A phylogenetic analysis of the adipokinetic neuropeptides of Ensifera

Abstract.  Adipokinetic neuropeptides, from the corpora cardiaca of various species of the suborder Ensifera, encompassing members of all superfamilies (except the Gryllacridoidea), were isolated by liquid chromatography, and identified structurally by comparison of retention times and mass spectrometry data with respect to information from known members of this peptide family. Ensiferan species always contain only one adipokinetic hormone (AKH) peptide, as assessed for a few species by monitoring typical AKH mass peaks from a crude corpora cardiaca extract. This AKH is an octapeptide, and is either Scg-AKH-II (pGlu-Leu-Asn-Phe-Ser-Thr-Gly-Trp amide) which occurs in all Tettigoniidea (except Schizodactyloidea) and in Gryllotalpoidea, or Grb-AKH (pGlu-Val-Asn-Phe-Ser-Thr-Gly-Trp amide) which occurs in Grylloidea (except Gryllotalpoidea) and Schizodactyloidea. Using the structural information of these neuropeptides in conjunction with morpho-anatomical characters, these data are interpreted in a phylogenetic framework. The lack of a decapeptide and the presence of the octapeptide Scg-AKH-II are ancestral in Ensifera. The ancestral Scg-AKH-II twice underwent an independent and convergent modification to Grb-AKH.     

Structural diversity of adipokinetic hormones in the hyperdiverse coleopteran Cucujiformia

Seventeen species of the coleopteran series Cucujiformia are investigated for the presence and sequence of putative adipokinetic hormones (AKHs). Cucujiformia includes species from the major superfamilies, that is, Chrysomeloidea, Curculionoidea, Cucujoidea, and Tenebrionoidea. The clade Phytophaga in which the Chrysomeloidea and Curculionoidea reside, harbor very detrimental species for agriculture and forestry. Thus, this study aims not only to demonstrate the structural biodiversity of AKHs in these beetle species and possible evolutionary trends but also to determine whether the AKHs from harmful pest species can be used as lead substances for a future putative insecticide that is harmless to beneficial insects. Sequence analysis of AKHs is achieved by liquid chromatography coupled to mass spectrometry. Most of the investigated species contain AKH octapeptides in their corpora cardiaca, although previously published work also found a few decapeptides, which we comment on. The signature and sole AKH in cerambycidae Chrysomeloidea and Curculionoidea is Peram‐CAH‐I (pEVNFSPNW amide), which is also found in the majority of chrysomelidae Chrysomeloidea and in the one investigated species of Cucujoidea albeit in a few cases associated with a second AKH which can be either Peram‐CAH‐II (pELTFTPNW amide), Emppe‐AKH (pEVNFTPNW amide), or Micvi‐CC (pEINFTPNW amide). The most often encountered AKH in Tenebrionoidea, family Meloidae as well as family Tenebrionidae, is Tenmo‐HrTH (pELNFSPNW amide) followed by Pyrap‐AKH (pELNFTPNW amide) and a Tenmo‐HrTH extended decapeptide (in Meloidae). Finally, we examine AKH sequences from 43 species of cucujiform beetles, including the superfamily Coccinelloidea for a possible lead compound for producing a cucujiform‐specific pesticide.     

Water scorpions (Heteroptera, Nepidae) and giant water bugs (Heteroptera, Belostomatidae): sources of new members of the adipokinetic hormone/red pigment-concentrating hormone family

