Nucleinsäuren

Abstract

The effect of the acid hydrolysis on nuclear chromatin in histological sections of mouse spleen and liver and in smears of rat thymus was investigated by means of Feulgen reaction (FR) and some staining methods. The data of a number of authors for the loss of Feulgen-positive material (apurinic acid) during a prolonged hydrolysis with n HC1 at 60° C were confirmed. It was established that the high temperature of the hydrolyzing solution and not the acid itself was responsible for the removal of the apurinic acid from sections. In this respect warm water at 60° C exhibits the same effect on apurinic acid as n 1101 at 60° C. The standard 8 to 12 minutes’ hydrolysis with nHCl at 60° C causes a transition from only a part of DNA to apurinic acid capable to give FR. This fact besides the possibility of a partial removal of apurinic acid from the sections for the same time makes the standard hydrolysis inconvenient for quantitative cytophotometric studies. Hydrolysis with 5nHC1 at room temperature carried out on sections fixed in formol-containing fluids (Serra, 10 per cent neutral formol, formol-acetic acid) achieves for about 35 minutes a complete converting of DNA into apurinic acid and fails to remove the latter for hours from the sections. Therefore such a hydrolysis procedure seems to be much more convenient for cytophotometric application of FR.