dun, Can; Fu, Zhen F; Niu, Xuefeng; Guo, Xiaofeng

    2014-01-01

    The rabies virus (RABV) glycoprotein (G) is the principal antigen responsible for the induction of virus neutralizing antibodies (VNA) and is the major modality of protective immunity in animals. A recombinant RABV HEP-Flury strain was generated by reverse genetics to encode two copies of the G-gene (referred to as HEP-dG). The biological properties of HEP-dG were compared to those of the parental virus (HEP-Flury strain). The HEP-dG recombinant virus grew 100 times more efficiently in BHK-21 cell than the parental virus, yet the virulence of the dG recombinant virus in suckling mice was lower than the parental virus. The HEP-dG virus can improve the expression of G-gene mRNA and the G protein and produce more offspring viruses in cells. The amount of G protein revealed a positive relationship with immunogenicity in mice and dogs. The inactivated HEP-dG recombinant virus induced higher levels of VNA and conferred better protection against virulent RABV in mice and dogs than the inactivated parental virus and a commercial vaccine. The protective antibody persisted for at least 12 months. These data demonstrate that the HEP-dG is stable, induces a strong VNA response and confers protective immunity more effectively than the RABV HEP-Flury strain. HEP-dG could be a potential candidate in the development of novel inactivated rabies vaccines. PMID:24498294

  20. Construction of recombinant Escherichia coli strains for secretory expression of artificial genes for human granulocyte-macrophage colony stimulating factor

    SciTech Connect

    Petrovskaya, L.E.; Ruzin, A.V.; Shingarova, L.N.; Korobko, V.G.

    1995-11-01

    A number of recombinant plasmids for expression of artificial genes encoding human granulocyte-macrophage colony stimulating factor (GM-CSF) were constructed. A hybrid gene was obtained that contains a sequence encoding the leader peptide and a tandem of two IgG-binding domains of protein A from Staphylococcus aureus coupled, through an enteropepdidase linker, to a synthetic gmcsf gene. The construction enables Escherichia coli to carry out biosynthesis of the hybrid protein and its subsequent transport into the periplasmic space of bacteria. Another hybrid gene, combining sequences for the signal peptide of the E. coli outer membrane protein OmpA and GM-CSF, was obtained using polymerase chain reaction. The localization of the mature protein produced by the hybrid gene was found to depend on the strength of the promoter used. 39 refs., 6 figs.

  1. [Relation of Lac promotor and the expression of cholera toxin subunit B gene in recombinant Escherichia coli MM2].

    PubMed

    Fang, H; Zhao, S; Yu, G; Ma, Q

    1997-08-01

    Effects of different carbon sources including glucose, lactate and acetate and IPTG induction on the expression of ctb gene, which is on the downstream of lac promotor, in recombinant Escherichia coli MM2 were studied. In medium YC were added 0.048mol/L glucose, 0.102mol/L lactate or 0.167mol/L acetate which separately produce the same energy in the condition of complete oxidization. Addition of glucose largely decreased the expression level of ctb gene because of decrease of pH during culture process. Addition of lactate increased the expression level of ctb gene by 1.15 fold and did not inhibit the growth of MM2 strain. Addition of acetate increasd the expression level of ctb gene by 0.97 fold and inhibited the growth of MM2 strain. Induction by IPTG at different time and different concentration did not increase the expression level of ctb gene, so the lac promotor had no or a little influence upon the expression of ctb gene in recombinant MM2 strain. PMID:9863203

  2. Re-Designed Recombinant Hepatitis B Virus Vectors Enable Efficient Delivery of Versatile Cargo Genes to Hepatocytes with Improved Safety

    PubMed Central

    Bai, Weiya; Cui, Xiaoxian; Chen, Ruidong; Tao, Shuai; Hong, Ran; Zhang, Jiming; Zhang, Junqi; Wang, Yongxiang; Xie, Youhua; Liu, Jing

    2016-01-01

    Hepatitis B virus (HBV) takes humans as its sole natural host, and productive infection in vivo is restricted exclusively to hepatocytes in the liver. Consequently, HBV-derived viral vectors are attractive candidates for liver-targeting gene therapies. Previously, we developed a novel recombinant HBV vector, designated 5c3c, from a highly replicative clinical isolate. 5c3c was demonstrated to be capable of efficiently delivering protein or RNA expression into infected primary tupaia hepatocytes (PTH), but the design of 5c3c imposes stringent restrictions on inserted sequences, which have limited its wider adoption. In this work, we addressed issues with 5c3c by re-designing the insertion strategy. The resultant vector, designated 5dCG, was more replicative than parental 5c3c, imposed no specific restrictions on inserted sequences, and allowed insertion of a variety of cargo genes without significant loss of replication efficiency. 5dCG-based recombinant HBV effectively delivered protein and RNA expression into infected PTH. Furthermore, due to the loss of functional core ORF, 5dCG vectors depend on co-infecting wild type HBV for replication and efficient expression of cargo genes. Development of the improved 5dCG vector makes wider applications of recombinant HBV possible, while dependence on co-infecting wild type HBV results in improved safety for certain in vivo applications. PMID:27171107

  3. Construction of recombinant eukaryotic expression plasmid containing murine CD40 ligand gene and its expression in H22 cells

    PubMed Central

    Jiang, Yong-Fang; He, Yan; Gong, Guo-Zhong; Chen, Jun; Yang, Chun-Yan; Xu, Yun

    2005-01-01

    AIM: To construct a recombinant murine CD40 ligand (mCD40L) eukaryotic expression vector for gene therapy and target therapy of hepatocellular carcinoma (HCC). METHODS: mCD40L cDNA was synthesized by RT-PCR with the specific primers and directly cloned into T vector to generate middle recombinant. After digestion with restriction endonuclease, the target fragment was subcloned into the multi-clone sites of the eukaryotic vector. The constructed vector was verified by enzyme digestion and sequencing, and the product expressed was detected by RT-PCR and immunofluorescence methods. RESULTS: The full-length mCD40L-cDNA was successfully cloned into the eukaryotic vector through electrophoresis, and mCD40L gene was integrated into the genome of infected H22 cells by RT-PCR. Murine CD40L antigen molecule was observed in the plasma of mCD40L-H22 by indirect immuno-fluorescence staining. CONCLUSION: The recombined mCD40L eukaryotic expression vector can be expressed in H22 cell line. It provides experimental data for gene therapy and target therapy of hepatocellular carcinoma. PMID:15633212

  4. Re-Designed Recombinant Hepatitis B Virus Vectors Enable Efficient Delivery of Versatile Cargo Genes to Hepatocytes with Improved Safety.

