Project description:Food safety evaluation of new, genetically modified (GM) plant varieties has led to basic questions regarding the safety assessment of new plant varieties and whole foods derived thereof. An important part of the hazard identification in the European approach is a targeted compositional analysis of new GM plant varieties compared to one or more conventional reference varieties. Comparative analysis will become much more informative with unbiased analytical approaches, such as omics profiling. Analysis tools that estimate the similarity of new varieties to the reference would in turn greatly facilitate hazard identification. Further in-depth biological, functional and eventually toxicological analysis of the data would then only be necessary for varieties that fall outside the scale of those with a history of safe human consumption. For this purpose, the use of a one-class classifier tool was explored in this study to assess and classify transcriptome profiles of potato varieties. Five potato varieties were grown in the Netherlands during the same year (NL samples) and included four biological replicates for four varieties or two biological replicates for the fifth one. They were all analysed in 2011. A sixth variety was grown in the UK in a previous study and a previous year, for which the data are submitted in E-MTAB-605. The two UK samples were analysed in the original study in 2008 and again together with the NL samples in the present study, resulting in four profiles for two samples.
Project description:According to the Canadian Food Inspection Agency and Health Canada, genetically modified crops are considered safe if they are substantially equivalent to a conventional crop in regards to agronomic, physiological and compositional characteristics. A recurring issue in safety assessment of genetically modified crops is the paucity of analytical methods to detect unintended or unexpected outcomes of genetic modification. Traditional targeted compound comparative analyses are limited in scope and capacity to detect unintended changes in chemical composition. This study explored the potential of using microarray technology to assess the substantial equivalence of gene expression profiles between genetically modified and conventional soybean cultivars. Different pre processing methods were applied to the raw expression data from the arrays, and clustering methods were used to try and differentiate the genetically modified cultivars from the conventional cultivars. Results showed that more variation existed between different strains of conventional cultivars than between conventional and genetically modified cultivars. For more information, please see: Cheng, K.C., Beaulieu, J., Iquira, E., Belzile, F.J., Fortin, M.G. and Strömvik, M.V. (2008). âEffect of transgenes on global gene expression in soybean is within the natural range of variation of their conventional counterparts.â Journal of Agricultural and Food Chemistry (in press) Experiment Overall Design: Five samples (biological replicates) of total RNA from each of the five different soybean varieties were selected for hybridization to Affymetrix Soybean GeneChips, for a total of 25 chips (following total RNA integrity assessment). Spike controls B2, bio-B, bio-C, bio-D and Cre-x were added to each hybridization cocktail. Arrays were washed and stained in an Affymetrix Fluidics Station prior to scanning on the Affymetrix GeneChip Scanner 3000. Image acquisition and processing was done with the Affymetrix Microarray Analysis Suite 5.0.
Project description:Several organisms belonging to diverse animal groups have retained Dnmt2 as their only bona fide DNA methyltransferase gene. However, recent studies have shown that Dnmt2 functions as a tRNA methyltransferase, which prompted us to analyze the methylomes of Dnmt2-only organisms at single-base resolution. Using whole-genome bisulfite sequencing we show here that the genomes of Schistosoma mansoni and Drosophila melanogaster lack detectable DNA methylation patterns. Residual unconverted cytosine residues shared many attributes with bisulfite deamination artifacts and were observed at comparable levels in a Dnmt2-deficient fly strain. Furthermore, genetically modified mouse embryonic stem cells that had retained Dnmt2 as their only bona fide DNA methyltransferase gene, did not show any detectable DNA methylation patterns. Our results thus uncover fundamental differences among animal methylomes and suggest that Dnmt2-only organisms lack biologically relevant DNA methylation patterns. Whole methylome analysis of Mus musculus. One sample was analyzed containing DNA from Dnmt1-/-, Dnmt3a-/- and Dnmt3b-/- mice.