Dzialowski 2013 Abstract MiP2013
|Dzialowski EM, Ream S, Duquaine A, Sirsat TS, Goy Sirsat SK (2013) Mitochondrial function and the development of endothermy in the precocial Pekin duck (Anas pekin). Mitochondr Physiol Network 18.08.|
Development of endothermy is associated with maturation of aerobic capacity in developing avian species. In the embryonic state, precocial species, such as the Pekin ducks (Anas pekin), display an ectothermic phenotype. Aerobic capacity increases and ducks become endothermic rapidly after hatching. A major source of heat generation is shivering thermogenesis of leg muscles. Development of endothermy involves maturation of multiple organs and systems involved in O2 delivery to the tissues and maturation of mitochondrial function. Here we examined the role of mitochondrial function during attainment of endothermy in precocial Pekin ducks by first measuring whole animal O2 consumption (Vo2) as ambient temperature decreased from 35 down to 15 °C. Mitochondrial function was assessed at the site of shivering thermogenesis, the thigh flexor muscles, and a muscle group not associated with shivering thermogenesis, breast muscle. To characterize development of mitochondrial function associated with obtaining endothermy, we measured citrate synthase activity as a proxy for mitochondria content and mitochondrial O2 flux of permeabilized skeletal muscle. Animals were examined at the prehatch, internally pipped (IP) and externally pipped (EP) stages through 19 h post hatching.
Animals obtained an endothermic phenotype rapidly after hatching. The Vo2 of IP and EP embryos decreased during gradual cooling from 35 to 15 °C. In hatchlings as early as 0 h post hatching, Vo2 increased significantly during gradual cooling from 35 °C down to 15 °C. While body mass did not differ between EP embryos and hatchlings, whole ventricle mass increased significantly upon hatching. Citrate synthase activity of thigh flexor muscle increased significantly with age. In contrast, citrate synthase activity of breast muscle did not change upon hatching and was significantly lower than that of thigh muscle. Mitochondrial O2 flux in permeabilized thigh flexor muscle increased significantly upon hatching. There were no changes in LEAK respiration between IP, EP, and hatchling muscle fibers. There was a significant increase in mitochondrial oxidative phosphorylation (OXPHOS) capacity through Complex I in muscle fibers from EP embryos and hatchlings when compared with IP embryo fibers. OXPHOS capacity through Complex I and II and maximal ET-pathway capacity were significantly greater in hatchling muscle fibers when compared with both IP and EP fibers. Increased metabolic capacity necessary to attain endothermy was associated with increasing metabolic capacity of the tissue and increasing O2 delivery capacity. This change in aerobic capacity was obtained rapidly upon hatching as evident by the increase in whole animal Vo2 and OXPHOS capacity of thigh muscle fibers in hatchlings.
• O2k-Network Lab: US TX Denton Dzialowski EM
Labels: MiParea: Respiration, mt-Biogenesis;mt-density, Comparative MiP;environmental MiP, Developmental biology
Organism: Birds Tissue;cell: Skeletal muscle Preparation: Intact organism, Permeabilized tissue Enzyme: Marker enzyme Regulation: Flux control, Temperature Coupling state: LEAK, OXPHOS, ET Pathway: F, N, S, NS HRR: Oxygraph-2k
Thermogenesis, MiP2013, S04
Developmental Integrative Biology Research Cluster, Dept of Biological Sciences, University of North Texas, Denton, USA. - Email: [email protected]
Supported by NSF IOS 1146758 (EMD) and HHMI to Lee Hughes.