THE SEQUENCE AND EXPRESSION PATTERN OF THE CALLIPHORA-ERYTHROCEPHALA YOLK PROTEIN-A AND PROTEIN-B GENES

The yolk protein genes (yps) are expressed in a temporal, tissue- and sex-specific fashion in Drosophila melanogaster. Here we report the se quence of two related genes in Calliphora erythrocephala. The predicte d Calliphora yolk protein (YP) sequences are well conserved, especiall y at the C-terminal end when compared to those of D. melanogaster and Ceratitis capitata. Database searches with the Calliphora yolk protein B (CeYPB) sequence identify the vertebrate lipase similarity reported for the YPs of Drosophila and Ceratitis. Moreover, sequences with ide ntity to divalent ion-binding sites were observed, which colocalized w ith putative tyrosine sulfation sites. Calliphora oogenesis differs fr om Drosophila in that it is cyclic in response to a meat feed. The Cal liphora yp genes are expressed in the follicle cells of the egg chambe r during vitellogenesis, as shown by in situ hybridization, and the yp message levels correlate with YP synthesis. The synthesis of the yp t ranscripts in ovaries of Calliphora occurs in the same pattern as that for ovarian transcripts in Drosophila. In the carcass, yp transcript levels are correlated with the production of a batch of eggs.