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GM food detection method (DNA BASED)

Friday, July 9, 2010

2. DNA-Based

• Southern blot
Southern blotting is designed to locate a particular sequence of DNA within a large, complex sample of DNA. For example, Southern Blotting can locate a single specific gene within an entire genome

http://www.biochem.arizona.edu/classes/bioc471/pages/Lecture2/Lecture2.html

• Quantitative end-point PCR
It is a crucial aspect of analysis of GMOs in food is quantitation, because maximum limits of GMOs in foods are the basis for labeling in the EU .Therefore, more quantitative PCR approaches were needed. PCR was shown to be quantitative if an internal DNA standard was coamplified with target DNA. In systems such as the quantitative-competitive (QC)-PCR method (Fig. 3), the presence of PCR inhibitors will be noticed immediately because the amplification of both internal standard and target DNA will be simultaneously affected. QC-PCR consists of four steps: (1) coamplification of standard- and target-DNA in the same reaction tube; (2) separation of the products by anappropriate method, such as agarose gel electrophoresis and staining the gel by ethidium bromide; (3) analysis of the gel densitometrically; and (4) estimation of the relative amounts of target and standard DNA by regression analysis.

[Farid E.Ahmed.Detection of genetically modified organisms in foods. (2002)]