Isolation and spectroscopic characterization of a recombinant bell pepper hydroperoxide lyase.
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Fatty acid hydroperoxide (HPO) lyase is a component of the oxylipin pathway and holds a central role in elicited plant defense. HPO lyase from bell pepper has been identified as a heme protein which shares 40% homology with allene oxide synthase, a cytochrome P450 (CYP74A). HPO lyase of immature bell pepper fruits was expressed in Escherichia coli and the enzyme was purified and characterized by spectroscopic techniques. The electronic structure and ligand coordination properties of the heme were investigated by using a series of exogenous ligands. The various complexes were characterized by using UV-visible absorption and electron paramagnetic resonance spectroscopy. The spectroscopic data demonstrated that the isolated recombinant HPO lyase has a pentacoordinate, high-spin heme with thiolate ligation. Addition of the neutral ligand imidazole or the anionic ligand cyanide results in the formation of hexacoordinate adducts that retain thiolate ligation. The striking similarities between both the ferric and ferrous HPO lyase-NO complexes with the analogous P450 complexes, suggest that the active sites of HPO lyase and P450 share common structural features. (+info)
Genetically modified plants and human health risks: Can additional research reduce uncertainties and increase public confidence?
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So long as the risks to human health from transgenic plants remain potential rather than actual, and, in any event, appear lower than those from traditional plant breeding, hazard assessment need not be extensive. However, in view of current public attitudes to transgenic plants, it is necessary that those tests that are required, be based on logic, on sound science, and in accordance with the best scientific methodology. This is particularly the case with testing for food allergenicity. Current testing is largely indirect and based on comparisons with other known food allergens. Development of direct tests that involve interaction between the actual transgenic protein in question and the immune system is essential if confidence in the regulatory system is to be restored. (+info)
Antimutagenic activity against trp-P-1 of the edible Thai plant, Oroxylum indicum vent.
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A methanolic extract of Oroxylum indicum strongly inhibited the mutagenicity of Trp-P-1 in an Ames test. The major antimutagenic constituent was identified as baicalein with an IC50 value of 2.78+/-0.15 microM. The potent antimutagenicity of the extract was correlated with the high content (3.95+/-0.43%, dry weight) of baicalein. Baicalein acted as a desmutagen since it inhibited the N-hydroxylation of Trp-P-2. (+info)
Starlink corn: a risk analysis.
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Modern biotechnology has dramatically increased our ability to alter the agronomic traits of plants. Among the novel traits that biotechnology has made available, an important group includes Bacillus thuringiensis-derived insect resistance. This technology has been applied to potatoes, cotton, and corn. Benefits of Bt crops, and biotechnology generally, can be realized only if risks are assessed and managed properly. The case of Starlink corn, a plant modified with a gene that encodes the Bt protein Cry9c, was a severe test of U.S. regulatory agencies. The U.S. Environmental Protection Agency had restricted its use to animal feed due to concern about the potential for allergenicity. However, Starlink corn was later found throughout the human food supply, resulting in food recalls by the Food and Drug Administration and significant disruption of the food supply. Here we examine the regulatory history of Starlink, the assessment framework employed by the U.S. government, assumptions and information gaps, and the key elements of government efforts to manage the product. We explore the impacts on regulations, science, and society and conclude that only significant advances in our understanding of food allergies and improvements in monitoring and enforcement will avoid similar events in the future. Specifically, we need to develop a stronger fundamental basis for predicting allergic sensitization and reactions if novel proteins are to be introduced in this fashion. Mechanisms are needed to assure that worker and community aeroallergen risks are considered. Requirements are needed for the development of valid assays so that enforcement and post market surveillance activities can be conducted. (+info)
Milestones in chloroplast genetic engineering: an environmentally friendly era in biotechnology.
