Heat shock protein gene expression in fish across space and time

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Temperature is one of the most important environmental variables affecting all organisms. Distribution patterns of species in nature, physiological systems, and biochemical reaction rates are all shaped by its pervasive effects. One of the most universal molecular-level responses to temperature change is the synthesis of a highly conserved group of proteins called heat shock proteins (Hsps). Hsps respond to stress-induced increases in damaged proteins by stabilizing partially unfolded proteins and preventing protein aggregation. Hsps also play a role during non-stress conditions as 'molecular chaperones' where they facilitate protein folding, transport and cell signaling. The prevalence of this response, and the high degree of Hsp gene sequence conservation between completely divergent organisms, highlights its importance and emphasizes the need for further understanding. Ectothermic (cold-blooded) organisms are especially vulnerable to temperature change and thus make excellent models in which to examine its environmental regulation. In this context, my research program combines field studies and laboratory experiments to quantify how thermal stress impacts the expression and regulation of Hsp genes in fish. This program will provide the first analysis of Hsp expression across a wide latitudinal distribution of a fish and will contribute valuable information about how the heat shock response participates in determining species range boundaries. It will also examine the impact of thermal history on gene expression of Hsps and growth indicators, providing insight into the physiological costs associated with temperature change. Tissue-specific and temporal changes in gene expression could suggest new mechanisms of temperature tolerance and shed light on the evolution of this adaptive response in vertebrates. Examining the role of the cell membrane in temperature sensing will enhance our knowledge about the mechanisms that control this adaptive response and contribute to its observed plasticity in nature. This program will advance our understanding of the physiological effects of thermal stress on fish and enhance our power to predict, and perhaps even mitigate, some of the biological consequences of future climate change.