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Teaching Issues and Experiments in Ecology

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Teaching Issues and Experiments in Ecology

TIEE

    Teaching Issues and Experiments in Ecology - Volume 2, August 2004

ISSUES FIGURE SET

What Are the Ecological Impacts

    of Plant Biotechnology?

     12Dara Zycherman* and Jason Taylor

    1 - U.S. Green Building Council, 1015 18th Street

    NW, Washington, DC 20036,

    202-828-7422 x156, dzycherman@usgbc.org

    2 - Ecological Society of America, 1400 Spring St.,

    Suite 330, Silver Spring, MD, 20910-2749,

    301-588-3873, x311, jason@esa.org

    * corresponding author Green and red peppers, ? B. W. Grant

     Figure Set 1: Evidence for Brazil Nut Allergen in Transgenic Soybeans

Purpose: To show that allergens can be transferred from one plant to another

     through crop biotechnology and, thus, may pose a food safety issue. Teaching Approach: pairs share

    Cognitive Skills: (see Bloom's Taxonomy) comprehension, analysis, evaluation Student Assessment: minute paper

CITATION:

    Zycherman, D., and J. Taylor. August 2004, posting date. What Are the Ecological Impacts of Plant

    Biotechnology? Teaching Issues and Experiments in Ecology, Vol. 2: Issues Figure Set #1

    [online]. http://tiee.ecoed.net/vol/v2/issues/figure_sets/biotech/abstract.html

    ? 2004 Dara Zycherman, Jason Taylor, and the Ecological Society of America Teaching Issues and Experiments in Ecology, TIEE Volume 2 (tiee.ecoed.net)

page 2 Dara Zycherman and Jason Taylor TIEE Volume 2, August 2004

    BACKGROUND

    This TIEE Issues Figure Set explores the safety of biotech crops for the case of transgenic soybeans. The presence of GMO’s in our diet has caused some concern in the field of plant biotechnology because the safety of these organisms is not always well studied. Scientists are currently researching the potential health effects of biotech crops and caution that genetic manipulation can produce unintended side-effects such as increasing the levels of natural plant toxins in food or even creating or adding new toxins. These can occur in unexpected ways such as by switching on genes that produce toxins or by switching off genes that suppress them.

    In addition, more subtle effects can occur due to inadvertent food allergy transmission during transgenic modification. A gene transferred from one plant into another could cause an allergic reaction in the consumer who is allergic to products of genes that were transferred. Thus, plant biotechnology may not only be transferring traits that are beneficial to humans, but also those that may be harmful to some people as well. Much research may still need to be conducted to fully understand how genetic manipulation of plants affects the quality and safety of biotech food products.

    In the United States, three federal agencies share responsibility for food and environmental safety issues for genetically engineered crops. According to FDA Commissioner Dr. J. E. Henney, from an interview for the FDA publication FDA Consumer published in 2000: "FDA is responsible for the safety and labeling of all foods and animal feeds derived from crops, including biotech plants. EPA regulates pesticides, so the BT used to keep caterpillars from eating the corn would fall under its jurisdiction. USDA's Animal and Plant Health Inspection Service oversees the agricultural environmental safety of planting and field testing genetically engineered plants." (Thompson 2000).

    Interestingly, under US Law (Food, Drug, and Cosmetic Act - US Code, Title 21, Chapter 9, {available at www.access.gpo.gov/uscode/title21/chapter9_.html}) transgenic foods are not covered under the more stringent regulations for food additives (food colors, sweeteners, preservatives, etc.) because, according to FDA Commissioner Henney, "we are talking about adding some DNA to the plant that directs the production of a specific protein. DNA already is present in all foods and is presumed to be GRAS [generally recognized as safe]... adding an extra bit of DNA does not raise any food safety issues." (Thompson 2000). Thus, under US Law, because it is only DNA that is being added and all plants have DNA, GMO crops are generally recognized as safe (GRAS status). In contrast, if the segments of biotechnologically inserted genetic material and the gene products they create were to be considered "additives," the US FDA would require an "intensive review" for which scientific data collection is mandated to assess if the plants with the added DNA and novel gene products are non-toxic, non-allergenic, and otherwise safe. However, this does not apply to most GMO crops in the US - and for many, this policy designation lies at the heart of the controversy.

? 2004 Dara Zycherman, Jason Taylor, and the Ecological Society of America

    Teaching Issues and Experiments in Ecology, TIEE Volume 2 (tiee.ecoed.net)

TIEE ISSUES FIGURE SET Ecological Impacts of Plant Biotechnology Figure Set 1 page 3

    Specifically regarding food allergies, although FDA Commissioner Henney does not dismiss the possibility that biotech foods can cause allergies, she contends that "we have no scientific evidence to indicate that any of the new proteins introduced into food by biotechnology will cause allergies" (Thompson 2000).

