Metabolomic fingerprint of cryo-stress in a freeze tolerant insect.

This study employed H-NMR spectroscopy to assay the metabolome of the high Arctic freeze-tolerant dipteran larvae, Heleomyza borealis, after recovery from exposure to a range of sub-zero temperature treatments. Our data demonstrate the resilience of freeze tolerance in individuals of this permanently freeze-tolerant species that were acclimated to summer temperatures (5 degree C): recovery of homeostasis after 48 h was not significantly disturbed by 2h exposures to -3, -12, or -20 degree C. Evidence of homeostatic perturbation to cryo-stress - both in terms of changes in specific metabolite concentrations as well as systemic changes in metabolism determined using multivariate pattern recognition techniques - was expressed almost entirely at a temperature coincident with the significant onset of mortality (-25 degree C) and considerably below the minimum winter temperatures of its over-wintering habitat (c.-12 degree C).