Molecular principles and control of cellular stress responses upon temperature and oxygen stress in Daphnia

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Knowledge of causal connections between severe environmental changes (stressors), stress signaling, and stress-induced gene expressions is particularly important for an understanding of environmental acclimatization and evolutionary adaptation. Consequently, this application focuses on the nature of stress signaling in conjunction with stress-induced gene expressions in Daphnia. The connections between stressors, stress signals, transcription factor levels, and cellular stress responses (gene expressions on transcript and protein levels) will be investigated upon temperature and oxygen stress in a time-resolved manner in order to analyze and understand the molecular principles and control of cellular stress responses in Daphnia. As experimental animals, two Daphnia species (D. pulex and D. magna) will be used, which offer exceptional experimental advantages as genetic (http://daphnia.cgb.indiana.edu), biochemical or physiological model organisms, and for which differences in stress response dynamics have been proven. As add-on projects, effects of the stressor ‚starvation‘ on stress signals and responses will be studied with the main focus on iron metabolism and homeostasis, and the relationship between de novo glutathione and protein syntheses will be investigated to test for possible negative effects of elevated protein synthesis rate on antioxidant buffering capacity.