Characterization and levels of the RNA polymerases during the embryogenesis of Artemia salina.

Dormant embryos at the gastrula stage of Artemia salina contain three DNA-dependent RNA polymerases: I, II, and III. The enzymes are solubilized from whole embryos and they are separated by chromatography on DEAE Sephadex. The ratio of activities with native and denatured DNA at the optimal salt concentrations is 3.5 for RNA polymerase I, 0.1 for RNA polymerase II and 1.0 for RNA polymerase III.Mn(i2+) is more efficient than Mg(2+) for the three enzymes. RNA polymerase II is 50% inhibited by 5 ng/ml of alpha-amanitin while RNA polymerases I and III are 10% and 30% inhibited by 1 mg/ml. During the embryonic development there is am independent variation of the levels of the RNA polymerases. RNA polymerase I increases its specific activity 4-5-fold, RNA polymerase III increases 2-fold, and RNA polymerase II less than 2-fold. The increase in RNA polymerase activity may represent a mechanism to control the rate of synthesis of RNA during the embryogenesis of A. salina.