    In spite of the FDA’s stance, some contend that since consumers have never eaten many of the foreign proteins and other gene products now in GMO foods, stringent credible pre-market safety-testing is essential to protect public health. There is still public fear about GMO’s and without appropriate labeling, consumers do not have a choice, especially if they are very sensitive to specific foods.

    This problem was exemplified in a study that is the focus of this TIEE Issue. Nordlee et al. (1996), in the New England Journal of Medicine, identified a Brazil nut allergen in transgenic soybeans. To improve the nutritional quality of soybeans as feed for poultry, methionine, an essential amino acid, had been added through modern biotechnology. This was accomplished by inserting into the soybean genome the gene for 2S albumin, a protein high in methionine, from the Brazil nut.

    Unfortunately, many people are allergic to Brazil and other nuts. For these people, an overreaction of their immune system to a specific allergen in Brazil nuts can produce severe allergic reactions such as rashes, shortness of breath, vomiting, shock, or even death. The human immunoglobulin IgE (one of the five types of human immunoglobulins) is often the key to allergic sensitivity. Therefore in this study, the allergenicity of the transgenic soybeans was determined by assessing the binding affinity of the 2S albumin protein to IgE from people who are allergic to Brazil nuts.

    Lastly, it is worth noting that the research reported in Nordlee et al. (1996) was funded by the Dupont subsidiary Pioneer Hi-Bred International, which originally developed the transgenic soybeans of study. The research was conducted at the University of Nebraska-Lincoln. This is a nice example of a corporate-University partnership leading to a ground breaking case study of allergen transfer through biotechnology. In fact, as a direct result of the research by Nordlee et al., Pioneer decided to discontinue its research program on transgenic soybeans using 2S albumin from Brazil nuts long before any products reached the commercial market (Pioneer 2004).

Literature cited:

    Nordlee, J. A., S. L. Taylor, J. A. Townsend, L. A. Thomas, R. K. Bush. 1996.

    Identification of a Brazil-nut allergen in transgenic soybeans. The New England

    Journal of Medicine 334: 688-692.

    Pioneer Hi-Bred International (Dupont). 2004. Press Room: Biotechnology - Biotech

    Soybeans and Brazil Nut Protein. www.pioneer.com/biotech/brazil_nut

    Thompson, L. 2000. Are bioengineered foods safe? FDA Consumer 34: No. 1, January-

    February 2000: 1-6. {available online at

    www.fda.gov/fdac/features/2000/100_bio.html}

    ? 2004 Dara Zycherman, Jason Taylor, and the Ecological Society of America

    Teaching Issues and Experiments in Ecology, TIEE Volume 2 (tiee.ecoed.net)

page 4 Dara Zycherman and Jason Taylor TIEE Volume 2, August 2004

    STUDENT INSTRUCTIONS

    Soybeans are nutritional superstars by providing essential dietary amino and fatty acids. In addition, consumption of soy products have been shown to reduce cholesterol levels, and reduce risks of kidney and heart disease, osteoporosis, and possibly some cancers. However, soybeans are not a "complete" protein source for people and animals since soybeans lack the essential amino acid methionine (―essential‖ here means that animals cannot create methionine themselves). To rectify this deficiency, plant biotechnologists used methods of recombinant-DNA technology to insert a gene into a strain of soybeans to enable them to synthesize this missing amino acid.

    The problem with this approach was that the original source of the gene for methionine, "2S albumin," came from Brazil nuts (Bertholletia excelsa). Many people

    are allergic to Brazil nuts and their reaction can range from severe rashes to anaphylactic shock. The study we focus on here by Nordlee et al. (1966) addresses this issue.

    As a reminder of basic human immuno-biology, allergic or immediate hypersensitivity reactions are caused by binding of the antibody Immunoglobulin E (IgE) to the allergen (in this case, the methionine rich 2S albumin). This causes a series of reactions including the release of substances such as histamine, prostaglandins, and other compounds that produce the symptoms of an allergic reaction listed above. A glossary below lists some terms you may not be familiar with.

    The purpose of the study by Nordlee et al. (1996) was to determine the extent to which the transgenic soybeans, containing the Brazil nut 2S albumin gene, caused allergic reactions similar to Brazil nuts.

    Figure 1 is based on data from a radioallergosorbent test (RAST) in which a sample of blood from a potentially allergic person is checked