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


The purpose and principal conclusion of Nordlee et al.'s (1996) paper is well articulated by the authors with:

Despite the clarity and simplicity of the above statements, the purpose, procedure, and output of the radioallergosorbent assay test, RAST (Figure 1) can be quite challenging for many students, as well as for faculty who have not recently taken an immunology course.

We suggest that you some time to explain the RAST assay. The take home message is that the RAST assay is an allergy test performed on a sample of blood that checks for allergic sensitivity to specific substances by measuring binding rates between the putative allergen and IgE. Recall that proteins that trigger the production of IgE (allergen specific immunoglobulin) are likely to be allergens. An excellent description of RAST tests is provided by the US Food and Drug Administration Center for Devices and Radiological Health.

In Nordlee et al. (1996), multiple RAST assays are used to determine the relative allergenicity of Brazil nuts, transgenic and non-transgenic soybeans by testing the ability of liquid protein extracts to bind to IgE from people who are allergic to Brazil nuts. In Figure 1, the "inhibitor proteins" are the protein extracts from Brazil nuts, transgenic and non-transgenic soybeans that compete with the Brazil nut 2S albumin protein (in solid phase) for binding to the IgE from allergic people. The labeled antibody (IgE) is allowed to bind to 2S albumin and the unbound antibody that remains is washed away. The degree of binding of the antibody (indicated using an index of relative binding affinity on the y-axis of this figure) is measured by the radioactivity still remaining.

In addition, we suggest that you discuss your students' understanding of the term bioethics. In this case, this term refers to ethical problems that may or may not arise from biological research. There are many web resources for bioethics and food labeling.

You will have to decide how much time your students will need to interpret the figure. Then, ask each question aloud, giving each question between 1-3 minutes, depending on difficulty, so students pace themselves.

After discussing the figure, provide a brief lecture, or reading assignment, that encompasses the importance of scientific-based concerns about biotechnology. If you wish to emphasize the ethical element in your discussion, you could focus on the reasons for GM food labeling. Also, you should emphasize that scientists disagree about crop biotechnology and the value of risk assessment.

The intention of the Student Assessment question is for students to use scientific evidence and information to support their point of view. You will probably need to explain this and perhaps give an example of the kinds of evidence you are looking for. It is second nature for scientists to use scientific evidence and reasoning in support of arguments, but this is a sophisticated skills that students need to be shown how to do - even after you have spend a long time discussing the "science."

There are many web resources for bioethics and food labeling including:

Bioethics and the NIH: Biotechnology Industry Organization: http://www.bio.org/
IFT Expert Report on Biotechnology and Foods: http://www.ift.org/publications/docshop/ft_shop/09-00/09_00_pdfs/09-00-bio-label.pdf

Student Assessment:

Address the following question in writing: What is your opinion of food labeling for GM foods? Support your opinion with scientific information from our discussion. 300-500 words.