CICADAS CONTAIN NOVEL MEMBERS OF THE AKH RPCH FAMILY PEPTIDES WITH HYPERTREHALOSEMIC ACTIVITY/

Two new members of the adipokinetic hormone/red pigment-concentrating hormone (AKH/RPCH) family of peptides were identified in the cicadas P latypleura capensis and Munza trimeni using heterologous (in migratory locusts and cockroaches) and homologous (in Fl capensis) bioassays. T he two peptides were isolated from the corpora cardiaca of the two cic ada species by reversed-phase high performance liquid chromatography. Edman sequencing after deblocking the N-terminal 5-oxopyrrolidine-2-ca rboxylic acid residue revealed that both peptides have the amino acid sequence (pGlu)-Val-Asn-Phe-Ser-Pro-Ser-Trp-Gly-Asn. Mass spectrometry , however, showed that peptide 1 (eluting first on HPLC) had a mass 35 2 Dalton higher than peptide 2; the exact modification of peptide 1 is not known yet. The N- and C-terminal blocked decapeptide 2 was synthe sised and shown to be chromatographically indistinguishable from the n atural compound under various HPLC conditions. Because this synthetic peptide increases the carbohydrate concentration in the haemolymph of Fl capensis when injected, it is named Plc-HrTH-II, Platypleura capens is hypertrehalosaemic hormone II. Flight experiments with Fl capensis confirmed that this species uses carbohydrates for flight: glycogen in the flight muscle and carbohydrates in the blood decreased by 70% and 40%, respectively.