Ecological and Evolutionary Physiology of the Stress Response and Stress Proteins

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9408216 Feder Almost all organisms synthesize a number of characteristic proteins in response to high temperatures and other stresses; these are termed "stress proteins" or "heat-shock protein". In the laboratory, improved resistance to stress coincides with the synthesis of these proteins. At present, major gaps in scientific knowledge include: (1) Whether the conditions that induce these proteins in the laboratory are ever encountered in nature; (2) Whether the proteins are adaptive under natural conditions; (3) How these proteins actually improve resistance to stress. This project will contribute to the filling of these gaps by examining strains of fruit flies (Drosophila) that have been genetically engineered to synthesize very different levels of a key stress protein, hsp70. The project first will document natural exposure of wild Drosophila to two likely stresses (temperature and ethanol), and measure corresponding hsp70 concentrations in these organisms. Next, it will use this information to design laboratory experiments in which Drosophila strains differing in hsp70 expression undergo exposure to each stress. After first confirming that the expected differences in hsp70 actually occur under experimental conditions, the project will assess the consequences of differential hsp70 expression for the ability of Drosophila to grow and reproduce successfully under stress. Finally, the project will engineer Drosophila cell lines differing in hsp70 expression with a light-emitting protein to test whether hsp70 can repair a stress-damaged protein. The proposed research is significant because (1) it will gather basic but presently unavailable data on the natural conditions experienced by Drosophila, one of the primary models in modern biological research; (2) it will assess the linkages, if any between manifestations of the stress response at the molecular/cellular level and organismal performance; (3) it will prospectively identify candidate mechanisms for study at the cellular/molecular level; and (4) it will lay the groundwork for a priori predictions and test of the evolution of physiological characteristics. ***