Abstract
Excitatory synaptic stimulation of the R2 neuron in the abdominal ganglion of Aplysia californica causes an increased incorporation of 3Huridine into RNA. However, this could be the result of a change in precursor specific activity rather than an increase in RNA synthesis. We find that at low external uridine concentrations (1.5 μM) there is no increase in 3H‐uridine incorporation correlated with synaptic stimulation. In addition, no change in incorporation of 3H‐leucine into total protein or in the pattern of newly‐synthesized proteins, resolved by electrophoresis on SDS‐polyacrylamide gels, was detected with stimulation. Since the R2 neuron can be stimulated without a detectable change in RNA or protein synthesis, we conclude that the increase in incorporation observed at high external uridine concentrations (100 μM) could be caused by increased specific activity in a precursor pool rather than by an RNA synthesis change.
