Determination of nucleic acids in animal tissues.

As reported in a previous paper (l), a new microchemical method for the determination of deoxyribonucleic acid (DNA) has been devised which permits the evaluation of DNA in amounts as small as 2.5 y per ml. The method is particularly useful with very small quantities of tissue. For this reason a study was undertaken to learn the best conditions for the application of the method to the determination of DNA in animal tissues. The reaction of DNA with indole was compared with the diphenylamine reaction according to Dische (2). At the same time, a modification of the Barrenscheen and Peham (3) method for ribose determination with orcinol was worked out in order to determine pentose nucleic acid (PNA) in the same organ extracts. Total nucleic acid P of tissues was calculated from the PNA and DNA contents, found by means of color reactions. These values were compared to those obtained by a direct chemical method. Readings were also taken at 260 and 268 rnp and their values compared with those calculated from the results of the color reactions.