CLEGG, J.S.; University of California, Davis: Adaptations Underlying Desiccation Tolerance in the Animal Extremophile, Artemia

Encysted embryos of the primitive crustacean, Artemia, can be considered as extremophiles of the animal kingdom based on their ability to exist and thrive in the face of a wide variety of severe stresses. Those abilities, essential to the survival of this organism in nature, will be summarized briefly, but the focus of the presentation will be on reversible desiccation, at which they are remarkably good. Although considerable previous work has been done on desiccation in these embryos, much remains to be understood. In the present case, results of studies dealing with the following questions will be presented: 1. How much intracellular water can be removed without loss of viability? 2. What determines the longevity of dry (~0.1 g water / g dry weight) embryos? 3. To what extent is metabolic activity required as embryos undergo desiccation and re-hydration? 4. Does the complex shell play any role in these processes? 5. Are stress proteins involved in desiccation tolerance? I doubt that I will be able to answer the last question unambiguously. Although these results refer to Artemia embryos, specifically, I will take the position that some of them have broader significance within the area of animal cell desiccation-tolerance. Supported in part by grant MCB-9807762 from the U.S. National Science Foundation.