RELATIONSHIP BETWEEN PROTEINS OF HAEMOLYMPH AND FAT BODY DURING DEVELOPMENT OF PIERIS BRASSICAE

The relationship between the proteins of the haemolymph and fat body was examined during metamorphosis of the large white butterfly, Pieris brassicae. The protein analysis results showed that about 4·9 mg protein was lost from the haemolymph of an individual insect between the prepupal and newly ecdysed pupal stages, while during the same period the fat body gained about 5·5 mg protein. From the change in distribution of 14C protein between these two tissues it was concluded that the fat body was storing the lost haemolymph protein at pupation. A more detailed examination using disk electrophoresis of labelled and unlabelled proteins from these two tissues showed that the fat body was in fact selectively storing two major haemolymph proteins. It was found that these proteins accumulated in the haemolymph during the fourth and fifth instars before being transferred to the fat body at the pharate pupal stage. No changes were detected in either haemolymph or fat body proteins during pupal diapause. However, the adult moulting cycle was marked by partial histolysis and release of degraded fat body proteins and the loss of another major protein from the haemolymph, not into the fat body, but presumably into the differentiating adult tissues. The changing rôles that the fat body and haemolymph play in the synthesis, storage, translocation, or degradation of proteins during development are discussed. © 1969.