Meeting Abstract
63.5 Sunday, Jan. 5 14:30 Development of Endothermy in the Altricial Red-Wing Blackbird (Agelaius phoeniceus) GOY SIRSAT, S.K.*; SIRSAT, T.S.; SOTHERLAND, P.R.; DZIALOWSKI, E.M.; University of North Texas, Denton; University of North Texas, Denton; Kalamazoo College, Kalamazoo; University of North Texas, Denton sarahsirsat@gmail.com
We examined development of endothermy in altricial Red-winged Blackbirds (Agelaius phoeniceus) by measuring oxygen consumption, body temperature and ventilation from 35 to 15°C. Mitochondrial respiration of permeabilized muscle (breast-pectoralis and thigh-quadriceps) was also measured. Animals were examined at externally pipped (EP) stage through fledging (12 days post hatch, dph). Nestling whole-body metabolic rate began an endothermic response to cold temperature midway between hatching and fledging. Neonates less than 5 dph were unable to maintain elevated oxygen consumption and body temperature when exposed to decreasing temperature, whereas 7 dph nestlings could maintain oxygen consumption until ~25°C, after which metabolism dropped. From 10 dph to fledging, animals maintained elevated oxygen consumption and body temperature when exposed to cold: full endothermic capacity was achieved. Ventilation followed a similar developmental trend. LEAK respiration of breast was significantly higher than thigh after 3 dph, while breast oxidative phosphorylation (OXPHOS) of complex I (CI) increased significantly from thigh after 10 dph. Breast OXPHOS through CI+II was significantly higher than thigh after 5 dph. Thigh OXPHOS through CI and CI+II increased significantly with age after 5 dph, while breast LEAK and both types of OXPHOS increased significantly with age after 3 dph. Increased metabolic capacity at the cellular level occurred prior to that of the whole animal. This change in capacity was obtained steadily upon hatching as evidenced by the shift of metabolic rate from an ectothermic to endothermic phenotype, and the increase of mitochondrial activity of the primary shivering muscles of this avian species. Supported by NSF IOS 1146758 (EMD).
