The purpose of this project is to examine the role of stress proteins (SPs) in adaptation to thermal stress by using, as a model system, two closely related species of intertidal limpets (Mollusca, Gastropoda) which have different tolerances to elevated temperatures. In preliminary studies, enhances thermotolerance has been correlated with a quantitative increase in the stress protein response (SPR). We propose to compare the SPR in the temperature tolerant Collisella scabra and temperature sensitive Collisella pelta. to study the role of the SPR in adaptation to elevated temperatures. This goal will be addressed through experiments to: (A) characterize the SPR in each species induced at different temperatures that will delineate (1) the kinetics of induction and recovery of the SPR, (2) half-lives (turnover) and the rates of synthesis of the SPs involved, and (3) level of accumulation of the major SP70 class; (B) conduct "acquired tolerance" experiments to establish the role of stress proteins in protection and repair of damage from subsequent heat-shock; and (C) examine the SPR in situ to determine the physiological role of the SPR under natural environmental conditions. SPs will be labeled with 35-S methionine, analyzed by one and two dimensional electrophoresis and visualized by fluorography and direct beta scanning. Levels of SP accumulation will be determined by Western blotting with antibodies made against mammalian SPs. If the data demonstrate that the SPR correlates with enhanced tolerance to elevated temperatures, then it will provide an excellent mechanistic example of how modifications in genetic and cellular processes can be used to increase an organism's capacity to adapt to environmental perturbations. Because of the striking similarity of the SPR in diverse groups of organisms and its general protective/repair function against damage caused by many types of metabolic stress, data from these experiments will contribute to our understanding of fundamental cellular mechanisms underlying adaptation.