. Basic mechanisms in radiobiology. TOTAL P32 INORGANIC META P TOTAL ACTIVITY ORTHO P ACID SOLUBLE IN CELLS P AVERAGE VALUES Figure 3. Comparison of the specific ac- tivity of various fractions from X-irradi- ated and nonirradiated yeast (T utilis). Inorganic orthophosphate, ^g- P relative to control; metaphosphate and total acid soluble phosphate, ^g M-P or TAS-Pdivided by [ inorganic P relative to control. I I NONIRRADIATED â CYTIDYLIC ADENYLIC GUANYLIC URIDYLIC ACID ACID ACID ACID Figure 4. The relative specific activity of RNA mononucleo
. Basic mechanisms in radiobiology. TOTAL P32 INORGANIC META P TOTAL ACTIVITY ORTHO P ACID SOLUBLE IN CELLS P AVERAGE VALUES Figure 3. Comparison of the specific ac- tivity of various fractions from X-irradi- ated and nonirradiated yeast (T utilis). Inorganic orthophosphate, ^g- P relative to control; metaphosphate and total acid soluble phosphate, ^g M-P or TAS-Pdivided by [ inorganic P relative to control. I I NONIRRADIATED â CYTIDYLIC ADENYLIC GUANYLIC URIDYLIC ACID ACID ACID ACID Figure 4. The relative specific activity of RNA mononucleotides from irradiated and nonirradiated yeast. (|ig. RNA-tideP/cts.^| inorg. O-P). of concentrations of ammonium sulfate that were nonlimiting for growth. Our interpretation was in terms of the rela- tive amount of irreparable damage to the fermentation enzymes. More recently, we have been looking at the effect of irradiation on the phosphorus metabolism (17). This has been done by incubating the cells after irradiation with inorganic p32 for peri- ods of about an hour. In these experi- ments, the cells are put into a medium that will allow them to divide. Howev- er, an appreciable number of new cells does not form in an hour at this incuba- tion temperature. Nonirradiated cells begin to form buds, but bud formation is not apparent in the irradiated cells. In Figure 3, the activity of various frac- tions is compared in irradiated and non- irradiated cells. There is a marked in- crease in the total uptake of phosphorus by the irradiated cells. However, there is little difference in the specific activi- ty of inorganic orthophosphate or of to- tal acid soluble phosphate. The meta- phosphate picture isn't as clear. In some of the 100,000 r experiments, the metaphosphate values for irradiated cells are fairly near those for nonirra- diated cells; in other experiments, they are considerably depressed. BENNETT: What fraction ac- counts for the increase then? SHER
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