Meeting Abstract
Aerobic metabolism is assumed to impose costs in terms of production of reactive oxygen species (ROS) through damage to biomolecules. A positive relation between standard metabolic rate (SMR) and ROS production is generally assumed, but recent findings in fish revealed the opposite pattern, a negative relationship. At present, it is still unknown whether the amount of ROS indeed relates to the level of damage and whether environmental factors can affect damage status by affecting energy use. Here we investigated whether acclimation to thermal regimes imposing different SMR causes corresponding variation in damage load and antioxidant capacity in an ectothermic animal, the grass snakes (Natrix natrix). We acclimated 14 snakes for six months to either warm (32oC) or cold (18oC) ambient temperatures before we determined SMR and oxidative status. As expected, warm-acclimated snakes showed higher SMR compared to cold-acclimated ones. Damage load (micronuclei count and dROMs) showed a pattern opposite to SMR, being higher in cold-acclimated snakes. Antioxidant defense was not different between temperatures. Our results corroborate a negative relation between SMR and ROS production and now expand this pattern to the level of damage. Various SMR-dependent mechanisms may contribute to the lower amount of damage. Higher SMR in warm environment reduces the costs in terms of damage to biomolecules and such a link between metabolism and damage could represent the trigger for the evolution of endothermy. Thermogenesis may represent a strategy to cope with high damage stress in cold environment through active elevation of body temperature and associated higher mitochondrial uncoupling.
