PHOSPHORUS METABOLISM IN YEAST ACCOMPANYING AN INHIBITION OF CELL DIVISION BY X-RAYS

The phosphorus and nitrogen content of continuously irradiated and nonirradiated yeast cultures was measured at 0, 2, 4, and 6 hr as the cultures grew rapidly for most of this time. Division was completely stopped at a 3.9 kr/ hr X-radiation dose, but not at a 2 kr/hr dose, while growth was reduced relatively little. A striking change in irradiated cells was an increase in acid insoluble polyphosphate at 2 hr. Pentosenucleic acid phosphorus and protein nitrogen on a dry weight basis also increased in irradiated cells as compared to nonirradiated cells. Amounts of phos phorus and nitrogen in the trichloracetic acid extract decreased, as did the phosphorus of the lipid extract. Apparently no reduction in deoxypentosenucleic acid formation had occurred at 2 hr, and thus a effect on this material did not appear responsible for the inhibition of cell division. It is conceivable that the polyphosphate increase was related to the inhibition of this cell function. (auth)