Interrelationships between water and cellular metabolism in Artemia cysts. IV. Adenosine 5'-triphosphate and cyst hydration.

The concentration of ATP in cysts of the brine shrimp, Artemia salina, has been studied as a function of cyst hydration. Cysts dried over CaSO4 contain 0.02 gH2O/g cysts and 0.54 +/- 0.05 (S.D.) mumoles of ATP/g dried cysts. Addition of water up to 0.05 g/g cysts produced no net change in the level of ATP during incubation. Hydration levels between 0.05 and 0.62 g/g cysts resulted in a net loss of ATP, whereas above 0.65 g/g cysts a net increase was observed with incubation time. No net change in the amount of ATP, compared with dried cysts, was detected between the latter two hydrations. These results, when integrated with those from previous work, indicate that conventional aerobic energy metabolism does not begin until cyst hydrations of about 0.65 g/g are achieved. The fate of ATP in cysts hydrated to levels lower than 0.65 g/g was discussed.