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Barbara Stay - One of the best experts on this subject based on the ideXlab platform.

  • evidence for a phe gly leu amide like Allatostatin in the beetle tenebrio molitor
    Peptides, 2010
    Co-Authors: Karen L Elliott, Kuen Kuen Chan, Barbara Stay
    Abstract:

    The Allatostatins (ASTs) with Phe-Gly-Leu-amide C-terminal sequence are multifunctional neuropeptides discovered as inhibitors of juvenile hormone (JH) synthesis by corpora allata (CA) of cockroaches. Although these ASTs inhibit JH synthesis only in cockroaches, crickets, termites and locusts, isolation of peptides or of cDNA/genomic DNA or analysis of genomes indicates their occurrence in many orders of insects with the exception of coleopterans. The gene for these ASTs has not been found in the genome of the red flour beetle Tribolium castaneum (Family Tenebrionidae). Yet, in view of widespread occurrence of these peptides in insects, crustaceans and nematodes, they would be expected to occur in beetles. This study provides evidence for the presence of FGLa-like ASTs in the tenebrionid beetle, Tenebrio molitor, and scarabid beetle, Popillia japonica. Extract of brain from both beetles inhibited JH synthesis by cockroach CA dose dependently and reversibly. 20 brain equivalents of T. molitor and P. japonica extracts inhibited JH synthesis 64 ± 5 and 65 ± 0.6% respectively. Antibody against cockroach Allatostatin (Diploptera punctata AST-7) used in an enzyme-linked immunosorbent assay reacted with brain extract of these beetles. Antibody against D. punctata AST-5 localized FGLa-like ASTs in the brain and subesophageal ganglion of T. molitor and P. japonica. In addition, pretreatment of T. molitor brain extract with anti-D. punctata AST-5 reduced the inhibition of JH synthesis and pretreatment of anti-D. punctata AST-5 with D. punctata AST-5 diminished the immunoreactivity of the antibody. Thus we predict that FGLa-like Allatostatins will be found in beetles.

  • identification of phe gly leu amide type Allatostatin 7 in reticulitermes flavipes its localization in tissues and relation to juvenile hormone synthesis
    Peptides, 2009
    Co-Authors: Karen L Elliott, Lynn M Teesch, Kuen Kuen Chan, Omar Clor, Barbara Stay
    Abstract:

    Abstract The Allatostatins (ASTs), with a Tyr/Phe-Xaa-Phe-Gly-Leu/Ile-amide C-terminus, are neuropeptides that occur in many orders of insects, but are known to inhibit juvenile hormone (JH) synthesis by corpora allata (CA) only in cockroaches, crickets, and termites. 5 AST peptides with similar sequences to those of 6 species of cockroaches have been isolated and sequenced from extract of brain tissue of the termite Reticulitermes flavipes. The amino acid sequence of a 6th peptide, R. flavipes AST-7, determined by LC–MS/MS following HPLC fractionation of brain extract, is S-P-S-S-G-N-Q-R-L-Y-G-F-G-L-NH2. The 8 terminal amino acids are identical to AST-7 of the cockroach Diploptera punctata. R. flavipes and D. punctata AST-7s inhibited JH synthesis by CA of both species equally and their affinity for antibody against D. punctata AST-7 is similar. Immunoreactivity of termite tissue with this antibody indicates neuro- and myomodulatory activity of the peptide in addition to its demonstrated allatostatic function. The density of AST immunostaining in axons within the CA of R. flavipes and the rate of JH synthesis by similar glands were negatively correlated. This is evidence that when AST is abundant in the glands it is being released in vivo to limit JH production.

  • isolation of cockroach phe gly leu amide Allatostatins from the termite reticulitermes flavipes and their effect on juvenile hormone synthesis
    Journal of Insect Physiology, 2008
    Co-Authors: Koichiro J Yagi, Stephen S Tobe, Karen L Elliott, Lynn M Teesch, Barbara Stay
    Abstract:

    Immunoreactivity to cockroach Diploptera punctata Allatostatin-7 (Dippu AST-7) has been demonstrated previously in axons innervating the corpora allata of the termite Reticulitermes flavipes. This peptide and Dippu AST-11 inhibited juvenile hormone (JH) synthesis by corpora allata (CA) of brachypterous neotenic reproductives (secondary reproductives) of termites. The present study shows that R. flavipes CA are also inhibited by Dippu AST-2, AST-5, AST-8, and AST-9 at approximately the same rank order of potency as demonstrated in D. punctata. Another Allatostatin from Periplaneta americana (Peram AST-12) also inhibits JH synthesis by R. flavipes CA. Sensitivity to the Allatostatins is higher in glands with low rates of JH synthesis than in those with relatively high JH synthetic rates as has been demonstrated in CA from male and female secondary reproductives as well as in those from non-egg-laying and egg-laying females. The identical inhibitory effects of R. flavipes brain extract on CA from both D. punctata and R. flavipes and the isolation and identification of five cockroach Allatostatins (Dippu AST-1, AST-2, AST-5, AST-8, and Peram AST-12) from termite brain extract reflect the close relationship between cockroaches and termites.

