A fluorescent red basic xanthene dye, the chloride of tetramethyldiaminoxanthene, pyronin Y or pyronin G (C.I. 45005), or of tetraethyldiaminoxanthene, pyronin B (C.I. 45010). These dyes, especially pyronin Y, are used in combination with methyl green for differential staining of RNA (red) and DNA (green); difference in staining result is probably due to the higher degree of polymerization of DNA; pyronin Y is also used as a tracking dye for RNA in electrophoresis.
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Examples: glitazone, GI cocktail, etc.