Biochemical adaptation for cold hardiness in insects

Abstract

Specific biochemical adaptations permit winter survival at subzero temperatures by both freeze-tolerant and freeze-avoiding insects. Common to both survival strategies is the accumulation of high concentrations of polyols, providing deep supercooling point depression for freeze-avoiding forms and regulating cell volume reduction during extracellular freezing in freeze-tolerant insects. Studies in my laboratory have elucidated the molecular mechanisms (temperature effects on enzyme properties, allosteric regulation, reversible protein phosphorylation) that control the massive conversion of glycogen to polyols and, in some species, regulate the differential synthesis of dual polyols. New studies have highlighted the importance of aerobic ATP production for glycerol biosynthesis, suggested the importance of microcompartmentation for optimal conversion efficiency, documented seasonal changes in the capacity for polyol synthesis versus reconversion to glycogen and analysed the role of protein phosphorylation in enzyme regulation during polyol synthesis.