Dragonfly Erythemis simplicicollis contains a novel adipokinetic neuropeptide

We have isolated a novel member of the adipokinetic hormone family of pepti des from a methanolic extract of corpora cardiaca of the libellulid dragonf ly Erythemis simplicicollis by using a single-step reversed-phase high perf ormance liquid chromatography method and monitoring biological activity in various heterologous bioassays and a homologous one. The sequence, as deter mined by Edman degradation and mass spectrometry, was of an uncharged block ed octapeptide: pGlu-Leu-Asn-Phe-Thr-Pro-Ser-Trp amide. The structure was c onfirmed by chemical synthesis. The synthetic peptide increased hemolymph l ipids in the dragonfly and was active in another libellulid (Orthetrum juli a-falsum) as well, but to a lesser extent than the conspecific peptide Lia- AKH, which is an isoform of the novel peptide differing by a Val (instead o f Leu) at position 2. Since lipids are apparently used as substrate for mus cle contraction during flight of Erythemis simplicicollis and the native pe ptide induces lipid mobilization, this novel peptide is denoted Ers-AKH. (C ) 1999 Wiley-Liss, Inc.