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

ENGLISH 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 alter enzymically deblocking the N-terminal pyroglutamatre 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. *************************** AFRIKAANSE OPSOMMING: Die corpora cardiaca van die Namibwoestynkewers Onymacris plana, O. rugatipennis en Physadesmia globosa, (familie Tenebrionidae) bevat hiperlipemiese en/of hipertrehalosemiese faktore, soos aangetoon deur heterolo biotoetse in treksprinkane en Amerikaanse kakkerlakke. Hierdie verbindings is ge soleer uit die drie spesies deur omgekeerde fase ho doeltreffendheid vloeistofchromatografie. Die retensietye van die verbindings vir al drie spesies was identies. Aminosuursamestellingsdata, tesame met die bepaling van die primêre struktuur deur 'pulsed-liquid phase' volgordebepaling met behulp van die Edmanproses,nadat die N-terminale piroglutamaatresidu ensiematies gedeblokkeer is, lewer 'n identiese oktapeptied op vir die drie spesies wat ondersoek is: pGlu-Leu-Asn-Phe-Ser-Pro-Asn-TrpNH2. Hierdie peptied, genaamd Tem-HrTH, is 'n lid van die groot adipokinetiese hormoon/rooi pigment konsentrerende hormoon-familie, en is voorheen gevind in twee ander kewers van die Tenebrionidae, wat slegs verlangs verwant is aan die Namibkewers. Dit wil dus voorkom of slegs een peptied van die AKH/RPKH-familie verwerf is tydens die evolusie van die kewers. AFRIKAANSE TREFWOORDE: corpora cardiaca, Namibwoestynkewers, Onymacris plana, O. rugatipennis, Physadesmia globosa, Tenebrionidae bevat hiperlipemiese , hipertrehalosemiese faktore, heterolo biotoetse, treksprinkane, Amerikaanse kakkerlakke