Studies of the Radiation Syndrome in Drosophila melanogaster

Irradiation with approximately 60,000r kills fasted adult Drosophila melanogaster within one day and is lethal to 60% of the non-fasted flies within two weeks. Males die sooner than females. However, males show little or no modification of phosphorus turnover and maintain their weights at control values. In contrast, the rate of growth of irradiated females is slowed down, but the flies eventually reach weights in excess of controls. Irradiated females have fast and slow phases of phosphorus turnover with lengthened half-times. The phase systems of fast and slow half time are affected to different degrees by irradiation. However, irradiation does not affect the amount of phosphorus lost by each phase or the total phosphorus content of either sex of flies. The biological half time for phosphorus is 0.9 days for normal females, 8.0 days for irradiated females and 1.8 days for normal or irradiated males. Irradiation does not have an immediate effect upon the efficiency of phosphorus extraction from yeast by the gut. It does have an immediate depressing effect upon food intake and a depressing effect six days after treatment upon the oxygen consumption of the flies.