Two novel octapeptide members of the AKH/RPCH family have been identified from the corpora cardiaca (CC) of two species of water bugs. The giant water bug Lethocerus indicus (family: Belostomatidae) contains a peptide code-named Letin-AKH with the sequence pGlu-Val-Asn-Phe-Ser-Pro-Tyr-Trp amide, and the water scorpion Nepa cinerea (family: Nepidae) has the peptide code-named Nepci-AKH with the sequence pGlu-Leu/Ile-Asn-Phe-Ser-Ser-Gly-Trp amide. The sequences were deduced from the multiple MS(N) electrospray mass data from crude CC extracts. Synthetic peptides were made and co-elution on reversed-phase high performance liquid chromatography (RP-HPLC) with the natural peptide from crude gland extract confirmed the accuracy of the deduced sequence for Letin-AKH and demonstrated that Nepci-AKH contains a Leu residue at position 2 and not an Ile residue. A previously characterized member of the AKH/RPCH family was identified in the stick water scorpion Ranatra linearis by mass spectrometry: Grybi-AKH (pGlu-Val-Asn-Phe-Ser-Thr-Gly-Trp amide) has the same mass (919 Da) as Nepci-AKH and differs in two positions from Nepci-AKH (residues 2 and 6). The apparent function of the peptides is to achieve lipid mobilization in the species under investigation; indications for this came from conspecific bioassays using the appropriate synthetic peptides for injecting into the insects. This function is very likely linked to dispersal flight metabolism of water bugs. Swimming activity in N. cinerea also results in an increase in lipid concentration in the hemolymph.     

The newly discovered insect order Mantophasmatodea contains a novel member of the adipokinetic hormone family of peptides

A novel member of the AKH/RPCH family of peptides has been identified from the corpus cardiacum of an, as yet, unidentified species of the newly discovered insect order Mantophasmatodea from Namibia. The primary sequence of the peptide, which is denoted Manto-CC, was deduced from multiple MS(N) electrospray mass data to be an octapeptide: pGlu-Val-Asn-Phe-Ser-Pro-Gly-Trp amide. Synthetic Manto-CC co-elutes on reversed-phase HPLC with the natural peptide from the gland of the insect. Interestingly, Manto-CC is structurally very closely related (only one point mutation) to the AKH/RPCH peptides previously identified in mostly more basal insect taxa (Odonata, Blattodea, and Ensifera) and in Crustacea, the sister group of insects, whereas larger structural differences occur with peptides from Mantodea and Phasmatodea, which are thought to be close relatives of Mantophasmatodea. Functionally, Manto-CC may be employed to activate glycogen phosphorylase to mobilize carbohydrates.     

The adipokinetic hormone of the coleopteran suborder Adephaga: Structure,function, and comparison of distribution in other insects

The aim of the current study is to identify the adipokinetic hormone(s) (AKHs) of a basal suborder of the species‐rich Coleoptera, the Adephaga, and possibly learn more about the ancestral AKH of beetles. Moreover, we wanted to compare the ancestral AKH with AKHs of more advanced beetles, of which a number are pest insects. This would allow us to assess whether AKH mimetics would be suitable as insecticides, that is, be harmful to the pest species but not to the beneficial species. Nine species of the Adephaga were investigated and all synthesize only one octapeptide in the corpus cardiacum, as revealed by Edman degradation sequencing techniques or by mass spectrometry. The amino acid sequence pGlu‐Leu‐Asn‐Phe‐Ser‐Thr‐Gly‐Trp corresponds to Schgr‐AKH‐II that was first identified in the desert locust. It is assumed that Schgr‐AKH‐II—the peptide of a basal beetle clade—is the ancestral AKH for beetles. Some other beetle families, as well as some Hymenoptera (including honey bees) also contain this peptide, whereas most of the pest beetle species have different AKHs. This argues that those peptides and their receptors should be explored for developing mimetics with insecticidal properties. A scenario where Schgr‐AKH‐II (the only AKH of Adephaga) is used as basic molecular structure to derive almost all other known beetle AKHs via single step mutations is very likely, and supports the interpretation that Schgr‐AKH‐II is the ancestral AKH of Coleoptera.     