    PubMed

    Bai, Weiya; Cui, Xiaoxian; Chen, Ruidong; Tao, Shuai; Hong, Ran; Zhang, Jiming; Zhang, Junqi; Wang, Yongxiang; Xie, Youhua; Liu, Jing

    2016-01-01

    Hepatitis B virus (HBV) takes humans as its sole natural host, and productive infection in vivo is restricted exclusively to hepatocytes in the liver. Consequently, HBV-derived viral vectors are attractive candidates for liver-targeting gene therapies. Previously, we developed a novel recombinant HBV vector, designated 5c3c, from a highly replicative clinical isolate. 5c3c was demonstrated to be capable of efficiently delivering protein or RNA expression into infected primary tupaia hepatocytes (PTH), but the design of 5c3c imposes stringent restrictions on inserted sequences, which have limited its wider adoption. In this work, we addressed issues with 5c3c by re-designing the insertion strategy. The resultant vector, designated 5dCG, was more replicative than parental 5c3c, imposed no specific restrictions on inserted sequences, and allowed insertion of a variety of cargo genes without significant loss of replication efficiency. 5dCG-based recombinant HBV effectively delivered protein and RNA expression into infected PTH. Furthermore, due to the loss of functional core ORF, 5dCG vectors depend on co-infecting wild type HBV for replication and efficient expression of cargo genes. Development of the improved 5dCG vector makes wider applications of recombinant HBV possible, while dependence on co-infecting wild type HBV results in improved safety for certain in vivo applications. PMID:27171107

  5. Organ distribution of transgene expression following intranasal mucosal delivery of recombinant replication-defective adenovirus gene transfer vector

    PubMed Central

    Damjanovic, Daniela; Zhang, Xizhong; Mu, Jingyu; Fe Medina, Maria; Xing, Zhou

    2008-01-01

    It is believed that respiratory mucosal immunization triggers more effective immune protection than parenteral immunization against respiratory infection caused by viruses and intracellular bacteria. Such understanding has led to the successful implementation of intranasal immunization in humans with a live cold-adapted flu virus vaccine. Furthermore there has been an interest in developing effective mucosal-deliverable genetic vaccines against other infectious diseases. However, there is a concern that intranasally delivered recombinant viral-based vaccines may disseminate to the CNS via the olfactory tissue. Initial experimental evidence suggests that intranasally delivered recombinant adenoviral gene transfer vector may transport to the olfactory bulb. However, there is a lack of quantitative studies to compare the relative amounts of transgene products in the respiratory tract, lung, olfactory bulb and brain after intranasal mucosal delivery of viral gene transfer vector. To address this issue, we have used fluorescence macroscopic imaging, luciferase quantification and PCR approaches to compare the relative distribution of transgene products or adenoviral gene sequences in the respiratory tract, lung, draining lymph nodes, olfactory bulb, brain and spleen. Intranasal mucosal delivery of replication-defective recombinant adenoviral vector results in gene transfer predominantly in the respiratory system including the lung while it does lead to a moderate level of gene transfer in the olfactory bulb. However, intranasal inoculation of adenoviral vector leads to little or no viral dissemination to the major region of the CNS, the brain. These experimental findings support the efficaciousness of intranasal adenoviral-mediated gene transfer for the purpose of mucosal immunization and suggest that it may not be of significant safety concern. PMID:18261231

  6. Inter-allelic recombination in the Plasmodium vivax merozoite surface protein 1 gene among Indian and Colombian isolates

    PubMed Central

    Maestre, Amanda; Sunil, Sujatha; Ahmad, Gul; Mohmmed, Asif; Echeverri, Marcela; Corredor, Mauricio; Blair, Silvia; Chauhan, Virander S; Malhotra, Pawan

    2004-01-01

    Background A major concern in malaria vaccine development is the polymorphism observed among different Plasmodium isolates in different geographical areas across the globe. The merozoite surface protein 1 (MSP-1) is a leading vaccine candidate antigen against asexual blood stages of malaria parasite. To date, little is known about the extent of sequence variation in the Plasmodium vivax MSP-1 gene (Pvmsp-1) among Indian isolates. Since P. vivax accounts for >50% of malaria cases in India and in Colombia, it is essential to know the Pvmsp-1 gene variability in these two countries to sustain it as a vaccine candidate. The extent of polymorphism in Pvmsp-1 gene among Indian and Colombian isolates is described. Methods The sequence variation in the region encompassing the inter-species conserved blocks (ICBs) five and six of Pvmsp-1 gene was examined. PCR was carried out to amplify the polymorphic region of Pvmsp-1 and the PCR products from twenty (nine Indian and 11 Colombian) isolates were sequenced and aligned with Belem and Salvador-1 sequences. Results Results revealed three distinct types of sequences among these isolates, namely, Salvador-like, Belem-like and a third type sequence which was generated due to interallelic recombination between Salvador-like sequences and Belem-like sequences. Existence of the third type in majority (44%) showed that allelic recombinations play an important role in PvMSP1 diversity in natural parasite population. Micro-heterogeneity was also seen in a few of these isolates due to nucleotide substitutions, insertions as well as deletions. Conclusions Intergenic recombination in the Pvmsp-1 gene was found and suggest that this is the main cause for genetic diversity of the Pvmsp-1 gene. PMID:15003129

  7. Properties of a herpes simplex virus multiple immediate-early gene-deleted recombinant as a vaccine vector

    SciTech Connect

    Watanabe, Daisuke; Brockman, Mark A.; Ndung'u, Thumbi; Mathews, Lydia; Lucas, William T.; Murphy, Cynthia G.; Felber, Barbara K.; Pavlakis, George N.; Deluca, Neal A.; Knipe, David M. . E-mail: david_knipe@hms.harvard.edu

