[A fluorometric method of determining DNA in cells]

A convenient express method is proposed for cell lysis and DNA solubilization in the presence of sarcosyl and sodium citrate. The DNA content was determined in cell lysates by registration of fluorescence enhancement with Hoechst No 33258 ("Serva", FRG). In 0.5 M NaCl solution the Hoechst-RNA fluorescence is negligible. An optimal molar ratio of DNA and Hoechst is in the range from 0.2 to 2.0. Beyond the range the accuracy of DNA quantification become poor. An optimal range of DNA quantification in cells is 200-2000 ng/ml.