Depression of carbon flow to the glycogen pool induced by nitrogen assimilation in intact cells of Anacystis nidulans

Abstract

The influence of nitrate and ammonium assimilation on glycogen metabolism has been determined in intact Anacystis nidulans cell actively fixing CO2. Assimilation of nitrate or ammonium resulted in significant decreases in both the incorporation into glycogen of newly fixed carbon and the accumulation of glycogen by the cells, the magnitude of these effects depending on the light intensity. The depression in glycogen synthesis induced by nitrogen assimilation was more marked at low light intensity, and especially when ammonium was the nitrogen source. Under these conditions, specific radioactivity of the glycogen pool was particularly high, indicating enhanced turnover of glycogen. Thus, in addition to a more general depressing effect of nitrogen assimilation on the carbon flow to glycogen, degradation of glycogen appears to be stimulated by ammonium assimilation at low (but not at high) light intensity.