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PubMed1976

Radiobiochemistry of phytodrugs: I. role of juvenile hormones and analogs in the biosynthesis of proteins and RNA in drosophila larvae.

The present communication concerns the investigations of the effect of Juvenile Hormone (J.H.) and its analogs (J.H.A.), such as Altosid (R) and Altozar(R), used as insecticides, on the biosynthesis of proteins and RNA in subcellular preparations of drosophila larvae with Leucine-U-14C and Uridine-2-14C respectively. The incorporation of leucine into proteins decreases progressively from crude homogenate to the microsome-free fraction in the same way as the degradation of the compounds. During RNA biosynthesis the incorporation of uridine increases from the crude homogenate up to mithocondria-free fraction and with Altosid is always below the test controls. The reduced incorporation of uridine into RNA and leucine into proteins in the presence of Altosid and Altozar indicates a genetic action of this compounds comparable to that of natural J.H. but slightly more efficient.

Animals↗

PubMed1992

Nucleotide sequence of cDNA for the eclosion hormone of the silkworm, Bombyx mori, and the expression in a brain.

The cDNAs encoding eclosion hormone (EH) of the silkworm, Bombyx mori, were isolated and sequenced. The results showed that the pre-EH molecule contains a 26-amino acid signal peptide and a 62-amino acid mature EH. The deduced amino acid sequence agreed with that previously determined by the peptide analysis. The presence of leucine residue at the carboxyl terminal of EH, which had not been detected directly by the peptide analysis, was proved. Primer extension and Northern hybridization analyses revealed that 0.9 kb mRNA is transcribed and it has a 66-nucleotide non-translated sequence at the 5'-end region. In situ hybridization showed that the EH gene is expressed in two pairs of nuerosecretory cells in the brain of 5th instar larva.

Amino Acid Sequence↗

PubMed1986

The release of the prothoracicotropic hormone in the tobacco hornworm, Manduca sexta, is controlled intrinsically by juvenile hormone.

Pupal development is elicited early in the last larval instar of the tobacco hornworm, Manduca sexta (Johannson), by a precise temporal and quantitative increase in the haemolymph titre of 20-hydroxyecdysone. This increase in the titre is referred to as the pupal commitment peak, and it occurs once the titre of juvenile hormone (JH) has dropped. If the haemolymph titre of JH remains elevated at this time due to topical application of the hormone or of its analogue ZR512, commitment is delayed or inhibited in a dose-dependent manner. This delay or inhibition is due to the curtailment of the commitment peak in the ecdysteroid titre, which results from a failure of the prothoracic glands (PG) to increase the synthesis/secretion of the premoulting hormone, ecdysone. Since the PG from ZR512- and JH 1-treated larvae are capable of being activated in vitro by the prothoracicotropic hormone (PTTH), the effect of JH on the PG does not involve suppression of gland sensitivity to PTTH. The locus of the JH effect was determined to be the brain-retrocerebral complexes (Br-CC-CA), on the basis of experiments which tested the effect of implanted Br-CC-CA from pre-commitment larvae treated with JH on the occurrence of pupal commitment in head-ligated larval hosts. The implanted, JH-treated Br-CC-CA exhibited a delayed release of PTTH, and the effect was at concentrations of JH that were physiological. These results argue that JH functions to control the time during the last larval instar when pupal commitment occurs by dictating when PTTH will undergo gated release.

Animals↗

PubMed1986

Hormonal control of fat-body glycogen mobilization for locust flight.

Fat-body phosphorylase in locusts injected with adipokinetic hormone (AKH I) is highly activated, as revealed by the relative proportions of the three forms present. Activation of phosphorylase during flight is strongly reduced when locusts are ligated at the neck, indicating that this activation is due to a factor from the head, which upon flight is released into the hemolymph. Flight-induced activation of phosphorylase is prevented when the release of AKH from the corpus cardiacum is blocked by the presence of high trehalose levels in the hemolymph, and also when the production of AKH is made impossible by prior removal of the corpus cardiacum glandular lobe. These results are discussed in relation to the possible involvement of AKH in the control of fat-body phosphorylase activity during flight.

