Reactivity of Zn 2+ on nuclear DNA and RNA biosynthesis of regenerating rat liver

Abstract

Partially hepatectomized rats have been employed for a study of the reactivity of zinc ions on DNA, RNA and protein biosynthesis of liver nuclei. Intraperitoneal injections of this metal ion increased the incorporation rate of [6- 14C]orotic acid into rapidly synthesized nuclear RNA while [ 3H]thymidine uptake of nuclear DNA was progressively diminished with increasing Zn 2+ concentrations. No change of nuclear protein biosynthesis was observed. RNA polymerase activity of isolated enzymatically active whole liver nuclei from Zn 2+ injected rats remained constant compared to control groups. However, when zinc ions were added in vitro to liver nuclei from uninjected rats RNA polymerase activity was strongly inhibited. Intraperitoneal injections of low Zn 2+ concentrations have been found to stimulate the incorporation rate of [ 3H]thymidine into nuclear liver DNA of zinc deficient rats. This result appears to be significant since the same Zn 2+ concentrations were ineffective on the DNA biosynthesis of rats restricted to a normal Zn 2+ providing stock diet.