Temperature Effect on Protein Synthesis in a Heat-Synchronized Protozoan Treated with Actinomycin D

Protein synthesis was studied in the ciliated protozoan Tetrahymena pyriformis GL after actinomycin D was added to the culture medium. When the temperature rose above that optimum for growth, there were significant reductions in protein synthesis. Lipid biosynthesis under the same conditions was slightly stimulated, an indication that the eflect was not due to an underlying reduction in energy sources. The phenomenon appears to be unique to the protein synthesizing system. Correlation with previous data suggests that it is due to nontranslational destruction of template RNA.