The drosulfakinin 0 (DSK 0) peptide encoded in the conserved Dsk gene affects adult Drosophila melanogaster crop contractions.

We report that the drosulfakinin 0 (DSK 0; NQKTMSFNH2) structure and genomic organization are conserved. The DSK 0 C-terminus, SFNH2, is widely distributed in the animal kingdom suggesting it defines a novel peptide family. We also report the first description of DSK 0 activity.

The structure of the FMRFamide receptor and activity of the cardioexcitatory neuropeptide are conserved in mosquito.

Numerous peptides are structurally related to the cardioexcitatory tetrapeptide FMRFamide. One subgroup of FMRFamide-related peptides (FaRPs) contains an FMRFamide C terminus. Searches of the Drosophila melanogaster genome database identified the first invertebrate FMRFamide G-protein coupled receptor (GPCR), DrmFMRFa-R (Cazzamali and Grimmelikhuijzen, Meeusen et al.

The different effects of three Drosophila melanogaster dFMRFamide-containing peptides on crop contractions suggest these structurally related peptides do not play redundant functions in gut.

A Drosophila melanogaster dFMRFamide gene product, TPAEDFMRFamide, decreased crop contractions. However, DPKQDFMRFamide and SDNFMRFamide, also encoded in dFMRFamide, did not affect crop motility, which suggests these peptides are not functionally redundant in the crop and their unique N-terminal structures are important for activity. TPAEDFMRFamide-specific antisera did not stain the crop, which suggests it acts as a hormone.