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At least 163 records · Page 9Linked to original sources
PubMed2005

Arabitol dehydrogenase as a selectable marker for rice.

Arabitol dehydrogenase has been adapted for use as a plant selectable marker. Arabitol is a five-carbon sugar alcohol that can be used by E. coli strain C, but not by the laboratory K12 strains. The enzyme converts the non-plant-metabolizable sugar arabitol into xylulose, which is metabolized by plant cells. Rice was transformed with a plant-expression-optimized synthetic gene using Biolistic-mediated transformation. Selection on 2.75% arabitol and 0.25% sucrose yielded a transformation efficiency (9.3%) equal to that obtained with hygromycin (9.2%). Molecular analyses showed that the atlD gene was integrated into the rice genome of selected plants and was inherited in a Mendelian manner. This study indicates that arabitol could serve as an effective means of plant selection.

Agriculture↗
PubMed2005

Development of plant regeneration and transformation protocols for the desiccation-sensitive weeping lovegrass Eragrostis curvula.

A tissue culture protocol, suitable for transformation, was established for the pasture grass Eragrostis curvula. Callus was generated in the dark from leaf and seed tissues on a medium comprising MS salts supplemented with 2 mg/l 2,4-D, 0.01 mg/l BAP and 2% sucrose. Plant regeneration occurred via organogenesis on the same medium with 6% and 3% sucrose for shoot and root formation, respectively. Optimal regeneration (50 plantlets per callus) occurred when light of 45 micromol/m2 per s was used. The yeast Saccharomyces cerevisiae Hsp12 gene was cloned into the Sac1 of the pCAMBIAUbeeQ vector and callus was transformed by biolistic bombardment. Best transformation (30%) occurred when the target tissue was bombarded twice at a distance of 70 mm using a bombardment pressure of 9,100 kPa. Although successful transformation and transcription of the Hsp12 gene occurred, no Hsp12 protein was found present in tissue extracts of transformed grass.

Agriculture↗
PubMed2007

Generation of secondary small interfering RNA in cell-autonomous and non-cell autonomous RNA silencing in tobacco.

Small interfering RNA (siRNA) species with 21-25 nucleotides in length guide mRNA cleavage, translational arrest, and heterochromatin formation in RNA interference (RNAi). To delineate the target region of RNAi, a construct harboring a transcriptional fusion between parts of the target mRNA and the beta-glucuronidase gene was biolistically delivered into tobacco leaves showing an RNAi phenotype and the assay sequence was transiently expressed. The RNAi effect was monitored by amplification of this chimeric transcript. By using this assay method, we addressed the transitive RNA silencing of a tobacco endoplasmic reticulum omega-3 fatty acid desaturase gene (NtFAD3). In the NtFAD3 RNAi plants, the target region of RNAi was restricted in the inducer region corresponding to a stem sequence of the hairpin double-stranded RNA, indicating that endogenous NtFAD3 mRNA was not a template for an RNA-dependent RNA polymerase. The secondary NtFAD3 siRNAs were produced in the crossbred plants between the NtFAD3 overexpressed plant and the NtFAD3 RNAi plant. Similarly, the secondary siRNAs were generated in the systemically silenced scion. Although these secondary siRNAs originated preferentially from the 3' region downstream of the inducer region, the secondary siRNAs produced in the silenced scion (non-cell autonomous secondary siRNAs) resulted in the strong degradation of the target mRNA, but the secondary siRNAs in the crossbred plants (cell-autonomous secondary siRNAs) showed limited RNA degradation activity. These results showed that this in vivo assay for determination of RNAi efficiency is a useful tool to delineate RNAi mechanisms.

Biolistics↗
PubMed2004

Prevention of long-term IgE antibody production by gene gun-mediated DNA vaccination.

