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Results for “Plants, Genetically Modified”

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At least 73 records · Page 4Linked to original sources
PubMed2005

Site-specific recombination in Zea mays.

The elimination of marker genes after selection is recommended for the commercial use of genetically modified plants. We compared the applicability of the two site-specific recombination systems Cre/lox and Flp/FRT for marker gene elimination in maize plants. The selection marker gene pat surrounded by two identically directed lox or FRT sites was introduced into maize. Sexual crossing with plants harboring the corresponding constitutively expressed recombinase led to the precise and complete excision of the lox-flanked marker gene in the F1 progeny, whereas Flp-mediated recombination of FRT sequences occurred rarely. Further examination of site-specific integration was done by biolistic bombardment of immature embryos harboring only one lox site with a lox.uidA sequence with results indicating directed integration.

Bacteriophage P1↗
PubMed2002

Approaches to assessment of the allergenic potential of novel proteins in food from genetically modified crops.

The safety assessment of food derived from genetically modified plants continues to attract considerable attention. Among the important issues that need to be considered is whether the products of novel genes introduced into crop plants will have the potential to induce allergic sensitization or to elicit allergic disease. Hierarchical approaches to allergenicity testing have been proposed, and these incorporate evaluation of the structural and sequence homology and serological identity of novel proteins with known allergens, measurement of resistance to proteolytic digestion, and assessment of allergenic potential using animal models. Accounts of these approaches are available elsewhere, and it is not the purpose of this article to provide a detailed critique of specific methods. Our intention is rather to look more broadly at the strategy for assessment of allergenic potential, the challenges such assessments pose for the practicing toxicologist, and how some of these might best be addressed.

Allergens↗
PubMed2006

Bisexual sterility conferred by the differential expression of barnase and barstar: a simple and efficient method of transgene containment.

To establish a simple and an efficient system to minimize the environmental risk of genetically modified plants, we tested the applicability of the barnase/barstar system in conferring bisexual sterility; that is, in preventing plants setting seeds by self-fertilization and out-crossing. Transgenic tobacco plants were generated to express barnase, a cell death inducing ribonuclease, under the control of the gamete-specific AtDMC1 promoter, and barstar, a specific inhibitor of barnase, under the control of the ACT2 promoter, which is constitutively active in almost all tissues except gametes. In contrast to control plants harboring the barstar expression unit only, which set seeds normally with self-pollination, all transformants harboring both barnase and barstar were bisexually sterile. They produced aberrant anthers containing no detectable pollen and failed to set seeds even after pollination with wild-type tobacco pollen.

Arabidopsis↗
PubMed2003

Consumption of snowdrop lectin (Galanthus nivalisagglutinin) causes direct effects on adult parasitic wasps.

Honeydew is a common sugar-rich excretion of aphids and other phloem-feeding insects and represents the primary sugar in many agricultural systems. When honeydew-producing insects feed on genetically modified plants, the honeydew can contain amounts of the transgene product. Here we address whether this route of exposure poses a risk for non-target insects. Three species of parasitic wasps were selected: i.e. Aphidius colemani, Trichogramma brassicae and Cotesia glomerata, all of which are known to use honeydew as a carbohydrate source in the field. Wasps were fed sucrose solutions with varying concentrations of snowdrop lectin ( Galanthus nivalisagglutinin, GNA), a protein that has been engineered into crops to confer resistance against homopteran pests and that has been detected in honeydew. Parameters evaluated included gustatory response, longevity, fecundity, progeny emergence and sex ratio. While A. colemani and T. brassicae, but not C. glomerata, were able to detect GNA, this gustatory recognition had no effect on the acceptance of a GNA-sucrose solution. In all three species, GNA ingestion reduced parasitoid survival significantly. However, in respect to fecundity, negative effects were observed for T. brassicae but not for A. colemani. The results suggest that the effect of GNA consumption may depend on the specifics of a parasitoid's biology, especially its longevity and its mode of egg maturation.

Animals↗
PubMed2004

Persistence of DNA studied in different ex vivo and in vivo rat models simulating the human gut situation.

