Oligonucleotides with rapid turnover of the phosphate groups occur endogenously in eukaryotic cells.

Endogenous oligonucleotides were found in trichloroacetic acid extracts of hamster lung fibroblasts and Tetrahymena cells. Peaks of radioactivity that eluted with retention times similar to oligonucleotide markers (5- to 50-mer) were found by HPLC in cells labeled briefly with 32Pi. Only minute amounts of UV-absorbing material were detected, consistent with a rapid turnover of phosphate groups.

Mutations in the phosphoglucose isomerase gene can lead to marked alterations in cellular ATP levels in cultured fibroblasts exposed to simple nutrient shifts.

The generation of ATP in a hamster fibroblast mutant devoid of the enzyme phosphoglucose isomerase (PGI) has been studied and compared with that in the parental line, which is PGI+. Both cell lines could be maintained for 24 hr in hexose media devoid of L-glutamine. Under these conditions in mannose medium, both the parental line and the PGI mutant maintained high intracellular ATP levels.

Phosphorylation in vivo of Ribosomes in Tetrahymena pyriformis.

Phosphorylation of ribosomal proteins in vivo was studied in exponentially growing and starved cells of the ciliated protozoan, Tetrahymena pyriformis. No phosphorylation of ribosomal proteins could be demonstrated in cells growing exponentially in complex nutrient media. However, when Tetrahymena cells were transferred into a non-nutrient medium, pronounced phosphorylation of a single ribosomal protein was observed.

Conservation of active ribosomes in acetone-treated cells of Tetrahymena pyriformis.

The preparation of an acetone powder of cells of Tetrahymena pyriformis GL is described. A comparison of ribosomal particles isolated from acetone-treated and untreated cells shows that structurally and functionally intact ribosomes can be isolated from acetone-treated cells. Fully active ribosomes have been isolated from acetone powder of Tetrahymena that had been stored for more than 6 months at 4 degrees C.