BACKGROUND: Vaccination with allergen-encoding DNA represents a promising approach for the treatment of allergic diseases. OBJECTIVE: In a mouse model of type I allergy, we analyzed the ability of biolistic transfection to inhibit antigen-specific IgE production and to modulate TH2 responses. METHODS: BALB/c mice were vaccinated by means of gene gun-mediated DNA immunization with plasmid vector pCMV-betaGal, encoding beta-galactosidase as a model allergen. Subsequently, mice were immunized by means of repeated intraperitoneal injection of beta-galactosidase adsorbed to the adjuvant aluminum hydroxide. Development of IgE, IgG1, and IgG2a antibody titers during the course of immunization was followed, and anaphylactic potential of sera was determined by using RBL-2H3 degranulation assay. Spleen cells of vaccinated mice and unvaccinated control animals were stimulated in vitro to analyze cytokine production and induction of CD8 + effector T cells. RESULTS: Gene gun-mediated DNA immunization with pCMV-betaGal very efficiently prevented IgE antibody production on a long-term basis. Concomitantly, IgG1 antibody levels in vaccinated mice were strongly reduced, whereas IgG2a antibody production was increased. Analysis of cytokine profiles indicated immune deviation from a TH2-biased response in control mice toward a mixed TH1/TH2 response in vaccinated mice. In addition, substantial numbers of IFN-gamma-producing CD8 + effector T cells were found in vaccinated mice. CONCLUSION: Gene gun-mediated DNA vaccination prevents the induction of long-lasting IgE antibody production.

Animals↗
PubMed2005

Ballistic labeling and dynamic imaging of astrocytes in organotypic hippocampal slice cultures.

Protoplasmic astrocytes in mammalian CNS tissues in vivo have a highly complex 3D morphology, but in dissociated cell cultures they often assume a flattened, fibroblast-like morphology bearing only a few, simple processes. By fluorescent labeling and confocal reconstruction we show that many astrocytes in organotypic hippocampal slice cultures exhibit a more native complex cytoarchitecture. Although astrocytes at the surface of slice cultures show a reactive form with several thick glial fibrillary acidic protein (GFAP)-positive processes, astrocytes situated in deeper portions of tissue slices retain a highly complex 3D morphology with many fine spine- or veil-like protrusions. Dozens of astrocytes can be labeled in single slice cultures by gene gun-mediated ballistic delivery of gold or tungsten particles carrying cDNAs (Biolistics), lipophilic dyes (DiOlistics), or fluorescent intracellular calcium indicators (Calistics). Expression of a membrane-targeted form of eGFP (Lck-GFP) is superior to soluble eGFP for resolving fine astrocytic processes. Time-lapse confocal imaging of Lck-GFP transfected astrocytes or "calistically" labeled astrocytes show structural remodeling and calcium transients, respectively. This approach provides an in vitro system for investigating the functional architecture, development and dynamic remodeling of astrocytes and their relationships to neurons and glia in live mammalian brain tissues.

Animals↗
PubMed2006

Utilization of the venturi effect to introduce micro-particles for epidermal vaccination.

Skin represents a potent immunological induction site, with a dense network of special antigen-presenting cells (APCs) in the epidermal layer. DNA vaccination targeting APCs offers a promising new therapeutic intervention for a wide range of diseases. A unique biomedical device, the venturi powdered injection system (venturi), is proposed for the epidermal delivery of DNA vaccines. The novelty of this hand-held venturi device is in using the venturi effect to entrain DNA-coated micro-particles into an established quasi-steady transonic helium flow and accelerate them to an appropriate momentum for penetrating the skin or mucosal tissue to achieve an immunological effect. In this paper, computational fluid dynamics (CFD) has been employed to scrutinize an experimental venturi device. Key features of gas dynamics and gas-particle interactions have been presented. A parallel extension was added to improve the uniformity of gas and particle flow for a better particle penetration distribution. The overall capability of the venturi biolistic configuration for delivering micro-particles has been explored and discussed. Statistical analysis has shown that the modelled micro-particles have achieved a mean velocity of 654m/s for intracellular DNA vaccine delivery applications.

Antigen-Presenting Cells↗
PubMed2004

DNA immunisation: altering the cellular localisation of expressed protein and the immunisation route allows manipulation of the immune response.

