Meeting Abstract

P3.76  Monday, Jan. 6 15:30  Development of Endothermy in the Bobwhite Quail (Colinus virginianus) SIRSAT, T.S.*; GOY SIRSAT, S.K.; DZIALOWSKI, E.M.; University of North Texas, Denton; University of North Texas, Denton; University of North Texas, Denton

Development of endothermy is associated with the maturation of aerobic capacity in avian species. In precocial species such as the Bobwhite quail (Colinus virginianus), aerobic capacity increases and they become endothermic rapidly after hatching. Development of endothermy involves maturation of multiple organs and systems involved in oxygen delivery to tissues and increased mitochondria function. We quantified the changes in Bobwhite endothermic capacity by measuring oxygen consumption, ventilation, and mitochondrial respiration of permeabilized skeletal muscle (thigh and breast). Heart-ventricle mass, hemoglobin, and hematocrit were examined as parameters of oxygen delivery capacity. Animals were tested on embryonic day 20 (85% development), externally pipped (EP) stage, and through 6 days post hatching (dph). Oxygen consumption of day 20 embryos through 24 hours post hatch (hph) and ventilation rate of 1dph decreased when ambient temperature was lowered. During cold temperature exposure, 3 dph hatchlings increased oxygen consumption and ventilation rate until 25°C, after which they declined, while 6 dph hatchlings were able to increase oxygen consumption and ventilation rate when exposed to 15°C, exhibiting a stronger endothermic response. Among the tissues, thigh mitochondria showed higher oxidative phosphorylation (OXPHOS) than breast and increased significantly through development. Heart ventricle mass increased significantly upon hatching and was the greatest fraction of body mass by 3 dph. The metabolic capacity necessary to attain endothermy was associated with increased tissue metabolic capacity and oxygen delivery capacity and was obtained after hatching. Supported by NSF IOS 1146758 (EMD).