Abstract
1. The nature of the differential staining of nucleic acids with methyl green-pyronin was investigated by way of comparing tissue staining with methyl green and pyronin, individually and in mixture, with experiments in which aqueous solutions of these dyes, both alone and mixed together, were added with different types of nucleic acids and nucleoproteins and the precipitates formed were observed microscopically.
2. Evidences have been presented which suggest that differential staining with methyl green-pyronin is not due to true selectivity of non-disaggregated DNA to methyl green on the one hand and of disaggregated DNA and PNA to pyronin on the other hand, but rather to preferential tendencies of these nucleic acids in combining with respective dyes in fixed tissues as well as in aqueous solutions.
3. Some of the discrepancies among the data published by different investigators on the nature of methyl green-pyronin staining are discussed.
Acknowledgements. I would express my hearty thanks to Dr. O. Itikawa, Director of the Medico-Biological Institute, Minophagen Pharmaceutical Co., for his interest in this work and encourragement throughout the course of investigation. Thanks are also due to late Miss H. Kawamata, Miss S. Takeda, Minophagen Pharmaceutical Co., and to Dr. H. Matsuda, Mr. M. Fukuda and Mr. O. Harikane, University of Osaka for their assistance. Further it is my pleasant duty to mention my indebtedness to Prof. S. Hosoya and Dr. T. Homma, Institute for Infec-tious Diseases, University of Tokyo, for facilities in utilizing laboratory equipments in the course of extracting pDNA used in this investigation.
