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PubMed1987

Isolation and primary structure of the eclosion hormone of the tobacco hornworm, Manduca sexta.

Eclosion hormone was isolated from trimmed pharate adult heads of Manduca sexta by an eight step purification procedure using a Heliothis virescens in vivo bioassay. The neuropeptide was active in second stadium M. sexta. The primary structure was determined by sequence analyses of the intact peptide and fragment peptides generated by lysyl endopeptidase, endoproteinase Glu-C, and proline-specific endopeptidase. The nature of the carboxyl terminus as a free acid was elucidated by analysis of amino acids from digestion of the intact peptide with lysyl endopeptidase, which liberated leucine, but no leucine amide. The complete primary structure of M. sexta closion hormone is H-Asn-Pro-Ala-Ile-Ala-Thr-Gly-Tyr-Asp-Pro-Met-Glu-Ile-Cys-Ile-Glu-Asn-Cy s-Ala- Gln-Cys-Lys-Lys-Met-Leu-Gly-Ala-Trp-Phe-Glu-Gly-Pro-Leu-Cys-Ala-Glu-Ser- Cys-Ile Lys-Phe-Lys-Gly-Lys-Leu-Ile-Pro-Glu-Cys-Glu-Asp-Phe-Ala-Ser-Ile-Ala-Pro- Phe-Leu-Asn-Lys-Leu-OH.

Amino Acid Sequence↗
PubMed2002

Identification of the cockroach neuropeptide Pea-CAH-II as a second adipokinetic hormone in the firebug Pyrrhocoris apterus.

A new member of the AKH/RPCH family was isolated from the corpora cardiaca of the firebug Pyrrhocoris apterus. It is the second adipokinetic peptide identified in this species. The peptide was characterized and its structure was deduced from the multiple MS(N) electrospray mass spectra as that of an octapeptide with the sequence pGlu-Leu-Thr-Phe-Thr-Pro-Asn-Trp-NH(2.) The peptide differs from the original P. apterus AKH (Pya-AKH) by one amino acid in position 3. Topical application and/or injection of the peptide induced lipid mobilization, but was inactive in mobilization of carbohydrates.

Animals↗
PubMed1986

Octopamine and cyclic AMP mediate release of adipokinetic hormone I and II from isolated locust neuroendocrine tissue.

Octopamine serves as a neurotransmitter in the glandular lobe of the locust corpus cardiacum where it regulates adipokinetic hormone (AKH) secretion from intrinsic neurosecretory cells. Two AKHs (AKH I and II) from the corpus cardiacum of Locusta have been sequenced and synthesized. We have now demonstrated that octopamine mediates release of both AKH I and II from Locusta corpora cardiaca in vitro. Octopamine, IBMX, and forskolin have previously been shown to elevate levels of cAMP in the glandular lobe. In this paper we demonstrate that IBMX and forskolin mediate secretion of AKH I and AKH II thus mimicking the effects of octopamine in this tissue. The cAMP analogs dibutyryl cAMP and 8-bromo cAMP also elicit release of AKH and a subthreshold concentration of IBMX potentiates the effects of octopamine. These observations demonstrate that cAMP participates in regulating AKH release and support the hypothesis that octopamine mediates hormone release at least in part via changes in intracellular levels of cAMP. The release of AKH I and AKH II is apparently regulated by similar mechanisms. The hyperlipemic activity of AKH II released into the perfusates following stimulation by octopamine and agents which elevate cAMP levels is significantly lower than that of AKH I. This differential response is probably due both to the reduced lipid-mobilizing effect of AKH II relative to AKH I, as well as to the release of greater amounts of AKH I.

Animals↗
PubMed1995

Isolation of two AKH-related peptides from cicadas.

Two peptides related to locust adipokinetic hormone and crustacean red pigment concentrating hormone were isolated by high performance liquid chromatography from the cicadas Cacama valavata and Diceroprocta semicincta. Both species have the same peptides. The structure of one of the peptides is pGlu-Val-Asn-Phe-Ser-Pro-Ser-Trp-Gly-Asn-amide. The mass spectrum, amino acid composition, and amino acid sequence of the other peptide suggest that it is almost identical to the first peptide. However, the exact nature of the difference between the two peptides could not be determined.

Amino Acid Sequence↗
PubMed1995

Characterization of a spectrophotometric assay for juvenile hormone esterase.

Two surrogate substrates, methyl 1-heptylthioacetothioate (HEPTAT) and methyl 1-hexylthioacetothioate (HEXTAT) were utilized to compare a new spectrophotometric assay with the standard radiochemical partition assay used to quantify juvenile hormone esterase (JHE) activity. The surrogate substrates were made with one common factor being a thiol ester moiety substituting for the ester moiety found in juvenile hormones (JHs) and a thioether replacing the 2,3-olefin of the JHs. As a result, nucleophilic attack by the serine residue of JHE at the carbonyl functional group results in a hydrolytic reaction and release of methanethiol. In the presence of Ellman's Reagent (DTNB) methanethiol will cleave the disulfide bond of DTNB resulting in a chromophore detectable at 405 nm. Methyl 1-hexylthioacetothioate and its oxygen ester analogue, methyl-1-hexylthioacetate, were compared for JHE activity. Statistical analysis of the slopes indicated a very small but significant difference between the hydrolytic rates for the thiol ester and oxygen ester. However, the data indicate that thiol esters can replace oxygen esters to quantify hydrolytic activity by the JHEs examined. Results gathered from different preparations of JHE including tissue culture media from a baculovirus expression system, affinity- and DEAE-purified enzyme, as well as insect hemolymph indicate an excellent correlation between the two assays. Isoelectric focusing of pure and crude JHE preparations resulted in coinciding peaks of hydrolytic activity when using the standard partition assay and the spectrophotometric assay, with no other peaks of activity found in the crude preparations with either substrate. Several esterase bands were found at different isoelectric points when gels were stained with alpha-naphthyl acetate.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetates↗
PubMed1996

Neuropeptide-stimulated cyclic guanosine monophosphate immunoreactivity in the neurosecretory terminals of a neurohemal organ.