Adipose Tissue↗

PubMed1986

Effect of adipokinetic hormone on the structure and properties of lipophorin in locusts.

The reversible association of a low molecular weight hemolymph protein (mol wt 20,000 estimated by SDS-polyacrylamide gel electrophoresis) with lipophorin, following treatment with adipokinetic hormone (AKH), was demonstrated by density gradient ultracentrifugation and by specific precipitation of lipophorin from the hemolymph of resting and AKH-injected locusts. The injection of AKH also stimulated the loading of diacylglycerol from fat body by lipophorin and resulted in a lower density lipophorin ("activated lipophorin"). The activated lipophorin particles (diameter 21.7 +/- 3.0 nm, 15.8 to 33.6 nm) were larger and more heterogeneous in size than those of resting lipophorin (14.5 +/- 1.6 nm, 11.9 to 19.2 nm). A theoretical analysis based on the experimental data (e.g., density gradient profile, electron microscopic observation, and diacylglycerol content) suggests that very large lipophorin particles result from intermolecular fusion of the lipophorin molecules that are activated by AKH. Attempts to demonstrate the effect of AKH on the structure of lipophorin, in vitro, were unsuccessful.

Animals↗

PubMed1996

Protein phosphatase activity is required for prothoracicotropic hormone-stimulated ecdysteroidogenesis in the prothoracic glands of the tobacco hornworm, Manduca sexta.

The multiple phosphorylation of ribosomal protein S6 appears to be required for prothoracicotropic hormone (PTTH)-stimulated protein synthesis and ecdysteroidogenesis by the prothoracic glands of Manduca sexta. The present study investigated the role of protein phosphatase in these phenomena by analyzing the effects of pretreatment of prothoracic glands with the phosphatase inhibitors okadaic acid and calyculin A in both basal and PTTH-stimulated glands. Okadaic acid or calyculin A treatment enhanced ribosomal S6 phosphorylation in control glands to a level similar to that observed with PTTH-stimulated glands. This treatment also prevented S6 dephosphorylation but had no apparent synergistic effect on S6 phosphorylation in PTTH-stimulated glands. Most importantly, okadaic acid or calyculin A treatment inhibited, rather than augmented, ecdysteroidogenesis in both PTTH-stimulated and non-stimulated glands. The composite data suggest that protein phosphatase activity sensitive to okadaic acid or calyculin A is required for PTTH-stimulated ecdysteroidogenesis.

Animals↗

PubMed2004

Drosophila dFOXO controls lifespan and regulates insulin signalling in brain and fat body.

In Drosophila melanogaster, ageing is slowed when insulin-like signalling is reduced: life expectancy is extended by more than 50% when the insulin-like receptor (InR) or its receptor substrate (chico) are mutated, or when insulin-producing cells are ablated. But we have yet to resolve when insulin affects ageing, or whether insulin signals regulate ageing directly or indirectly through secondary hormones. Caenorhabditis elegans lifespan is also extended when insulin signalling is inhibited in certain tissues, or when repressed in adult worms, and this requires the forkhead transcription factor (FOXO) encoded by daf-16 (ref. 6). The D. melanogaster insulin-like receptor mediates phosphorylation of dFOXO, the equivalent of nematode daf-16 and mammalian FOXO3a. We demonstrate here that dFOXO regulates D. melanogaster ageing when activated in the adult pericerebral fat body. We further show that this limited activation of dFOXO reduces expression of the Drosophila insulin-like peptide dilp-2 synthesized in neurons, and represses endogenous insulin-dependent signalling in peripheral fat body. These findings suggest that autonomous and non-autonomous roles of insulin signalling combine to control ageing.

Aging↗

PubMed1992

Structure and expression of bombyxin-related peptide genes of the moth Samia cynthia ricini.

