We investigate the spatio-temporal dynamics of single mRNA molecules in living yeast cells using the MS2-system. This method exploits the high affinity of the viral coat protein of the bacteriophage MS2 - which we tag with fluorescent proteins - to certain stem-loop nucleotide sequences. In our lab, we genetically integrate these sequences into mRNAs of interest. The transcripts of the tagged gene become visible as the fluorescently tagged coat proteins accumulate on the stem-loop sequence. Importantly, all parts of this system are genetically encoded and no exogenous labels need to be added for imaging. We further develop this technique by improving fluorescent tags.