DNA immunisation by intramuscular (IM) injection induces Th1 responses, whereas gene gun (GG) immunisation into the skin stimulates Th2 responses. Three ovalbumin (OVA) cDNA constructs, in which OVA is cytoplasmic (CYT), secreted (SECR), or transmembrane (TM), were compared in immunisation studies using intramuscular injection or biolistic bombardment of the skin. Gene gun immunisation with OVA-CYT or OVA-TM led to strong OVA-specific CTL responses, but not following OVA-SECR immunisation. In contrast, intramuscular immunisation with OVA-SECR or OVA-TM led to potent CTL while immunisation with OVA-CYT was ineffective. OVA-specific antibodies were detected following gene gun immunisation with all three constructs, whereas only the OVA-SECR construct induced antibody production following intramuscular immunisation. These results demonstrate the capacity to manipulate the nature of the immune response by altering the cellular localization of expressed proteins and the route of DNA immunisation.

Animals↗
PubMed2005

Engineering of needle-free physical methods to target epidermal cells for DNA vaccination.

A challenge in epidermal DNA vaccination is the efficient and targeted delivery of polynucleotides to immunologically sensitive Langerhans cells. This paper investigates this particular challenge for physical delivery approaches. The skin immunology and material properties are examined in the context of the physical cell targeting requirements of the viable epidermis. Selected current physical cell targeting technologies engineered to meet these needs are examined: needle and syringe; diffusion patches; liquid jet injectors; microneedle arrays/patches; and biolistic particle injection. The operating methods and relative performance of these approaches are discussed, with a comment on potential future developments and technologies.

Biolistics↗
PubMed2002

Brugia malayi: transient transfection by microinjection and particle bombardment.

To develop a method for the introduction of DNA into filarial parasites, several methods that have proven successful in other organisms were evaluated for their ability to transform Brugia malayi. Luciferase activity was detectable in embryos bombarded with gold particles coated with a construct consisting of a luciferase reporter gene under the control of the 5S rRNA intergenic spacer (SL promoter). Similar results were seen in adult parasites and infective larvae bombarded with this construct, or in adult female parasites microinjected with the plasmid. In similar experiments employing the SL promoter driving a green fluorescent protein (GFP) reporter, expression of the reporter was detectable in the intrauterine embryos of the microinjected adult parasites, and in the sub-cuticular tissues of biolistically transfected adult female parasites. A similar pattern of GFP expression to that seen in the SL promoter construct transfected parasites was noted in parasites transfected with constructs consisting of the upstream domain derived from an aspartyl aminoacyl tRNA synthetase gene of B. malayi. The ability to transfect B. malayi embryos may provide a foundation for studies of the regulation of gene expression and function in these organisms.

Animals↗
PubMed2003

The Potato virus X TGBp3 protein associates with the ER network for virus cell-to-cell movement.

Potato virus X (PVX) TGBp3 is required for virus cell-to-cell movement. Cell-to-cell movement of TGBp3 was studied using biolistic bombardment of plasmids expressing GFP:TGBp3. TGBp3 moves between cells in Nicotiana benthamiana, but requires TGBp1 to move in N. tabacum leaves. In tobacco leaves GFP:TGBp3 accumulated in a pattern resembling the endoplasmic reticulum (ER). To determine if the ER network is important for GFP:TGBp3 and for PVX cell-to-cell movement, a single mutation inhibiting membrane binding of TGBp3 was introduced into GFP:TGBp3 and into PVX. This mutation disrupted movement of GFP:TGBp3 and PVX. Brefeldin A, which disrupts the ER network, also inhibited GFP:TGBp3 movement in both Nicotiana species. Two deletion mutations, that do not affect membrane binding, hindered GFP:TGBp3 and PVX cell-to-cell movement. Plasmids expressing GFP:TGBp2 and GFP:TGBp3 were bombarded to several other PVX hosts and neither protein moved between adjacent cells. In most hosts, TGBp2 or TGBp3 cannot move cell-to-cell.

Amino Acid Sequence↗
PubMed2001

Mechanical transmission of poleroviruses.

Previously, transmission of poleroviruses has relied solely on the use of their aphid vectors. Biolistic inoculation allowed for the first time the mechanical transmission of Beet western yellows virus (BWYV) and Potato leafroll virus (PLRV) to several host plants. Inoculation with purified preparations and viral RNA extracts of PLRV resulted in 30-50% systemically infected Nicotiana occidentalis P1 plants and 15-30% infected Nicotiana clevelandii plants. Particle bombardment was also used successfully to infect N. clevelandii plants with in vitro RNA transcripts of full-length cDNA of BWYV.

