The effect of temperature on the respiration and metabolism of the African burrowing scorpion (Opistophthalmus latimanus)

It is well known that scorpions are highly adapted to thermal temperatures. However, little is known of the metabolic and respiration adaptations caused by temperature fluctuations in these animals. Therefore we used the African burrowing scorpion Opistophthalmus latimanus to measure the effect of temperature on its metabolism and respiration.Radioactive d-glucose was injected into the ventral sinus of the circulatory system and metabolites of d-glucose were determined after six hour incubation at four temperatures (7, 17, 25 and 37 °C). The oxygen consumption rate (ṀO2) and carbon dioxide production rate (ṀCO2) were measured simultaneously at 17, 25 and 37 °C. The metabolomics investigation included LC-MS, GC–MS and NMR analytical platforms.The average radioactivity recovered after the carbon-14 d-glucose injection, glycogen precipitation and column fractionation at the four temperatures was between 92.4% and 95.0%. Strong acids, CO2 and neutral compounds all increased with temperature, while glycogen and neutral sugars decreased as the temperature increased. Weak acids initially increased with temperature, then decreased again as the temperature was increased to 37 °C. Respiration also gradually increased as the temperature was increased. Metabolomics identified 23 metabolites that were significantly influenced by temperature. Pathway analysis of these metabolites indicated numerous metabolic pathways that were affected by temperature, clearly demonstrating that the scorpion uses proteins, lipids and carbohydrates at higher temperatures to generate energy. However, protein catabolism seems to be the main source of energy at higher temperatures in these animals, although this needs to be confirmed in a more targeted metabolomics study.