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ADVERSE IMPACTS OF TRANSGENIC CROPS/FOODS :A COMPILATION OF SCIENTIFIC REFERENCES WITH ABSTRACTSdistribution of transgene loci among the highly heterochromatic C genome andthe A/D genomes of hexaploid oat, nor among chromosomes within the genomes.Transgene integration sites were detected at different locations along individualchromosomes, although the majority of transformants had transgenes integratedinto subtelomeric and telomeric regions. Transgene integration sites exhibiteddifferent levels of structural complexity, ranging from simple integration structuresof two apparently contiguous transgene copies to tightly linked clusters of multiplecopies of transgenes interspersed with oat DNA. The size of the genomicinterspersions observed in these transgene clusters was estimated from FISHresults on prometaphase chromosomes to be megabases long, indicating thatsome transgene loci were significantly larger than previously determined bySouthern blot analysis. Overall, 6 of the 25 transgene loci were associated withrearranged chromosomes. These results suggest that particle bombardmentmediatedtransgene integration may result from and cause chromosomalbreakage and rearrangements.www.pawlowski.cit.cornell.edu/2000.pdf46. Weigel D, Ahn JH, Blazquez MA, et al. (2000) : Activation tagging inArabidopsis. Plant Physiology. 2000;122(4) :1003–1013.Activation tagging using T-DNA vectors that contain multimerized transcriptionalenhancers from the cauliflower mosaic virus (CaMV) 35S gene has been appliedto Arabidopsis plants. New activation-tagging vectors that confer resistance tothe antibiotic kanamycin or the herbicide glufosinate have been used to generateseveral tens of thousands of transformed plants. From these, over 30 dominantmutants with various phenotypes have been isolated. Analysis of a subset ofmutants has shown that overexpressed genes are almost always foundimmediately adjacent to the inserted CaMV 35S enhancers, at distances rangingfrom 380 bp to 3.6 kb. In at least one case, the CaMV 35S enhancers led primarilyto an enhancement of the endogenous expression pattern rather than toconstitutive ectopic expression, suggesting that the CaMV 35S enhancers usedhere act differently than the complete CaMV 35S promoter. This has importantimplications for the spectrum of genes that will be discovered by this method.http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1539247/47. Amedeo P, Habu Y, Afsar K, Mittelsten Scheid O, Paszkowski J. (2000) :Disruption of the plant gene MOM releases transcriptional silencing ofmethylated genes. Nature. 405 (6783): 203-6.Epigenetic modifications change transcription patterns in multicellular organismsto achieve tissue-specific gene expression and inactivate alien DNA such astransposons or transgenes. In plants and animals, DNA methylation is involvedin heritability and flexibility of epigenetic states, although its function is far fromclear. We have isolated an Arabidopsis gene, MOM, whose product is required forthe maintenance of transcriptional gene silencing. Mutation of this gene or(26)