Enzyme activity in cryobiological systems: Studies on glycolytic enzymes and low temperature-induced glycerol accumulation in hymenoptera

Abstract

Studies of the biochemistry of low temperature-induced glycerol accumulation in adult insects of the order Hymenoptera have been undertaken. An examination of the characteristics of glycerol buildup in the adult carpenter ant C. pennsylvanicus has been made in conjunction with studies designed to examine the low temperature characteristics of their glycolytic enzymes. Glycerol accumulation commences immediately upon cold stress; the buildup induced by a range of temperatures from +4 to −3°C is quite uniform, and the polyol is distributed quite uniformly throughout the insect's body. Glycogen levels have been found to decrease when glycerol accumulates, suggesting that it may be a precursor of the polyol. Glyceraldehyde-3-phosphate dehydrogenase purified from extracts of Camponotus and A. mellifera (honeybee) show kinetic characteristics different from the yeast and mammalian forms of the enzyme. Most importantly, the insect enzymes display a cooperativity of inactivation at 0°C in the presence of ATP that is not shown by yeast and mammalian enzymes. This property of the insect enzymes allows for low temperature activity under conditions which inactivate the yeast and mammalian enzymes. A definite relationship between known hibernation character and cold-induced glycerol accumulation was also found to exist in 14 species of ichneumon wasps. This observation strongly suggests that glycerol accumulation plays an important role in the overwintering process of this group of insects.