  • phe gly leu amide Allatostatin in the termite reticulitermes flavipes content in brain and corpus allatum and effect on juvenile hormone synthesis
    Journal of Insect Physiology, 2005
    Co-Authors: Koichiro J Yagi, Rodney Kwok, Stephen S Tobe, K K Chan, R R Setter, Timothy G Myles, Barbara Stay
    Abstract:

    In the subterranean termite Reticulitermes flavipes, Allatostatins (ASTs) with the C-terminus Phe-Gly Leu-amide were localized by immunocytochemistry with antibody against a cockroach AST, Dippu AST-7. AST-immunoreactivity occurred in the corpus cardiacum and corpus allatum and in the lateral and medial neurosecretory cells of the brain that innervate these organs as well as in many other nerve cells of the brain. This was observed in workers, nymphs, soldiers and secondary reproductives. A radioimmunoassay, using anti-Dippu AST-11, demonstrated about 40 fmole equivalents of AST in brains of soldiers and secondary reproductives. The product of the corpora allata in this species was determined to be juvenile hormone III. Its synthesis by corpora allata of secondary reproductives, determined by in vitro radiochemical assay, was inhibited in a dose-dependent fashion by two cockroach Allatostatins, Dippu AST-7 and Dippu AST-11. Thus, as in cockroaches and crickets, Allatostatin-containing nerves innervate the corpora allata of this termite species and their production of juvenile hormone is inhibited by these neuropeptides.

  • localization and physiological effects of rfamides in the corpora allata of the cockroach diploptera punctata in relation to Allatostatins
    Peptides, 2003
    Co-Authors: Barbara Stay, J R Zhang, Rodney Kwok
    Abstract:

    The distribution of FMRFamide immunoreactivity in the brain-retrocerebral complex of adult female Diploptera punctata was examined. Immunoreactivity was observed in the brain and corpus allatum as well as in the corpus cardiacum. Immunoreactivity co-localized with Allatostatin immunoreactivity within several lateral neurosecretory cells of the brain and in their endings within the corpus allatum. By in vitro radiochemical assay of juvenile hormone release, the effect of two native D. punctata RFamides, an FLRFamide (Leucomyosuppressin) and an FIRFamide were examined. The latter, for which the sequence (SKPANFIRFamide) is reported here, stimulated juvenile hormone release but acted only on corpora allata from females at the end of vitellogenesis (day 6). The interaction of these two RFamides and three D. punctata Allatostatins, Dippu-AST 2, 5, and 7 were similarly examined. Only Dippu-AST 2 stimulated release of RFamides from the corpora allata and only on day 6 whereas both RFamides were able to attenuate the inhibitory activity of Dippu-AST 2.

Koichiro J Yagi - One of the best experts on this subject based on the ideXlab platform.

  • isolation of cockroach phe gly leu amide Allatostatins from the termite reticulitermes flavipes and their effect on juvenile hormone synthesis
    Journal of Insect Physiology, 2008
    Co-Authors: Koichiro J Yagi, Stephen S Tobe, Karen L Elliott, Lynn M Teesch, Barbara Stay
    Abstract:

    Immunoreactivity to cockroach Diploptera punctata Allatostatin-7 (Dippu AST-7) has been demonstrated previously in axons innervating the corpora allata of the termite Reticulitermes flavipes. This peptide and Dippu AST-11 inhibited juvenile hormone (JH) synthesis by corpora allata (CA) of brachypterous neotenic reproductives (secondary reproductives) of termites. The present study shows that R. flavipes CA are also inhibited by Dippu AST-2, AST-5, AST-8, and AST-9 at approximately the same rank order of potency as demonstrated in D. punctata. Another Allatostatin from Periplaneta americana (Peram AST-12) also inhibits JH synthesis by R. flavipes CA. Sensitivity to the Allatostatins is higher in glands with low rates of JH synthesis than in those with relatively high JH synthetic rates as has been demonstrated in CA from male and female secondary reproductives as well as in those from non-egg-laying and egg-laying females. The identical inhibitory effects of R. flavipes brain extract on CA from both D. punctata and R. flavipes and the isolation and identification of five cockroach Allatostatins (Dippu AST-1, AST-2, AST-5, AST-8, and Peram AST-12) from termite brain extract reflect the close relationship between cockroaches and termites.

  • phe gly leu amide Allatostatin in the termite reticulitermes flavipes content in brain and corpus allatum and effect on juvenile hormone synthesis
    Journal of Insect Physiology, 2005
    Co-Authors: Koichiro J Yagi, Rodney Kwok, Stephen S Tobe, K K Chan, R R Setter, Timothy G Myles, Barbara Stay
    Abstract:

    In the subterranean termite Reticulitermes flavipes, Allatostatins (ASTs) with the C-terminus Phe-Gly Leu-amide were localized by immunocytochemistry with antibody against a cockroach AST, Dippu AST-7. AST-immunoreactivity occurred in the corpus cardiacum and corpus allatum and in the lateral and medial neurosecretory cells of the brain that innervate these organs as well as in many other nerve cells of the brain. This was observed in workers, nymphs, soldiers and secondary reproductives. A radioimmunoassay, using anti-Dippu AST-11, demonstrated about 40 fmole equivalents of AST in brains of soldiers and secondary reproductives. The product of the corpora allata in this species was determined to be juvenile hormone III. Its synthesis by corpora allata of secondary reproductives, determined by in vitro radiochemical assay, was inhibited in a dose-dependent fashion by two cockroach Allatostatins, Dippu AST-7 and Dippu AST-11. Thus, as in cockroaches and crickets, Allatostatin-containing nerves innervate the corpora allata of this termite species and their production of juvenile hormone is inhibited by these neuropeptides.

