Meeting Abstract
Rapid cold-hardening (RCH) describes an extremely swift response of insects to enhance their cold tolerance. A brief exposure to a moderately low temperature dramatically increases insect survival to a subsequent cold exposure that would be lethal otherwise. In the flesh fly, Sarcophaga bullata, as little as 15 min at 5°C significantly improved organismal survival at -7°C from 0 to 66.7±11.1%. Previous studies have demonstrated that the induction of RCH occurs at the cellular level through calcium signaling and activation of p38 MAP kinase. In this project, we examined the changes in the oxygen consumption during the RCH induction, using isolated flight muscles of S. bullata. Compared to tissues that had been maintained at 5°C for 2 h, those at 5°C for 10 min, therefore during the early phase of RCH induction, exhibited significantly higher rates of oxygen consumption (1.18±0.09 vs. 2.82±0.29 μl O2 mg-1 DM h-1). When these tissues were exposed to LaCl3, blocker of calcium channels that has been previously described to inhibit the RCH response, their oxygen consumption rates were reduced significantly to a level similar to those that had been maintained at 5°C for 2 h. Our initial results suggest that the high rate of oxygen consumption is associated with the RCH induction, likely to meet the energetic demand of eliciting this protective response.
