Sirsat 2016 J Comp Physiol B

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Sirsat SK, Sirsat TS, Crossley JL, Sotherland PR, Dzialowski EM (2016) The 12-day thermoregulatory metamorphosis of Red-winged Blackbirds (Agelaius phoeniceus). J Comp Physiol B 186:651-663.

» PMID: 27003423

Sirsat SK, Sirsat TS, Crossley JL, Sotherland PR, Dzialowski EM (2016) J Comp Physiol B

Abstract: We examined development of endothermy in altricial Red-winged Blackbirds (Agelaius phoeniceus) by measuring oxygen consumption [Formula: see text], body temperature and ventilation at ambient temperatures from 35 to 15 °C. Mitochondrial respiration of permeabilized skeletal muscle was also measured from breast (pectoralis) and thigh (femorotibialis) muscles. Animals were studied from the first day of hatching through fledging (12 days post-hatch, dph). Nestling whole-body metabolic rate began to show an endothermic response to cold temperature midway between hatching and fledging. Nestlings less than 5 dph were unable to maintain elevated [Formula: see text] and body temperature when exposed to gradually decreasing temperature, whereas 7 dph nestlings maintained [Formula: see text] until ~25 °C, after which [Formula: see text] decreased. From 10 dph to fledging, animals maintained elevated [Formula: see text] and body temperature when exposed to gradual cooling; full endothermic capacity was achieved. Ventilation followed a similar developmental trend to that of [Formula: see text], with increases in 10 dph fledglings occurring in tidal volume rather than ventilation frequency. LEAK respiration and oxidative phosphorylation (OXPHOS) through complex I of breast muscle mitochondria increased significantly after 3 dph. Expression of avUCP and PCG-1α mRNA increased significantly at 3 dph and remained elevated in both skeletal muscle types. Increased metabolic capacity at the cellular level occurred prior to that of the whole animal. This change in whole animal metabolic capacity increased steadily upon hatching as evidenced by the shift of metabolic rate from an ectothermic to endothermic phenotype and the increase of mitochondrial OXPHOS activity of the shivering muscles of this altricial avian species. Keywords: Altricial, Bird, Development, Endothermy, Mitochondria

O2k-Network Lab: US TX Denton Dzialowski EM

Labels: MiParea: Respiration, Comparative MiP;environmental MiP, Developmental biology 

Stress:Temperature  Organism: Birds  Tissue;cell: Skeletal muscle  Preparation: Permeabilized tissue 

Coupling state: LEAK, OXPHOS  Pathway:HRR: Oxygraph-2k