From the genomic DNA of the moth Samia cynthia ricini, we cloned and characterized six clustered genes that encode precursor molecules for peptides structurally related to bombyxin, a Bombyx mori brain secretory peptide that is structurally like insulin and functionally like the prothoracicotropic hormone. The precursor molecules deduced from these genes have the domain organization of signal peptide/B-chain/C-peptide/A-chain, as in preprobombyxins and preproinsulins. The Samia bombyxin-related peptide (SBRP) genes are classified into families A and B according to their sequence homology. Two genes belonging to different families are arranged close to each other to form a pair with opposite transcriptional orientations (A-1/B-1, A-2/B-2, and A-3/B-3). None of these genes have introns, and gene B-3 has an in-frame stop codon representing a pseudogene. Four genes, A-1, A-3, B-1, and B-2, are expressed in Samia brain. Genomic Southern hybridization suggests that the Samia genome contains many other SBRP genes.

Amino Acid Sequence↗

PubMed1994

The prothoracicotropic hormone (PTTH) of the commercial silkmoth, Bombyx mori, in the CNS of the tobacco hornworm, Manduca sexta.

Immunocytochemistry revealed that a Bombyx mori prothoracicotropic hormone (PTTH)-like peptide is expressed by the Manduca sexta big PTTH-producing neurons, the lateral neurosecretory cell group III (L-NSC III). Independent PCR of genomic DNA and a L-NSC III cDNA library yielded products with 99% sequence similarity to the cDNA encoding Bombyx PTTH. This similarity necessitated evaluation of the relationship between Manduca big PTTH and Bombyx PTTH by 1) bioassay of IEF separated Manduca PTTH and 2) direct assessment of Bombyx PTTH biological activity with Manduca prothoracic glands. Together, these studies indicate that Bombyx PTTH and Manduca PTTH are different peptides expressed by the L-NSC III. The possible physiological significance of a Bombyx PTTH-like peptide in Manduca and its coexpression with Manduca big PTTH by the L-NSC III are discussed.

Animals↗

PubMed2002

Control of phospholipase A(2) activity in cockroach (Periplaneta americana) fat body trophocytes by hypertrehalosemic hormone: the role of calcium.

Recently, synthetic HTH-I and HTH-II have been shown to increase the formation of free fatty acids in cockroach (Periplaneta americana) fat body. In this study we show that HTH-II increases PLA(2) activity in dispersed trophocytes, thus implying that phospholipid is a potential source of the fatty acids. The increase in HTH-induced PLA(2) activity is triggered by an increase in [Ca(2+)](i) but extracellular Ca(2+) is also required for a maximal Ca(2+) signal: an effect that can be blocked by the introduction of BAPTA into the trophocytes. Treating trophocytes with ryanodine blocks the increase in PLA(2) activity that follows treatment of the cells with HTH-II. This indicates that the Ca(2+) release channels are distinct from those that respond to inositol trisphosphate. Thapsigargin, which releases Ca(2+) to the cytosol from an intracellular store, increases PLA(2) activity. The data show that the enzyme is translocated from the cytosol to the plasma membrane.

Acetophenones↗

PubMed1988

Neuropeptide-degrading endopeptidase activity of locust (Schistocerca gregaria) synaptic membranes.

Locust adipokinetic hormone (AKH, pGlu-Leu-Asn-Phe-Thr-Pro-Asn-Trp-Gly-Thr-NH2) was used as the substrate to measure neuropeptide-degrading endopeptidase activity in neutral membranes from ganglia of the locust Schistocerca gregaria. Initial hydrolysis of AKH at neural pH by peptidases of washed neural membranes generated pGlu-Leu-Asn and Phe-Thr-Pro-Asn-Trp-Gly-Thr-NH2 as primary metabolites, demonstrating that degradation was initiated by cleavage of the Asn-Phe bond. Amastatin protected the C-terminal fragment from further metabolism by aminopeptidase activity without inhibiting AKH degradation. The same fragments were generated on incubation of AKH with purified pig kidney endopeptidase 24.11, and enzyme known to cleave peptide bonds that involve the amino group of hydrophobic amino acids. Phosphoramidon (10 microM), a selective inhibitor of mammalian endopeptidase 24.11, partially inhibited the endopeptidase activity of locust neural membranes. This phosphoramidon-sensitive activity was shown to enriched in a synaptic membrane preparation with around 80% of the activity being inhibited by 10 microM-phosphoramidon (IC50 = 0.2 microM). The synaptic endopeptidase was also inhibited by 1 mM-EDTA, 1 mM-1,10-phenanthroline and 1 microM-thiorphan, and the activity was maximal between pH 7.3 and 8.0. Localization of the phosphoramidon-sensitive enzyme in synaptic membranes is consistent with a physiological role for this endopeptidase in the metabolism of insect peptides at the synapse.