    2007-01-20

    Herpes simplex virus (HSV) recombinants induce durable immune responses in rhesus macaques and mice and have induced partial protection in rhesus macaques against mucosal challenge with virulent simian immunodeficiency virus (SIV). In this study, we evaluated the properties of a new generation HSV vaccine vector, an HSV-1 multiple immediate-early (IE) gene deletion mutant virus, d106, which contains deletions in the ICP4, ICP27, ICP22, and ICP47 genes. Because several of the HSV IE genes have been implicated in immune evasion, inactivation of the genes encoding these proteins was expected to result in enhanced immunogenicity. The d106 virus expresses few HSV gene products and shows minimal cytopathic effect in cultured cells. When d106 was inoculated into mice, viral DNA accumulated at high levels in draining lymph nodes, consistent with an ability to transduce dendritic cells and activate their maturation and movement to lymph nodes. A d106 recombinant expressing Escherichia coli {beta}-galactosidase induced durable {beta}-gal-specific IgG and CD8{sup +} T cell responses in naive and HSV-immune mice. Finally, d106-based recombinants have been constructed that express simian immunodeficiency virus (SIV) gag, env, or a rev-tat-nef fusion protein for several days in cultured cells. Thus, d106 shows many of the properties desirable in a vaccine vector: limited expression of HSV gene products and cytopathogenicity, high level expression of transgenes, ability to induce durable immune responses, and an ability to transduce dendritic cells and induce their maturation and migration to lymph nodes.

  8. Fine regulation of cI857-controlled gene expression in continuous culture of recombinant Escherichia coli by temperature.

    PubMed Central

    Villaverde, A; Benito, A; Viaplana, E; Cubarsi, R

    1993-01-01

    The expression at different temperatures of the lacZ gene, which is controlled by the lambda pL and pR tandem promoters and the cI857 temperature-sensitive repressor, was studied in Escherichia coli continuous cultures. At temperatures between 30 and 42 degrees C, beta-galactosidase activity behaved according to an exponential equation. By inducing a culture at a temperature within this range, predefined, nearly constant submaximal levels of gene expression and recombinant product yield can be obtained. PMID:8250569

  9. [Transcatheter delivery of recombinant adenovirus vector containing exogenous aquaporin gene in treatment of Sjögren's syndrome].

    PubMed

    Hong, H E; Jieqiong, Zhang; Yan, Fan; Xiaoshuang, Sun; Yuhao, Zhu

    2016-05-25

    Sjögren's syndrome is a kind of autoimmune disease, whose main clinical symptoms are dry mouth, dry eye and chronic parotid glandular inflammation. The conservative treatments include artificial tears or saliva,oral administration of corticosteroids,and immunosuppressantsl with limited effectiveness. Along with the development of molecular biology, vast attentions are being paid to researches on gene therapy for Sjögren's syndrome, hopefully to bring gospel to patients with Sjögren's syndrome. This article reviews the recent research progresses on transcatheter delivery of recombinant adenovirus vector with aquaporin gene in experimental treatment of Sjögren's syndrome. PMID:27045247

  10. Effects of gene dosage, promoters, and substrates on unfolded protein stress of recombinant Pichia pastoris.

    PubMed

    Hohenblum, Hubertus; Gasser, Brigitte; Maurer, Michael; Borth, Nicole; Mattanovich, Diethard

    2004-02-20

    The expression of heterologous proteins may exert severe stress on the host cells at different levels. Depending on the specific features of the product, different steps may be rate-limiting. For the secretion of recombinant proteins from yeast cells, folding and disulfide bond formation were identified as rate-limiting in several cases and the induction of the chaperone BiP (binding protein) is described. During the development of Pichia pastoris strains secreting human trypsinogen, a severe limitation of the amount of secreted product was identified. Strains using either the AOX1 or the GAP promoter were compared at different gene copy numbers. With the constitutive GAP promoter, no effect on the expression level was observed, whereas with the inducible AOX1 promoter an increase of the copy number above two resulted in a decrease of expression. To identify whether part of the product remained in the cells, lysates were fractionated and significant amounts of the product were identified in the insoluble fraction containing the endoplasmic reticulum, while the soluble cytosolic fraction contained product only in clones using the GAP promoter. An increase of BiP was observed upon induction of expression, indicating that the intracellular product fraction exerts an unfolded protein response in the host cells. A strain using the GAP promoter was grown both on glucose and methanol and trypsinogen was identified in the insoluble fractions of both cultures, but only in the soluble fraction of the glucose grown cultures, indicating that the amounts and distribution of intracellularly retained product depends on the culture conditions, especially the carbon source. PMID:14755554

  11. Polymorphism, recombination and alternative unscrambling in the DNA polymerase alpha gene of the ciliate Stylonychia lemnae (Alveolata; class Spirotrichea).

    PubMed Central

    Ardell, David H; Lozupone, Catherine A; Landweber, Laura F

    2003-01-01

    DNA polymerase alpha is the most highly scrambled gene known in stichotrichous ciliates. In its hereditary micronuclear form, it is broken into >40 pieces on two loci at least 3 kb apart. Scrambled genes must be reassembled through developmental DNA rearrangements to yield functioning macronuclear genes, but the mechanism and accuracy of this process are unknown. We describe the first analysis of DNA polymorphism in the macronuclear version of any scrambled gene. Six functional haplotypes obtained from five Eurasian strains of Stylonychia lemnae were highly polymorphic compared to Drosophila genes. Another incompletely unscrambled haplotype was interrupted by frameshift and nonsense mutations but contained more silent mutations than expected by allelic inactivation. In our sample, nucleotide diversity and recombination signals were unexpectedly high within a region encompassing the boundary of the two micronuclear loci. From this and other evidence we infer that both members of a long repeat at the ends of the loci provide alternative substrates for unscrambling in this region. Incongruent genealogies and recombination patterns were also consistent with separation of the two loci by a large genetic distance. Our results suggest that ciliate developmental DNA rearrangements may be more probabilistic and error prone than previously appreciated and constitute a potential source of macronuclear variation. From this perspective we introduce the nonsense-suppression hypothesis for the evolution of ciliate altered genetic codes. We also introduce methods and software to calculate the likelihood of hemizygosity in ciliate haplotype samples and to correct for multiple comparisons in sliding-window analyses of Tajima's D. PMID:14704164

