title: Two novel tyrosine-containing peptides (Tyr(4)) of the adipokinetic hormone family in beetles of the families Coccinellidae and Silphidae.
abstract: Novel members of the adipokinetic hormone family of peptides have been identified from the corpora cardiaca (CC) of two species of beetles representing two families, the Silphidae and the Coccinellidae. A crude CC extract (0.3 gland equivalents) of the burying beetle, Nicrophorus vespilloides, was active in mobilizing trehalose in a heterologous assay using the cockroach Periplaneta americana, whereas the CC extract (0.5 gland equivalents) of the ladybird beetle, Harmonia axyridis, exhibited no hypertrehalosemic activity. Primary sequences of one adipokinetic hormone from each species were elucidated by liquid chromatography coupled to electrospray mass spectrometry (LC-MS). The multiple MS(N) electrospray mass data revealed an octapeptide with an unusual tyrosine residue at position 4 for each species: pGlu-Leu-Thr-Tyr-Ser-Thr-Gly-Trp amide for N. vespilloides (code-named Nicve-AKH) and pGlu-Ile-Asn-Tyr-Ser-Thr-Gly-Trp amide for H. axyridis (code-named Harax-AKH). Assignment of the correct sequences was confirmed by synthesis of the peptides and co-elution in reversed-phase high-performance liquid chromatography with fluorescence detection or by LC-MS. Moreover, synthetic peptides were shown to be active in the heterologous cockroach assay system, but Harax-AKH only at a dose of 30 pmol, which explains the negative result with the crude CC extract. It appears that the tyrosine residue at position 4 can be used as a diagnostic feature for certain beetle adipokinetic peptides, because this feature has not been found in another order other than Coleoptera.
authors.affiliation: Department of Biological Sciences, University of Cape Town, Private Bag, Rondebosch, 7700, South Africa. gerd.gade@uct.ac.za.
authors.forename: Gerd
authors.initials: G
authors.lastname: Gäde
authors.affiliation: Biology Centre, Czech Academy of Sciences, 37005, Ceske Budejovice, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Šimek
authors.affiliation: Department of Biological Sciences, University of Cape Town, Private Bag, Rondebosch, 7700, South Africa.
authors.forename: Heather G
authors.initials: HG
authors.lastname: Marco
mesh_terms: D054392:Adipokines / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D000595:Amino Acid Sequence; D000818:Animals; D001517:Coleoptera / Q000737:chemistry* / Q000235:genetics; D007301:Insect Hormones / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D019476:Insect Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D014443:Tyrosine / Q000737:chemistry
chemical_list: D054392:Adipokines; D007301:Insect Hormones; D019476:Insect Proteins; D010455:Peptides; D014443:Tyrosine
keywords: Adipokinetic hormone family; Beetles; Coccinellidae; Insects; Mass spectrometry; Silphidae