Adaptive changes of mitochondrial bioenergetics and glucocorticoids in different environmental gradients

Individuals vary significantly in how they respond to energetic challenges. Generally, baseline glucocorticoid levels increase in response to an increased work-load, but individuals differ in the degree of this response. One explanation is that trade-offs between immediate survival and fitness are resolved differently in accordance with an individual’s physiological condition, such as metabolic efficiency and organismal energetic state. To see how these energetic challenges play out in “real life”, I study  birds in aviaries and in the field, i.e. starlings trained to fly in a wind tunnel, racing pigeons freely flying home from different locations and great tits exposed to natural variation in energetic demands.

Latest publications of this project:
Mitochondrial metabolism in blood more reliably predicts whole-animal energy needs compared to other tissues
Tools to measure energy metabolism in free-ranging animals are limited. In this study, we examined metabolic rate (MR) of bird tissues as potential proxy for organism MR. Blood predicted whole-organism MR better than pectoralis, heart, brain and liver and blood MR gauges use of whole bird energy needs with quick and minimal invasiveness.

Mitochondrial metabolism in blood more reliably predicts whole-animal energy needs compared to other tissues (2023). Stefania Casagrande, Maciej Dzialo, Lisa Trost, Kasja Malkoc, Edyta Teresa Sadowska, Michaela Hau, Barbara Pierce, Scott McWilliams, Ulf Bauchinger. iScience more
Inferring whole-organism metabolic rate from red blood cells in birds
Metabolic rate is a key ecological variable that quantifies the energy expenditure required for almost all biological processes in an organism. In the paper, we present a stress-free methodology to quantify the energy expenditure of free-living individuals. 

Kasja Malkoc, Stefania Casagrande, and Michaela Hau, "Inferring whole-organism metabolic rate from red blood cells in birds," Frontiers in Physiology 12, 691633 (2021). more
Integrating mitochondrial aerobic metabolism into ecology and evolution
Our review discusses the dynamics of mitochondrial aerobic metabolism, including variation in ROS, ATP, proton leak, and heat. This is key to understanding among- and within-individual variation strategies in relation to fitness.

Rebecca E. Koch, Katherine L. Buchanan, Stefania Casagrande, Ondi Crino, Damian K. Dowling, Geoffrey E. Hill, Wendy R. Hood, Matthew McKenzie, Mylene M. Mariette, Daniel W. A. Noble, Alexandra Pavlova, Frank Seebacher, Paul Sunnucks, Eve Udino, Craig R. White, Karine Salin, and Antoine Stier, "Integrating mitochondrial aerobic metabolism into ecology and evolution," Trends in Ecology and Evolution 36 (4), 321-332 (2021). more
Berries regulate metabolic stress in migratory birds
Migratory starlings are avian athletes that fly long distances in conditions that can push them very close to their physiological limits. Glucocorticoids are hormones that increase during endurance exercise to provide ready-to-use fuel to satisfy the high energy demands; however, prolonged exposure to high glucocorticoids is detrimental. A new study of researchers from Seewiesen, the US and Poland with European starlings in the wind tunnel show that dietary anthocyanins – antioxidants present in colored berries selected by birds especially during migration  –control excessive secretion of glucocorticoids when birds are flying for long durations. This supports the novel idea that dietary anthocyanins have important metabolic functions that also attenuate the endocrine stress response triggered by endurance flight.

Stefania Casagrande, Kristen J. DeMoranville, Lisa Trost, Barbara Pierce, Amadeusz Bryla, Maciej Dzialo, Edyta T. Sadowska, Ulf Bauchinger, and Scott R. McWilliams, "Dietary antioxidants attenuate the endocrine stress response during long-duration flight of a migratory bird," Proceedings of the Royal Society B: Biological Sciences 287 (1929), 20200744 (2020). more
Great tits detox at the expense of a lower life expectancy
Males of great tits compensated higher energetic demands during their reproductive phase by with loss of body weight and more stress hormons in the blood. Some produced more of an enzyme important for detoxifying free radicals. These birds were less likely to survive the next winter.

Stefania Casagrande and Michaela Hau, "Enzymatic antioxidants but not baseline glucocorticoids mediate the reproduction-survival trade-off in a wild bird," Proceedings of the Royal Society B: Biological Sciences 285 (1892), 2018.2141 (2018). more
Go to Editor View