  • terminal stages in juvenile hormone biosynthesis in corpora allata of diploptera punctata developmental changes in enzyme activity and regulation by Allatostatins
    Journal of Insect Physiology, 1994
    Co-Authors: Zhiwei Wang, Koichiro J Yagi, Qi Ding, Stephen S Tobe
    Abstract:

    Abstract The O -methyltransferase, which is responsible for the methylation of farnesoic acid in the corpora allata of Diploptera punctata , is a cytosolic enzyme. The activity of O -methyltransferase closely parallels JH biosynthesis in last instars and adult females. Because Allatostatin 4 (AST 4) from D. punctata and cAllatostatin 5 (CAST 5) from Calliphora vomitoria can inhibit juvenile hormone biosynthesis, their effects on the activity of O -methyltransferase and epoxidase, the enzymes involved in the final two steps of juvenile hormone biosynthesis, were investigated in vitro . AST 4 can inhibit methyltransferase activity whereas CAST 5 stimulates it. AST 4 inhibits epoxidase activity slightly whereas CAST 5 inhibits it significantly (36%). Treatment of corpora allata with farnesoic acid (40 μM) can reverse the inhibitory effect of AST 4 and CAST 5 on JH release by corpora allata. Thus, Allatostatins appear to exert their inhibitory effect on JH biosynthesis at least partially through inhibition of the activity of terminal enzymes. Two biosynthetic pathways for the conversion of farnesoic acid to JH may exist in corpora allata of D. punctata : the predominant pathway is farnesoic acid to methyl farnesoate, then to JH whereas the other, representing about 5–10% of total JH production, is farnesoic acid to JH III acid, then to JH.

  • cAllatostatins neuropeptides from the blowfly calliphora vomitoria with sequence homology to cockroach Allatostatins
    Proceedings of the National Academy of Sciences of the United States of America, 1993
    Co-Authors: Hanne Duve, Alan G Scott, Cao G Yu, Anders H Johnsen, Koichiro J Yagi
    Abstract:

    Abstract Five neuropeptides with C-terminal amino acid sequence homology to cockroach Allatostatins have been identified in the blowfly Calliphora vomitoria. Three have the same pentapeptide C-terminal amino acid sequence as Allatostatin 1 of the cockroach Diploptera punctata. A hexadecapeptide designated cAllatostatin 1, isolated from thoracic ganglia, brains, and heads, has the sequence Asp-Pro-Leu-Asn-Glu-Glu-Arg-Arg-Ala-Asn-Arg-Tyr-Gly-Phe-Gly-Leu-NH2. CAllatostatins 2 and 3 have been isolated from heads and thoracic ganglia, respectively; they comprise the last 14 and 8 residues of cAllatostatin 1. CAllatostatin 4, isolated from thoracic ganglia, has the sequence Xaa-Arg-Pro-Tyr-Ser-Phe-Gly-Leu-NH2, where Xaa is either Asp or Asn. This peptide, with a serine substitution for glycine at position 5, has a C-terminal pentapeptide sequence identical to that of Allatostatins 3 and 4 of D. punctata. CAllatostatin 5, with the sequence Gly-Pro-Pro-Tyr-Asp-Phe-Gly-Met-NH2, was identified from whole flies. All five peptides inhibit juvenile hormone production by the corpora allata of D. punctata in vitro. CAllatostatin 5 was the most potent Allatostatin so far tested in this species, with maximum inhibition occurring at 1 nM. In contrast, none of the cAllatostatins or the Allatostatins showed allatostatic activity in mature female C. vomitoria when tested at concentrations of 100 to 0.1 microM. In accordance with these results, immunoreactivity to an antiserum directed against the common C terminus of cAllatostatin 1 and Allatostatin 1 was observed in the corpora allata of D. punctata but not in the corpus allatum of C. vomitoria, despite its presence in neurons of the brain. Neurons in the thoracic ganglion of C. vomitoria that are immunoreactive against this antiserum project to the hindgut, rectum, rectal papillae, and oviduct, suggestive of a function different from that of a true Allatostatin.

