The Effect of HCl Hydrolysis on the Retention of Thymidine in DNA

Allium roots grown in C¹⁴-thymidine and H³-thymidine media were treated with N hydrochloric acid at 60°C. as in standard Feulgen hydrolysis. The retention of the radioactive thymidine in DNA as a function of hydrolysis time was studied autoradiographically. No significant loss of label was detected until hydrolysis was extended beyond the optimal time for Feulgen staining. The data are consistent with the assumption that there is no significant loss of DNA during normal Feulgen hydrolysis in the material used.