9306652 Hand This work will investigate how certain cells and tissues are able to survive long periods of time in dormant state, where energy metabolism and development are shutdown. Shrimp embryos (Artemia franciscana)are the focus of the outlined experiments, because their remarkable capacity to survive dormancy for months and even years is well known. For any dormant state, there are two problems that must be solved if an organisms is to tolerate bouts of quiescence. First, there must be a coordinated suppression of both energy use and energy production. Second, the integrity of macromolecules must be preserved during this period when little energy is available for their replacement or repair. Previous work with these embryos suggests that one cellular signal may be involved in mediating both of these phenomena. The first goal of the work is to explain how an energy consuming process like the synthesis of protein is indeed shutdown. The relative effect of limiting the copies of message (i.e., messenger RNA) that direct the cell to synthesize proteins, versus actually inhibiting the machinery itself (ribosomes) that builds the proteins will be compared. Finally, since synthesis is in some way suppressed during dormancy, then the rate of protein degradation must also be arrested in order to avoid depletion of macromolecules. Therefore, the second aim is to understand how degradation of protein (a normal process in an active cell)is reduced. Explaining how proteins are preserved during dormancy (in effect, placed into suspended animation) should provide insights that will be useful for other biological systems where survival depends on successful recovery from physical and chemical insults. The mechanisms by which cells can withstand long bouts of quiescence are apt to have important implications for numerous cases where metabolism is unavoidably suppressed or disrupted-- organ tissue transplantation, acute blockage of blood flow to tissues, and oxygen deprivation. ***
