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A study was undertaken to assess the nutritional value of tubers of transgenic lines of potato cv. Desiree with repression of a and c isoforms of 14-3-3 proteins obtained by means of antisense transformations. Isoforms of 14-3-3 protein are responsible for metabolism of carbohydrates, amino acids and calcium. Repression of that protein, i.e. reduction of its synthesis in a potato plant, results in: a decrease in total protein content of tuber with a slight but favourable change in the amino acid profile, enhanced synthesis of starch, small differentiation in contents of minerals – diminished concentrations of Fe, P, and Ca. The 30% addition of dried transgenic potato tubers with repression of isoform a, c as well as a and c of 14-3-3 protein was found not to affect values of digestibility coefficients of nutrients. Repression of 14-3-3 protein was demonstrated to affect diversification of the chemical composition of tuber and contents of nutrients only to a small extent, without diminishing the nutritional value of potato tubers.
Investigations were carried out on: potato tubers of 4 clones of cultivar Irga, transformed with viral genome sequences in order to improve their resistance to a necrotic strain of potato virus Y (PVYN); tubers of parent cultivar; two selected commercial cultivars. Tissue texture (expressed by puncture force and energy) and microstructure were observed after blanching and frying potato strips. A statistical analysis of the variability of texture of raw and heat-treated potatoes enabled classifying Irga and its genetically-modified clones as similar, and did not allow distinguishing a clone of special usability for frying. No differences were revealed either in the texture of the parent cultivar Irga or its genetically-modified clones during 6-month storage. Depending on the type of the thermal treatment of potato tubers, typical deformation of parenchyma tissue resulted. Similar micro-structural changes of the parenchyma tissue were observed after the thermal treatment in both the stem-end zone and the middle part of fried strips.
For 4 weeks, male outbred IF2Jaz rats, divided into 4 groups (n=10), were administered ad libitum diets with 30% addition of dried tubers of transgenic potatoes with repression of isoform a, c as well as a and c of 14-3-3 protein (experimental groups) or with the addition of non-transgenic potatoes of Desiree cultivar (control group). The administration of transgenic potatoes did not affect the growth rate of model animals nor most of the analysed parameters of their health status. Neither anti-nutritional, nor immunostimulatory or toxic effects of the experimental diets were demonstrated. Yet, in liver tissue of rats fed a diet with transgenic potatoes J4 and G1 the concentration of 8-oxo-2’deoxyguanosine – a biomarker of oxidative damage to DNA – was higher than in animals administered a diet with non-transgenic potatoes. Results obtained in the study indicate a threat to the health status of animals fed diets with a high content of genetically-modified potatoes with repression of 14-3-3 protein.
In the presented work the effects of 3-year own investigations relative to technological usability of potato tubers of parental cultivar and its genetically-modified clones were recapitulated. Potato tubers of cultivar Irga were transformed with viral genome sequences in order to improve their resistance to a necrotic strain of potato virus Y (PVYN) at the Institute of Biochemistry and Biophysics, Warsaw, and tubers of the transgenic clones were produced at the Plant Breeding and Acclimatisation Institute, Młochów, in 2000-2002. At the first stage, the variability of parameters characterizing raw material quality was determined. The characteristics of physical properties (size, shape, and mechanical resistance of tubers), microstructure, and content of main chemical constituents (starch, protein, ash, ascorbic acid, glycoalkaloids: α-solanine and α-chaconine) of 15 genetically-modified clones were investigated during three successive years. Tubers of these GM clones were next subjected to culinary processing (microwaving, cooking, and frying) and physico-chemical changes, which are decisive for texture formation and texture properties of end-use product, have been investigated and technological usability of GM potatoes was established. In this work, due to a considerable number of collected data, the final results were presented as means for modification group or, in two cases, as results relative to single clones representative for modification groups. Analysis of variability of physical and chemical parameters studied for the raw and heat-treated potato tubers enabled classifying Irga and its genetically-modified clones as similar, and did not allow distinguishing a clone of special usability for heat processing.
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