ARCHIVED - Insect Protected Cotton Event 15985
Novel Food Information - Food Biotechnology
Health Canada has notified Monsanto Canada Inc. that it has no objection to the food use of cottonseed oil from cotton lines containing insect resistant cotton event 15985, also known as Bollgard IIT, which is resistant to the lepidopteran family of insects. The Department conducted a comprehensive assessment of this cottonseed oil according to its Guidelines for the Safety Assessment of Novel Foods. These Guidelines are based upon internationally accepted principles for establishing the safety of foods with novel traits.
The following provides a summary of the Monsanto Canada Inc. notification to Health Canada and results of the safety assessment and contains no confidential business information.
In 1996, Health Canada issued a letter of no objection for the transgenic cotton event 531 (NF-10, trade name Bollgard T), which confers resistance to lepidopteran pests by expressing the Cry1Ac protein and expresses the selectable markers neomycin phosphotransferase type II (NPTII) and aminoglycoside adenyltransferase (AAD). A commercial line, DP50B, containing this event (531) was subsequently transformed to express the novel proteins Cry2Ab and -glucuronidase (GUS) in addition to the already present, Cry1Ac, NPTII and AAD. As a result, this new event, 15985, confers enhanced resistance to insects of the lepidopteran family, the main insect pest problem in cotton, and is the subject of this review.
2. Development and Production of the Modified Plant
Cotton event 15985 was produced using particle mediated transformation to introduce a plasmid DNA sequence (PV-GHBK11L) into cotton cells. The introduced sequence consists of the cry2Ab and gus genes and the associated gene regulatory components necessary for their expression in the cotton plant.
The cry2Ab gene is derived from the common soil microorganism Bacillus thuringiensis subspecies kurstaki (Btk). The wild-type cry2Ab protein is not naturally expressed in this organism, due to a faulty promoter in the cry2Ab gene. Nevertheless, it shares at least 75% sequence identity with the Cry2A protein which is expressed in Btk and is an active ingredient in some commercial pesticides registered for use in Canada. GUS is commonly used as a scorable marker in plant transformation. GUS protein was originally isolated from E. coli which is ubiquitous in the digestive system of vertebrates, including humans.
One copy of the introduced plasmid's DNA sequence was detected at a single locus in cotton event 15985. This information was obtained by Southern blot analysis of event 15985. No additional new DNA, other than that associated with the cry2Ab and gus cassettes, was detected. Stability of the introduced traits was confirmed using Southern blot analysis over multiple generations. Polymerase chain reaction (PCR) analysis and DNA sequencing were used to verify the junction sequences of the insert with the plant genome as well as the intactness of the 5' and 3' ends of the insert.
3. Product Information
Cotton event 15985 differs from its parental counterpart (commercial line DP50B containing event 531) in the addition of the novel cry2Ab and gus gene sequences into the genome, and the expression of two proteins (Cry2Ab and GUS). The proteins encoded by these genes are expressed at different levels throughout the plant tissue and throughout the life of the plant. Refined cottonseed oil does not contain any detectable protein and consists almost entirely of triglycerides. Only the refined oil from cotton lines containing cotton event 15985 will be available for human consumption.
4. Dietary Exposure
The genetic modification of cotton event 15985 will not result in any change in the consumption pattern for this product. As the introduced gene products are not detectable in the refined oil produced from the modified cotton (commercial processing of refined cottonseed oil removes proteins), there will be no human exposure to these proteins based on normal consumption patterns. Cottonseed products besides the oil can be used as human food, but this is not common and this submission is limited to use of the oil.
The nutritional assessment considered compositional data comparing the major components (protein, fat, ash, moisture, carbohydrate, fibre and calories), the amino acid and fatty acid composition, the mineral content, vitamin E and gossypol levels of cottonseed from cotton containing event 15985 to cottonseed from control lines and conventional cotton cultivars. The nutrient data provided in Monsanto Canada's submission for cotton event 15985 demonstrate that the composition of cottonseed from cotton containing event 15985 is comparable to cottonseed from its non-transgenic parent, DP50, its transgenic parent DP50B and seed from commercial cotton. It is expected that refined oil from cottonseed lines containing event 15985 would be comparable with commercial cottonseed oil, and that there would be no nutritional concerns related to its consumption by Canadians.
The unlikelihood of the cotton event 15985 Cry2Ab protein being a potential food allergen or toxin is indicated by its lack of toxicity in the acute toxicity study, its lack of homology to known protein allergens or toxins, and its rapid digestion in the stomach. Furthermore, the data demonstrate that the Cry2Ab protein was undetectable at the limit of detection of the protein in cottonseed oil (1.3 g/ml of oil), which provides further protection against any potential for this protein to cause toxic or allergic adverse reactions.
The GUS protein also demonstrated a lack of acute toxicity, a lack of sequence similarity to known toxins or allergens, and a susceptibility to digestion under conditions of the mammalian stomach. In addition, as noted above, humans are already exposed to this enzyme which is contained in the normal microbial flora of the human gut and a large variety of safely consumed foods.
Health Canada's review of the information presented in support of the food use of insect-resistant cotton event 15985 concluded that the use of the cottonseed oil from this cotton does not raise concerns related to safety. Health Canada is of the opinion that cottonseed oil from cotton lines containing cotton event 15985 are as safe and nutritious as oils from current commercial cotton varieties.
Health Canada's opinion deals only with the cottonseed oil food use of insect-resistant cotton event 15985. Issues related to its use as animal feed have been addressed separately through existing regulatory processes in the Canadian Food Inspection Agency.
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