The adipokinetic hormones of African water bugs of the Heteropteran families Nepidae and Belostomatidae

Four African species of true water bugs (Nepomorpha: Hemiptera: Heteroptera) are studied by mass spectrometry and biological assays to gain information on the presence, structure and function of peptides from the adipokinetic hormone (AKH) family, which are produced in the corpora cardiaca (CC). The water scorpion Laccotrephes fabricii Stål (Nepidae) has the peptide code‐named Peram‐CAH‐I with the sequence pGlu‐Val‐Asn‐Phe‐Ser‐Pro‐Asn‐Trp amide, whereas Appasus grassei Poisson (Belostomatidae) produces Anaim‐AKH, which is a Ser⁷ analogue of Peram‐CAH‐I (pGlu‐Val‐Asn‐Phe‐Ser‐Pro‐Ser‐Trp amide). The giant water bug Hydrocyrius columbiae Spinola (Belostomatidae) has two adipokinetic hormone family members: Anaim‐AKH and Letin‐AKH, which again differ only at position 7 (Ser⁷ versus Tyr⁷). When the sequence data are compared with current molecular phylogenetic analyses of Nepomorpha, they are essentially in agreement with the newest ideas on phylogenetic relationships among the families. Functional investigation of these peptides reveals a mainly lipid‐based energy metabolism in these insects, as demonstrated by a hyperlipaemic response after injecting crude CC extract or the appropriate peptide into the respective species. The carbohydrate concentration in the haemolymph is not affected by such injections, and the carbohydrate level in most cases is lower than that of the circulating lipids. During physical exercise, such as swimming for 1 h, carbohydrates may contribute to some extent to the provision of energy; the substantial increase in the concentration of lipids in the haemolymph, however, is a strong indicator that the peptides are released from the CC and act primarily as true adipokinetic hormones during this period of intense muscular activity.     

A novel adipokinetic peptide in a water boatman (Heteroptera, Corixidae) and its bioanalogue in a saucer bug (Heteroptera, Naucoridae)

The corpora cardiaca (CC) of two water bug species, the water boatman Corixa punctata and the saucer bug Ilyocoris cimicoides, contain a substance that cause hyperlipemia in the migratory locust. The primary sequence of one octapeptide belonging to the adipokinetic hormone (AKH)/red pigment-concentrating hormone (RPCH) family was deduced from the multiple MS(N) electrospray mass data of CC material from each species. Whereas the saucer bug contains the known octapeptide pGlu-Val-Asn-Phe-Ser-Pro-Ser-Trp amide, code-named Anaim-AKH, the water boatman has a novel peptide identified as pGlu-Leu/Ile-Asn-Phe-Ser-Pro-Ser-Trp amide, code-named Corpu-AKH. The ambiguity about the amino acid at position 2, i.e. Leu or Ile, in Corpu-AKH was solved by isolating the peptide in a single-step by reversed-phase HPLC and establishing co-elution with the synthetic peptide containing Leu at position 2. Functionally, the peptides regulate lipid mobilization, as evidenced by an adipokinetic effect after injecting synthetic Anaim-AKH and Corpu-AKH into the respective acceptor species. Swimming activity of I. cimicoides also causes hyperlipemia.     

Phylogenetic and Functional Implications of the Rhabdom Patterns in the Eyes of Chrysomeloidea (Coleoptera)

Ultrastructural data from 108 species of Chrysomeloidea show that all rhabdom-patterns can be assigned to one of two basic patterns. The insula-pattern: two central rhabdomeres (Rh 7/8) are spatially isolated from the six peripheral ones (Rh 1–6). The ponticulus-pattern: Rh 7/8 fuse at two sites with the ring of Rh 1–6. The distance between the two systems may prevent optical or electrical coupling in the insula-p. The structure of the ponticulus-p may allow electrical coupling as well as contrast-intensifying lateral filtering. Potential relative polarization and absolute sensitivities differ interspecifically between homologous cells and intraspecifically between Rh7/8 and Rh 1–6, and between Rh 7 and Rh 8. The Bruchidae show only the insula-p, the Chrysomelidae and Cerambycidae both. The distribution of the two patterns is subfamily-specific within the Chrysomelidae, but not in the Cerambycidae. Identical patterns must have developed convergently within the Chrysomeloidea. Both basic patterns are subdivided in different subfamilies or tribes.     

