R code and dataset of "Incubation temperature differentially shapes metabolism and morphology across embryonic developmental in Japanese quail"

The cellular mechanisms explaining how incubation temperature affects morphology and energy metabolism in bird embryos and juveniles are poorly understood. We incubated Japanese quail eggs at low (36.0°C), medium (37.5°C) or high (39.0°C) temperature and studied energy metabolism (mitochondrial respiration, content, and thermal sensitivity; reactive oxygen species (ROS) production) and morphology (organ-, body-, and yolk mass) during embryogenesis and at hatching. High incubation temperature accelerated growth and was associated with higher mitochondrial metabolism compared to the other groups. Low incubation temperature slowed embryonic development and was related to a lower phosphorylating respiration in both liver and heart, as well as reduced thermal sensitivity of proton leak in heart tissue. Neither treatment affected ROS production. However, the net phosphorylation efficiency was higher in cold-incubated embryos, which could have partly offset a lower rate of ATP-production, without increasing ROS production due to a tighter electron transport system. An increase in mitochondrial content (indexed by citrate synthase activity) with temperature during embryogenesis could explain temperature-effects on mitochondrial respiration. All temperature-dependent effects on mitochondrial respiration and morphology had disappeared by hatching, but cold-incubated hatchlings had higher mitochondrial content compared to the other groups. This suggests that thermal suppression of embryonic metabolism may be compensated by a combination of increased developmental time and late-occurring upregulation of mitochondrial content. In a climate change context, it is likely that chronic exposure to higher temperature affects the ontogeny of embryonic metabolism, but the consequences for mitochondrial metabolism after hatching require further study