Screening food products for the presence of CaMV 35S promoter and NOS 3′ terminator

Abstract

Biotechnology has enabled the modification of agricultural materials in a very precise way, thereby improving productivity and yields of economically important crops. There are a number of methods available for detecting genetically modified organisms (GMOs). In the present investigation, a qualitative PCR technique has been adopted in order to discriminate between genetically modified and non-modified food products. The qualitative PCR assay employs primers specific for genetic elements that are used to generate genetically engineered agricultural crops. Two of the most common primers used for the detection of GMOs, 35S promoter and NOS 3 terminator, have been tested over a panel of 24 food products purchased from the local market. The results indicated that, out of the 24 food products tested, three products gave positive results with the 35S promoter. The NOS 3 primers gave negative results with all tested samples. INTRODUCTIONPlants are consumed directly as a whole or are processed into many types of foods. Early farmers selected and preserved plant variants that had desirable food or agronomic attributes, such as larger fruit or uniform dormancy and maturation times for seeds. The objectives of plant breeders for the improvement of agricultural crops later focused on increasing yield, improving quality and reducing production costs by, for example, identifying traits that increase resistance to pests and diseases. Recent advances in biotechnology have managed, by directly modifying genes, to alter living organisms more quickly and more precisely than has been done by nature and humans over millennia. 1 Production of genetically modified (GM) plants proceeds by inserting selected foreign genes of interest into their genomes. The process by which the foreign DNA is constructed requires the splicing of several elements to form a functional genetic unit. Modification generally includes two regulatory elements, a promoter and a terminator, as well as a gene that confers a selectable advantage. 2 Two of the most commonly used regulatory elements are the constitutive 35S promoter from the cauliflower mosaic virus and the NOS 3 terminator isolated from nopaline synthase gene (NOS) of Agrobacterium tumefaciens. These two elements are present either together or separately in most of the transformed organisms. 3,4 The cauliflower mosaic virus (CaMV) 35S promoter is constitutively

Biological impact of feeding rats with a genetically modified-based diet

“…This diet was experimentally proven to be genetically modified. Several products in Egypt were previously reported to be GM (Oraby et al, 2003(Oraby et al, , 2005 without being labeled as such. The laboratory diet samples fed to the rats throughout this experiment gave positive results when they were screened with specific primers for the presence of NPTII (Neomycin phosphotransferase II) and P-35S/CTP (CaMVP-35S/glyphosate-tolerant enzymes (CP4epsps)).…”

Monitoring of MON810 genetically modified maize in foods in Brazil from 2005 to 2007

“…There are few reports about the distribution of GMO in foods sold commercially published in the literature, five reports about products commercialized in Brazil, two reports about products commercialized in Argentina and one report about products commercialized in Egypt (Greiner and Konietzny, 2008;Cardarelli et al, 2005;Oraby et al, 2005;Margarit et al, 2006;. One hundred Brazilian foods containing maize sold in 2000 and 2001 were analyzed, 17 samples were positive for GM maize, 3 out of 18 maize flour and 6 out of 18 polenta samples contained GM maize .…”

Reliability of PCR based screening for identification and quantification of GMOs

“…Our findings clearly show that the methods targeting the screening elements including those suited for quantification have only informative value, however, such approaches are still used (Oraby et al 2005;Reiting et al 2007). If the individual validated event specific real-time PCR assays are used instead, the process of analysis slows down and the prices for the analysis of one sample increase.…”