Mitochondrial metabolism in blood more reliably predicts whole-animal energy needs compared to other tissues
Stefania Casagrande,
Maciej Dzialo,
Lisa Trost,
Kasja Malkoc,
Edyta Teresa Sadowska,
Michaela Hau,
Barbara Pierce,
Scott McWilliams,
Ulf Bauchinger
Affiliations
Stefania Casagrande
Max Planck Institute for Biological Intelligence, Evolutionary Physiology Group, 82319 Seewiesen, Germany; Corresponding author
Maciej Dzialo
Jagiellonian University, Institute of Environmental Sciences, 30-387 Kraków, Poland
Lisa Trost
Max Planck Institute for Biological Intelligence, Department for Behavioral Neurobiology, 82319 Seewiesen, Germany
Kasja Malkoc
Max Planck Institute for Biological Intelligence, Evolutionary Physiology Group, 82319 Seewiesen, Germany
Edyta Teresa Sadowska
Jagiellonian University, Institute of Environmental Sciences, 30-387 Kraków, Poland
Michaela Hau
Max Planck Institute for Biological Intelligence, Evolutionary Physiology Group, 82319 Seewiesen, Germany; University of Konstanz, Department of Biology, 78464 Konstanz, Germany
Barbara Pierce
Sacred Heart University, Department of Biology, Fairfield, CT 06825, USA
Scott McWilliams
University of Rhode Island, Department of Natural Resources Science, Kingston, RI 02881, USA
Ulf Bauchinger
Jagiellonian University, Institute of Environmental Sciences, 30-387 Kraków, Poland; Nencki Institute of Experimental Biology, PAS, 02-093 Warsaw, Poland
Summary: Understanding energy metabolism in free-ranging animals is crucial for ecological studies. In birds, red blood cells (RBCs) offer a minimally invasive method to estimate metabolic rate (MR). In this study with European starlings Sturnus vulgaris, we examined how RBC oxygen consumption relates to oxygen use in key tissues (brain, liver, heart, and pectoral muscle) and versus the whole organism measured at basal levels. The pectoral muscle accounted for 34%–42% of organismal MR, while the heart and liver, despite their high mass-specific metabolic rate, each contributed 2.5%–3.0% to organismal MR. Despite its low contribution to organismal MR (0.03%–0.04%), RBC MR best predicted organismal MR (r = 0.70). Oxygen consumption of the brain and pectoralis was also associated with whole-organism MR, unlike that of heart and liver. Overall, our findings demonstrate that the metabolism of a systemic tissue like blood is a superior proxy for organismal energy metabolism than that of other tissues.
