ROLE OF RNA POLYMERASE IN CONTROL OF RNA SYNTHESIS IN VITRO FROM RANA PIPIENS EMBRYO CHROMATIN

DNA-RNA hybridization experiments were employed to examine the qualitative aspects of RNA synthesis during the early development of Rana pipiens. 1. 1. With the addition of exogenous RNA polymerase, a greater portion of the genome was transcribed from isolated chromatin of larvae (4.5%) and tailbud embryos (3.5%) than was transcribed from the chromatin of gastrulae (2.7%). This stagewise difference was lost when the chromatin of these stages was deproteinized to similar levels before use as templates. In this case, the RNA made from all three stages hybridized with 20.5% of the genome. 2. 2. When nuclei were used to generate RNA in vitro, without the addition of exogenous RNA polymerase, gastrulae and neurulae produced quantitatively more RNA and qualitatively more kinds of RNA than did isolated nuclei from later stage embryos. 3. 3. The activity of RNA polymerase isolated with the chromatin and free in the nuclear supernatant was determined. Higher RNA polymerase activity was found associated with the chromatin and in the nuclear sap of the early embryos (gastrulae and neurulae) than in tailbud embryos and larvae. © 1969.