An invertebrate [hydroxyproline]-modified neuropeptide: further evidence for a close evolutionary relationship between insect adipokinetic hormone and mammalian gonadotropin hormone family

An octapeptide of the adipokinetic hormone (AKH) peptide family is identified in the corpora cardiaca of the stink bug, Nezara viridula, by ESI-MS^N (electrospray ionization multistage MS). This is the second AKH in N. viridula and it has a hydroxyproline residue at position 6, whereas the major AKH (known as Panbo-RPCH) has Pro as the sixth amino acid residue. The correct sequence assignment of [Hyp⁶]-Panbo-RPCH is confirmed by retention time and MS spectra of the synthetic peptide. Various extraction procedures were followed to ascertain whether the hydroxylation is an artefact of extraction, or whether it is due to a true post-translational modification at the prohormone level. The proline hydroxylation is unique for invertebrate neuropeptides, while it has been described in the vertebrate gonadotropin-releasing hormone (GnRH). The current finding is another piece of evidence that AKH and GnRH form a peptide superfamily and are closely related evolutionarily. Biologically, [Hyp⁶]-Panbo-RPCH is active in vivo as an AKH, causing hyperlipaemia in the stink bug at low doses, indicating again that it is an endogenous, mature and functional hormone in this insect species.     

Higher‐level phylogeny of longhorn beetles (Coleoptera: Chrysomeloidea) inferred from mitochondrial genomes

Cerambycidae (longhorn beetles) and related families in the superfamily Chrysomeloidea are important components of forest ecosystems and play a key role in nutrient cycling and pollination. Using full mitochondrial genomes and dense taxon sampling, the phylogeny of Chrysomeloidea with a focus on Cerambycidae and allied families was explored. We used 151 mitochondrial genomes (75 newly sequenced) covering all families and 29 subfamilies of Chrysomeloidea. Our results reveal that (i) Chrysomelidae (leaf beetles) are sister to all other chrysomeloid families; (ii) Cerambycidae sensu stricto (s. s.) is polyphyletic due to the inclusion of other families that split Cerambycidae into a ‘lamiine’ clade comprising Lepturinae sensu lato (s. l.) + (Lamiinae + Spondylidinae) and a ‘cerambycine’ clade comprising Dorcasominae + (Cerambycinae + Prioninae s. l.); (iii) the subfamilies within the two clades of Cerambycidae s. s. were monophyletic, except for the placement of Necydalinae nested in Lepturinae, and the placement of Parandrinae within Prioninae (now considered as tribes Necydalini and Parandrini, respectively); (iv) smaller families were grouped into two major clades: one composed of Disteniidae+Vesperidae and the other composed of Orsodacnidae + (Megalopodidae + Oxypeltidae); (v) relationships among the four major clades were poorly supported but were resolved as ((cerambycines + (Disteniidae + Vesperidae) + Orsodacnidae + (Megalopodidae + Oxypeltidae)) + lamiines. Divergence time analyses estimated that Chrysomeloidea originated ca. 154.1 Mya during the late Jurassic, and most subfamilies of Cerambycidae originated much earlier than subfamilies of Chrysomelidae. The diversification of families within Chrysomeloidea was largely coincident with the radiation of angiosperms during the Early Cretaceous.     

A possible molecular ancestor for mollusk APGWamide,insect adipokinetic hormone,and crustacean red pigment concentrating hormone

