Abstract
We characterized the macromolecular synthesis of 3 "short-survival" (3YltsA106, 3YltsB107, and 3YltsC113) and 4 "long-survival" (3YltsD123, 3YltsF121, 3YltsG125, and 3YltsH203) temperature-sensitive mutants of rat 3Y1 diploid fibroblasts under various conditions. Inhibition of RNA synthesis was the earliest event detectable in 3YltsB107 and 3YltsC113, and DNA synthesis was inhibited in all the long-survival mutants. In the long-survival mutants, levels of RNA synthesis of temperature-arrested and density-arrested states differed. Results of cycloheximide treatment of temperature-arrested cells after shifting down to 33.8°C suggest that de novo protein synthesis is necessary for DNA synthesis to resume and also that inhibition of protein synthesis delays initiation of DNA synthesis in 3YltsD123, 3YltsF121, and 3Y1tsG125.