This study aimed to evaluate the possibility of DNA sequences from genetically modified plants to persist in the gastrointestinal (GI) tract. PCR analysis and transformation assays were used to study DNA persistence and integrity in various ex vivo and in vivo systems using gnotobiotic rats. DNA studied was either plasmid DNA, naked plant DNA or plant DNA embedded in maize flour. Ex vivo experiments performed by incubating plant DNA in intestinal samples, showed that DNA is rapidly degraded in the upper part of the GI tract whereas degradation is less severe in the lower part. In contrast, plasmid DNA could be recovered throughout the GI tract when intestinal samples were taken up to 5 h after feeding rats with plasmid. Furthermore, DNA isolated from these intestinal samples was able to transform electro-competent Escherichia coli, showing that the plasmid was still biologically active. The results indicate that ingested DNA may persist in the GI tract and consequently may be present for uptake by intestinal bacteria.

Animals↗
PubMed2004

Detection and traceability of genetically modified organisms in the food production chain.

Both labelling and traceability of genetically modified organisms are current issues that are considered in trade and regulation. Currently, labelling of genetically modified foods containing detectable transgenic material is required by EU legislation. A proposed package of legislation would extend this labelling to foods without any traces of transgenics. These new legislations would also impose labelling and a traceability system based on documentation throughout the food and feed manufacture system. The regulatory issues of risk analysis and labelling are currently harmonised by Codex Alimentarius. The implementation and maintenance of the regulations necessitates sampling protocols and analytical methodologies that allow for accurate determination of the content of genetically modified organisms within a food and feed sample. Current methodologies for the analysis of genetically modified organisms are focused on either one of two targets, the transgenic DNA inserted- or the novel protein(s) expressed- in a genetically modified product. For most DNA-based detection methods, the polymerase chain reaction is employed. Items that need consideration in the use of DNA-based detection methods include the specificity, sensitivity, matrix effects, internal reference DNA, availability of external reference materials, hemizygosity versus homozygosity, extrachromosomal DNA, and international harmonisation. For most protein-based methods, enzyme-linked immunosorbent assays with antibodies binding the novel protein are employed. Consideration should be given to the selection of the antigen bound by the antibody, accuracy, validation, and matrix effects. Currently, validation of detection methods for analysis of genetically modified organisms is taking place. In addition, new methodologies are developed, including the use of microarrays, mass spectrometry, and surface plasmon resonance. Challenges for GMO detection include the detection of transgenic material in materials with varying chromosome numbers. The existing and proposed regulatory EU requirements for traceability of genetically modified products fit within a broader tendency towards traceability of foods in general and, commercially, towards products that can be distinguished from each other. Traceability systems document the history of a product and may serve the purpose of both marketing and health protection. In this framework, segregation and identity preservation systems allow for the separation of genetically modified and non-modified products from "farm to fork". Implementation of these systems comes with specific technical requirements for each particular step of the food processing chain. In addition, the feasibility of traceability systems depends on a number of factors, including unique identifiers for each genetically modified product, detection methods, permissible levels of contamination, and financial costs. In conclusion, progress has been achieved in the field of sampling, detection, and traceability of genetically modified products, while some issues remain to be solved. For success, much will depend on the threshold level for adventitious contamination set by legislation.

Animals↗
PubMed2006

Random amplified polymorphic DNA analysis of genetically modified organisms.

Randomly amplified polymorphic DNA (RAPD) was used to analyzed 78 samples comprises of certified reference materials (soya and maize powder), raw seeds (soybean and maize), processed food and animal feed. Combination assay of two arbitrary primers in the RAPD analysis enable to distinguish genetically modified organism (GMO) reference materials from the samples tested. Dendrogram analysis revealed 13 clusters at 45% similarity from the RAPD. RAPD analysis showed that the maize and soybean samples were clustered differently besides the GMO and non-GMO products.

Food Analysis↗
PubMed2002

Agricultural biotechnology and the UK public.

It might be an exaggeration to claim that UK agriculture is in a state of crisis, but it is certainly a time for decisions. Uncertainties abound: the implications of growing free trade; a steady reduction in subsidies; the ongoing drift of people to towns and what some regard as the stranglehold of retailers both on food prices and on what the farmer gets. To all of this has to be added the backwash of bovine spongiform encephalopathy (BSE) and foot-and-mouth disease (FMD), and the advent of new technologies, especially those based on modern genetics.

Agriculture↗