  12. Construction of PR39 recombinant AAV under control of the HRE promoter and the effect of recombinant AAV on gene therapy of ischemic heart disease

    PubMed Central

    SUN, LIJUN; HAO, YUEWEN; NIE, XIAOWEI; ZHANG, XUEXIN; YANG, GUANGXIAO; WANG, QUANYING

    2012-01-01

    The objective of this study was to investigate the effect of the PR39 recombinant adeno-associated virus (AAV) controlled by the hypoxia-responsive element (HRE) on gene therapy of ischemic heart disease. The minimal HRE was artificially synthesized and the AAV vector controlled by HRE was introduced with NT4-TAT-His-PR39 to investigate the expression of AAV-PR39 in hypoxic vascular endothelial cells (VEC) of human umbilical vein (CRL-1730 cell line) and the angiogenesis-promoting effect in pigs with acute myocardial infraction (AMI). The minimal HRE/CMV was designed and artificially synthesized using the PCR method and cloned with the T vector cloning method. The pSS-HRE-CMV-NT4-6His-PR39-PolyA-AAV plasmid was constructed. Using the calcium phosphate precipitation method, HEK-293 cells were co-transfected with three plasmids to produce the recombinant virus. An equal volume of pSS-HRE-CMV-NT4-6His-PR39-PolyAAAV and enterovirus (EV, blank virus) was transfected into CRL-1730 cell lines, respectively. The immunohistochemical method was used to assay the expression of 6xHis in CRL-1730 cell lines and the expression of PR39 under hypoxia. Eighteen AMI miniature pigs were randomized into the experimental group (HRE-AAV-PR39 group), control group 1 (physical saline group) and control group 2 (EV group). The area of ischemia was assessed with conventional MRI and myocardium perfusion MRI. Pigs were sacrificed at preset time-points to obtain samples of ischemic myocardium. Morphological and pathological data were collected. According to data in the literature and databases, the minimal HRE was designed and synthesized with the PCR method. A large number of HREs were connected to modified pSSHGAAV (pSSV9int-/XbaI) vector followed by insertion of the NT4-6His-PR39 gene segment and, thus, the recombinant plasmid pSS-HRE-CMV-NT4-6His-PR39-PolyA-AAV was successfully constructed. The expression of 6xHis in CRL-1730 cells under the regulation of HRE was assayed using the

  13. Immunogenic response to a recombinant pseudorabies virus carrying bp26 gene of Brucella melitensis in mice.

    PubMed

    Yao, Lan; Wu, Chang-Xian; Zheng, Ke; Xu, Xian-Jin; Zhang, Hui; Chen, Chuang-Fu; Liu, Zheng-Fei

    2015-06-01

    Brucellae are facultative intracellular bacterial pathogens of a zoonotic disease called brucellosis. Live attenuated vaccines are utilized for prophylaxis of brucellosis; however, they retain residual virulence to human and/or animals, as well as interfere with diagnosis. In this study, recombinant virus PRV ΔTK/ΔgE/bp26 was screened and purified. One-step growth curve assay showed that the titer of recombinant virus was comparable to the parent strain. Mice experiments showed the recombinant virus elicited high titer of humoral antibodies against Brucella detected by enzyme-linked immunosorbent assay and against PRV by serum neutralization test. The recombinant virus induced high level of Brucella-specific lymphocyte proliferation response and production of interferon gamma. Collectively, these data suggest that the bivalent virus was capable of inducing both humoral and cellular immunity, and had the potential to be a vaccine candidate to prevent Brucella and/or pseudorabies virus infections. PMID:25890577

  14. Semiconservative DNA replication is initiated at a single site in recombination-deficient gene 32 mutants of bacteriophage T4.

    PubMed Central

    Dannenberg, R; Mosig, G

    1981-01-01

    We have investigated, by electron microscopy, replicative intermediate produced early after infection of Escherichia coli with two phage T4 gene 32 mutants (amA453 and tsG26) which replicate their parental DNA but are defective in secondary replications and in moderating the activities of recombination nucleases. Under conditions completely restrictive for progeny production, both of these mutant produced replicative intermediates, each containing a single internal loop. Both branches of these loops were double stranded; i.e., both leading and lagging strands were synthesized. The replicative intermediates of these mutants qualitatively and quantitatively resembled early replicating wild-type T4 chromosomes after solitary infection of E. coli. However, in contrast to intracellular wild-type T4 DNA isolated from multiple infection, the mutant DNAs showed neither multiple branches nor multiple tandem loops. These results demonstrate that a truncated gene 32 protein which consists of less than one-third of the wild-type T4 helix-destabilizing protein can facilitate the functions of T4 replication proteins, specifically those of T4 DNA polymerase and priming proteins. Our results also support the hypothesis that the generation of multiple tandem loops or branches in vegetative T4 DNA depends on recombination (Mosig et al., in B. Alberts, ed., Mechanistic Studies of DNA Replication and Genetic Recombination, p. 527-543, Academic Press, Inc., New York, 1980). Images PMID:7321104

  15. Molecular requirements for immunoglobulin heavy chain constant region gene switch-recombination revealed with switch-substrate retroviruses.

