Abstract
The presence of cyclic adenosine 3', 5'-monophosphate (cAMP) in the ciliated protozoan, Tetrahymena pyrifurmis W, was demonstrated by thin-layer chromatography (TLC). The content of cAMP in the cell increased abruptly in the early exponential phase, and then diminished with further culture. When cells in the exponential or stationary growth phase were cultured in a fresh medium, growth was inhibited by addition of dibutyryl cAMP (Bt2-cAMP) or methylxanthines. In synchronized cultures of Tetrahymena, Bt2-cAMP inhibited protein and RNA syntheses in the G1 phase and DNA synthesis in the S phase. These results indicate that cAMP regulates the growth of the protozoan in the G1 phase.
