Staining of DNA-phosphate groups with a mixture of azure A and acridine yellow

This paper deals with staining of DNA-phosphate groups with a mixture of an equal parts of aqueous solution of azure A and acridine yellow in a 1:1 proportion and also embodies a study of the absorption properties of the stained nuclei. It also embodies results of sequential staining of nuclei stained first with azure A followed by staining with acridine yellow and vice versa, after extraction of RNA with cold phosphoric acid. The results indicate that the absorption peaks of nuclei differ from those of nuclei stained for DNA-aldehyde molecules with azure A-SO2 or acridine yellow-SO2. The in vitro absorption characteristics of an aqueous solution of azure A and those of an aqueous solution of acridine yellow are also presented herein. The conclusion obtained from this study is that all the phosphate groups of DNA do not take part in the staining process when staining is carried out with azure A or acridine yellow alone after after RNA has been extracted. This is because the nuclei stained with these dyes sequentially show the presence of acridine yellow-DNA and azure A-DNA complex.