    PubMed

    Ott, D E; Marcu, K B

    1989-01-01

    We have employed a retroviral vector, ZN(Smu/S gamma 2b)tk1, as a means of introducing immunoglobulin heavy chain (IgH) switch (S) region sequences into B cell lines to directly measure their switch-recombinase activities. In an earlier study, we demonstrated that retrovector Smu-S gamma 2b recombination events occurred in two thymidine kinase (tk)-negative murine pre-B cell lines (18-8 and 38B9) upon selection in bromodeoxyuridine (BUdR) media for the loss of an Htk gene inserted in between the vector's Smu and S gamma 2b sequences. Here we have used this assay system to show that the 300-18 murine pre-B cell line possesses a very high level of switch-recombinase activity (greater than 1 event in 2500 cells/generation) while a terminally differentiated, antibody-secreting hybridoma line (A39R 1.1) has no detectable recombinase activity. Both S mu and S gamma 2b segments are required for switch region-mediated deletions. Retrovectors harboring only an Smu segment or an Smu segment and a portion of the murine c-myc gene in place of S gamma 2b sequences were both non-recombinagenic in this assay system. Nucleotide sequence analysis of six retrovector S segment recombinants, recovered from ZN(Smu/S gamma 2b) tk1-infected 18-8 and 39B9 pre-B lines, did not reveal homology at their sites of recombination. We conclude that: (1) S segment repetitive sequences play an essential but indirect role in IgCH gene switch-recombination, which occurs by an illegitimate, non-homologous mechanism; (2) the c-myc gene is not a significant target for switch-recombination; and (3) since endogenous Smu and S gamma 2b rearrangements were not observed in populations and clones of pre-B cells expressing a high level of switch-recombinase activity, multiple factors (presumably contributed in part by the degree of S segment accessibility) in addition to S recombinase activity are required for CH class switching. PMID:2489045

  16. Phylogenetic analysis of VP1 gene sequences of waterfowl parvoviruses from the Mainland of China revealed genetic diversity and recombination.

    PubMed

    Wang, Shao; Cheng, Xiao-Xia; Chen, Shao-Ying; Lin, Feng-Qiang; Chen, Shi-Long; Zhu, Xiao-Li; Wang, Jin-Xiang; Huang, Mei-Qing; Zheng, Min

    2016-03-01

    To determine the origin and evolution of goose parvovirus (GPV) and Muscovy duck parvovirus (MDPV) in the Mainland of China, phylogenetic and recombination analyses in the present study were performed on 32 complete VP1 gene sequences from China and other countries. Based on the phylogenetic analysis of the VP1 gene, GPV strains studied here from Mainland China (PRC) could be divided into three genotypes, namely PRC-I, PRC-II and PRC-III. Genotype PRC-I is indigenous to Mainland China. Only one GPV strain from Northeast China was of Genotype PRC-II and was thought to be imported from Europe. Genotype PRC-III, which was the most isolated genotype during 1999-2012, is related to GPVs in Taiwan and has been the predominant pathogen responsible for recent Derzy's disease outbreaks in Mainland China. Current vaccine strains used in Mainland China belong to Genotype PRC-I that is evolutionary distant from Genotypes PRC-II and PRC-III. In comparison, MDPV strains herein from Mainland China are clustered in a single group which is closely related to Taiwanese MDPV strains, and the full-length sequences of the VP1 gene of China MDPVs are phylogenetic closely related to the VP1 sequence of a Hungarian MDPV strain. Moreover, We also found that homologous recombination within VP1 gene plays a role in generating genetic diversity in GPV evolution. The GPV GDFSh from Guangdong Province appears to be the evolutionary product of a recombination event between parental GPV strains GD and B, while the major parent B proved to be a reference strain for virulent European GPVs. Our findings provide valuable information on waterfowl parvoviral evolution in Mainland China. PMID:26692144

  17. Sequence analysis of the gene for a novel superantigen produced by Yersinia pseudotuberculosis and expression of the recombinant protein

    SciTech Connect

    Yasuhiko, Ito; Abe, Jun; Kohsaka, Takao

    1995-06-01

    We previously reported that the Gram-negative bacterium Yersinia pseudotuberculosis produces a superantigen (YPM, Y. pseudotuberculosis-derived mitogen) that expands T cells bearing V{beta}s 3, 9, 13.1, and 13.2 in an MHC class II-dependent manner. Based on the previously determined N-terminal 23 amino acids of YPM (T-D-Y-D-N-T-L-N-S-I-P-S-L-R-I-P-N-I-A-T-Y-T-G- (one-letter code)), we cloned the ypm gene and analyzed the nucleotide sequence. The gene encodes a 151-amino acid protein with a 20-amino acid signal peptide at its N terminus. The recombinant YPM expressed by the cloned gene exerted a mitogenic activity on human PBMC at a concentration of approximately 1 pg/ml. T cells bearing V{beta} 13.3 were preferentially expanded as well as T cells bearing the same V{beta} repertoires stimulated by native YPM. T cells were stimulated by the recombinant YPM in the presence of either fixed or unfixed HLA class II-transfected mouse fibroblasts. Furthermore, sequence diversity in the junctional region of the TCR {beta}-chain containing the V{beta}3 element could be observed after stimulation by the recombinant YPM. These results indicate that YPM belongs to the category of superantigens and should be included as a novel member. The amino acid sequence of the mature protein showed no significant homology to other superantigens derived from Gram-positive bacteria such as Staphylococcus aureus and Streptococcus pyogenes. This observation, together with the substantially smaller m.w. suggest that ypm must have evolved from a different ancestral gene. 67 refs., 7 figs., 5 tabs.

  18. Subolesin/akirin orthologs from Ornithodoros spp. soft ticks: cloning, RNAi gene silencing and protective effect of the recombinant proteins.

    PubMed

    Manzano-Román, Raúl; Díaz-Martín, Verónica; Oleaga, Ana; Siles-Lucas, Mar; Pérez-Sánchez, Ricardo

    2012-04-30

    Subolesin/akirin is a well characterized protective antigen highly conserved across vector species and thus potentially useful for the development of a broad-spectrum vaccine for the control of arthropod infestations including hard ticks, mosquitoes, sand flies and the poultry red mite Dermanyssus gallinae. Soft ticks could be also targeted by this vaccine if proved that the soft tick subolesin orthologs are conserved and induce protective immune responses too. However, to date no soft tick subolesin orthologs have been fully characterized nor tested as recombinant antigens in vaccination trials. The objectives of the present work were to clone and characterize the subolesin orthologs from two important vector species of soft ticks as Ornithodoros erraticus and O. moubata, to evaluate the effect of subolesin gene silencing by RNAi, and to test the protective value of the recombinant antigens in vaccination trials. The obtained results demonstrate that both soft tick subolesins are highly conserved showing more than 69% and 74% identity with those of hard ticks in their nucleotide and amino acid sequences, respectively. Additionally, we demonstrate that both soft ticks possess fully operative RNAi machinery, and that subolesin gene silencing by dsRNA injection inhibits oviposition indicating the involvement of subolesin in tick reproduction. Finally, vaccination with the recombinant soft tick subolesins induced a partial protective effect resulting in the reduction of the oviposition rate. These preliminary results encourage further studies on the use of recombinant subolesins as vaccines for the control of soft tick infestations, either alone or in combination with other specific molecules. PMID:22105082

