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Title: Conserved chromatin-mediated gene silencing in yeast and plants
Author: Cruickshanks, Hazel Anne
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2003
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Cells must regulate gene expression to control development, differentiation, and respond to changes in the environment. The simplistic view of gene regulation states that an activator or repressor molecule binds to a specific sequence in DNA and exerts its effects upon transcription. However, the situation becomes more complicated when we consider that eukaryotic DNA is packaged into chromatin. Chromatin must be modified in order to control gene expression. Cells have adopted many ways of achieving this including: chromatin remodelling, DNA methylation and histone modification. The exact contribution of each of these need to be elucidated in order to fully understand gene regulation. Many common themes run through gene regulation between species, suggesting there are conserved mechanisms of gene control. Using the simple model organism, Saccharomyces cerevisiae, I have studied two types of gene repression found in plant species to compare and further determine their molecular bases. A repetitive DNA fragment previously found to induce de novo methylation and expression variegation in Petunia hybrida, was found to cause gene silencing in S. cerevisiae in a methylation independent manner. The possible mechanisms of this were dissected using gene replacement and protein expression studies. In a separate series of experiments, putative homologues of the S. cerevisiae transcriptional co-repressor, TUP1, were tested for chromatin remodelling ability in yeast. A TUP1 homologue from Arabidopsis thaliana was shown to repress transcription in S. cerevisiae but in a different manner from TUP1 indicating mechanistic similarities and differences between their functions. By using yeast as a tool to study gene regulation in higher eukaryotes, the principles of gene repression can be explored and we can speculate the roles of the individual features such as chromatin remodelling and DNA methylation.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available