Precursor structures of various members of the neuropeptide family adipokinetic hormone/red pigment concentrating hormone (AKH/RPCH) of mandibular arthropods and the APGWamide family of mollusks were compared. Amino acid alignments showed a common overall architecture (signal peptide, active peptide, related peptide), with a similar α helix–random coil secondary structure. DNA sequence alignments revealed close similarities between the genes encoding for the peptides of the two families. The APGWamide genes are larger than the AKH/RPCH genes. The sequence environment occupied by introns is similar in AKH/RPCH and APGWamide genes. Such similarities suggest that these peptide families might have been originated by gene rearrangements from a common ancestor having either an AKH/RPCH/APGWamide-like structure or both an AKH/RPCH-like and an APGWamide-like structures. In the former model, DNA fragments could have been gained when the ancestor evolved to mollusks and it could have lost nucleotides when the progression to mandibular arthropods took place. In the second model, AKH/RPCH-like structures could have been fused during evolution toward mandibular arthropods, whereas in mollusks they could have been lost with the possible amplification of the APGWamide-like structure. Loss of domains in exon 1 may have originated the signal peptide and the first codon of the active RPCH. In exon 2, loss of domains possibly determined the junctions of codons 2 to 5 with the loss of a APGWamide copy; exon 3 underwent fewer variations. The similarity of the mollusk APGWamide precursors is closer to that of the RPCH family than the insect AKH family, indicating an earlier evolutionary departure.     

The adipokinetic hormones of Heteroptera: a comparative study

The adipokinetic hormones (AKHs) from 15 species of heteropteran Hemiptera (encompassing eight families, six superfamilies and three infraorders) have been isolated and structurally identified using liquid chromatography coupled with mass spectrometry. None of the structures are novel and all are octapeptides. These peptide sequence data are used, together with the previously available AKH sequence data on Heteroptera, to create a larger dataset for comparative analyses. This results, in total, in AKH sequences from 30 species (spanning 13 families), which are used in a matrix confronted with the current hypotheses on the phylogeny of Heteroptera. The expanded dataset shows that all heteropterans have octapeptide AKHs; three species have two AKHs, whereas the overwhelming majority have only one AKH. From a total of 11 different AKH peptides known from Heteroptera to date, three AKHs occur frequently: Panbo‐red pigment‐concentrating hormone (RPCH) (×10), Schgr‐AKH‐II (×6) and Anaim‐AKH (×4). The heteropteran database also suggests that particular AKH variants are family‐specific. The AKHs of Heteroptera: Pentatomomorpha (all terrestrial) are not present in Nepomorpha (aquatic) and Gerromorpha: Gerridae (semiaquatic); AKHs with a Val in position 2 are absent in the Pentatomomorpha (only AKHs with Leu² are present), whereas Val² predominates in the nonterrestrial species. An unexpected diversity of AKH sequences is found in Nepomorpha, Nepoidea, Nepidae and Nepinae, whereas Panbo‐RPCH (which has been identified in all infraorders of decapod crustaceans) is present in all analysed species of Pentatomidae and also in the only species of Tessaratomidae investigated. The molecular evolution of Heteroptera with respect to other insect groups and to crustaceans is discussed     

Phylogenetic significance of the ventral nerve cord in the Chrysomeloidea (coleptera: Phytophaga)

Abstract The ventral nerve cord of adult Chrysomeloidea exhibits variation in the degree of fusion of the meso-and metathoracic ganglia. similar variation occurs also in the ganglia ofthe abdominal chain, and in the single or double connectives between them. In adult Chrysomeloidea (and Curculionoidea) there never seem to be more than five separate abdominalganglia, the first two being more or less fused to the metathoracic ganglion and the lasttwo more or lessconnate; the supposed primitive condition is retained in some Cerambycidae. Trends toward the fusion of aditional abdominal ganglia appear in several differentlines in Chrysomelidae (and in Cerambycidae), and in more than one line a conditiones is reached in which only the ganglion in the third abdominal segmetn remains free. Structures possibly representing 'perisynmpathetic organs' have been observed in a few of the seventy-eight European and Indian species studied. systematic and phylogenetic conclusions are drawwn.     

