Testing of genetically modified foods

　There are two ways to test genetically modified foods: detecting new proteins in food and direct detection of embedded genes.

　Our laboratory conducts qualitative and quantitative tests of genetically modified foods using the PCR (Polymerase Chain Reaction polymerase chain reaction) method. The PCR method is a method to confirm whether a specific DNA (gene) is contained by amplifying a specific site of the DNA.

　First, DNA is extracted from the specimens to be examined (such as bean grains, cornflower powder, and corn chips). There are several types of DNA extraction methods, but the appropriate methods are used depending on the sample.

　Next, the DNA is amplified by the PCR method to test whether the extracted DNA contains the genes.
　There are two types of PCR methods: a qualitative PCR method that determines whether or not a built-in gene is contained, and a quantitative PCR method that can determine the amount contained. In Japan, following the mandatory labeling under the JAS Law (Ministry of Agriculture, Forestry and Fisheries), the labeling of genetically modified foods became mandatory under the Food Sanitation Law (Ministry of Health, Labour and Welfare) from April 2001.

DNA extraction

Qualitative PCR device

　In qualitative PCR, electrophoresis is performed using an agarose gel after amplifying DNA using a qualitative PCR device. By electrophoresis, DNA can be separated by length, so you can check if the desired DNA is amplified. While qualitative PCR has a very good sensitivity, it also has the disadvantage that it is not clear exactly how much the desired DNA was originally contained.

DNA electrophoresis

Photo of electrophoresis

　In quantitative PCR, PCR is performed while monitoring fluorescence using a special reagent that emits fluorescence in proportion to DNA amplification using a quantitative PCR device. The analysis method of the device and data is more complicated than qualitative PCR, but it is possible to estimate the original concentration of the target DNA.

Quantitative PCR equipment

Amplification curve screen of quantitative PCR

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　Since fiscal 2001, we have been testing genetically modified foods.

　In qualitative tests, we check whether unapproved genetically modified foods such as Bt10 corn and Bt rice are distributed in Japan.

　In quantitative tests, approved varieties (round-up, ladies, soybeans, GA21 corn, etc.) are checked for proper labeling such as "not genetically modified".

　To date, there have been no violating specimens.

※Inability to detect ... In the test of genetically modified foods, the genes (intrinsic genes) of the crop are also examined at the same time as the recombinant genes.
　"Indetectable" means that the intrinsic gene that should be detected is not detected, and the test cannot be determined. The cause of this may be that the gene decomposes during processing such as heating and pressurization.

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