Neuropeptides associated with the frontal ganglion of larval Lepidoptera

Abstract

The occurrence of neuropeptides in the frontal ganglia of larvae of the tobacco hawkmoth, Manduca sexta, the tomato moth, Lacanobia oleracea and the cotton leafworm, Spodoptera littoralis was investigated using reversed-phase high performance liquid chromatography (RP-HPLC), matrix-assisted laser desorption time of flight mass spectrometry (MALDI-TOF MS) and enzyme-linked immunosorbent assay (ELISA). Only three types of peptides could be identified or assigned from frontal ganglion extracts; M. sexta allatostatin (Manse-AS), M. sexta allatotropin (Manse-AT), and F/YXFGL-NH 2 allatostatins. The peptide profiles of frontal ganglion of L. oleracea and S. littoralis were similar, with ten identical [M + H] + ions, seven of which could be assigned to known lepidopteran peptides (Manse-AT, cydiastatin 2, 3, 4 and helicostatin 1, 5, 9). In addition, mass ions corresponding to helicostatin 7 (which was confirmed by MALDI-post source decay analysis) and Manse-AS were present in frontal ganglia of L. oleracea and helicostatin 6 in frontal ganglia of S. littoralis. Only four mass ions from M. sexta frontal ganglia corresponded to known peptides, cydiastatin 3 and 4, helicostatin 1, and Manse-AT. The only difference between the profiles of frontal ganglia from different stages of L. oleracea were mass ions which could not be assigned, and no differences were observed in the allatoregulatory peptides present. In HPLC fractions of M. sexta frontal ganglia, F/YXFGL-NH 2 allatostatin-like immunoreactivity was widespread suggesting that more allatostatins were present than were identified.