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Chloroplast genomes defied the laws of Mendelian inheritance at the dawn of plant genetics, and continue to defy the mainstream approach to biotechnology, leading the field in an environmentally friendly direction. Recent success in engineering the chloroplast genome for resistance to herbicides, insects, disease and drought, and for production of biopharmaceuticals, has opened the door to a new era in biotechnology. The successful engineering of tomato chromoplasts for high-level transgene expression in fruits, coupled to hyper-expression of vaccine antigens, and the use of plant-derived antibiotic-free selectable markers, augur well for oral delivery of edible vaccines and biopharmaceuticals that are currently beyond the reach of those who need them most. (+info)
Possible involvement of the local renin-angiotensin system in exocrine pancreas responses to food components.
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The functioning of the exocrine and endocrine pancreas is strictly co-ordinated through an interdependent array of neural and endocrine, paracrine and autocrine hormonal factors. The responses of the exocrine pancreas to food are primarily initiated via hormones secreted by neuroendocrine cells in the gut. No role for the pancreatic renin-angiotensin system in these mechanisms has so far been established. However, because of its distribution throughout the pancreas, the renin-angiotensin system could have a function in fine-tuning of secretory responses or in integrating some of the actions of the endocrine and exocrine pancreas. In the normal diet, we are exposed to an array of bioactive (lectins, protease inhibitors, hormone-mimics, tannins, etc). Some can profoundly alter pancreas metabolism both in a beneficial or detrimental manner. Others could have beneficial effects on the pancreas renin-angiotensin system. The effects of these compounds need to be evaluated. (+info)
A systematic screening of total antioxidants in dietary plants.
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A predominantly plant-based diet reduces the risk for development of several chronic diseases. It is often assumed that antioxidants contribute to this protection, but results from intervention trials with single antioxidants administered as supplements quite consistently do not support any benefit. Because dietary plants contain several hundred different antioxidants, it would be useful to know the total concentration of electron-donating antioxidants (i.e., reductants) in individual items. Such data might be useful in the identification of the most beneficial dietary plants. We have assessed systematically total antioxidants in a variety of dietary plants used worldwide, including various fruits, berries, vegetables, cereals, nuts and pulses. When possible, we analyzed three or more samples of dietary plants from three different geographic regions in the world. Total antioxidants was assessed by the reduction of Fe(3+) to Fe(2+) (i.e., the FRAP assay), which occurred rapidly with all reductants with half-reaction reduction potentials above that of Fe(3+)/Fe(2+). The values, therefore, expressed the corresponding concentration of electron-donating antioxidants. Our results demonstrated that there is more than a 1000-fold difference among total antioxidants in various dietary plants. Plants that contain most antioxidants included members of several families, such as Rosaceae (dog rose, sour cherry, blackberry, strawberry, raspberry), Empetraceae (crowberry), Ericaceae (blueberry), Grossulariaceae (black currant), Juglandaceae (walnut), Asteraceae (sunflower seed), Punicaceae (pomegranate) and Zingiberaceae (ginger). In a Norwegian diet, fruits, berries and cereals contributed 43.6%, 27.1% and 11.7%, respectively, of the total intake of plant antioxidants. Vegetables contributed only 8.9%. The systematic analysis presented here will facilitate research into the nutritional role of the combined effect of antioxidants in dietary plants. (+info)
Plant breeding: a new tool for fighting micronutrient malnutrition.
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The final permanent solution to micronutrient malnutrition in developing countries is a substantial improvement in dietary quality--higher consumption of pulses, fruits, vegetables, fish and animal products that the poor already desire but cannot presently afford. Meanwhile breeding staple foods that are dense in minerals and vitamins provides a low-cost, sustainable strategy for reducing levels of micronutrient malnutrition. Getting plants to do the work of fortification, referred to as "biofortification," can reach relatively remote rural populations that conventional interventions are not now reaching and can even have benefits for increased agricultural productivity. Biofortification, thus, complements conventional interventions. The symposium articles discuss several examples of ongoing research projects to develop and disseminate nutrient-dense staple food crops and issues that remain to be resolved before successful implementation can be attained. (+info)