There are widespread examples of animals in nature that suppress metabolism and enter dormant states in response to suboptimal environmental conditions. Such a metabolic response would seem to require coordinated suppression of both energy-producing pathways and biosynthetic, energy-utilizing processes. One objective of the proposed studies is to identify the mechanisms responsible for the simultaneous, yet independent, arrest of protein biosynthesis and of catabolic pathways during anaerobic dormancy in embryos of the brine shrimp Artemia. Regulation of protein synthesis will be examined in the cytoplasmic as well as the intramitochondrial compartments. The same intracellular signal (acidic intracellular pH) may directly or indirectly mediate arrest of anabolic and catabolic pathways, and that rates of macromolecular degradation may ultimately limit the duration of dormancy. Secondly, the importance of intracellular solutes in disrupting metabolic organization during cellular dehydration will be studied. Thirdly, studies will be directed toward understanding the nature of developmental and metabolic arrest during diapause in Artemia embryos. Methods employed in these studies will include simultaneous microcalorimetry-respirometry, a cell free translation system for quantifying protein synthesis, permeabilization of embryos, and in vitro studies with isolated organelles. Results of these studies should have implication for a variety of biological systems that experience stress as a result of desiccation, oxygen deprivation an temperature extremes, or in general, for any tissue or cell where acute modulation of biosynthesis and energy metabolism is known to occur. //