  19. Ethanol production by recombinant Escherichia coli carrying genes from Zymomonas mobilis.

    PubMed

    Lawford, H G; Rousseau, J D

    1991-01-01

    Efficient utilization of lignocellulosic feedstocks offers an opportunity to reduce the cost of producing fuel ethanol. The fermentation performance characteristics of recombinant Escherichia coli ATCC 11303 carrying the "PET plasmid" (pLOI297) with the lac operon controlling the expression of pyruvate decarboxylase (pdc) and alcohol dehydrogenase II (adhB) genes cloned from Zymomonas mobilis CP4 (Alterthum & Ingram, 1989) were assessed in batch and continuous processes with sugar mixtures designed to mimic process streams from lignocellulosic hydrolysis systems. Growth was pseudoexponential at a rate (generation time) of 1.28 h at pH 6.8 and 1.61 h at pH 6.0. The molar growth yields for glucose and xylose were 17.28 and 7.65 g DW cell/mol, respectively (at pH 6.3 and 30 degrees C), suggesting that the net yield of ATP from xylose metabolism is only 50% compared to glucose. In pH-stat batch fermentations (Luria broth with 6% sugar, pH 6.3), glucose was converted to ethanol 4-6 times faster than xylose, but the glucose conversion rate was much less than can be achieved with comparable cell densities of Zymomonas. Sugar-to-ethanol conversion efficiencies in nutrient-rich, complex LB medium were near theoretical at 98 and 88% for glucose and xylose, respectively. The yield was 10-20% less in a defined-mineral-salts medium. Acetate at a concentration of 0.1M (present in lignocellulosic hydrolysates from thermochemical processing) inhibited glucose utilization (about 50%) much more than xylose, and caused a decrease in product yield of about 30% for both sugars. With phosphate-buffered media (pH 7), glucose was a preferred substrate in mixtures with a ratio of hexose to pentose of 2.3 to 1. Xylose was consumed after glucose, and the product yield was less (0.37 g/g). Under steady-state conditions of continuous culture, the specific productivity ranged from 0.76-1.24 g EtOH/g cell/h, and the maximum volumetric productivity, 2.5 g EtOH/L/h, was achieved with a rich

  20. Uricase production by a recombinant Hansenula polymorpha strain harboring Candida utilis uricase gene.

    PubMed

    Chen, Zhiyu; Wang, Zhaoyue; He, Xiuping; Guo, Xuena; Li, Weiwei; Zhang, Borun

    2008-06-01

    Uricase is an important medical enzyme which can be used to determine urate in clinical analysis, to therapy gout, hyperuricemia, and tumor lysis syndrome. Uricase of Candida utilis was successfully expressed in Hansenula polymorpha under the control of methanol oxidase promoter using Saccharomyces cerevisiae alpha-factor signal peptide as the secretory sequence. Recombinant H. polymorpha MU200 with the highest extracellular uricase production was characterized with three copies of expression cassette and selected for process optimization for the production of recombinant enzyme. Among the parameters investigated in shaking flask cultures, the pH value of medium and inoculum size had great influence on the recombinant uricase production. The maximum extracellular uricase yield of 2.6 U/ml was obtained in shaking flask culture. The yield of recombinant uricase was significantly improved by the combined use of a high cell-density cultivation technique and a pH control strategy of switching culture pH from 5.5 to 6.5 in the induction phase. After induction for 58 h, the production of recombinant uricase reached 52.3 U/ml (about 2.1 g/l of protein) extracellularly and 60.3 U/ml (about 2.4 g/l) intracellularly in fed-batch fermentation, which are much higher than those expressed in other expression systems. To our knowledge, this is the first report about the heterologous expression of uricase in H. polymorpha. PMID:18437374

  1. p53 modulates homologous recombination by transcriptional regulation of the RAD51 gene

    PubMed Central

    Arias-Lopez, Carmen; Lazaro-Trueba, Iciar; Kerr, Peter; Lord, Christopher J; Dexter, Tim; Iravani, Marjan; Ashworth, Alan; Silva, Augusto

    2006-01-01

    DNA repair by homologous recombination is involved in maintaining genome stability. Previous data report that wild-type p53 suppresses homologous recombination and physically interacts with Rad51. Here, we show the in vivo binding of wild-type p53 to a p53 response element in the promoter of Rad51 and the downregulation of Rad51 messenger RNA and protein by wild-type p53, favoured by DNA damage. Moreover, wild-type p53 inhibits Rad51 foci formation in response to double-strand breaks, whereas p53 contact mutant R280K fails to repress Rad51 mRNA and protein expression and Rad51 foci formation. We propose that transcriptional repression of Rad51 by p53 participates in regulating homologous recombination, and impaired Rad51 repression by p53 mutants may contribute to malignant transformation. PMID:16322760

  2. Generation of Antigenic Variants via Gene Conversion: Evidence for Recombination Fitness Selection at the Locus Level in Anaplasma marginale▿

    PubMed Central

    Futse, James E.; Brayton, Kelly A.; Nydam, Seth D.; Palmer, Guy H.