  • assessment of the role of cyclic nucleotides in Allatostatin induced inhibition of juvenile hormone biosynthesis in diploptera punctata
    Molecular and Cellular Endocrinology, 1992
    Co-Authors: Michel Cusson, Koichiro J Yagi, Guan Xuechen
    Abstract:

    Abstract In an effort to identify the signal transduction mechanism associated with the inhibition of juvenile hormone (JH) biosynthesis by the neuropeptides Allatostatins, levels of the cyclic nucleotides cAMP and cGMP were measured in corpora allata (CA) of virgin and mated Diploptera punctata females using radioimmunoassays. Treatment of isolated CA with varying concentrations of synthetic Allatostatins 1, 2, 3 or 4 did not elicit significant changes in the levels of either cAMP or cGMP in any of the test glands, suggesting that these compounds do not act as second messengers for the four Allatostatins tested. Simultaneous treatment of CA with Allatostatin 4 and the adenylate cyclase activator forskolin did not increase the degree of inhibition of juvenile hormone biosynthesis relative to that obtained with forskolin (5 or 50 μM) alone. We interpret these results as lending further support to the suggestion that cyclic nucleotides do not play a role in the signal transduction of Allatostatins 1–4 in cockroach CA.

Hanne Duve - One of the best experts on this subject based on the ideXlab platform.

  • Allatostatins and allatotropin in the corpus cardiacum corpus allatum complex of larval and adult lepidopterans studied by confocal laser scanning microscopy correlation to juvenile hormone biosynthesis
    Cell and Tissue Research, 2003
    Co-Authors: Hanne Duve, Neil Audsley, Rob Weaver, Alan Thorpe
    Abstract:

    Peptidergic innervation of the corpus cardiacum/corpus allatum (CC/CA) retrocerebral complex, and neurosecretory areas of the brain of the lepidopterans Lacanobia oleracea, Heliothis virescens and Manduca sexta was studied by immunocytochemistry linked to confocal laser scanning microscopy. The patterns of immunostaining resulting from the simultaneous application of fluorochrome-conjugated antibodies against Manduca sexta Allatostatin (Mas-AS), M. sexta allatotropin (Mas-AT), and a representative of the −Y/FXFGL-NH2 superfamily of Allatostatins was correlated with the physiological effects of these putative allatoregulatory peptides on juvenile hormone (JH) biosynthesis by the corpora allata. Whereas the two types of Allatostatin immunoreactivity are present in both larval and adult CA of the three species, allatotropin immunoreactivity occurs only in the adult gland. The conclusion that withdrawal of the stimulatory effect of allatotropin is unlikely to be involved in the downregulation of CA activity prior to the onset of metamorphosis, but that an inhibitory influence of at least Mas-AS is important, is borne out in physiological experiments on JH biosynthesis in M. sexta larvae (Mas-AS inhibitory, Mas-AT without effect). Immunoreactivity to the Y/FXFGL-NH2 Allatostatins is present in both larval and adult CA and CC, frequently co-localised with Mas-AS. The function of this peptide family in the retrocerebral complex remains enigmatic since experiments on JH biosynthesis, either when the peptide is administered alone, or together with Mas-AS, show no effect on JH biosynthesis.

  • identification of the dipteran leu cAllatostatin peptide family characterisation of the prohormone gene from calliphora vomitoria and lucilia cuprina
    Regulatory Peptides, 1996
    Co-Authors: Peter D East, Karen Tregenza, Hanne Duve
    Abstract:

    Abstract The prohormone gene encoding the Leu-cAllatostatin peptides has been isolated from a Calliphora vomitoria genomic DNA library and its homologue was cloned from genomic and cDNA libraries of another blowfly species, Lucilia cuprina. Gene and prohormone structure and organisation are essentially identical in the two species. The Leu-cAllatostatin gene consists of at least 3 exons. The prohormone is encoded on exons two and three and the two blocks of putative Leu-cAllatostatin peptides are carried on separate exons. It is 180 amino-acids long, begins with a short signal peptide and contains two blocks of tandemly arranged Leu-cAllatostatin peptides separated by an acidic spacer region. The prohormone contains 5 copies of the C-terminal sequence -YXFGL characteristic of the Leu-cAllatostatin family. Complete endoproteolytic processing at all possible pairs of basic amino acids would generate 5 different Leu-cAllatostatin octapeptides. Two larger Leu-cAllatostatins could be released if processing was not complete at two of the sites. None of the 3 peptides encoded in the first block was identified in previous purification studies of the cAllatostatin peptides. The second block, located at the carboxyl end of the prohormone, contains two peptide sequences identical to the previously isolated Leu-cAllatostatins 1 and 4. The absence of independent copies of Leu-cAllatostatins 2 and 3 on the prohormone establishes that endoproteolytic cleavage of the precursor does not invariably proceed to completion and that Leu-cAllatostatin 2 must be derived by N-terminal processing of the parent peptide Leu-cAllatostatin 1. Reverse transcriptase PCR analysis of mRNA from brain and midgut, the two major sites of Leu-cAllatostatin expression, shows that the prohormone sequence at these two sites is identical, ruling out the possibility that different populations of peptides are expressed in these two tissues as a result of alternative RNA splicing.

