Cation concentrations in the haemolymph of the fly Chironomus thummi, during development

Abstract

The concentrations of the haemolymph monovalent and divalent cations have been determined during the development of Chironomus thummi, a fly. The insect maintains a low and rather constant level of sodium and potassium ion throughout most of the fourth instar period until the time of the larval-pupal ecdysis (LL = 87.6 mM Na; 10.8 mM K; EPP = 77.4 mM Na; 11.2 mM K; LPP = 83 mM Na; 14.6 mM K). During the final period of development, as the pupa apolysis to a pharate adult there is a significant increase in sodium and potassium ion levels (EA = 149.4 mM Na; 49.6 mM K). This sharp change of the haemolymph environment is coincident with the occurrence of many of the dramatic metamorphic changes in the animal, e.g., the breakdown of the salivary gland, and the initiation of vitellogenesis, among others. Artificial media containing the same concentrations of ions as the haemolymph enabled the in vitro maintenance of salivary glands for periods of up to 48 to 72 hr. The importance of the present information in studies of chromosomal puffing and in other cellular activities such as those leading to cell breakdown has been discussed.