Applicability of the Quantification of Genetically Modified Organisms to Foods Processed from Maize and Soy

Abstract

The applicability of quantifying genetically modified (GM) maize and soy to processed foods was investigated using heat treatment processing models. The detection methods were based on real-time quantitative polymerase chain reaction (PCR) analysis. Ground seeds of insect resistant GM maize (MON810) and glyphosate tolerant Roundup Ready (RR) soy were dissolved in water and were heat treated by autoclaving for various time intervals. The calculated copy numbers of the recombinant and taxon specific deoxyribonucleic acid (DNA) sequences in the extracted DNA solution were found to decrease with time. This decrease was influenced by the PCR-amplified size. The conversion factor (Cf), which is the ratio of the recombinant DNA sequence to the taxon specific DNA sequence and is used as a constant number for calculating GM% at each event, tended to be stable when the sizes of PCR products of two DNA sequences were nearly equal. The results suggested that the size of the PCR product plays a key role in the quantification of GM organisms in processed foods. It is believed that the Cf of the endosperm (3n) is influenced by whether the GM originated from a paternal or maternal source. The embryos and endosperms were separated from the F1 generation seeds of five GM maize events, and their Cf values were measured. Both paternal and maternal GM events were identified. In these, the endosperm Cf was lower than that of the embryo, and the embryo Cf was lower than that of the endosperm. These results demonstrate the difficulties encountered in the determination of GM% in maize grains (F2 generation) and in processed foods from maize and soy.

Combined effects of temperature, pressure and low pH on the amplification of DNA of plant derived foods

“…The food processing triggers off DNA degradation and may affect DNA-based food analysis (Bauer et al 2003(Bauer et al , 2004Tilley 2004;Yioshimura et al upper: 1 -standard 100 bp; 2 -negative control (116 bp); 3 -raw sample; 4 -pH 7.6, 2 min; 5 -pH 2.25, 2 min; 6 -pH 7.6, 5 min; 7 -pH 2.25, 5 min; 8 -pH 7.6, 10 min; 9 -pH 2.25, 10 min; 10-11 -negative control (469 bp); 12 -raw sample; 13 -pH 7.6, 2 min; 14 -pH 2.25, 2 min; 15 -pH 7.6, 5 min; 16 -pH 2.25, 5 min; 17 -pH 7.6, 10 min; 18 -pH 2.25, 10 min Lower: 1 -standard 100 bp; 2 -negative control (116 bp); 3 -raw sample; 4 -pH 7.6, 10 min; 5 -pH 2.25, 10 min; 6 -pH 7.6, 20 min; 7 -pH 2.25, 20 min; 8 -pH 7.6, 30 min; 9 -sample of preserved (Commercial Products); 10-11 -negative control (469 bp); 12 -raw sample; 13 -pH 7.6, 10 min; 14 -pH 2.25, 10 min; 15 -pH 7.6, 20 min; 16 -pH 2.25, 20 min; 17 -pH 7.6, 30 min; 18 -pH 2.25. 30 min 2004; Moreano et al 2005;Gryson et al 2008;ISO 2005) of GM and non-GM plant samples.…”

Threshold Level and Traceability of Roundup Ready Soybean in Tofu Production

“…The efficiency of GMO determination in processed foods is affected by the degree of degradation of recombinant and taxon-specific DNA sequence (6). It is currently not possible to avoid different degrees of degradation in these two DNA sequences and to reliably determine whether the GMO content (in %) in processed foods is in line with the actual values in the raw materials (7).…”

Rapid Quantification Methods for Genetically Modified Maize Contents Using Genomic DNAs Pretreated by Sonication and Restriction Endonuclease Digestion for a Capillary-Type Real-Time PCR System with a Plasmid Reference Standard

“…Fluorescence resonance energy transfer (FRET) hybridization probes were used for quantification in the LightCycler Ò real-time PCR system (Roche Diagnostics, Mannheim, Germany). In the Japanese official standard real-time PCR methods, the SSIIb 3 system (SSIIb 3-5 0 and SSIIb 3-3 0 with SSIIb-Taq) is used as primers and probe for quantification of the taxon specific gene encoding SSIIb, 19) and the P35S-1 system (P35S 1-5 0 and P35S 1-3 0 with P35S-Taq) is used for quantification of P35S as the screening quantification method of GM maize. The target sequence of the P35S-1 system to detect the 35S promoter region is derived from the cauliflower mosaic virus.…”

“…[2][3][4] The enforcement of these threshold values has created a demand for the development of reliable GMO analysis methods with rapid and inexpensive features. [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] Hence many real-time PCR systems based on fluorescent detection, such as TaqMan Ò chemistry, have been developed to identify and quantify GM maize, GM soybeans, and GM varieties of other agricultural commodities. [22][23][24][25][26][27][28][29][30][31][32][33] Real-time PCR systems using TaqMan Ò chemistry are based on the use of a fluorescent TaqMan Ò probe that monitors the formation of the PCR product during each cycle of the reaction.…”