Pyronin Y

Pyronin Y (Pyronine G) is a cationic dye that intercalates RNA and has been used to target cell structures including RNA, DNA and organelles. Pyronin Y forms fluorescent complexes with double-stranded nucleic acids (especially RNA) enabling semi-quantitative analysis of cellular RNA. Pyronin Y can be used to identify specific RNA subspecies of ribonuclear proteins complexes in live cells^[1][2][5]. In Vitro: Pyronin Y forms fluorescent complexes with double-stranded nucleic acids, especially RNA, enabling semi-quantitative analysis of cellular RNA in flow cytometry, to estimate the RNA content per cell in formalin fixed EL4 leukosis tumor cells, enzyme dispersed R3327-G rat prostatic adenocarcinoma cells, mouse spleen cells stimulated with concanavalin A, and human peripheral blood lymphocytes stimulated with phytohemagglutinin^[1].
A fluorescent staining procedure based on pyronin Y is described. The technique has been used to stain RNA in human reticulocytes for subsequent flow analysis and sorting^[2].
In viable cells this dye also accumulates in mitochondria. At a concentration of 1.7 to 3.3 μM, pyronin Y is localized almost exclusively in mitochondria of cultured cells, similar to another mitochondria! probe, rhodamine 123. At that concentration PY is not toxic but suppressed cell growth, arresting cells^[3].
Pyronin Y has long been used, in combination with other dyes such as Methyl Green, as a differential stain for nucleic acids in paraffin tissue sections. In sections stained with Methyl Green-pyronin Y, red blood cells, elastic fibre of blood vessels, zymogen granules of pancreatic acinar cells, surface membrane of heptocytes and kidney tubular cells showed strikingly strong green and/or red fluorescence, while the nuclei of cells appeared non-fluorescent^[4].
Pyronin Y binds to double stranded RNA (dsRNA) including messenger RNA (mRNA), transfer RNA (tRNA) and ribosomal RNA (rRNA)^[5].