Percorrer por autor "Oliveira, Margarida"
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- Environmental stress is the major cause of transcriptomic and proteomic changes in GM and non-GM plantsPublication . Batista, Rita; Fonseca, C.; Planchon, Sébastien; Negrão, Sónia; Renaut, Jenny; Oliveira, MargaridaThe approval of genetically modified (GM) crops is preceded by years of intensive research to demonstrate safety to humans and environment. We recently showed that in vitro culture stress is the major factor influencing proteomic differences of GM vs. non-GM plants. This made us question the number of generations needed to erase such “memory”. We also wondered about the relevance of alterations promoted by transgenesis as compared to environment-induced ones. Here we followed three rice lines (1-control, 1-transgenic and 1-negative segregant) throughout eight generations after transgenesis combining proteomics and transcriptomics, and further analyzed their response to salinity stress on the F6 generation. Our results show that: (a) differences promoted during genetic modification are mainly short-term physiological changes, attenuating throughout generations, and (b) environmental stress may cause far more proteomic/transcriptomic alterations than transgenesis. Based on our data, we question what is really relevant in risk assessment design for GM food crops.
- Plant natural variability may affect safety assessment dataPublication . Batista, Rita; Oliveira, MargaridaBefore market introduction, genetic engineered (GE) food products, like any other novel food product, are subjected to extensive assessment of their potential effects on human health. In recent years, a number of profiling technologies have been explored aiming to increase the probability of detecting any unpredictable unintended effect and, consequently improving the efficiency of GE food safety assessment. These techniques still present limitations associated with the interpretation of the observed differences with respect to their biological relevance and toxicological significance. In order to address this issue, in this study, we have performed 2D-gel electrophoresis of five different ears of five different MON810 maize plants and of other five of the non-transgenic near-isogenic line. We have also performed 2D-gel electrophoresis of the pool of the five protein extractions of MON810 and control lines. We have notice that, in this example, the exclusive use of data from 2D-electrophoresed pooled samples, to compare these two lines, would be insufficient for an adequate safety evaluation. We conclude that, when using ‘‘omics” technologies, it is extremely important to eliminate all potential differences due to factors not related to the ones under study, and to understand the role of natural plant-to-plant variability in the encountered differences.
- Selection of the best comparator for the risk assessment of GM plants- conventional counterpart vs. negative segregantPublication . Fonseca, Cátia; Planchon, Sébastien; Serra, Tânia; Chandler, Subhash; Saibo, Nelson; Renaut, Jenny; Oliveira, Margarida; Batista, RitaAbstract for 12th international Symposium on biosafety of genetically modified organisms The identification of similarities and differences between GM plants and derived food/feed and their comparators plays a central role in risk assessment strategy. Therefore, selecting the right comparators must be one of the top priorities. The question is which control would allow us to better evaluate the potential unintended effects related directly to the transgene and/or DNA rearrangements, discounting the potential effects caused by in vitro culture procedures; since, these are non-controversial procedures also used in conventional breeding. Aiming to answer the previous question we have used Multiplex fluorescence 2D gel electrophoresis technology (DyeAGNOSTICS Refraction-2D) coupled with MS to characterize the proteome of three different rice lines (Oriza sativa L. ssp. Japonica cv Nipponbare): A control conventional counterpart. An Agrobacterium transformed transgenic line. A negative segregant (homozygous negative progeny) from a different transgenic line. We have observed that transgenic and negative segregant plant lines grouped together (only 1 differentially regulated spot - fold difference > 1.5, ANOVA, P<0.05,) and apart from control (49 spots with fold difference >1.5, ANOVA, P<0.05, in both transgenic and negative segregant lines comparing to control line). Additionally, the 35 proteins identified (using MS) in this study, were already associated with stress response by other authors. The only feature in common between the transgenic and negative segregant lines is that they have both suffered in vitro culture procedures. Hence, the results obtained indicate that, in this study, different gene disruption and/or DNA rearrangements and the presence/absence of transgene were factors with less impact on rice proteome than the proteomic promoted differences caused by in vitro culture, and eventually the stress caused by this process. This work highlights the importance of continuous revision and upgrade of the guidance criteria to be followed for the selection of suitable comparators in GMO risk assessment.