Yeast cells accumulate large amounts of arginine and polyphosphate in their vacuoles and utilize these compounds as endogenous nitrogen or phosphate sources under conditions of starvation. We examined a vacuoleless mutant, end1, and found that it stored virtually no arginine or polyphosphate when grown on a medium with arginine as the sole nitrogen source. When starved of nitrogen or phosphate it stopped growing much faster than the wildtype. Unlike the wildtype, end1 showed no accumulation of polyphosphate and, concomitantly, of arginine after a period of phosphate starvation. The results support the concept that vacuoles contain the main reserves of nitrogen and phosphate in fungi.
