[Genetic engineering].
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OBJECTIVE: To determine whether perceived benefit alters personal risk perception associated with eating genetically engineered soybeans, consumer desire for labeling, preferred phrase on a label symbol, and desired information in an educational brochure. DESIGN: Comparison of responses of two consumer groups who completed one of two survey versions. SUBJECTS/SETTINGS: One hundred fifty supermarket shoppers, age 21 years and older, for each survey or n=300 total. Focus groups and a pilot test were used to develop the final survey in which consumers read a description of a genetically engineered soybean with either no obvious consumer benefit or an obvious consumer benefit and then completed a set of attitude questions and evaluated a voluntary label design and educational brochure content. Main outcome measures were mean opinion scores of personal risk and desire for labeling and ranking of desired label phrase and brochure topics. STATISTICAL ANALYSIS: Chi;(2) and t Tests were used. RESULTS: Consumers reading about the soybean with obvious consumer benefit were significantly more comfortable eating these than those reading about the soybean with no obvious consumer benefit (2.9+/-1.1 vs 3.4+/-1.0, respectively; P</=.001). However, the groups did not differ in desire for labeling of foods made with these soybeans or preferred brochure content. They did differ significantly in preferred phrase on the symbol (P</=.05). APPLICATIONS/CONCLUSIONS: Dietitians can use descriptions of genetic engineering applications such as those in this study to help consumers assess these applications. Dietitians can play a critical role in explaining labeling terms and designing educational materials when the FDA finalizes voluntary labeling regulations for genetically engineered foods.
Viral vector recombinant DNA vaccines, so called genetically engineered vaccines, are introduced directly into cells to induce an antigen specific immune response. This is a new approach to vaccination that represents a new concept in immunotherapy, which attempts to induce a long-term effective, anti-specific, viral antigen immune response. These vaccines may also prove more potent than currently used vaccines when it comes to inducing cellular immune responses in addition to humoral immune response. In the case of influenza, an immune response with humoral characteristics was induced using an influenza hemagglutinin(HA) DNA vaccine. On the other hand, injection of influenza virus nucleoprotein(NP) induced a Th-1 type cellular immune response including CTL. Genetically engineered vaccines have the potential to effectively overcome the problem of unresponsiveness to currently used vaccines.
BACKGROUND: Vaccination of tumor-bearing animals with tumor cells genetically engineered to secrete cytokines including interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) has been shown to induce effective tumor-specific immune responses capable of inhibiting local and metastatic disease. Previous unsuccessful attempts to enhance this immune response by means of the secretion of multiple cytokines possessing different immunologic mechanisms of action may have been due to the inherent inefficiency of the gene transfer systems used. We postulated that tumor cells genetically engineered by means of a novel gene transfer method resulting in high level secretion of both cytokines would be more effective than tumor cells secreting a single cytokine in inhibiting the growth of existing tumors. METHODS: Nonimmunogenic, murine pancreatic cancer cells (Panc02) were engineered to secrete IL-2, IFN-gamma, IL-2 and IFN-gamma, or neomycin phosphotransferase. Mice were inoculated with 5 x 10(5) parental Panc02 tumor cells subcutaneously. Beginning 3 days later, animals then received a series of four weekly vaccinations with irradiated Panc02/Neo, Panc02/IL2, Panc02/IFN, or Panc02/IL-2/IFN. RESULTS: Treatment with Panc02/Neo, Panc02/IL-2, or Panc02/IFN resulted in 0%, 40%, and 30% tumor-free survival, respectively. In contrast, 80% of animals vaccinated with Panc02/IL2/IFN were free of tumor at 100 days. All animals free of disease were resistant to subsequent tumor challenges. CONCLUSIONS: These data show that vaccination with tumor cells that secrete high levels of multiple cytokines was more effective in treating established pancreatic tumors and represents an improvement over existing single cytokine strategies.
