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Identifier uch.biology.msc//2001papaeythimiou
Title Μελέτη της μετα-μεταγραφικής σίγησης γονιδίων (PTGS) σε φυτά μολυσμένα με το ιοειδές PSTVd
Author Παπαευθυμίου, Ιωάννης
Thesis advisor Τσαγρή, Ευθυμία
Abstract Post-transcriptional gene silencing (PTGS) - also known in animals as RNAi - is a fundamental regulatory mechanism operating in diverse types of organisms, however the cellular components of the gene silencing machinery and the regulation of the process are not understood. PTGS has diverse roles in different organisms, from resistance against viruses in plants to developmental regulation in Drosophila and C elegans. In all cases, PTGS is manifestated by specific targeted degradation of mRNA and production of 21-23 nt long double-stranded and single-stranded RNAs. There is also evidence of systemic acquired PTGS in different organisms. This systemic acquired PTGS is possibly triggered by a PTGS product, which can be transported intracellularly or extracellularly. In the present work, the ability of Potato Spindle Tuber Viroid (PSTVd) - a non-coding pathogenic RNA molecule - to trigger PTGS after infection of tomato plants was investigated. Indeed, northern analysis of PSTVd-infected tomato plants showed that 21-23 nt long RNAs are present, indicating that the replicating viroid is subjected to a mechanism which resembles PTGS. Biochemical characterization of the 5' and 3' end groups of these small RNA molecules was initiated in order to speculate on possible known enzymes that are involved in the PTGS mechanism and to indicate a tagged systemic silencing signal among the small RNA species. Given the fact that plant viruses have developed a mechanism that suppresses PTGS, preliminary cloning of the cDNA of a known viral suppressor of PTGS into a binary plant expression vector was carried out in an effort to illuminate a possible role of this suppressor in the PSTVd-triggered-post transcriptional gene silencing.
Language Greek
Issue date 2001-07-26
Collection   School/Department--School of Sciences and Engineering--Department of Biology--Post-graduate theses
  Type of Work--Post-graduate theses
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