Adipokinetic hormones provide inference for the phylogeny of odonata

Adipokinetic neuropeptides from the corpora cardiaca of 17 species of Odonata encompassing mainly the families Corduliidae and Libellulidae were isolated and structurally elucidated using liquid chromatography coupled with ion trap electrospray ionization mass spectrometry. It became evident that all species of the family Corduliidae studied express the peptide code-named Libau-AKH (pGlu-Val-Asn-Phe-Thr-Pro-Ser-Trp amide), which is also present in all but one libellulid species, Erythemis simplicicollis which expresses Erysi-AKH (pGlu-Leu-Asn-Phe-Thr-Pro-Ser-Trp amide). This divergence from all other Libellulids is due to a nonsynonymous missense single nucleotide polymorphism (SNP) in the nucleotide coding sequence (CDS) of prepro-AKH CDS and supports the polyphyletic nature of Sympetrinae and other subfamilies of libellulids. Despite this exception, these findings then support the hypothesis that Corduliidae and Libellulidae are closely related as stated in most phylogenies. The presence of Anaim-AKH (pGlu-Val-Asn-Phe-Ser-Pro-Ser-Trp amide) in Macromiidae likely distinguishes species in this family from Corduliidae. Current molecular genetic phylogenies and our AKH findings suggest that Syncordulia gracilis, which expresses Anaim-AKH, does not belong in Corduliidae. Evolution of AKHs in anisopteran Odonata are likely due to nucleotide substitution involving nonsynonymous missense SNPs in the CDS of prepro-AKH.     

The adipokinetic hormone of Mantodea in comparison to other Dictyoptera

Six species of the order Mantodea (praying mantises) are investigated for the presence and sequence of putative adipokinetic hormones (AKHs). The selected species span a wide evolutionary range of various families and subfamilies of the clade Mantodea. The corpora cardiaca of the different species are dissected, methanolic extracts prepared, peptides separated by liquid chromatography, and AKHs detected and sequenced by ion trap mass spectrometry. All six species investigated contain an octapeptide with the primary structure pGlu‐Val‐Asn‐Phe‐Thr‐Pro‐Asn‐Trp amide, which is code‐named Emppe‐AKH and had been found earlier in three other species of Mantodea. Conspecific bioassays with the species Creoboter sp. (family Hymenopodidae) reveal an adipokinetic but not a hypertrehalosemic function of Emppe‐AKH. Comparison with other members of the Dictyoptera (cockroaches, termites) show that Emppe‐AKH is only found in certain termites, which have been recently placed into the Blattaria (cockroaches) as sister group to the family Cryptocercidae. Termites and cockroaches both show biodiversity in the sequence of AKHs, and some cockroach species even contain two AKHs. In contrast, all praying mantises—irrespective of their phylogenetic position—synthesize uniformly only one and the same octapeptide Emppe‐AKH.     

Flight substrates and their regulation by a member of the AKH/RPCH family of neuropeptides in Cerambycidae

The pattern of metabolic changes during tethered flight with lift-generation was investigated in two South African species of long-horned beetles (family: Cerambycidae), namely Phryneta spinator and Ceroplesis thunbergi. Energy substrates were measured in haemolymph and flight muscles at rest, after a flight period of 1 min at an ambient temperature of 25-29 degrees C, and 1 h thereafter. Flight diminished the levels of proline and carbohydrates in the haemolymph and proline and glycogen in the flight muscles of both species, and caused an increase in the levels of alanine in both compartments. The concentration of lipids in the haemolymph, however, was not changed upon flight in either species. The resting period of 1 h following a 1 min flight episode, was sufficient to reverse the metabolic situation in haemolymph and flight muscles to pre-flight levels in both species. Purification of an extract of the corpora cardiaca from the two beetle species on RP-HPLC, resulted in the isolation and subsequently in the identification (by mass spectrometry, Edman degradation and RP-HPLC) of an octapeptide of the AKH/RPCH family, denoted Pea-CAH-I (pGlu-Val-Asn-Phe-Ser-Pro-Asn-Trpamide), present in each species. It was demonstrated that low doses of Pea-CAH-I elicited increases in the concentration of proline, as well as carbohydrates, in the haemolymph of both species. The levels of lipids, however, remained unchanged upon injection of this peptide. It is concluded that, upon stimulation by flight, the peptide Pea-CAH-I is released from the corpus cardiacum of a cerambycid beetle and is responsible for the regulation of the major flight substrates, proline and carbohydrates, of these beetles.     