  • identification of the dipteran leu cAllatostatin peptide family the pattern of precursor processing revealed by isolation studies in calliphora vomitoria
    Regulatory Peptides, 1996
    Co-Authors: Hanne Duve, Alan G Scott, Anders H Johnsen, Joseluis Maestro, Peter D East
    Abstract:

    Abstract Information from the Leu-cAllatostatin gene sequences of the blowflies Calliphora vomitoria and Lucilia cuprina was used to develop antisera specific for the variable post-tyrosyl amino-acid residues Ser, Ala and Asn of the common Leu-cAllatostatin C-terminal pentapeptide sequence −YXFGL-NH 2 . Radioimmunoassays based on these antisera were used to purify peptides from an extract of 40 000 blowfly heads. Five neuropeptides of the Leu-cAllatostatin family were identified. Three have a seryl residue in the post-tyrosyl position. Two of these are octapeptides that differ only at the N-terminal residue; NRPYSFGL-NH 2 and ARPYSFGL-NH 2 , whilst the third is the heptapeptide derived by N-terminal trimming; RPYSFGL-NH 2 . Two octapeptides in which X is Ala and Asn were also identified; VERYAFGL-NH 2 and LPVYNFGL-NH 2 . The latter peptide is derived by processing at the internal dibasic site of a putative heneicosapeptide encoded by the DNA. These findings stress the necessity to have putative structures verified at the peptide level. Potent, reversible inhibitory effects on the spontaneous contractile activity of the blowfly rectum were recorded for ARPYSFGL-NH 2 (monophasic dose-response curve with an IC 50 = 10 fM) and for LPVYNFGL-NH 2 (biphasic dose-response curve with IC 50 values of approximately 1 fM and 1 nM). It is suggested that regulation of gut motility in insects, rather than an allatostatic function, may represent an ancestral and universal function of the Allatostatins. One of the reasons for the large number of members of the Leu-cAllatostatin family appears to be in the provision of an integrated form of gut motility control, with different peptides controlling specific regions of the gut.

  • innervation of the foregut of the cockroach leucophaea maderae and inhibition of spontaneous contractile activity by cAllatostatin neuropeptides
    Physiological Entomology, 1995
    Co-Authors: Hanne Duve, Paul Wren, Alan Thorpe
    Abstract:

    Abstract. The innervation of the gut of the cockroach Leucophaea madera (F.) has been studied by means of wholemount immunocytochemistry with antisera raised against Leu-cAllatostatin, a cockroach Allatostatin homologue identified from neuropeptide isolation and gene studies in the blowfly Calliphora vomitoria. Leu-cAllatostatin-imunoreactive neurones in the brain, with axon trajectories in the stomatogastric nervous system, innervate the foregut and midgut. Neurones in the last abdominal ganglion supply the hindgut and the midgut via the proctodeal nerve. In addition to a rich cAllatostatin-immunoreactive nerve supply, the midgut, including the midgut caeca, contain numerous cAllatostatin-immunoreactive endocrine cells. Physiological studies show that the spontaneous contractile activities of the foregut, but not the hindgut, are inhibited by cAllatostatin neuropeptides. Leu-cAllatostatin 3 was the most potent of the range of Leu-and Met-cAllatostatins tested, with a dose-dependent response between 10-13 and 10-7 M. This is similar to the results obtained with the previously identified myoinhibitory peptide of L. maderae, leucomyosuppressin. However, this peptide, with a different type of structure to the Allatostatins, inhibits both foregut and hindgut motility equally. Experiments with a series of analogues of the Met-cAllatostatins showed that the free acid (as opposed to the carboxyamidated peptide) and N-terminally truncated peptides were inactive. These morphological and physiological results are thought to be representative of the, as yet unidentified, naturally occurring Allatostatin homologues of L. maderae. This family of peptides should be added to the increasing list of insect gut myoinhibitory substances.

  • allatostatic neuropeptides from the cockroach blattella germanica l dictyoptera blattellidae identification immunolocalization and activity
    Regulatory Peptides, 1994
    Co-Authors: Joseluis Maestro, Anders H Johnsen, Maria-dolors Piulachs, Hanne Duve
    Abstract:

    Four allatostatic neuropeptides were isolated from extracts of the brain of the cockroach Blattella germanica. The primary structures of these peptides were assigned as Leu-Tyr-Asp-Phe-Gly-Leu-NH2 (BLAST-1), Asp-Arg-Leu-Tyr-Ser-Phe-Gly-Leu-NH2 (BLAST-2), Ala-Gly-Ser-Asp-Gly-Arg-Leu-Tyr-Ser-Phe-Gly-Leu-NH2 (BLAST-3) and Ala-Pro-Ser-Ser-Ala-Gln-Arg-Leu-Tyr-Gly-Phe-Gly-Leu-NH2 (BLAST-4). Each of the peptides showed C-terminal amino acid sequence similarity to cockroach Allatostatins and blowfly cAllatostatins. The four peptides inhibited in vitro juvenile hormone production by corpora allata from virgin females of B. germanica. Immunoreactivity against Allatostatins was seen in the lateral neurosecretory neurons and in the axonal pathway leading to the corpora allata.

Stephen S Tobe - One of the best experts on this subject based on the ideXlab platform.

