High incubation temperatures enhance mitochondrial energy metabolism in reptile embryos.

Bao-Jun Sun,Wei-Guo Du,Liang Ma,Jing Gao,Teng Li

doi:10.1038/srep08861

Abstract

Developmental rate increases exponentially with increasing temperature in ectothermic animals, but the biochemical basis underlying this thermal dependence is largely unexplored. We measured mitochondrial respiration and metabolic enzyme activities of turtle embryos (Pelodiscus sinensis) incubated at different temperatures to identify the metabolic basis of the rapid development occurring at high temperatures in reptile embryos. Developmental rate increased with increasing incubation temperatures in the embryos of P. sinensis. Correspondingly, in addition to the thermal dependence of mitochondrial respiration and metabolic enzyme activities, high-temperature incubation further enhanced mitochondrial respiration and COX activities in the embryos. This suggests that embryos may adjust mitochondrial respiration and metabolic enzyme activities in response to developmental temperature to achieve high developmental rates at high temperatures. Our study highlights the importance of biochemical investigations in understanding the proximate mechanisms by which temperature affects embryonic development.

Highlights

High incubation temperatures enhance mitochondrial energy metabolism in reptile embryos Bao-Jun Sun[1], Teng Li1,2, Jing Gao[1,2], Liang Ma1,2 & Wei-Guo Du1
Incubation temperature significantly affected mitochondrial respiration, with embryos incubated at high temperature showing greater State 3 (F2, 15 5 37.25, P, 0.001) and State 4 (F2, 15 5 31.78, P, 0.001) respirations than those incubated at low temperature (Fig. 2a,b)
Our results suggest that developmental temperature may adjust mitochondrial respiration and enzyme activities, with better mitochondrial performance observed at higher incubation temperatures in reptile embryos

Summary

Introduction

High incubation temperatures enhance mitochondrial energy metabolism in reptile embryos Bao-Jun Sun[1], Teng Li1,2, Jing Gao[1,2], Liang Ma1,2 & Wei-Guo Du1. A number of studies have demonstrated that temperature may affect mitochondrial properties and the activities of metabolic enzymes in different lineages of animals (e.g. insects[7]; fish[8]; frogs[9,10]). The developmental rate depends on the metabolic rate, that is, the rates of energy utilization, transformation, and allocation[14,15], which are in turn related to the function of mitochondria[16].To enhance its developmental rate, an embryo may increase energy metabolism with increasing temperature In addition to this same general rule of biochemical reactions underpinning all life activities, we envisage another potential pathway that an embryo might use to enhance its developmental rate. LDH activity was enhanced as test temperature increased (F2, 30 5 106.25, P , 0.0001), and was higher in embryos incubated at 28uC and 32uC than those incubated at 24uC (F2, 15 5 10.308, P 5 0.002) (Fig. 2d)

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