Phosphofructokinase as a possible key enzyme regulating glycerol or trehalose accumulation in diapausing insects

Abstract

The activity of phosphofructokinase in fat body of glycerol-accumulating insects (diapausing pupae of Papilio machaon and diapausing prepupae of Monema flavescens) was twenty-fold higher than it was in trehalose-accumulating insects (diapausing pupae of Philosamia cynthia and diapausing prepupae of Trichiocamps populi). In addition, the highest activity of glycerol 3-phosphate dehydrogenase was observed in fat body of the Papilio pupae (glycerol-accumulating type) and the lowest activity in fat body of the Trichiocamps prepupae (trehalose-accumulating type), but high activity was also observed in fat body of the Philosamia pupae (trehalose-accumulating type). The above observations strongly suggest that phosphofructokinase acts as a primary key enzyme that regulates the end product, either glycerol or trehalose, of glycogen breakdown during diapause; the relatively high activity of glycerol 3-phosphate dehydrogenase found in the glycerol-accumulating insects may also facilitate the formation of glycerol.