Animals↗
PubMed2002

Resistance to wheat streak mosaic virus in transgenic wheat engineered with the viral coat protein gene.

Wheat (Triticum aestivum) plants were stably transformed with the coat protein (CP) gene of wheat streak mosaic virus (WSMV) by the biolistic method. Eleven independently transformed plant lines were obtained and five were analyzed for gene expression and resistance to WSMV. One line showed high resistance to inoculations of two WSMV strains. This line had milder symptoms and lower virus titer than control plants after inoculation. After infection, new growth did not show symptoms. The observed resistance was similar to the 'recovery' type resistance described previously using WSMV NIb transgene and in other systems. This line looked morphologically normal but had an unusually high transgene copy number (approximately 90 copies per 2C homozygous genome). Northern hybridization analysis indicated a high level of degraded CP mRNA expression. However, no coat protein expression was detected.

Biolistics↗
PubMed2003

Foot-and-mouth disease virus VP1 protein fused with cholera toxin B subunit expressed in Chlamydomonas reinhardtii chloroplast.

A Chlamydomonas reinhardtii chloroplast expression vector, pACTBVP1, containing the fusion of the foot and mouth disease virus (FMDV) VP1 gene and the cholera toxin B subunit (CTB) gene was constructed and transfered to the chloroplast genome of C. reinhardtii by the biolistic method. The transformants were identified by PCR, Southern blot, Western blot and ELISA assays after selection on resistant medium and incubation in the dark. The CTBVP1 fusion protein was expressed in C. reinhardtii chloroplast and accounted for up to 3% of the total soluble protein. The fusion protein also retained both GM1-ganglioside binding affinity and antigenicity of the FMDV VP1 and CTB proteins. These experimental results support the possibility of using transgenic chloroplasts of green alga as a mucosal vaccine source.

Animals↗
PubMed2002

Optimization of sorghum transformation parameters using genes for green fluorescent protein and beta-glucuronidase as visual markers.

Early and reliable detection of plant transformation events is essential for establishing efficient transformation protocols. We have compared the effectiveness of using the gene encoding a green fluorescent protein (GFP) and a beta-glucuronidase (gus) as reporter genes for early detection of transgene expression in explants subjected to biolistic bombardment and Agrobacterium-mediated transformation. The results indicate that gfp gene is superior to gus gene in following transgene expression in transiently transformed materials in both methods of transformation. Using GFP as the screenable marker, we have optimized sorghum transformation with respect to the conditions for transformation, type of explants, promoters, and inbreds. These optimized conditions have been used to obtain stably transformed explants for subsequent regeneration.

Biolistics↗
PubMed2001

Direct transfection and activation of human cutaneous dendritic cells.

Gene therapy techniques can be important tools for the induction and control of immune responses. Antigen delivery is a critical challenge in vaccine design, and DNA-based immunization offers an attractive method to deliver encoded transgenic protein antigens. In the present study, we used a gene gun to transfect human skin organ cultures with a particular goal of expressing transgenic antigens in resident cutaneous dendritic cells. Our studies demonstrate that when delivered to human skin, gold particles are observed primarily in the epidermis, even when high helium delivery pressures are used. We demonstrate that Langerhans cells resident in the basal epidermis can be transfected, and that biolistic gene delivery is sufficient to stimulate the activation and migration of skin dendritic cells. RT-PCR analysis of dendritic cells, which have migrated from transfected skin, demonstrates the presence of transgenic mRNA, indicating direct transfection of cutaneous dendritic cells. Importantly, transfected epidermal Langerhans cells can efficiently present a peptide derived from the transgenic melanoma antigen MART-1 to a MART-1-specific CTL. Taken together, our results demonstrate direct transfection, activation, and antigen-specific stimulatory function of in situ transduced human Langerhans cells.

Biolistics↗
PubMed1999

Genetic engineering of the multicellular green alga Volvox: a modified and multiplied bacterial antibiotic resistance gene as a dominant selectable marker.

