1. 1. Nuclear DNA-dependent RNA polymerases from liver of mouse, Mus musculus, were separated chromatographically on DEAE-Sephadex A-25. 2. 2. Five major enzyme peaks were obtained from each sample of liver. The sensitivity of the enzymes to ct-amanitin was as follows: la and Ib, insensitive; lia and lib, highly sensitive; and III, slightly sensitive. 3. 3. The percentage distributions, activities per mg DNA, specific activities and purifications of the enzymes from BDF1, C3H/HeJ, C57BL/6J and Swiss albino mice were compared and discussed. 4. 4. Statistically significant differences (P < 0.05) were found between some strains of mice for percentage distribution, activity per mg DNA, and purification of some RNA polymerases.