Chloroplast genetic engineering offers a number of unique advantages, including high-level transgene expression, multigene engineering in a single transformation event, transgene containment via maternal inheritance, lack of gene silencing, position and pleiotropic effects and undesirable foreign DNA. More than 40 transgenes have been stably integrated and expressed via the tobacco chloroplast genome to confer desired agronomic traits or express high levels of vaccine antigens and biopharmaceuticals. Despite such significant progress, this technology has not been extended to other important plant species. For example, Arabidopsis may be an ideal model system for chloroplast functional genomics. The employment of chloroplast transformation technology in Arabidopsis has been hampered by the lack of an efficient and reproducible protocol that provides fertile chloroplast transgenic plants. Transformation of the Arabidopsis chloroplast genome was achieved via organogenesis but the efficiency was at least a 100-fold lower than in tobacco and had the drawback of polyploidy in the leaf tissue that resulted in sterile transgenic plants. This problem can be overcome by adapting procedures that are now available to regenerate plants from both diploid and tetraploid explants via callus. In addition, it is feasible to regenerate Arabidopsis via somatic embryogenesis. Recent breakthroughs in highly efficient plastid transformation of recalcitrant crops such as cotton and soybean have opened the possibility of engineering Arabidopsis plastid genome via somatic embryogenesis. Therefore, protocols of recent improvements in tissue culture, DNA delivery, and the novel vector designs are provided here in order to achieve highly efficient plastid transformation in Arabidopsis.
"Manipulation" per se is not bad. The crucial question in the moral debate about genetic engineering is: When and how are we allowed to manipulate? Unfortunately, the moral discussion surrounding this question is itself being manipulated. There are moral manipulations (by those who wish to either reassure or to alarm) and there are ethical manipulations (the failed utilitarian calculus and the centering of the discussion only around rules, rights, and duties). A different ethical approach is needed: one based on virtues. The duty of ethics is to help us understand the moral possibilities in each situation, i.e., to develop our moral sensibility. In the area of genetic engineering research we are motivated by a will to know, but at the same time we fear total self knowledge. We want to control, to improve our world and ourselves, but we recoil at obtaining ultimate perfection. Therefore, we must value the unknowable, the uncontrollable. Our everincreasing capacity to mould the world and ourselves is making it more difficult to develop a sensitivity for what is given and cannot be made. It is dangerous for our ethics to assume the activistic traits of our technology. We risk losing a fundamental element of what we are, or ought to be. We should train ourselves in moral passivity.
The present state of genetic engineering (GE) of forest woody plants is considered with special reference to the materials of the International Conference "Wood, Breeding, Biotechnology and Industrial Expectations" held in France in June, 2001. Main tree species subjected to GE are listed, aims of constructing transgenic plants discussed, and methods described. Major achievements in the field are considered along with the problems associated with the employment of GE in the breeding of forest woody plants.
Monoclonal antibodies (MAbs) may be considered 'magic bullets' due to their ability to recognize and eradicate malignant cells. MAbs, however, have practical limitations for their rapid application in the clinics. The structure of antibody molecules can be engineered to modify functional domains such as antigen-binding sites and/or effector functions. Advances in genetic engineering have provided rapid progress in the development of new immunoglobulin constructs of MAbs with defined research and therapeutic application. Recombinant antibody constructs are being engineered, such as human-mouse chimeric, domain-dispositioned, domain-deleted, humanized and single-chain Fv fragments. Genetically-engineered antibodies differ in size and rate of catabolism. Pharmacokinetic studies show that the intact IgG (150 kD), enzymatically derived fragments Fab' (50 kD) and single chain Fv (28 kD) have different clearance rates. These antibody forms clear 50% from the blood pool in 2.1 days, 30 minutes and 10 minutes, respectively. Genetically-engineered antibodies make a new class of immunotherapeutic tracers for cancer treatment.
Genetic engineering and screening in human cells are powerful techniques for the precise and comprehensive identification and analysis of gene and protein domain functions. Genome-wide knockout screens have been extensively utilized to discover essential genes, tumor suppressors, and genes that regulate responses to various chemicals, including antimitotic and therapeutic drugs. The advent of base editors, which facilitate the targeted mutation of single amino acids, has advanced the identification of critical and functional domains or motifs. In this context, we outline methods for creating efficient base editor and inducible knockout cell lines for targeted gene manipulation and conducting genetic screens to elucidate the roles of genes and their domains within a specific cell biological context.
