SOLUBLE PROTEINS OF DEVELOPING CALLIPHORA ERYTHROCEPHALA, PARTICULARLY CALLIPHORIN, AND SIMILAR PROTEINS IN OTHER INSECTS

Eggs, larvae, pupae, pharate adults, and emerged adults of the blowfly Calliphora erythrocephala have been examined for the presence of calliphorin, a protein of molecular weight 540,000; immunodiffusion, immunoelectrophoretic, ultracentrifugal, and electron-microscopic procedures were used. Calliphorin is absent from the eggs and appears first in 2-day larvae; it is present during the remainder of larval, pupal, and pharate adult life and in adults up to 6 days after emergence; it accounts for about 60, 40, and 10 per cent of the extractable soluble protein 4 days after hatching, 2 days after puparium formation, and 3 days after emergence, respectively; and it is present in haemolymph, making up some three-quarters of the haemolymph protein of 6-day larvae. It may be a storage protein used in the formation of adult tissues. It is accompanied by another protein (Protein II) of similar sedimentation but different electrophoretic properties. Immunoelectrophoresis discloses fourteen (possibly fifteen) antigens in extracts of Calliphora pupae or pharate adults, and the incidence of these various antigens at different stages of the life cycle is described. Extracts of larvae and pupae of other insects have been tested immunologically for calliphorin. Of four genera of Cyclorrhapha (other than Calliphora), Sarcophaga and Lucilia contained an antigen giving a reaction of complete identity with calliphorin when tested with antiserum against Calliphora calliphorin, whereas Gastrophilus and Drosophila gave reactions of partial identity. Four genera of the sub-order Brachycera gave reactions of partial identity with calliphorin, but of three genera of the sub-order Nematocera only Simulium gave a cross-reaction with calliphorin, and no reaction was found with Tenebrio, Pieris, or Locusta. All insects found to possess calliphorin yielded extracts which, as shown by electron microscopy, contained large numbers of particles similar in size and appearance to calliphorin molecules. Particles of this kind, and proteins of similar molecular size to calliphorin, have been found by others as well as by ourselves in a variety of insects, especially Lepidoptera. © 1969.