ABSTRACT
1. The effect of cyclic nucleotides on aggregates of dispersed embryonic neural retina cells was examined in order to study their influence upon macromolecular synthesis, i.e. protein and DNA. 2. Cyclic AMP, dibutyryl cAMP, cyclic GMP and dibutyryl cGMP were used at various concentrations (5 x 10(-4) -5 mM). 3. The incorporation of labeled precursors into DNA and protein were used to monitor the effect of cyclic nucleotides on cultured aggregates. 4. All nucleotides exhibited a stimulatory effect at 5 x 10(-4) and 5 x 10(-3) mM on macromolecular synthesis, with resulting growth and proliferation of chick neural retina cells. 5. High concentrations (5 x 10(-1) and 5 mM) of cyclic nucleotides exhibited an inhibitory effect upon macromolecular synthesis and a marked cytotoxic effect.