This paper examines issues concerned with the environmental release of genetically-engineered micro-organisms. Besides the obvious social and economic benefits from the technology, genetically-engineered micro-organisms can have considerable beneficial effects on environmental concerns, such as the degradation of pollutants and toxic chemical wastes, and less use of hazardous pesticides and chemicals. There may be uncertain negative effects arising from the technology. The hazards of the technology and possible policy approaches are discussed. It is concluded that, overall, the applications arising from this technology are likely to be benign, because its effects on the environment can largely be anticipated by an increase in scientific knowledge gained from field trials and greater experience with releases.
Until recent years, plant genetic was involved in heredity studies through the analysis of segregations in progenies after crossing. New potentiality arose as genetic tools with the use of dissociated plant elements, transforming and cultivating them in vitro. When plants are regenerated from manipulated tissues, new structures of varieties (clones) new genotypes (transgenic plants) and new regulations of genes expression (vitrovariants) open new ways for plant genetic engineering. Progressively these technological tools are integrated in the methods of plant breeding. Yet all possible consequences of these new types of heredity and of these new genetic structures must be evaluated. As first priority the analysis of possible incidences in the field of food, nutrition and health gives the basis for diagnostics and organisations aiming to avoid the release of genotypes which could have unwanted effects.
Mouse fibroblasts (H-2(b)) were genetically engineered to express a costimulatory B7.1 and an interleukin-7 (IL-7; Fb/B7.1/IL7). The Fb/B7.1/IL7 cells were then pulsed with an ovalbumin (OVA) epitope (amino acids 257-264, SIINFEKL, H-2 K(b) restricted; Fb/B7. 1/IL7/OVA) and tested for the induction of OVA-specific cytotoxic T lymphocytes (CTLs) in C57BL/6 mice (H-2(b)). The genetically engineered fibroblasts lacking either B7.1 or IL-7 were constructed and used as controls. Immunization with the Fb/B7.1/IL7/OVA cells induced strong cytotoxic activities against OVA-expressing EL4 (EG7) tumor cells. The magnitude of the cytotoxic response in mice with the Fb/B7.1/IL7/OVA cells was significantly higher than the response in mice immunized with any other cell constructs. CD8(+) T cells were a major effector cell-type of antitumor response in the immunized mice with the Fb/B7.1/IL7/OVA cells. Furthermore, immunization with the Fb/B7.1/IL7/OVA cells significantly prolonged the survival period of mice when the mice were injected with EG7 tumor cells one week after the immunization. These results suggest that fibroblasts can be genetically modified to an efficient cell vaccine for the induction of antitumor response.
Erythropoietin (Epo) is a glycoprotein hormone produced by genetic engineering. Many pathologic conditions could benefit from its administration, such as chronic renal failure or hemoglobinopathies. Epo secretion from genetically modified tissued could be proposed to patients only if the protocol is low cost and low risk. For that purpose, retroviral vectors and adeno-associated vectors expressing the Epo cDNA were developed. Gene transfer was performed into skeletal muscles. To avoid polycythemia, a tetracycline-regulated system was used to control the levels of protein secretion in vivo. beta-thalassemias are among diseases that could benefit from an Epo gene transfer. beta-thalassemias are attributable to deficient synthesis of beta-globin and accumulation of unpaired alpha-chains. Stimulation of fetal globin synthesis is one strategy to correct the globin chain imbalance. There is evidence that Epo could play this role. In a mouse model of beta-thalassemia, an adeno-associated vector expressing the Epo cDNA was injected intramuscularly. Epo was secreted continuously during at least 1 yr. Erythropoiesis was improved in those mice by increasing the synthesis of fetal hemoglobin.
Major crop losses occur annually as a result of biotic and abiotic stresses. The ability to hyperexpress foreign proteins, single-step multigene engineering, lack of positive effect and gene silencing, vector sequences and pleiotropic effects have resulted in several hundred-fold more tolerance to the environmental stresses via chloroplast genetic engineering than nuclear genetic engineering. Maternal inheritance of chloroplast expressed transgenes renders the technology environmentally safe and promotes public acceptance. This review provides protocols for engineering agronomic traits like insect, herbicide and disease resistance; salt and drought tolerance; and phyto-remediation via chloroplast genome.
The use of a variety of genetic-engineering techniques to introduce foreign DNA into living yeast cells has resulted in the production in these cells of the corresponding proteins. These include enzymes, antibodies, vaccines, anti-viral agents, and hormones. This article discusses the techniques of genetic engineering in yeast and suggests the lines of future progress in the economic production of novel proteins for use in therapy.