The Role of the Expansion Segment 7 of 25S rRNA During Oxidative Stress in Saccharomyces cerevisiae

Translation is an essential process for protein expression in both eukaryotes and prokaryotes. Like any cellular process, translational factors are prone to damage when the cell is under stress. One common stressor that nearly all cells may experience is abnormal levels of reactive oxygen species (ROS). Damage caused by ROS has been associated with disease ranging from neurodegenerative impairments, to the aging process of cells. These oxygen radicals are capable of damaging a litany of molecules including nucleic acids, and molecular factors involved in translation. It has been shown that tRNA can be cleaved upon ROS-induced stress and these fragments come to serve as signaling molecules. However, to date there is very little research that has been done to investigate whether or not rRNAs are capable of similar signaling. Presented in this dissertation is an observed endonucleolytic cleavage in the ES7c region of eukaryotic 25S rRNA, which results in rRNA fragments formation. Herein, experimentation is presented that shows a relationship between elevated levels of ROS, in particular H2O2, and ES7c-cleavage. The results presented in this dissertation aim to provide further understanding of this observed rRNA cleavage. The groundwork established during this project serves as a foundation for further research into the nature of this phenomenon. The protocols and procedures that were developed during this project will provide our laboratory with necessary tools for future projects regarding ROS, apoptosis, and rRNA fragmentation