Modified Feulgen staining of DNA with aqueous solution of pinacyanol

The paper reports on the use of a quinoline dye, pinacyanol, towards staining of acid hydrolysed DNA. The dye as an aqueous solution can be used after treatment of mammalian tissue sections in concentrated phosphoric acid at 5 degrees C for 20 min followed by hydrolysis in 6N HCl at room temperature for 15 min, for staining DNA-aldehyde molecules. It has also been observed that staining of DNA-phosphate groups is also possible in sections treated with cold concentrated phosphoric acid after selective extraction of RNA. Both in situ absorption characteristics of stained nuclei as well as in vitro absorption data of an aqueous solution of the dye have been presented. It has been suggested that staining DNA-aldehydes with pinacyanol, without any primary amino group in its molecules is due to a modified Feulgen reaction.