Temperature drives the pace, not the price, of postprandial growth in Burmese pythons (Python bivittatus)

Abstract

Body temperature influences all physiological processes in ectotherms, including the rise in metabolism upon feeding (SDA response). In reptiles, elevated temperatures increase the magnitude of the SDA response but shorten its duration with total energy expenditure remaining unaffected. Recent studies show that feeding induces a several-fold elevation of protein synthesis in various organs of pythons, but the effects of temperature on postprandial protein synthesis remain unexplored. We therefore measured relative changes in postprandial protein synthesis in skeletal muscle and visceral organs of the Burmese pythons (Python bivittatus) as well as the rate of oxygen consumption (V̇O₂) and mass of selected organs at 25 and 35 °C. Measurement were made at the peak of the SDA response (72 and 24 h post feeding at 25 and 35 °C, respectively). Protein synthesis was assessed from the rate of puromycin-incorporation and V̇O₂ was measured with closed respirometry. As expected, V̇O₂ increased with temperature in both fasted and digesting snakes. Feeding induced a several fold rise in protein synthesis, with higher rates at 35 compared to 25 °C in most tissues, but mass specific organ masses were similar between fed snakes at both temperatures. This supports the concept that SDA represents the energetic cost of growth, resulting in the same level of growth is achieved over a shorter period for the 35 °C group compared to the 25 °C group. Moreover, the strong correlation between organ-specific protein synthesis and V̇O₂ further reinforces this concept. Our results demonstrate that elevated temperature accelerates postprandial protein synthesis without changing total growth, suggesting that temperature effects on the SDA response are primarily mediated by changes in the rate of protein synthesis.