Meeting Abstract
Ectotherms overwintering in temperate climates may freeze, causing damage and death. Some insects – such as juveniles of the spring field cricket, Gryllus veletis – are freeze tolerant: they survive internal ice formation. However, we have limited understanding of the mechanisms underlying insect freeze tolerance and its limits. A fall-like laboratory acclimation induces freeze tolerance in G. veletis, along with substantial changes in its transcriptome and metabolome. Freeze-tolerant crickets accumulate three potentially cryoprotectant molecules (trehalose, proline, and myo-inositol) in their hemolymph and fat body tissue, and differentially express several stress tolerance genes. To investigate cryoprotectant function in freeze tolerance, we elevated their concentrations in vivo and ex vivo. No cryoprotectant – either in isolation or in combination – was sufficient to confer freeze tolerance on freeze-sensitive morphs of G. veletis (in vivo) or their fat body tissue (ex vivo). However, injecting cryoprotectants into freeze-tolerant crickets improved survival at the lower lethal temperature (LLT) and lethal time (Lt). High exogenous cryoprotectant concentrations improved freeze-tolerant G. veletis fat body survival at the cellular LLT and Lt when frozen ex vivo. No cryoprotectant or combination of cryoprotectants improved both organismal and cellular survival at the LLT and Lt. These results suggest that cryoprotectants differentially contribute to cellular and whole organism survival of freeze-tolerant G. veletis, and several mechanisms contribute to preventing mortality in the frozen state.
