Synthesis and Release of RNA by Isolated Nuclei of Plant Cells in Relation to Nucleoside Triphosphates and Divalent Cations

Abstract

An in vitro system for nuclei from freely suspended callus cells from Petroselinum crispum is described. A filtration technique allowed the measurement of transcription and release of RNA simultaneously. Both can be stimulated by nucleoside triphosphates and divalent cations in equimolar concentrations. Divalent cations have an inhibitory effect on the release of RNA. Nucleoside triphosphates, by means of their complex-forming capacity, can remove divalent cations, and so stimulate RNA translocation. Sodiumpyrophosphate also forms chelates with divalent cations and increasesRNA release. Apparently, nucleoside triphosphates are used as a complex in translocating RNA.—The stimulatory effect on RNA synthesis results from increasing complex concentrations formed by nucleoside triphosphates and divalent cations, indicating that the complex could be the substrate of the RNA polymerases. The experiments with sodiumpyrophosphate show that the chelating effect could also be a part of the process. With ADP RNA synthesis can be inhibited.—Isolated nuclei exhibit a powerful NTPase and pyrophosphatase activity, whereas ADP is not split by the nuclei.—The effects of ATP, sodiumpyrophosphate and ADP on maintaining or reducing RNA synthesis should be seen in connection with the enzymatic splitting of these compounds by various phosphatases (pyrophosphatase, NTPase).