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FDA/CFSAN’s Science-based Approach to the Safety of Foods Derived from Modern Biotechnology Thomas A. Cebula, Ph.D. Director, Office of Applied Research and Safety Assessment Center for Food Safety and Applied Nutrition
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The Process Requests notification when industry plans to market a product derived by bioengineered plants Encourages that industry consult with us and provide necessary documentation to ensure ‘reasonable certainty of no harm’ Opportunity to discuss plans for future cultivars
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The Process Specific tests are not specified Intent: To focus on the characteristics of the food product
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Scientific Evaluation u Food Safety u Strengths/Limitations
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Approach is multidisciplinary Agronomic and quality characteristics Characteristics of new substances Chemical and nutritional analysis Genetic analysis A bioengineered variety is evaluated relative to its traditional counterpart Scientific Evaluation u Food Safety
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Identity and source of introduced genetic materials Genetic stability Intended changes to the composition of the food Scientific Evaluation u Food Safety
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Scientific Evaluation u Food Safety Allergenicity Toxins Nutrient Levels Antibiotic Resistance
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Food Safety Assessment Description of rDNA plant Description of the host plant & use as food Description of the donor organism(s) Description of the genetic modification Characterization of the genetic modification
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Safety Assessment, cont’d Expressed substances (non-nucleic acid) Compositional analyses (key components) Evaluation of metabolites Food processing Nutritional modification Other considerations (e.g. marker genes)
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Description of the Genetic Modification The transformation process/host plant –Specific method (Agrobacterium-mediated) –Source, identity, function of DNA –Intermediate hosts The DNA to be introduced All genetic components (genes, markers, regulatory sequences, etc.) Size, identity; location/orientation; function
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Characterization of the Genetic Modification/DNA Insertion Number of sites & organization; copy number & sequence data of insert & surrounding region, sufficient to identify expressed substances, or analysis of transcripts or expression products that may be present in food. Open reading frames & insertions with contiguous plant DNA (fusion proteins)
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Characterization of the Genetic Modification/ Expressed Substances Gene products, including un-translated RNA Function & phenotype Level & site of expression; level of metabolites in food Amount of target gene product, if function is to alter endogenous mRNA or protein
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Genetic Modification Additional Information Arrangement of genetic material Whether modifications to protein sequence affect post-translation/function Intended effect & heritable stability Expression in appropriate tissues & any evidence that host plant is affected Identity & expression of any fusion protein
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As only one or a few genes are being incorporated into the plants, there is a limited number of manipulations. As we move forward, traditional breeding will likely be used to transfer a desired rDNA modification into desired plant varieties. u Strengths/Limitations Scientific Scientific Evaluation
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Evaluating Bioengineered Plants What tests are necessary? Are there tests that should be required?
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What tests are necessary? Are there tests that should be required? RR vs rr: 62 of 636 protein spots on a 2-D gel are qualitatively different. R-locus affects sugar content, lipid content, storage protein composition, and shape and size of starch granules. Evaluating Bioengineered Plants
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What tests are necessary? Are there tests that should be required? Afila (af) mutants which replace leaflets with tendrils, and the tendril-less (tl) mutant which replaces tendrils with leaflets. Both tl/tl and af/af lines have the identical 686 protein profiles. --Gottlieb & de Vienne, Genetics, 119:705-710 (1988) Evaluating Bioengineered Plants
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Pleiotropy is virtually universal, i.e., essentially all gene substitutions have multiple phenotypic consequences when the phenotype is examined in sufficient detail.
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Can Pattern Recognition Work?
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