Common functional elements of Drosophila melanogaster seminal peptides involved in reproduction of Drosophila melanogaster and Helicoverpa armigera females

Sex peptide (SP) and Ductus ejaculatorius peptide (Dup) 99B are synthesized in the retrogonadal complex of adult male Drosophila melanogaster, and are transferred in the male seminal fluid to the female genital tract during m ating. They have been sequenced and shown to exhibit a high degree of homol ogy in the C-terminal region. Both affect subsequent mating and oviposition by female D. melanogaster. SP also increases in vitro juvenile hormone (JH ) biosynthesis in excised corpora allata (CA) of D. melanogaster and Helico verpa armigera. We herein report that the partial C-terminal peptides SP8-3 6 and SP21-36 of D. melanogaster, and the truncated N-terminal SP6-20 do no r, stimulate JH biosynthesis in vitro in CA of both species. Both of these C-terminal peptides reduce JH-III biosynthesis significantly. Dup99B, with no appreciable homology to SP in the N-terminal region, similarly lacks an effect on JH production by H. armigera CA. In contrast, the N-terminal pept ides - SP1-11 and SP1-22 - do significantly activate JH biosynthesis of bot h species in vitro. We conclude that the first five N-terminal amino acid r esidues at the least, are essential for allatal stimulation in these dispar ate insect species. We have previously shown that the full-length SP1-36 de presses pheromone biosynthesis in H. armigera In vivo and in vitro. We now show that full-length Dup99B and the C-terminal partial sequence SP8-36 at low concentrations strongly depress tin the range of 90% inhibition) PBAN-s timulated pheromone biosynthesis of H. armigera. In addition, the N-termina l peptide SP1-22, the shorter N-terninal peptide SP1-11 and the truncated N -terminal SP6-20 strongly inhibit pheromone biosynthesis at higher concentr ations. (C) 2000 Elsevier Science Ltd. All rights reserved.