TEMPERATURE-ACCLIMATION AND SEASONAL RESPONSES BY ENZYMES IN COLD-HARDY GALL INSECTS

Changes in the activity of over 20 enzymes of intermediary metabolism in 15 degrees C or -4 degrees C acclimated goldenrod gall moth (Epible ma scudderiana) and gall fly (Eurosta solidaginis) larvae were measure d. Increased activities of glycogenolytic and hexose monophosphate shu nt enzymes in cold-acclimated Epiblema scudderiana suggest a role for coarse control in the conversion of glycogen reserves into glycerol cr yoprotectant synthesis. In Eurosta solidaginis, high glycogen phosphor ylase activity with decreased activities of glycolytic enzymes may acc ount in part for the temperature-dependent switch from glycerol to sor bitol synthesis in these larvae upon cold acclimation. Isoelectric foc using analyses of five enzymes in overwintering Epiblema scudderiana r evealed transient mid-winter changes in the isoelectric points of phos phofructokinase and pyruvate kinase, suggesting seasonal changes in th e phosphorylation state of these enzymes. A distinct developmental pat tern of aldolase isozymes suggests a role for a new isozyme during ove rwintering or upon spring emergence. Regulation of metabolism by chang es in enzyme activities is indicated for both larvae. (C) 1995 Wiley-L iss, Inc.