A NOVEL ADIPOKINETIC OCTAPEPTIDE FOUND IN THE DAMSELFLIES PSEUDAGRION-INCONSPICUUM AND ISCHNURA-SENEGALENSIS

A member of the adipokinetic hormone family of peptides was identified in the damselflies Pseudagrion inconspicuum and Ischnura senegalensis using a heterologous (in migratory locusts and American cockroaches) and a homologous (in P. inconspicuum) bioassay. After isolation of the peptide by reversed-phase h.p.l.c. of corpora cardiaca, its structure was determined by automated Edman degradation and matrix-assisted las er-desorption ionization m.s. The sequence of a blocked uncharged octa peptide was established: pGlu-Val-Asn-Phe-Thr-Pro-Gly-TrpNH(2). One co rpus cardiacum of P. inconspicuum contains about 2.4 pmol of this nove l peptide. The synthetic peptide was chromatographically indistinguish able from the natural compound, and on injection in low quantities int o the damselfly P. inconspicuum, haemolymph levels of lipids were incr eased. It is concluded that the novel peptide may be involved in contr olling lipid mobilization during flight. Hence the peptide is designat ed Psi-AKH, Pseudagrion inconspicuum adipokinetic hormone.