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DHAC-induced transgene overexpression in 35S-gshI GMO poplar (Populus × canescens)
Published November 15, 2007
78-83

Relative gene expression levels of transgene gshI (γ-glutamylcysteine synthetase cloned from E. coli) were analyzed by qRT-PCR in two transgenic poplar (Populus × canescens) clones (11ggs and 6lgl) and wild type (WT). An extremely high expression level of transgene gshI was observed in the 6lgl clone (13.5-fold) compared to 11ggs (1.0) sample...s, which level was doubled (1.8-fold) in the DHAC (5.6-dihydro-5'-azacytidine hydrochloride) treated (at 10-4 M for 7 days) 6lgl samples but not in the 11ggs clone (0.4-fold). Contrary to this result, relative copy number of transgene gshI in the 6lgl clone was found to be less 60% less (1.0) then in the 11ggs samples (1.6). Relative expression levels of proper poplar gene gsh1-poplar showed significantly higher responsiveness to DHAC treatment than transgene gshI with the highest expression level in the untransformed (WT) poplar
clone (19.7-fold) compared to transformed 6lgl (8.7-fold) and 11ggs (2.5-fold) clones. For internal controls constitutively expressed housekeeping genes a-tubulin were applied. For data analysis, the 2−ΔΔCt method was used. DHAC applied in long-term cultures (27 days) at low concentrations (10-8 – 10-6 M) showed morphogenetic activity by initiating de novo root development of leaf discs.

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Qualitative detection of genetically modified organisms in plant samples
Published July 16, 2007
309-313

We analysed the GMO content of corn samples by polymerase chain reaction following the appropriate optimization of the reaction. The analysis included two main steps: extraction of DNA from the sample, and detection of the GMO content by polymerase chain reaction. The polymerase chain reaction is an in vitro method to multiply chromosomatic or ...cloned DNA (cDNA) sequences through the enzymatic pathway. The reaction is sensitive enough to produce DNA in sufficient amount for the analysis from a single DNA. We identified the PCR products by agarose gel electrophoresis. When optimizing the reaction, the MgCl2 concentration, reaction time and temperature have to be taken into consideration. The temperature of the anellation has to be increased until the highest specificity and yield is reached. If the temperature of the anellation is too high, the primer is linked to non-specific sites as well; in the gel visualization, more lines can be seen at one sample. If the temperature of the anellation is too high, the primer is insufficiently linked or is not linked at all (too few lines in the gel visualization). After optimization, the GMO content in the unknown sample can be determined along with the appropriate positive and negative controls.

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