The effect of water content and postirradiation storage on radiation sensitivity of brine shrimp cysts (eggs).

ships found are similar to those well known in the radiation biology of seeds. Caldecott conditioned barley seeds to equilibrium water content values of 4%, 7%, 9%, 16%, and 24% by storage at carefully controlled humidities. On irradiation with X-ray doses of 10 to 50 kr he found for dry seeds an approximately inverse relation of water content and radiation sensitivity, judged by seedling height after growth on wet blotting paper (2-4). The driest seeds were the most sensitive. No further decrease in seedling height sensitivity to radiation dose was observed as water content values increased beyond 16%. Even seeds wet enough to germinate are not markedly more sensitive if cool temperature prevents development. Caldecott and others working with seeds have also shown postirradiation effects of temperature, moisture, and gases present in the environment (5-10). Storage in air after irradiation increases the radiation sensitivity in very dry seeds. In this paper we now report also for Artemia cysts that radiation sensitivity increases with dehydration and that it increases also for postirradiation storage of the very dry cysts in air.