Temperature acclimation and seasonal responses by enzymes in cold‐hardy gall insects

Abstract

AbstractChanges in the activity of over 20 enzymes of intermediary metabolism in 15°C or −4°C acclimated goldenrod gall moth (Epiblema scudderiana) and gall fly (Eurosta solidaginis) larvae were measured. Increased activities of glyco‐genolytic and hexose monophosphate shunt enzymes in cold‐acclimated Epiblema scudderiana suggest a role for coarse control in the conversion of glycogen reserves into glycerol cryoprotectant synthesis. In Eurosta solidaginis, high glycogen phosphorylase activity with decreased activities of glycolytic enzymes may account in part for the temperature‐dependent switch from glycerol to sorbitol synthesis in these larvae upon cold acclimation. Isoelectric focusing analyses of five enzymes in overwintering Epiblema scudderiana revealed transient mid‐winter changes in the isoelectric points of phosphofructokinase and pyruvate kinase, suggesting seasonal changes in the phosphorylation state of these enzymes. A distinct developmental pattern of aldolase isozymes suggests a role for a new isozyme during overwintering or upon spring emergence. Regulation of metabolism by changes in enzyme activities is indicated for both larvae. © 1995 Wiley‐Liss, Inc.