Synthesis and turnover of haemolymph proteins during the reproductive cycle of Glossina austeni

Abstract

The synthesis of haemolymph proteins during the first two pregnancy cycles of the tsetse fly, Glossina austeni, has been investigated by observing the incorporation of 14C-tyrosine and 3H-leucine into the TCA-precipitable fraction. In general, there is a rapid synthesis of haemolymph proteins, with a preferential utilization of 3H-leucine, in newly emerged flies. By the time of the first ovulation, the level of synthesis has dropped, and after this time, there is an apparent preferential incorporation of l4C-tyrosine into haemolymph protein. However, at the first larviposition (L1), there is a rise in incorporation of both amino acids. Haemolymph protein rich in tyrosine has a lower rate of turnover than leucine-rich protein.The percentage incorporation of both 3H-leucine and 14C-tyrosine into haemolymph protein was also determined. At most times during the first-two pregnancy cycles, there is about 2% incorporation. However, in newly emerged flies, the incorporation of 3H-leucine reaches 7%, whereas at L1, about 7% of the 14C-tyrosine is incorporated into haemolymph protein.TCA-soluble label remaining in the haemolymph has been observed during the pregnancy cycles. Whereas 3H-leucine is apparently continuously removed from the haemolymph, 14C-tyrosine, at least at certain stages, may be released into the haemolymph. The significance of these results is discussed in terms of nutrient transfer in Glossina.