Spectral phasor analysis of Pyronin Y labeled RNA microenvironments in living cells

We show that the spectral phasor approach of the fluorescent dye Pyronin Y (PY) can be used to identify specific RNA subspecies of ribonuclear proteins complexes in live cells. We applied spectral phasors to isolate intracellular RNA species with similar spectral properties. We identified at least 4 different PY labeled species in live cells and further spatially mapped their presence at the pixel level. Most notable were transcripts in the nucleoli which were spectrally similar to RNA clusters in the cytoplasm. We propose that these species represent ribosomal RNA and clustered ribonucleoprotein complexes. Further, we observed within this cluster Cajal bodies in the proximity of the nucleolus. In addition, transcripts in the cytoplasm undertook a filamentous morphology composed of multiple puncti structures which individually localized along and close to mitochondria but were distinct from mitochondria.