Azure B staining of DNA-aldehyde molecules of acid-hydrolysed tissue sections

This communication presents a method for the preparation of azure B-SO2 with trichloracetic acid (TCA) and potassium metabisulphite for in situ demonstration of DNA-aldehyde molecules following acid hydrolysis of tissue sections. The shelf-life of such a dye-reagent is slightly more than that of the control, prepared with N HCl and potassium metabisulphite. The slightly increased shelf-life of the experimental dye-reagent has been considered to be due to a somewhat higher pH as compared with that of the control. The in situ absorption characteristics of nuclei stained for DNA-aldehyde molecules with either an aqueous solution of azure B or with TCA-azure B-SO2 show peak-absorption at 600 nm in both cases. This phenomenon has been interpreted as due to the fact that azure B does not contain any primary amino group in its molecules and, therefore, the mode of binding of DNA-aldehydes with this dye is different from that with dyes that contain primary amino group. The implications of some of the findings have been discussed.