    2009-01-01

    Multiple bacterial and protozoal pathogens utilize gene conversion to generate antigenically variant surface proteins to evade immune clearance and establish persistent infection. Both the donor alleles that encode the variants following recombination into an expression site and the donor loci themselves are under evolutionary selection: the alleles that encode variants that are sufficiently antigenically unique yet retain growth fitness and the loci that allow efficient recombination. We examined allelic usage in generating Anaplasma marginale variants during in vivo infection in the mammalian reservoir host and identified preferential usage of specific alleles in the absence of immune selective pressure, consistent with certain individual alleles having a fitness advantage for in vivo growth. In contrast, the loci themselves appear to have been essentially equally selected for donor function in gene conversion with no significant effect of locus position relative to the expression site or origin of replication. This pattern of preferential allelic usage but lack of locus effect was observed independently for Msp2 and Msp3 variants, both generated by gene conversion. Furthermore, there was no locus effect observed when a single locus contained both msp2 and msp3 alleles in a tail-to-tail orientation flanked by a repeat. These experimental results support the hypothesis that predominance of specific variants reflects in vivo fitness as determined by the encoding allele, independent of locus structure and chromosomal position. Identification of highly fit variants provides targets for vaccines that will prevent the high-level bacteremia associated with acute disease. PMID:19487473

  3. Growth properties and vaccine efficacy of recombinant pseudorabies virus defective in glycoprotein E and thymidine kinase genes.

    PubMed

    Wu, Ching-Ying; Liao, Chih-Ming; Chi, Jiun-Ni; Chien, Maw-Sheng; Huang, Chienjin

    2016-07-10

    Pseudorabies virus (PRV) is an alphaherpesvirus that causes pseudorabies (PR), an economically important viral disease of pigs. Marker vaccines were widely used in PR prevention and eradication programs. The purpose of this study was to construct a novel recombinant virus with deletions at defined regions in the glycoprotein E (gE) and thymine kinase (TK) genes by homologous recombination. This study also evaluated the safety and efficacy of the virus for a live attenuated marker vaccine. No significant difference was observed in virus replication between gE gene-deleted (gE(-)), gE/TK double gene-deleted (gE(-)TK(-)), and wild-type PRV by growth curve analysis. However, gE(-)TK(-) PRV was completely attenuated in mice. To evaluate the immunogenicity of gE(-)TK(-) PRV, four 12-week-old specific-pathogen-free pigs per group were immunized intramuscularly with viral titers of 1×10(4), 1×10(5), or 1×10(6) TCID50, followed by intranasal challenge infection with virulent PRV (1×10(8) TCID50) at 3 weeks post vaccination. The gE(-)TK(-) PRV-vaccinated pigs displayed no general adverse effects after immunization and had protective immune responses after PRV challenge. Thus, gE(-)TK(-) PRV was safe and efficacious and might be a potential candidate for a live attenuated marker vaccine against PRV. PMID:27164258

  4. Recombineering, transfection, Western, IP and ChIP methods for protein tagging via gene targeting or BAC transgenesis.

    PubMed

    Hofemeister, Helmut; Ciotta, Giovanni; Fu, Jun; Seibert, Philipp Martin; Schulz, Alexander; Maresca, Marcello; Sarov, Mihail; Anastassiadis, Konstantinos; Stewart, A Francis

    2011-04-01

    Protein tagging offers many advantages for proteomic and regulomic research. Ideally, protein tagging is equivalent to having a high affinity antibody for every chosen protein. However, these advantages are compromised if the tagged protein is overexpressed, which is usually the case from cDNA expression vectors. Physiological expression of tagged proteins can be achieved by gene targeting to knock-in the protein tag or by BAC transgenesis. BAC transgenes usually retain the native gene architecture including all cis-regulatory elements as well as the exon-intron configurations. Consequently most BAC transgenes are authentically regulated (e.g. by transcription factors, cell cycle, miRNA) and can be alternatively spliced. Recombineering has become the method of choice for generating targeting constructs or modifying BACs. Here we present methods with detailed protocols for protein tagging by recombineering for BAC transgenesis and/or gene targeting, including the evaluation of tagged protein expression, the retrieval of associated protein complexes for mass spectrometry and the use of the tags in ChIP (chromatin immunoprecipitation). PMID:21195765

  5. Adenovirus-Mediated Somatic Genome Editing of Pten by CRISPR/Cas9 in Mouse Liver in Spite of Cas9-Specific Immune Responses.

    PubMed

    Wang, Dan; Mou, Haiwei; Li, Shaoyong; Li, Yingxiang; Hough, Soren; Tran, Karen; Li, Jia; Yin, Hao; Anderson, Daniel G; Sontheimer, Erik J; Weng, Zhiping; Gao, Guangping; Xue, Wen

    2015-07-01

    CRISPR/Cas9 derived from the bacterial adaptive immunity pathway is a powerful tool for genome editing, but the safety profiles of in vivo delivered Cas9 (including host immune responses to the bacterial Cas9 protein) have not been comprehensively investigated in model organisms. Nonalcoholic steatohepatitis (NASH) is a prevalent human liver disease characterized by excessive fat accumulation in the liver. In this study, we used adenovirus (Ad) vector to deliver a Streptococcus pyogenes-derived Cas9 system (SpCas9) targeting Pten, a gene involved in NASH and a negative regulator of the PI3K-AKT pathway, in mouse liver. We found that the Ad vector mediated efficient Pten gene editing even in the presence of typical Ad vector-associated immunotoxicity in the liver. Four months after vector infusion, mice receiving the Pten gene-editing Ad vector showed massive hepatomegaly and features of NASH, consistent with the phenotypes following Cre-loxP-induced Pten deficiency in mouse liver. We also detected induction of humoral immunity against SpCas9 and the potential presence of an SpCas9-specific cellular immune response. Our findings provide a strategy to model human liver diseases in mice and highlight the importance considering Cas9-specific immune responses in future translational studies involving in vivo delivery of CRISPR/Cas9. PMID:26086867

  6. Mutational analysis of the Drosophila DNA repair and recombination gene mei-9.

    PubMed Central

    Yildiz, Ozlem; Kearney, Hutton; Kramer, Benjamin C; Sekelsky, Jeff J

    2004-01-01

    Drosophila mei-9 is essential for several DNA repair and recombination pathways, including nucleotide excision repair (NER), interstrand crosslink repair, and meiotic recombination. To better understand the role of MEI-9 in these processes, we characterized 10 unique mutant alleles of mei-9. These include a P-element insertion that disrupts repair functions but not the meiotic function; three nonsense mutations, one of which has nearly wild-type levels of protein; three missense mutations, one of which disrupts the meiotic function but not repair functions; two small in-frame deletions; and one frameshift. PMID:15166153

  7. Vaccinia Virus Recombinants: Expression of VSV Genes and Protective Immunization of Mice and Cattle

    NASA Astrophysics Data System (ADS)

    Mackett, M.; Yilma, T.; Rose, J. K.; Moss, B.

