The aim of the study is to examine the mechanisms involved in regulating the stability of messenger RNAs (mRNA). An early focus will be on the mechanism of RNA turnover and the enzymes involved, using a combination of genetic and biochemical approaches. The model system will be the yeast Saccharomyces cerevisiae, and both cytoplasmic and mitochondrial mRNA stabilities will be examined, ultimately. The regulation of gene expression in eukaryotic organisms involves the coordination of both initiation of transcription as well as RNA processing at the post-transcriptional level. This study is aimed at elucidating the mechanism of RNA turnover and an understanding of the enzymes that catalyze this significant process.