The green alga Volvox represents the simplest multicellular organism: Volvax is composed of only two cell types, somatic and reproductive. Volvox, therefore, is an attractive model system for studying various aspects of multicellularity. With the biolistic nuclear transformation of Volvox carteri, the powerful molecular genetic manipulation of this organism has been established, but applications have been restricted to an auxotrophic mutant serving as the DNA recipient. Therefore, a dominant selectable marker working in all strains and mutants of this organism is required. Among several gene constructs tested, the most advantageous results were obtained with a chimeric gene composed of the coding sequence of the bacterial ble gene, conferring resistance to the antibiotic zeocin, modified with insertions of two endogenous introns from the Volvox arylsulfatase gene and fused to 5' and 3' untranslated regions from the Volvox beta 2-tubulin gene. In the most suitable plasmid used, the gene dosage was increased 16-fold by a technique that allows exponential multiplication of a DNA fragment. Co-transformation of this plasmid and a non-selectable plasmid allowed the identification of zeocin resistant transformants with nuclear integration of both selectable and non-selectable plasmids. Stable expression of the ble gene and of genes from several non-selectable plasmids is demonstrated. The modified ble gene provides the first dominant marker for transformation of both wild-type and mutant strains of Volvox.

3' Untranslated Regions↗
PubMed2001

Distribution of an NMDA receptor:GFP fusion protein in sensory neurons is altered by a C-terminal construct.

The NMDA receptor plays an important role in mediating sensory input to the spinal cord. Domains within the C-terminus of the NMDA receptor bind to cytoskeletal proteins and facilitate membrane targeting and synaptic clustering, and may participate in regulation of receptor function. One strategy to manipulate NMDA receptor function is to express C-terminal constructs in neurons to disrupt synaptic clustering via competition for binding motifs in cytoskeletal proteins and postsynaptic densities. Biolistic particle-mediated gene transfer was used to deliver plasmid DNA into organotypic cultures of dorsal root ganglia (DRG). Fusion proteins consisting of recombinant (r)NMDA receptor subunit 1-1 (rNR1-1) deletion constructs and enhanced green fluorescent protein (GFP) were expressed in sensory neurons and demonstrated unique distribution patterns within the cell. Expression of the full length rNR1-1:GFP construct was cytosolic and localized to membranous patches similar to endogenous NR1-1 protein expression in sensory neurons. Expression of a construct containing only the C-terminus, GFP:C0C1C2, demonstrated nuclear and membranous localization. When the GFP:C0C1C2 construct was co-expressed with rNR1-1 in sensory neurons, membranous localization of rNR1-1 was disrupted. In contrast, co-expression of a C-terminal cassette lacking the C1 exon cassette, GFP:C0C2, with rNR1-1 did not alter the membranous distribution of rNR1-1. This observation verifies the utility of a gene transfer strategy to diminish membranous NR1-1 content by expressing a construct containing the C1 exon cassette.

Active Transport, Cell Nucleus↗
PubMed2004

Simple and complex nuclear loci created by newly transferred chloroplast DNA in tobacco.

Transfer of organelle DNA into the nuclear genome has been significant in eukaryotic evolution, because it appears to be the origin of many nuclear genes. Most studies on organelle DNA transfer have been restricted to evolutionary events but experimental systems recently became available to monitor the process in real time. We designed an experimental screen to detect plastid DNA (ptDNA) transfers to the nucleus in whole plants grown under natural conditions. The resultant genotypes facilitated investigation of the evolutionary mechanisms underlying ptDNA transfer and nuclear integration. Here we report the characterization of nuclear loci formed by integration of newly transferred ptDNA. Large, often multiple, fragments of ptDNA between 6.0 and 22.3 kb in size are incorporated into chromosomes at single Mendelian loci. The lack of chloroplast transcripts of comparable size to the ptDNA integrants suggests that DNA molecules are directly involved in the transfer process. Microhomology (2-5 bp) and rearrangements of ptDNA and nuclear DNA were frequently found near integration sites, suggesting that nonhomologous recombination plays a major role in integration. The mechanisms of ptDNA integration appear similar to those of biolistic transformation of plant cells, but no sequence preference was identified near junctions. This article provides substantial molecular analysis of real-time ptDNA transfer and integration that has resulted from natural processes with no involvement of cell injury, infection, and tissue culture. We highlight the impact of cytoplasmic organellar genome mobility on nuclear genome evolution.

Base Sequence↗