Peptidomics of CNS-associated neurohemal systems of adult Drosophila melanogaster: a mass spectrometric survey of peptides from individual flies

Abstract

Neuropeptides are important messenger molecules that influence nearly all physiological processes. In insects, they can be released as neuromodulators within the central nervous system (CNS) or as neurohormones into the hemolymph. We analyzed the peptidome of neurohormonal release sites and associated secretory peptidergic neurons of adult Drosophila melanogaster. MALDI-TOF mass spectrometric analyzes were performed on single organs or cell cluster from individual flies. This first peptidomic characterization in adult fruit flies revealed 32 different neuropeptides. Peptides not directly predictable from previously cloned or annotated precursor genes were sequenced by tandem mass spectrometry. These peptides turned out to be either intermediate products of neuropeptide processing or shorter versions of known peptides. We found that the peptidome of the CNS-associated neurohemal organs is tagma-specific in Drosophila. Abdominal neurohemal organs and their supplying peptidergic neurons contain the capa gene products periviscerokinins and pyrokinin-1, thoracic neurohemal organs contain FMRFamides, and the neurohemal release sites of the brain contain pyrokinin-1(2-15), pyrokinin-2, corazonin, myosuppressin, and sNPF as their major putative release products. Our results show that peptidomic approaches are well suited to study differential neuropeptide expression or posttranslational modifications in morphologically defined parts of the nervous system and in a developmental and physiological context in animals as small as Drosophila melanogaster.