<Tr> <Td> </Td> <Td> </Td> </Tr> <P> Nile blue (or Nile blue A) is a stain used in biology and histology . It may be used with live or fixed cells, and imparts a blue colour to cell nuclei . </P> <P> It may also be used in conjunction with fluorescence microscopy to stain for the presence of polyhydroxybutyrate granules in prokaryotic or eukaryotic cells . Boiling a solution of Nile blue with sulfuric acid produces Nile red (Nile blue oxazone). </P> <P> Nile blue is a fluorescent dye . The fluorescence shows especially in nonpolar solvents with a high quantum yield . </P>

Nile blue can be used to test for the presence of