Isolation and structure elucidation of a neuropeptide from three species of Namib Desert tenebrionid beetles

Abstract

The corpora cardiaca of three Namib Desert beetles, Onymacris plana, O. rugatipennis and Physadesmia globosa (family Tenebrionidae), contain hyperlipaemic and/or hypertrehalosaemic factors as shown by heterologous bioassays in migratory locusts and American cockroaches. The compounds have been isolated by reversed-phase high performance liquid chromatography from the three species. The retention times of the compounds for all three species were identical. Amino acid composition data, in combination with determination of the primary structure by pulsed-liquid phase sequencing employing Edman chemistry after enzymically deblocking the N-terminal pyroglutamate residue, reveals an identical octapeptide for the three investigated species: pGlu-Leu-Asn-Phe-Ser-Pro-Asn-TrpNH₂. This peptide, code-named Tem-HrTH, is a member of the large adipokinetic hormone/red pigment-concentrating hormone family and was previously found in two other tenebrionid beetles which are only very distantly related to the Namib beetles. Thus, it appears that during evolution of tenebrionid beetles only one AKH/RPCH-family peptide was recruited.