Saccharomyces cerevisiae has the ability to alter its growth based on how much of a particular carbon source is present in the environment; when glucose is depleted the cells will enter the post-diauxic phase. Based on previous evidence, we suspect that mRNA that encode for mitochondrial proteins are degraded by a novel autophagic decay pathway in the post-diauxic phase, requiring the ribonucleases Xrn1 and Rny1 for proper mitochondrial growth. First, we tested the localization of the ribonucleases Xrn1 and Rny1 to determine if their localization changes due to stressful conditions, and if these results can indicate a change in their function. Second, to test if an autophagic mRNA decay pathway exists, we used the MS2 labeling technique to fluorescently tag specific mRNAs within the cell in order to see if they associate with structures that maybe involved in autophagic mRNA decay, such as autophagosomes and stress granules. We tested three specific mRNAs for their localization: PGK1, DPI8 and COX5A. PGK1 encodes for a protein kinase that aids in metabolism, while DPI8 and COX5A both encode for mitochondrial proteins. We were able to determine that we can visualize mRNA using the MS2-CP-GFP fusion protein, however we believe that the MS2-CP-mCherry fusion did not detect MS2-tagged mRNAs. Using the MS2-CP-GFP assay, we were able to determine that PGK1 localizes to mitochondria in the post-diauxic phase.