Temperature Stress at the Metabolite Level

Anders Malmendal

University of Aarhus, Denmark

Body temperature of ectothermic animals may vary on a seasonal or daily timescale due to changing environmental conditions. This has led to the evolutionary emergence of protective biochemical and physiological responses that enables the organisms to deal with thermal variation. The underlying mechanisms of thermal adaptation and acclimation has been intensely studied at particular the gene and protein level. Here we use NMR metabolomic profiling to examine the biological response to heat and cold treatments in the model animal Drosophila melanogaster. Changes in the metabolite profile was followed after exposure to different heat or cold stress treatments. NMR metabolomic profiling proved to be suitable for characterization of the instantaneous physiological condition, enabling direct visualization of the perturbation of and return to homeostasis. Thus, both moderate and severe heat and cold stress resulted in characteristic changes of the metabolite profiles that varied with the intensity of the stress. These characteristic responses allowed us to further examine the role of heat and cold acclimation as well as genetic factors such as selection and inbreeding. As expected the response to heat and cold stress are totally different both in composition and timescale. Several responsive metabolites were identified, and could be related to known physiological and biochemical responses. Finally, comparisons to gene array data reveal both differences and similarities between the information obtained at these two levels.