Amino Acids↗

PubMed1991

In vitro bioassay for the brain allatotropic hormone of Galleria mellonella (Lepidoptera).

An in vitro sensitive bioassay for the Galleria mellonella brain allatotropic hormone (ATTH) was developed. This assay measures the rate of juvenile hormone (JH) synthesis in corpora cardiacacorpora allata complex (CC-CA) stimulated in vitro by ATTH released from the brain during short-term in vitro incubation, or by ATTH extracted from the tissue with methanol. CC-CA of the late VIth instar (VI3) larvae were used for assessment of ATTH. The maximum activation of test CC-CA by ATTH occurred at a concentration of 2 brain equivalents (per 100 ul medium). The highest ATTH activity was exhibited by the brains of chilled VII1 larvae: ATTH extracted from freshly dissected brains, or ATTH released from these brains during 6 h in vitro incubation, activated JH synthesis in the CC-CA nearly five or four times, respectively. The brain of VII1 hydroprenetreated larvae were ATTH inactive.

Animals↗

PubMed1989

Adipokinetic hormone gene sequence from Manduca sexta.

A gene sequence encoding the neuropeptide adipokinetic hormone (AKH) was isolated from a genomic library of the tobacco hornworm, Manduca sexta. 2.5 x 10(5) recombinant plaques were screened with a 29-mer oligonucleotide substituted with deoxyinosine at six ambiguous codon positions. One clone was obtained from which we deduced an intronless gene encoding the AKH precursor (prepro-AKH). From NH2 to COOH terminus, prepro-AKH consists of a signal peptide, a single AKH peptide block followed by a Gly-Lys-Arg processing site, and a 34-residue sequence that appears unrelated to known peptides. The cloned AKH gene sequence hybridized to one transcript from the adult corpus cardiacum/corpus allatum complex. The Manduca genome appears to contain one copy of the AKH gene. These studies are a basis for explaining synthesis of a representative from a widespread, physiologically important family of arthropod neuropeptides.

Amino Acid Sequence↗

PubMed1988

The EGPs: the eclosion hormone and cyclic GMP-regulated phosphoproteins. II. Regulation of appearance by the steroid hormone 20-hydroxyecdysone in Manduca sexta.

Two proteins (the EGPs) in the CNS of the tobacco hornworm Manduca sexta are phosphorylated by the action of the neuropeptide eclosion hormone (EH), which triggers ecdysis behavior (Morton and Truman, 1986, 1988). The onset of sensitivity to EH requires prior exposure to the steroid hormone 20-hydroxyecdysone (20-HE). A series of steroid removal and replacement experiments indicates that the EGPs are also regulated by 20-HE with a time course that is similar to that seen for the 20-HE regulation of behavioral sensitivity to EH. This suggests that the steroid regulation of EH sensitivity is due to the regulation of the EGPs. The appearance of the EGPs requires not only the presence of 20-HE, but also its subsequent removal. The appearance of the EGPs can be blocked in vivo and in vitro by maintaining artificially elevated levels of 20-HE, but only up to a particular time in development. The ending of this steroid-sensitive period occurs 4 hr before the normal appearance of the EGPs, consistent with the hypothesis that the EGPs are synthesized de novo in response to the removal of 20-HE.

Animals↗

PubMed1998

A hydrophobic peptide (VAP-peptide) of the silkworm, Bombyx mori: structure, expression and an enhancing function of diapause hormone activity.