    1985-01-01

    Vesicular stomatitis virus (VSV) causes a contagious disease of horses, cattle, and pigs. When DNA copies of messenger RNA's for the G or N proteins of VSV were linked to a vaccinia virus promoter and inserted into the vaccinia genome, the recombinants retained infectivity and synthesized VSV polypeptides. After intradermal vaccination with live recombinant virus expressing the G protein, mice produced VSV-neutralizing antibodies and were protected against lethal encephalitis upon intravenous challenge with VSV. In cattle, the degree of protection against intradermalingually injected VSV was correlated with the level of neutralizing antibody produced following vaccination.

  8. Characterization of two truncated forms of xylanase recombinantly expressed by Lactobacillus reuteri with an introduced rumen fungal xylanase gene.

    PubMed

    Cheng, Hsueh-Ling; Hu, Chun-Yi; Lin, Shiou-Hua; Wang, Jing-Ya; Liu, Je-Ruei; Chen, Yo-Chia

    2014-10-01

    The xylanase R8 gene (xynR8) from uncultured rumen fungi was cloned and successfully expressed in Lactobacillus reuteri. A xylanase activity of 132.1 U/mL was found in the broth of L. reuteri R8, the transformant containing pNZ3004 vector with xynR8 gene insertion. Two distinct forms of recombinant xylanase with different hydrophobicities and molecular weights were found in the broth after purification. According to the results of Western blotting, only the T7-tag, fused in the N-terminus of XynR8, could be bound to the expressed proteins, which indicated that the C-terminus of XynR8 had been truncated. These results, combined with tryptic digestion and mass spectrometry analyses, allow us to attribute the two xylanase forms to an optional cleavage of C-terminal sequences, and XynR8A, a 13 amino acid residues truncated form, and XynR8B, a 22 amino acid residues truncated form, were the main products in the extracellular fraction of L. reuteri R8. The specific activities of XynR8A and R8B were 1028 and 395 U/mg protein. Both forms of recombinant xylanase displayed a typical endoxylanase activity when they were reacted with xylan, but XynR8A demonstrated a better specific activity, catalytic efficiency and thermostability than XynR8B according to the results of enzyme characterization. These changes in enzyme properties were highly possibly caused by the present of the β-sheet in the C-terminal undeleted fragment of XynR8A. This study demonstrates that modified forms with different enzyme properties could be produced when a gene was recombinantly expressed by a L. reuteri transformant. PMID:25152410

  9. Nonradioactive assay for new microsatellite polymorphisms at the 5' end of the dystrophin gene, and estimation of intragenic recombination.

    PubMed Central

    Oudet, C; Heilig, R; Hanauer, A; Mandel, J L

    1991-01-01

    Indirect tracking of mutation by DNA polymorphisms is still essential for carrier and prenatal diagnosis of Duchenne/Becker muscular dystrophy, at least in the families where no deletion can be detected. Because of the relatively high level of intragenic recombination, informative and easily testable markers at both ends of the gene are necessary for efficient and accurate diagnosis. We report the characterization of two polymorphic microsatellite sequences (TG repeats) at the 5' end of the dystrophin gene, within 40 kb of the muscle-specific promoter. The most useful one (5' DYS MSA) has 10 alleles with a 57% heterozygosity and can be tested on small polyacrylamide gels in a nonradioactive PCR-based assay. Despite its large number of alleles, this microsatellite shows strong linkage disequilibrium with a two-allele polymorphism reported by Roberts et al., an indication of the stability of this type of sequences. We have used the new microsatellites at the 5' end, along with one we reported previously for the 3' end, to type the families in the CEPH (Centre d'Etude du Polymorphisme Humain) panel. While the number of informative families has increased by a factor of about two with respect to the study of Abbs et al., the estimates of the recombination fractions are in good agreement with this previous report, suggesting a 11% recombination across the gene (3% between the 5' end and the pERT87 region, 8% between pERT87 and the 3' end), which is about fivefold more than expected. However, these estimates still have wide confidence limits. Images Figure 2 Figure 3 Figure 4 Figure 5 PMID:1867193

  10. Developing an extended genomic engineering approach based on recombineering to knock-in heterologous genes to Escherichia coli genome.

    PubMed

    Sukhija, Karan; Pyne, Michael; Ali, Saad; Orr, Valerie; Abedi, Daryoush; Moo-Young, Murray; Chou, C Perry

    2012-06-01

    Most existing genomic engineering protocols for manipulation of Escherichia coli are primarily focused on chromosomal gene knockout. In this study, a simple but systematic chromosomal gene knock-in method was proposed based on a previously developed protocol using bacteriophage λ (λ Red) and flippase-flippase recognition targets (FLP-FRT) recombinations. For demonstration purposes, DNA operons containing heterologous genes (i.e., pac encoding E. coli penicillin acylase and palB2 encoding Pseudozyma antarctica lipase B mutant) engineered with regulatory elements, such as strong/inducible promoters (i.e., P( trc ) and P( araB )), operators, and ribosomal binding sites, were integrated into the E. coli genome at designated locations (i.e., lacZYA, dbpA, and lacI-mhpR loci) either as a gene replacement or gene insertion using various antibiotic selection markers (i.e., kanamycin and chloramphenicol) under various genetic backgrounds (i.e., HB101 and DH5α). The expression of the inserted foreign genes was subjected to regulation using appropriate inducers [isopropyl β-D: -1-thiogalactopyranoside (IPTG) and arabinose] at tunable concentrations. The developed approach not only enables more extensive genomic engineering of E. coli, but also paves an effective way to "tailor" plasmid-free E. coli strains with desired genotypes suitable for various biotechnological applications, such as biomanufacturing and metabolic engineering. PMID:21826554