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Abstract

Although most reef-building corals live near the upper threshold of their thermotolerance, some scleractinians are resilient to temperature increases. For instance, Pocillopora acuta specimens from an upwelling habitat in Southern Taiwan survived a 9-month experimental exposure to 30°C, a temperature hypothesized to induce stress. To gain a greater understanding of the molecular pathways underlying such high-temperature acclimation, the protein profiles of experimental controls incubated at 27°C were compared to those of conspecific P. acuta specimens exposed to 30°C for two, four, or eight weeks, and differentially expressed proteins (DEPs) were removed from the protein gels and sequenced with mass spectrometry. Sixty unique DEPs were uncovered across both eukaryotic compartments of the P. acuta-dinoflagellate (genus Symbiodinium) mutualism, and Symbiodinium were more likely to up-regulate protein expression in response to high temperature exposure than the coral hosts in which they resided at the 2-week sampling time. Furthermore, different cellular pathways were affected by elevated temperature exposure in each compartment; Symbiodinium tended to up-regulate the expression of proteins involved in the cellular stress response, whereas the differentially expressed host coral proteome featured numerous proteins involved in cytoskeletal structure, immunity, and metabolism. These proteome-scale data suggest that the coral host and its intracellular dinoflagellates have differing cellular strategies for acclimating to elevated temperatures. AbstractAlthough most reef-building corals live near the upper threshold of their thermotolerance, some scleractinians are resilient to temperature increases. For instance, Pocillopora acuta specimens from an upwelling habitat in Southern Taiwan survived a nine-month experimental exposure to 30°C, a temperature hypothesized to induce stress. To gain a greater understanding of the molecular pathways underlying such high-temperature acclimation, the protein profiles of experimental controls incubated at 27°C were compared to those of conspecific P. acuta specimens exposed to 30°C for two, four, or eight weeks, and differentially expressed proteins (DEPs) were removed from the protein gels and sequenced with mass spectrometry. Sixty unique DEPs were uncovered across both eukaryotic compartments of the P. acuta-dinoflagellate (genus Symbiodinium) mutualism, and Symbiodinium were more likely to up-regulate protein expression in response to high temperature exposure than the coral hosts in which they resided at the twoweek sampling time. Furthermore, different cellular pathways were affected by elevated temperature exposure in each compartment; Symbiodinium tended to up-regulate the expression of proteins involved in the cellular stress response, whereas the differentially expressed host coral proteome featured numerous proteins involved in cytoskeletal structure, immunity, and metabolism. These proteome-scale data suggest that the coral host and its intracellular dinoflagellates hav...