  • suppression of jh biosynthesis by jh analog treatment mechanism of suppression and roles of Allatostatins and nervous connections in the cockroach diploptera punctata
    Journal of Insect Physiology, 2009
    Co-Authors: Lisa E Lenkic, Shirley H K Tiu, Stephen S Tobe
    Abstract:

    Juvenile hormone analogs are known to inhibit the production of juvenile hormone (JH) by the corpora allata (CA). However, the mechanism of this inhibition remains undefined. We have used two JH mimics, fenoxycarb and pyriproxyfen, to examine the mechanism of suppression in the cockroach, Diploptera punctata. Denervation experiments demonstrated the importance of nervous connections between the brain and CA for the inhibition of JH biosynthesis by fenoxycarb. Fenoxycarb treatment alters the sensitivity of CA to Allatostatin treatment in vitro. Suppression of JH biosynthesis by fenoxycarb following denervation of the CA showed that innervation was in part responsible for the inhibition. Similarly, maximal inhibition by Dippu-AST7 requires intact nervous connections between the brain and CA, particularly during rapid vitellogenesis. qPCR analysis of brain, CA, ovary and midgut extracts revealed that both Allatostatin and its receptor Dippu-ASTR2 show increased levels of expression following topical fenoxycarb treatment, particularly in brain tissue on days 4 and 5 of the first gonadotrophic cycle and in CA on day 4. The correlation between inhibition of JH biosynthesis and increased expression of AST and ASTR2 in brains and CA, together with increased sensitivity of CA to Allatostatin in vitro, suggests that Allatostatin may be one of the effectors by which fenoxycarb inhibits JH biosynthesis.

  • isolation of cockroach phe gly leu amide Allatostatins from the termite reticulitermes flavipes and their effect on juvenile hormone synthesis
    Journal of Insect Physiology, 2008
    Co-Authors: Koichiro J Yagi, Stephen S Tobe, Karen L Elliott, Lynn M Teesch, Barbara Stay
    Abstract:

    Immunoreactivity to cockroach Diploptera punctata Allatostatin-7 (Dippu AST-7) has been demonstrated previously in axons innervating the corpora allata of the termite Reticulitermes flavipes. This peptide and Dippu AST-11 inhibited juvenile hormone (JH) synthesis by corpora allata (CA) of brachypterous neotenic reproductives (secondary reproductives) of termites. The present study shows that R. flavipes CA are also inhibited by Dippu AST-2, AST-5, AST-8, and AST-9 at approximately the same rank order of potency as demonstrated in D. punctata. Another Allatostatin from Periplaneta americana (Peram AST-12) also inhibits JH synthesis by R. flavipes CA. Sensitivity to the Allatostatins is higher in glands with low rates of JH synthesis than in those with relatively high JH synthetic rates as has been demonstrated in CA from male and female secondary reproductives as well as in those from non-egg-laying and egg-laying females. The identical inhibitory effects of R. flavipes brain extract on CA from both D. punctata and R. flavipes and the isolation and identification of five cockroach Allatostatins (Dippu AST-1, AST-2, AST-5, AST-8, and Peram AST-12) from termite brain extract reflect the close relationship between cockroaches and termites.

  • phe gly leu amide Allatostatin in the termite reticulitermes flavipes content in brain and corpus allatum and effect on juvenile hormone synthesis
    Journal of Insect Physiology, 2005
    Co-Authors: Koichiro J Yagi, Rodney Kwok, Stephen S Tobe, K K Chan, R R Setter, Timothy G Myles, Barbara Stay
    Abstract:

    In the subterranean termite Reticulitermes flavipes, Allatostatins (ASTs) with the C-terminus Phe-Gly Leu-amide were localized by immunocytochemistry with antibody against a cockroach AST, Dippu AST-7. AST-immunoreactivity occurred in the corpus cardiacum and corpus allatum and in the lateral and medial neurosecretory cells of the brain that innervate these organs as well as in many other nerve cells of the brain. This was observed in workers, nymphs, soldiers and secondary reproductives. A radioimmunoassay, using anti-Dippu AST-11, demonstrated about 40 fmole equivalents of AST in brains of soldiers and secondary reproductives. The product of the corpora allata in this species was determined to be juvenile hormone III. Its synthesis by corpora allata of secondary reproductives, determined by in vitro radiochemical assay, was inhibited in a dose-dependent fashion by two cockroach Allatostatins, Dippu AST-7 and Dippu AST-11. Thus, as in cockroaches and crickets, Allatostatin-containing nerves innervate the corpora allata of this termite species and their production of juvenile hormone is inhibited by these neuropeptides.