Dragonfly Erythemis simplicicollis contains a novel adipokinetic neuropeptide

We have isolated a novel member of the adipokinetic hormone family of peptides from a methanolic extract of corpora cardiaca of the libellulid dragonfly Erythemis simplicicollis by using a single‐step reversed‐phase high performance liquid chromatography method and monitoring biological activity in various heterologous bioassays and a homologous one. The sequence, as determined by Edman degradation and mass spectrometry, was of an uncharged blocked octapeptide: pGlu‐Leu‐Asn‐Phe‐Thr‐Pro‐Ser‐Trp amide. The structure was confirmed by chemical synthesis. The synthetic peptide increased hemolymph lipids in the dragonfly and was active in another libellulid (Orthetrum julia‐falsum) as well, but to a lesser extent than the conspecific peptide Lia‐AKH, which is an isoform of the novel peptide differing by a Val (instead of Leu) at position 2. Since lipids are apparently used as substrate for muscle contraction during flight of Erythemis simplicicollis and the native peptide induces lipid mobilization, this novel peptide is denoted Ers‐AKH. Arch. Insect Biochem. Physiol. 40:99–106, 1999. © 1999 Wiley‐Liss, Inc.     

The first decapeptide adipokinetic hormone (AKH) in Heteroptera: a novel AKH from a South African saucer bug, Laccocoris spurcus (Naucoridae, Laccocorinae)

A novel peptide of the adipokinetic hormone (AKH)/red pigment-concentrating hormone (RPCH) family has been elucidated by mass spectrometry from the corpora cardiaca of an African saucer bug species, Laccocoris spurcus. It is the first decapeptide member found in the species-rich taxon Heteroptera, has the primary sequence pGlu-Val-Asn-Phe-Ser-Pro-Ser-Trp-Gly-Gly amide and is denoted as Lacsp-AKH. The first eight amino acids are identical to the octapeptide Anaim-AKH of the European saucer bug, Ilyocoris cimicoides. The synthetic peptide Lacsp-AKH elevates lipids upon injection into the hemolymph of L. spurcus at a low dose of 3 pmol. Swimming activity in this saucer bug also causes a significant increase in the lipid concentration in the hemolymph. Thus, both results point to an apparent function of the endogenous new decapeptide Lacsp-AKH in L. spurcus, namely, to regulate lipid mobilization. Isolation of an AKH peptide from the corpora cardiaca of the water bug Aphelocheirus aestivalis (Aphelocheiridae) resulted in the assignment of the octapeptide Anaim-AKH, supporting current phylogenies on the infraorder Nepomorpha.     

Isolation and structure of a novel charged member of the red-pigment-concentrating hormone-adipokinetic hormone family of peptides isolated from the corpora cardiaca of the blowfly Phormia terraenovae (Diptera).

A hypertrehalosaemic neuropeptide from the corpora cardiaca of the blowfly Phormia terraenovae has been isolated by reversed-phase h.p.l.c., and its primary structure was determined by pulsed-liquid phase sequencing employing Edman chemistry after enzymically deblocking the N-terminal pyroglutamate residue. The C-terminus was also blocked, as indicated by the lack of digestion when the peptide was incubated with carboxypeptidase A. The octapeptide has the sequence pGlu-Leu-Thr-Phe-Ser-Pro-Asp-Trp-NH2 and is clearly defined as a novel member of the RPCH/AKH (red-pigment-concentrating hormone/adipokinetic hormone) family of peptides. It is the first charged member of this family to be found. The synthetic peptide causes an increase in the haemolymph carbohydrate concentration in a dose-dependent fashion in blowflies and therefore is named 'Phormia terraenovae hypertrehalosaemic hormone' (Pht-HrTH). In addition, receptors in the fat-body of the American cockroach (Periplaneta americana) recognize the peptide, resulting in carbohydrate elevation in the blood. However, fat-body receptors of the migratory locust (Locusta migratoria) do not recognize this charged molecule, and thus no lipid mobilization is observed in this species.