title: Applicability of plasmid calibrant pTC1507 in quantification of TC1507 maize: an interlaboratory study.
abstract: To enforce the labeling regulations of genetically modified organisms (GMOs), the application of DNA plasmids as calibrants is becoming essential for the practical quantification of GMOs. This study reports the construction of plasmid pTC1507 for a quantification assay of genetically modified (GM) maize TC1507 and the collaborative ring trial in international validation of its applicability as a plasmid calibrant. pTC1507 includes one event-specific sequence of TC1507 maize and one unique sequence of maize endogenous gene zSSIIb. A total of eight GMO detection laboratories worldwide were invited to join the validation process, and test results were returned from all eight participants. Statistical analysis of the returned results showed that real-time PCR assays using pTC1507 as calibrant in both GM event-specific and endogenous gene quantifications had high PCR efficiency (ranging from 0.80 to 1.15) and good linearity (ranging from 0.9921 to 0.9998). In a quantification assay of five blind samples, the bias between the test values and true values ranged from 2.6 to 24.9%. All results indicated that the developed pTC1507 plasmid is applicable for the quantitative analysis of TC1507 maize and can be used as a suitable substitute for dried powder certified reference materials (CRMs).
authors.affiliation: National Center for Molecular Characterization of Genetically Modified Organisms, SJTU-BorLuh Food Safety Center, School of Life Science and Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, People's Republic of China.
authors.forename: Yanan
authors.initials: Y
authors.lastname: Meng
authors.forename: Xin
authors.initials: X
authors.lastname: Liu
authors.forename: Shu
authors.initials: S
authors.lastname: Wang
authors.forename: Dabing
authors.initials: D
authors.lastname: Zhang
authors.forename: Litao
authors.initials: L
authors.lastname: Yang
mesh_terms: D002138:Calibration; D030821:Plants, Genetically Modified / Q000235:genetics*; D010957:Plasmids / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods / Q000592:standards*; D003313:Zea mays / Q000235:genetics*