  • biological activities of the Allatostatin family of peptides in the cockroach diploptera punctata and potential interactions with receptors
    Journal of Insect Physiology, 2000
    Co-Authors: Stephen S Tobe, B C Donly, J R Zhang, Paul R F Bowser, William G Bendena
    Abstract:

    Abstract Allatostatins are a family of peptides that inhibit the production of juvenile hormone in the cockroach, Diploptera punctata. It is likely that the Allatostatin prohormone precursor is processed to give rise to all 13 members of the family simultaneously. All members of the family show potency and efficacy, in terms of their ability to inhibit juvenile hormone production, albeit with dramatically different IC50 and ED50 values, ranging from a maximum of 0.014 nM for Dippu-AST 2 to 107 nM for Dippu-AST 1 (ED50). The likely occurrence of all 13 peptides in tissues and in haemolymph suggests that they may act in concert to produce physiological effects. We have employed combinations of the Allatostatins, including a cocktail of all 13, 12 (minus Dippu-AST 2) and 11 (minus Dippu-AST 2 and 5) as well as mixtures of high and low activity Allatostatins (Dippu-AST 5 plus either Dippu-AST 1 or 13) in dose–response studies to examine the possibility of synergistic or additive effects of the peptides on biological activity. None of the peptide combinations yielded evidence of synergistic interactions between Allatostatins. However, the data do provide insight into receptor–ligand interactions in cockroaches and suggest the Allatostatins regulate JH biosynthesis through a complex mix of differing affinity interactions with receptors in the corpora allata.

  • identification and partial characterization of receptors for Allatostatins in brain and corpora allata of the cockroach diploptera punctata using a binding assay and photoaffinity labeling
    Regulatory Peptides, 1995
    Co-Authors: Timothy K Hayes, Allison Strey, W G Bendena, Stephen S Tobe
    Abstract:

    Abstract We have developed both an in vitro binding assay and a photoaffinity labeling assay to demonstrate and partially characterize putative receptors for Allatostatins in brain and in corpora allata of Diploptera punctata . Isolated brain membranes were photoaffinity labeled with 125 I-RYBPA (photoaffinity analogue of dip-Allatostatin 5). Following labeling with 125 I-RYBPA, SDS-PAGE and autoradiography revealed the presence of a putative receptor (37 kDa) for dip-Allatostatin 5 and dip-Allatostatin 7. Specific labeling was demonstrated by dose-dependent competition with either dip-Allatostatin 5 or dip-Allatostatin 7. The in vitro binding assay indicated that the receptor for dip-Allatostatin 5 had a K d of (9.0 ± 0.9)·10 −10 M and B max of 2.2 ± 0.3 pmol/mg membrane protein. For dip-Allatostatin 7, two K d values of (1.5 ± 0.1)·10 −9 M and (3.8 ± 0.3)·10 −9 M were obtained, with B max values of 7.2 ± 0.7 pmol/mg membrane protein and 11.4 ± 1.0 pmol/mg membrane protein respectively. This indicates that there were probably two putative receptor sites for dip-Allatostatin 7 although only one band was observable following photoaffinity labeling. Binding was saturable, specific and reversible. Using the in vitro binding assay, the K d of the putative receptor in CA for dip-Allatostatin 7 was shown to be (7.2 ± 0.9)·10 −10 M.

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  • stick insect carausius morosus phasmatodea lonchodidae brain extract contains multiple fractions with allatostatic activity
    European Journal of Entomology, 2013
    Co-Authors: Gerd Gade, Matthias W. Lorenz, Klaus H Hoffmann
    Abstract:

    A first attempt to purify inhibitors of juvenile hormone biosynthesis from extracts of brains of the Indian stick insect, Carausius morosus, is reported here. A heterologous bioassay in the cricket, Gryllus bimaculatus, was used throughout the study. Separation of a prepurified extract using C-18 reversed-phase high performance liquid chromatography (RP-HPLC) resulted in a broad zone with biological activity. Upon re-chromatography of each of six active regions on a wide-pore C-18 column, the material separated in distinct peaks of biologically active fractions. Introducing a third purification step (C-8 column) resulted in a total of 18 absorbance peaks with allatostatic activity. It remains to be seen whether all these fractions contain authentic Allatostatins which are active in stick insects, or whether other functions can be attributed to them.

  • Factors regulating juvenile hormone and ecdysteroid biosynthesis in Gryllus bimaculatus (Ensifera: Gryllidae)
    European Journal of Entomology, 2013
    Co-Authors: Judith I. Lorenz, Matthias W. Lorenz, Klaus H Hoffmann
    Abstract:

    A family of neuropeptides (B-Allatostatins) from the cricket, Gryllus bimaculatus, which had been purified on the basis of their ability to inhibit juvenile hormone III biosynthesis by cricket corpora allata and which showed high sequence homology with a class of myo-inhibiting peptides from locusts and butterflies, also effectively inhibit ovarian ecdysteroid biosynthesis, thus acting as ecdysiostatins. Within a 3 h in vitro incubation, ecdysteroid production was inhibited between 45 and 50% at 10-7-10-9 M Grb-AST B1 and B2, respectively. Grb-AST B3 and B4 were less effective in inhibiting ecdysteroid biosynthesis (inhibition up to 30%). Additional ecdysiostatic and allatostatic factors occurred in testes from 2-4 day-old adult males. Solid phase fractionation on C18 SEP-PAK cartridges indicated the existence of several polar and non-polar substances with ecdysiostatic activity. Further purification of one of these fractions by means of reversed phase high performance liquid chromatography indicated that some of these factors are probably small peptides, and that at least one of these factors also inhibits juvenile hormone biosynthesis.

