A Brazilian study has found unintended differences in proteins between a GM maize and the non-GM parent variety.
Comparison of the GM and non-GM plants revealed a total of 32 different proteins that were differentially expressed. The proteins were either present, absent, up- or down-regulated in one of the hybrids, at a statistically significant level.
1. New study reveals molecular differences between transgenic and conventional maize
2. Comparative proteomic analysis of genetically modified maize grown under different agroecosystems conditions in Brazil - the study
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1. New study reveals molecular differences between transgenic and conventional maize
POR UM BRASIL ECOLÓGICO, LIVRE DE TRANSGÊNICOS & AGROTÓXICOS [For an Ecological Brazil, Free from GMOs and Pesticides], 17 Jan 2014
http://aspta.org.br/campanha/659-2/
[English translation of Portuguese original by GMWatch]
The journal Proteome Science, ranked among the top six publications in the proteomics field, published in December 2013 a survey showing molecular differences between genetically modified organisms and their non-GM counterparts. The article was written by a team of researchers from the Federal University of Santa Catarina and was noted by the editors of the magazine as among the most interesting in the field of mass spectrometry.
The study's major contribution is to challenge the main (pseudoscientific) concept used to justify the release of GMOs: so-called " substantial equivalence". According to this theory, transgenic plants are equivalent in their chemical composition to conventional plants and thus, in principle, do not pose risks. The concept was created by the U.S. government agency responsible for regulating food and drugs (FDA - Food and Drug Administration) after a former Monsanto attorney took the position of "deputy commissioner for policy" (a sort of policy adviser), a post specially created for him. The method is rather vague and does not specify the level of similarity between the chemical composition of plants that allow them to be considered "equivalent", but it still secured the release of GMOs in the USA and other countries and is still used today (including by CTNBio - National Technical Biosafety Commission) to justify not carrying out in-depth studies to assess risks of the new plants.
The article "Comparative proteomic analysis of genetically modified maize grown under different agroecosystems conditions in Brazil" showed differences between conventional maize and a Monsanto transgenic maize MON810, of the Bt type (modified to produce insecticidal toxins and kill the caterpillars that eat it). The experiments were conducted in two different agroecosystems in the municipalities of Santa Catarina: Campos Novos and Chapecó. The researchers found 16 different proteins between the two types of corn grown at each site (32 different proteins in total) - i.e., the differences were highly dependent on environmental conditions and were therefore more difficult to predict. The evidence also suggested that conventional maize is more stable, or has less variability, than the GM maize in different environments. The molecular functions of these proteins were mostly attributed to energy metabolism, metabolism of plant response, metabolism of genetic information processing, and metabolism of stress.
Each of these different proteins found could cause a change in a metabolic pathway or interaction within the cell, which in turn could generate new characteristics in the plants, with possible effects on human/animal health or the environment.
These differences in the proteome of plants do not pose a risk in themselves, but they are an indicator that there may be risks and that these should be confirmed by appropriate techniques that are not currently used in assessments of GMOs.
The new study provides further evidence that we are cultivating and consuming on a large scale [food produced with] a technology that has not been tested thoroughly and rigorously, and that in addition to important risks that have become apparent from independent surveys conducted in recent years, other unknown risks may be involved.
The article, "Comparative proteomic analysis of genetically modified maize grown under different agroecosystems conditions in Brazil", can be downloaded in full for free on the site of Proteome Science.
http://www.proteomesci.com/content/11/1/46
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2. Comparative proteomic analysis of genetically modified maize grown under different agroecosystems conditions in Brazil
Agapito-Tenfen, S et al. Proteome Science 2013, 11:46. doi:10.1186/1477-5956-11-46 http://www.proteomesci.com/content/11/1/46
Abstract
Background
Profiling technologies allow the simultaneous measurement and comparison of thousands of cell components without prior knowledge of their identity. In the present study, we used two-dimensional gel electrophoresis combined with mass spectrometry to evaluate protein expression of Brazilian genetically modified maize hybrid grown under different agroecosystems conditions. To this effect, leaf samples were subjected to comparative analysis using the near-isogenic non-GM hybrid as the comparator.
Results
In the first stage of the analysis, the main sources of variation in the dataset were identified by using Principal Components Analysis which correlated most of the variation to the different agroecosystems conditions. Comparative analysis within each field revealed a total of thirty two differentially expressed proteins between GM and non-GM samples that were identified and their molecular functions were mainly assigned to carbohydrate and energy metabolism, genetic information processing and stress response.
Conclusions
To the best of our knowledge this study represents the first evidence of protein identities with differentially expressed isoforms in Brazilian MON810 genetic background hybrid grown under field conditions. As global databases on outputs from “omics” analysis become available, these could provide a highly desirable benchmark for safety assessments.