The Effects of Temperature and Dinitrophenol on the Change of the Proportion of Pfr Controlling RNA Synthesis in Lemna gibba G3 in a Prolonged Dark Period

Abstract

Summary Pfr level regulating RNA synthesis in dark period was estimated by the null response method in a long-day duckweed, Lemna gibba G3. In spite of culture at different temperatures (20 to 33 °C) and of the presence of DNP, this level began to decrease at the same time (about 22nd hr after beginning of the dark period) and the lowering rate was constant. In the culture at 16 OC, however, Pfr level was high even at the 37 th or 61st hr of the dark period. The characteristics of the system holding high Pfr level, at usual temperatures, were similar to those of the physiological clock.