Characterisation of neuropeptides of the AKH/RPCH-family from corpora cardiaca of Coleoptera.

Abstract

Extracts of corpora cardiaca from two members of the family Tenebrionidae. Zophobas rugipes and Tenebrio molitor, from one member of the Chrysomelidae, Leptinotarsa decemlineata, and from three members of the Scarabaeidae, Pachnoda marginata, P. sinuata and Melolontha hippocastani, were assayed for adipokinetic and hypertrehalosaemic activity in acceptor locusts (Locusta migratoria) and cockroaches (Periplaneta americana), respectively. All corpus cardiacum material tested, except that from the cockchafer, M. hippocastani, gave positive bioassay results. Biological activities of corpus cardiacum extracts from all species investigated can be resolved on reversed-phase high performance liquid chromatography (RP-HPLC). Gland extracts from the two tenebrionid species each show a single peak of biological activity associated with a single peak of UV absorbance having an identical retention time in both species. The two biologically active fractions from the corpora cardiaca of the potato beetle, L. decemlineata, coelute with exogenous (synthetic) hypertrehalosaemic hormones I and II of the American cockroach. The two species of the genus Pachnoda contain two active compounds in their glands; compound I of each species is more abundant and elutes just ahead of the (synthetic) hypertrehalosaemic hormone of the cockroach Blaberus discoidalis. The gland material of M. hippocastani exhibits an absorbance peak with the same retention time as the major peak from the Pachnoda-species; however, this peak material does not elicit biological activity in the assays used here. After fractionation by RP-HPLC the main biologically active compounds were subjected to amino acid analyses. All factors are peptidic and contain 8 amino acid residues.(ABSTRACT TRUNCATED AT 250 WORDS)