The US agricultural system is a major exporter of raw materials such as grain and finished foods, a large portion of which consists of commodity crops. Many of these crops are genetically modified (GM) primarily with traits beneficial to their production. Many importing countries regulate which type of GM crops are allowed and often require labeling when the concentration of these materials in the food or grain shipment reaches a specified level. Thus testing is used both prior to export and at the point of import of US products. These tests often involve testing for specific DNA sequences that identify the genetically modified event or for the protein product of introduced genes. Because of the proliferation of testing protocols and reference materials, trade in grain and foods can be blocked due to inconsistencies in the testing and leading to financial loss.
Participants in the study were provided with a material to serve as a calibrant for quantitative PCR consisting of a plasmid containing the DNA sequences of segments of an endogenous gene target and a transgenic gene target. The ratios of transgenic and endogenous genes was certified to be 1:1 and quantified in units of copy number of plasmid. The endogenous gene target came from the high mobility group gene, which is a maize specific target. The transgenic target came from a genetically engineered maize event named 1507. The unknown samples to be analyzed were maize powders that contained a defined mass fraction of genetically engineered maize 1507 mixed with wild type maize. The unknown samples were blinded certified reference materials (CRMs) which had already been tested for homogeneity and stability.
Start Date:April 1, 2008
End Date:November 1, 2008
Lead Organizational Unit:mml
Related Programs and Projects:
CCQM BAWG K61 – Quantitation of a linearized plasmid DNA, based on a matched standard in a matrix of non-target DNA.