DNA and Protein-based methods have been developed and applied for the detection of GMO. For the detection of Genetically Modified Organisms (GMOs) at the level of DNA, PCR based methods are mainly used, whereas for protein-based detection, immunoassays such as Western blot, ELISA, and lateral strips methods are predominantly used.
DNA -based methods are primarily based on multiplying a specific DNA with the PCR technique. The PCR reaction allows the million or billion fold amplification of a specific target DNA fragment framed by two synthetic oligonucleotide primers. The PCR is done by a multiple-process with consecutive cycles of denaturation step to denature DNA, annealing step where primers find their correspondent complementary sequences on the template and extension or elongation step where Taq polymerase copies the complementary strand. In each cycle three different steps were progressed in different temperatures. To perform the reliable PCR test, it is important that specific primers were designed to bind selectively to the complementary sequences of the target DNA; the specific gene introduced, promoter and terminator, a sequence spanning between a regulatory sequence and a sequence between the gene and the flanking genome A prerequisite for the PCR-based technique is to know specific DNA sequence inserted in GMO, served as target and to find adequate standard materials to be used as positive analytical controls. Three kinds of PCR strategies are currently used for GMO detection; multiplex PCR, quantitative competitive PCR (QC-PCR) and real-time PCR.
Immunoassay is based on the specific binding between an antigen and an antibody. Thus, the availability of antibodies with the desired affinity and specificity is the most important factor for setting up immunoassay systems. This technology is ideal for qualitative and quantitative detection of many types of proteins, however can’t be applied in highly processed soy products
ELISA is an enzyme linked immuosorbant assay. This technique uses an antibody that recognizes specific proteins. Protein is bound to a well of a plastic plate instead of a membrane. Antigen and antibody bind and produce a stable complex, which can be visualized by addition of a second antibody linked to an enzyme. The advantages of ELISA are to be capable of quantitative analysis when a standard curve is included, and high throughput.
DNA -based methods are primarily based on multiplying a specific DNA with the PCR technique. The PCR reaction allows the million or billion fold amplification of a specific target DNA fragment framed by two synthetic oligonucleotide primers. The PCR is done by a multiple-process with consecutive cycles of denaturation step to denature DNA, annealing step where primers find their correspondent complementary sequences on the template and extension or elongation step where Taq polymerase copies the complementary strand. In each cycle three different steps were progressed in different temperatures. To perform the reliable PCR test, it is important that specific primers were designed to bind selectively to the complementary sequences of the target DNA; the specific gene introduced, promoter and terminator, a sequence spanning between a regulatory sequence and a sequence between the gene and the flanking genome A prerequisite for the PCR-based technique is to know specific DNA sequence inserted in GMO, served as target and to find adequate standard materials to be used as positive analytical controls. Three kinds of PCR strategies are currently used for GMO detection; multiplex PCR, quantitative competitive PCR (QC-PCR) and real-time PCR.
Immunoassay is based on the specific binding between an antigen and an antibody. Thus, the availability of antibodies with the desired affinity and specificity is the most important factor for setting up immunoassay systems. This technology is ideal for qualitative and quantitative detection of many types of proteins, however can’t be applied in highly processed soy products
ELISA is an enzyme linked immuosorbant assay. This technique uses an antibody that recognizes specific proteins. Protein is bound to a well of a plastic plate instead of a membrane. Antigen and antibody bind and produce a stable complex, which can be visualized by addition of a second antibody linked to an enzyme. The advantages of ELISA are to be capable of quantitative analysis when a standard curve is included, and high throughput.
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