Proteomics reveals the in vitro protein digestibility of seven transmembrane enzymes from the docosahexaenoic acid biosynthesis pathway

Twenty-eight years of GM Food and feed without harm: why not accept them?

Since the first genetically engineered or modified crops or organisms (GMO) were approved for commercial production in 1995, no new GMO has been proven to be a hazard or cause harm to human consumers. These modifications have improved crop efficiency, reduced losses to insect pests, reduced losses to viral and microbial plant pathogens and improved drought tolerance. A few have focused on nutritional improvements producing beta carotene in Golden Rice. Regulators in the United States and countries signing the CODEX Alimentarius and Cartagena Biosafety agreements have evaluated human and animal food safety considering potential risks of allergenicity, toxicity, nutritional and anti-nutritional risks. They consider risks for non-target organisms and the environment. There are no cases where post-market surveillance has uncovered harm to consumers or the environment including potential transfer of DNA from the GMO to non-target organisms. In fact, many GMOs have helped improve production, yield and reduced risks from chemical insecticides or fungicides. Yet there are generic calls to label foods containing any genetic modification as a GMO and refusing to allow GM events to be labeled as organic. Many African countries have accepted the Cartagena Protocol as a tool to keep GM events out of their countries while facing food insecurity. The rationale for those restrictions are not rational. Other issues related to genetic diversity, seed production and environmental safety must be addressed. What can be done to increase acceptance of safe and nutritious foods as the population increases, land for cultivation is reduced and energy costs soar?

Engineering Nutritionally Improved Edible Plant Oils

In contrast to traditional breeding, which relies on the identification of mutants, metabolic engineering provides a new platform to modify the oil composition in oil crops for improved nutrition. By altering endogenous genes involved in the biosynthesis pathways, it is possible to modify edible plant oils to increase the content of desired components or reduce the content of undesirable components. However, introduction of novel nutritional components such as omega-3 long-chain polyunsaturated fatty acids needs transgenic expression of novel genes in crops. Despite formidable challenges, significant progress in engineering nutritionally improved edible plant oils has recently been achieved, with some commercial products now on the market.

Food and Feed Safety of NS-B5ØØ27-4 Omega-3 Canola (Brassica napus): A New Source of Long-Chain Omega-3 Fatty Acids

DHA canola, a genetically engineered Brassica napus (OECD Unique Identifier NS-B5ØØ27-4), has been developed as one of the first land-based production systems for omega-3 long-chain polyunsaturated fatty acids (LCPUFA), whose health benefits are well-established. Yet, the marine sources of these nutrients are under high pressures due to over-fishing and increasing demand. DHA canola is a plant-based source for these essential fatty acids that produces a high level of docosahexaenoic acid (DHA). This terrestrial system allows for sustainable, scalable and stable production of omega-3 LCPUFA that addresses not only the increasing market demand, but also the complex interplay of agriculture, aquaculture, and human nutrition. The vector used to produce the desired oil profile in DHA canola contains the expression cassettes of seven genes in the DHA biosynthesis pathway and was specifically designed to convert oleic acid to DHA in canola seed. The characterization and safety evaluation of food and feed produced from DHA canola are described and supported by a detailed nutritional analysis of the seed, meal, and oil. Aside from the intended changes of the fatty acid profile, none of the other compositional analytes showed biologically meaningful differences when compared to conventional canola varieties. In addition, the meal from DHA canola is compositionally equivalent to conventional canola meal. Further evidence of nutritional value and safety of DHA canola oil have been confirmed in fish feeding studies. Given that most human populations lack sufficient daily intakes of omega-3 LCPUFA, a dietary exposure assessment is also included. In conclusion, the results from these studies demonstrate it is safe to use products derived from DHA canola in human foods, nutraceuticals, or animal feeds.

Development of a Brassica napus (Canola) Crop Containing Fish Oil-Like Levels of DHA in the Seed Oil

Plant seeds have long been promoted as a production platform for novel fatty acids such as the ω3 long-chain (≥ C20) polyunsaturated fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) commonly found in fish oil. In this article we describe the creation of a canola (Brassica napus) variety producing fish oil-like levels of DHA in the seed. This was achieved by the introduction of a microalgal/yeast transgenic pathway of seven consecutive enzymatic steps which converted the native substrate oleic acid to α-linolenic acid and, subsequently, to EPA, docosapentaenoic acid (DPA) and DHA. This paper describes construct design and evaluation, plant transformation, event selection, field testing in a wide range of environments, and oil profile stability of the transgenic seed. The stable, high-performing event NS-B50027-4 produced fish oil-like levels of DHA (9-11%) in open field trials of T3 to T7 generation plants in several locations in Australia and Canada. This study also describes the highest seed DHA levels reported thus far and is one of the first examples of a deregulated genetically modified crop with clear health benefits to the consumer.

Quantitation of seven transmembrane proteins from the DHA biosynthesis pathway in genetically engineered canola by targeted mass spectrometry

Examining tissue-specific expression and the measurement of protein abundance are important steps when assessing the performance of genetically engineered crops. Liquid chromatography-mass spectrometry offers many advantages over traditional methods for protein quantitation, especially when dealing with transmembrane proteins that are often difficult to express or generate antibodies against. In this study, discovery proteomics was used to detect the seven transgenic membrane-bound enzymes from the docosahexaenoic acid (DHA) biosynthetic pathway that had been engineered into canola. Subsequently, a targeted LC-MS/MS method for absolute quantitation was developed and applied to the simultaneous measurement of the seven DHA biosynthetic pathway enzymes in genetically modified canola grown across three sites. The results of this study demonstrated that the enzymatic proteins that drive the production of DHA using seed-specific promoters were detected only in mature and developing seed of DHA canola. None of the DHA biosynthesis pathway proteins were detected in wild-type canola planted in the same site or in the non-seed tissues of the transgenic canola, irrespective of the sampling time or the tissues tested. This study describes a streamlined approach to simultaneously measure multiple membrane-bound proteins in planta.