We have recently identified a unique lipophilic peptide (VAP-peptide) with diapause egg inducing activity in the silkworm, Bombyx mori (Imai et al., 1996). The cloning and sequencing of cDNA encoding VAP-peptide have demonstrated that the deduced amino acid sequence consisted of 84 amino acid residues, from which the mature VAP-peptide of 68 amino acid residues was released by cleaving a signal sequence. Searches of the GenBank data base revealed no significant sequence similarity to other proteins including diapause hormone (DH). VAP-peptide gene was selectively expressed just before and at adult eclosion in the head and the thorax not in the abdomen. By a Western blot analysis, VAP-peptide was also localized in the head and the thorax of adults. The purified recombinant VAP-peptide could not induce diapause eggs even when injected at a high dose of 10 nmol/pupa. Whereas, injection of a mixture of VAP-peptide and DH clearly decreased a half-maximum dose (ED50 value) and a threshold dose (TD value) of DH, and these values decreased according to increasing molar ratios of VAP-peptide to DH. Thus, the VAP-peptide is concluded to be an endogenous protein acting as a potent enhancer of DH activity through interaction with DH.

Amino Acid Sequence↗

PubMed2002

A protein from the cabbage looper, Trichoplusia ni, regulated by a bacterial infection is homologous to 3-dehydroecdysone 3beta-reductase.

During the screening of immune-regulated genes from the cabbage looper, Trichoplusia ni, a 3-dehydroecdysone 3beta-reductase homologue (DERH) was cloned. In the course of development, 3-dehydroecdysone 3beta-reductase mediates the conversion of 3-dehydroecdysone (3dE) secreted from the prothoracic glands to ecdysone (E), which is subsequently converted to 20-hydroxyecdysone (20E), the major insect molting hormone. The cloned gene is upregulated in fat body during development and is strongly induced after the larva is challenged with bacteria. The gene codes for a 308 amino acid residue protein which shows 42.5% identity to Spodoptera littoralis 3-dehydroecdysone 3beta-reductase. Using the baculovirus expression system, the recombinant DERH was expressed. The purified protein mediates the reduction of 3-dehydromakisterone A to makisterone A, and requires NADPH as a cofactor. Western blots using an antiserum to T. ni DERH revealed the presence of the protein in larval hemolymph and integument. The data indicate that the protein is regulated developmentally and is induced after a challenge with bacteria. Immunohistochemical studies localized the enzyme exclusively in the epidermis and the cuticle.

3-Hydroxysteroid Dehydrogenases↗

PubMed1990

The fruitfly Drosophila melanogaster contains a novel charged adipokinetic-hormone-family peptide.

A member of the RPCH/AKH (red-pigment-concentrating hormone/adipokinetic hormone) family of arthropod neuropeptides was identified in the fruitfly Drosophila melanogaster, and its structure was determined by automated Edman degradation and m.s. using fast-atom-bombardment ionization and a tandem hybrid instrument capable of high sensitivity. The sequence of this peptide, which we call 'DAKH', is pGlu-Leu-Thr-Phe-Ser-Pro-Asp-Trp-NH2 (where pGlu is pyroglutamic acid and Trp-NH2 is tryptophan carboxyamide). H.p.l.c. analyses of extracts of the three body segments revealed that more than 80% of the peptide is contained in the thorax. Although DAKH is typical of family members in its general structure and distribution in the animal, it is unique in containing a residue which is charged under physiological conditions. The evolutionary significance of this change is considered.

Amino Acid Sequence↗

PubMed2000

Structure elucidation and biological activity of an unusual adipokinetic hormone from corpora cardiaca of the butterfly, Vanessa cardui.

A structurally unusual member of the adipokinetic hormone/red pigment-concentrating hormone peptide family was isolated from corpora cardiaca of the painted lady butterfly, Vanessa cardui. Its primary structure was assigned by Edman degradation and nano-electrospray-time-of-flight mass spectrometry as pQLTFTSSWGGK (Vac-AKH). Vac-AKH represents the first 11mer and the first nonamidated peptide in this family. The peptide shows significant adipokinetic activity in adult specimens of V. cardui. Injection of 10 pmol of synthetic Vac-AKH into 4-day-old decapitated males resulted in an approximately 150% increase of hemolymph lipids after 90 min. Half maximal adipokinetic activity was achieved with about 0. 1 pmol of Vac-AKH. During a 2-h incubation of corpora cardiaca/corpora allata complexes in medium containing 50 mM KCl, significant amounts of Vac-AKH were released from the glands.

Amino Acid Sequence↗