Staining of DNA-phosphate groups and DNA-aldehyde molecules with dyes of the azine group

The investigation reports on the use of safranine-SO2 and phenosafranine-SO2, prepared with N HCl or oxalic acid plus potassium metabisulphite, for staining rat liver sections following Feulgen procedure. It has been found that optimum staining of DNA-aldehyde molecules is possible with safranine-SO2 and phenosafranine-SO2, prepared with N HCl and potassium metabisulphite, upto a duration of one week after the preparation of the dye-reagents. Thereafter, staining intensity of the nuclei produced by the dye-reagents is gradually diminished. Staining of acid-hydrolysed sections is also possible with aqueous solutions of these dyes. Moreover, DNA-phosphate groups can also be stained with aqueous solutions of these dyes after selective extraction of RNA with cold phosphoric acid. The in situ absorption spectra of nuclei, stained for DNA-aldehyde molecules with safranine-SO2, phenosafranine-SO2 and aqueous solutions of these dyes, have been presented in this paper. Also presented herein are absorption data of nuclei stained with these dyes after selective extraction of RNA. It has been found that absorption-peaks of nuclei stained differently are different from one another. The implications of these findings have been discussed.