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Identifier uch.biology.msc//2001delis
Title Διαγονιδιακά φυτά καπνού που υπερεκφράζουν την κατάλαση cat1 παρουσιάζουν αντοχή σε ποικίλες μορφές αβιοτικής οξειδωτικής καταπόνησης
Author Ντελής, Ιωάννης
Thesis advisor Ρουμπελάκη-Αγγελάκη, Καλλιόπη
Abstract Oxygen is essential for existence of aerobic life; however activated oxygen species (AOS) are generated in all aerobic organisms, and their levels are enhanced by exposure to chemical and environmental stress. The toxic effects of AOS, termed oxidative stress, are circumvented by a combination of enzymic and non-enzymic mechanisms, that can reduce oxidative damage by converting AOS to harmless compounds. Among the enzymes involved in anti-oxidant defense mechanisms, catalase (EC 1.11.1.6) plays a key role, catalyzing the dismutation of hydrogen peroxide to water and molecular oxygen at an extremely rapid rate. This rapid H2O2 dismutation represents the catalatic mode of action of catalase.Catalase is a ubiquitous peroxisomal matrix enzyme that is targeted to the peroxisome via a peroxisome trageting motif (PTM). Catalase with high catalatic activity (CAT-1) is the major isoform in leaves, and there is relatively less CAT-1 in stem and sepal tissue. In order to further investigate the possible involvement and role of catalase as protection against oxidative stress, we have over-expressed a cytoplasm targeted catalase, due to AOS formation in/or diffusion through cytoplasm in certain conditions of biotic or abiotic stress. Thus, an enhancement of the antioxidant capacity in the cytoplasm was attempted. Accordingly, we developed transgenic tobacco genotypes expressing the tobacco Cat1 gene lacking the peroxisome target motif. T1 progeny was analyzed for catalase specific activity in various developmental stages. Transgenic tobacco exhibited increased catalase specific activity from 1.2- to more than 2-fold compared to wild type plants. Transgenic plants were examined for tolerance to various abiotic stress conditions. Catalase over-expressing plants showed reduced levels of light-mediated cellular damage from the herbicide methyl viologen and exogenous H2O2.
Language Greek
Issue date 2001-12-06
Collection   School/Department--School of Sciences and Engineering--Department of Biology--Post-graduate theses
  Type of Work--Post-graduate theses
Permanent Link https://elocus.lib.uoc.gr//dlib/4/5/2/metadata-dlib-2001delis.tkl Bookmark and Share
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