Expression of a novel neuropeptide, NVGTLARDFQLPIPNamide, in the larval and adult brain of Drosophila melanogaster.

Advances in mass spectrometry and the availability of genomic databases made it possible to determine the peptidome or peptide content of a specific tissue. Peptidomics by nanoflow capillary liquid chromatography tandem mass spectrometry of an extract of 50 larval Drosophila brains, yielded 28 neuropeptides. Eight were entirely novel and encoded by five not yet annotated genes; only two genes had a homologue in the Anopheles gambiae genome. Seven of the eight peptides did not show relevant sequence homology to any known peptide. Therefore, no evidence towards the physiological role of these 'orphan' peptides was available. We identified one of the eight peptides, IPNamide, in an extract of the Drosophila adult brain as well. Next, specific antisera were raised to reveal the distribution pattern of IPNamide and other peptides from the same precursor, in larval and adult brains by means of whole-mount immunocytochemistry and confocal microscopy. IPNamide immunoreactivity is abundantly present in both stages and a striking similarity was found between the distribution patterns of IPNamide and TPAEDFMRFamide, a member of the FMRFamide peptide family. Based on this distribution pattern, IPNamide might be involved in phototransduction, in processing sensory stimuli, as well as in controlling the activity of the oesophagus.