  • immunolocalization of two types of Allatostatins in the central nervous system of the cricket gryllus bimaculatus ensifera gryllidae
    European Journal of Entomology, 2013
    Co-Authors: Gunther Witek, Matthias W. Lorenz, Peter Verhaert, Klaus H Hoffmann
    Abstract:

    Two anti-peptide antisera (anti-A and anti-B) raised against Gryllus bimaculatus Allatostatin A1 (Grb-AST A1) and B1 (Grb-AST B1), respectively, were applied in the peroxidase-antiperoxidase (PAP) immunohistochemical technique on complete series of sections from the brain, suboesophageal ganglion, corpora cardiaca (CC), and corpora allata (CA) of G. bimaculatus. Both antisera yielded intense staining of numerous cells and nerve fibres. Serial sections, alternately stained with anti-A and anti-B confirmed that the anti-B generally stained more cells and nerves. Extensive immunoreactivity in the retrocerebral complex suggests that the CC and CA may represent a storage and/or release site for both Allatostatin types or Allatostatin-like molecules produced in the brain.

  • neuropeptide regulators of the juvenile hormone biosynthesis in vitro in the beetle tenebrio molitor coleoptera tenebrionidae
    Archives of Insect Biochemistry and Physiology, 2010
    Co-Authors: Mohatmed Abdellatief, Klaus H Hoffmann
    Abstract:

    The genome of Tribolium castaneum encodes two Allatostatin [AS type B; W(X)6Wamide and AS type C; PISCF-OH] and one allatotropin (AT) precursor, but no AS type A (FGLamide) (Tribolium Genome Sequencing Consortium, 2008: Nature 452:949–955). Here we studied the activity (in vitro) of peptides derived from these precursors on the synthesis/release of juvenile hormone (JH) III. The corpora cardiaca-corpora allata (CC-CA) complexes of adult females of another tenebrionid beetle, the mealworm Tenebrio molitor, were used. Incubating the gland complexes in a medium containing Trica-AS B3 peptide, we showed that the peptide has allatostatic function in T. molitor. The activity of the type C AS depended on the age of the test animals and their intrinsic rate of JH III biosynthesis. The Trica-AS C peptide inhibited the JH release from CA of 3-day-old females with a high intrinsic rate of JH synthesis, but activated JH release from the CA of 7-day-old females with a lower intrinsic rate of JH production. The allatotropin peptide (Trica-AT) also activated the JH release from the CA of 7-day-old females in a dose-dependent and reversible manner. Unexpectedly, a type A AS derived from the precursor of the American cockroach Periplaneta americana (Peram-AS A2b) inhibited the JH release from the CA of younger and older females in the concentration range of 10−8 to 10−4 M, and the effects were fully reversible in the absence of peptide. These data suggest a complex role of allatoactive neuropeptides in the regulation of JH III biosynthesis in beetles. © 2010 Wiley Periodicals, Inc.

  • rna interference with the allatoregulating neuropeptide genes from the fall armyworm spodoptera frugiperda and its effects on the jh titer in the hemolymph
    Journal of Insect Physiology, 2008
    Co-Authors: Manuela Griebler, Stephanie A Westerlund, Klaus H Hoffmann, Martina Meyeringvos
    Abstract:

    The juvenile hormone (JH) titer was measured by liquid chromatography–mass spectrometry (LC–MS) with electrospray ionization (ESI). Three JH homologs, the JH I–III were detected in various amounts in larvae, prepupae and virgin adult females of Spodoptera frugiperda. In penultimate larvae, the JH II and III titers were relatively high, but decreased continuously during the 3 days of that stage, whereas JH I was detectable at low amounts only on the first 2 days. At the beginning of the last larval stage almost no JH could be detected but thereafter, a consistent low amount of JH III was present until the prepupal stage. In adult virgins, the JH titer peaked on the 2nd and 6th day after the imaginal molt. The measured hormone titers well agree with general lepidopteran physiology, because in larvae the JH titer should be high to prevent premature metamorphosis, but decrease in last instar larvae before pupation, whereas in adults JH returns to control various aspects of reproduction. JH biosynthesis is thought to be the main factor influencing the JH titer in the hemolymph and there is evidence that neuropeptides either act stimulatory (allatotropins) or inhibitory (Allatostatins) on this process. After silencing of either the Allatostatin AS-C-type (Spofr/Manse-AS) or the allatotropin AT 2 (Spofr-AT 2) gene the transcript level was reduced in brain and gut of last instar larvae as well as of adult S. frugiperda. This suppression led to an increased JH titer in larvae, suggesting an allatostatic activity of both the peptides in this stage. As a result of the elevated hormone titer, the last larval stage was prolonged. In prepupae, the JH titer was decreased, but the animals pupated and molted normally. In adult female virgin moths the effect on the JH titer was inversely dependent on the age of the moths and varied among the JH homologs, indicating that the peptides act either allatostatic or allatotropic. For both peptides, gene silencing clearly reduced the oviposition rates of adult females.