The neuropeptide eclosion hormone acts on the nervous system of the tobacco hornworm, Manduca sexta, to increase cyclic guanosine monophosphate (cGMP) levels. In this study I describe the localization of some of the sites where these increases occur. Prior to pupal ecdysis, eclosion hormone stimulates an increase in cGMP in a network of fibers in the transverse nerve of each abdominal ganglion. Double-label experiments with propidium iodide suggest that the cGMP immunoreactivity is primarily localized in neurosecretory nerve endings. The time course of the increase in cGMP immunoreactivity and its requirement for lipid metabolism is similar to that of the cGMP increase measured by radioimmunoassay. The cGMP response in the transverse nerve is stage-specific, occurring prior to pupal ecdysis and not prior to larval or adult ecdysis.

Animals↗
PubMed1983

Regulation of glycogen phosphorylase activity in fat body of Locusta migratoria and Periplaneta americana.

Saline extracts of the corpus cardiacum (CC) of Locusta migratoria activate glycogen phosphorylase in locust fat body. The response of phosphorylase to CC extracts and to synthetic adipokinetic hormone (AKH) suggests that the factor responsible for the activating effect of the CC on phosphorylase is AKH, supplemented to a minor degree with Compound II. Octopamine does not influence fat body phosphorylase activity in locusts, however, it elicits a rapid short-term hyperlipemia. In cockroaches, Periplaneta americana, injection of octopamine results in a strong activation of fat body phosphorylase within 1 min. Cockroach CC extract exerts a more prolonged effect on phosphorylase activity than does octopamine.

Adipose Tissue↗
PubMed1988

Juvenile hormone inhibits the synthesis of major larval haemolymph proteins in rice moth, Corcyra cephalonica.

Larval haemolymph proteins (LHP), LHP49 and LHP46 are produced in the penultimate and last larval instars. Starvation during the early and mid stage of last instar development prevents the production of both LHPs. Decapitation in early and mid last instar stimulates LHP synthesis and their concentration in haemolymph increases, while ligation in last instar larvae blocks the production of LHPs. Application of exogenous JH lowers the synthesis of LHP49 and LHP46 in Corcyra. These observations suggests that LHP49 and LHP46 synthesis is activated during the periods when JH titres are either low or undetectable.

Animals↗
PubMed1993

Characterization of two major isoforms of juvenile hormone esterase from Trichoplusia ni (Lepidoptera).

The two major isoforms of juvenile hormone (JH) esterase isolated from Trichoplusia ni were fragmented by cyanogen bromide and trypsin digestion. The resulting CNBr or CNBr/trypsin fragments were characterized and compared biochemically by SDS-PAGE, isoelectric focusing, two-dimensional electrophoresis and HPLC. Similar and unique fragments were examined for sequence, antigenic determinants and carbohydrate moieties. The studies identified small regions of the proteins which possess either potentially different sequences or different post-translational modifications. The location of a glycosylated asparagine residue was determined, as well as a region containing an epitope probably composed of a linear sequence of residues. An N-terminal region was identified that contained charge variation between the two isoforms and the sequence was obtained for the only unique CNBr/trypsin fragment detected from that region. These are the first data on mapping of regions of charge variation, epitope location and glycosylation sites for this enzyme from any insect species.

Amino Acid Sequence↗
PubMed1997

Purification and characterization of the prothoracicotropic hormone of Drosophila melanogaster.

The prothoracicotropic hormone (PTTH) of Drosophila melanogaster is a modulator of ecdysteroid (molting hormone) synthesis and was isolated and characterized from extracts of whole larvae (approximately 4 x 10(5) larvae). The purification protocol included delipidation, salt-extraction, heat treatment, conventional column chromatography, and HPLC, and yielded about 50 microg of pure hormone. Biological activity was followed using a ring gland in vitro assay in which ecdysteroidogenesis by control ring glands as measured by radioimmunoassay was compared with ring gland incubations containing active fractions. The molecular weight of the purified PTTH was 45 kDa and N-terminal amino acid sequence analysis indicated that those analyzed sequences displayed no significant homology with known peptides or peptide hormones, including PTTH from the silkmoth, Bombyx mori. Western blot analysis indicated that the native form of Drosophila PTTH was a single 66-kDa polypeptide with N-linked carbohydrate chains and intrachain disulfide bonds. The purified 45-kDa peptide is the deglycosylated form, a result of glycosidase activity present during preparation of the PTTH extract. The deglycosylated form shows heterogeneity, presumably as a result of varying degrees of deglycosylation at the N terminus.

Animals↗
PubMed2006

Both prothoracicotropic hormone and an autocrine factor are involved in control of prothoracic gland ecdysteroidogenesis in Locusta migratoria and Schistocerca gregaria.

In Bombyx mori, ecdysteroidogenesis by the prothoracic glands (PGs) is controlled by both prothoracicotropic hormone (PTTH) and a factor secreted by the glands themselves. This factor, which is active both in vitro and in vivo, has been named 'autocrine factor' (AF). To find out whether or not this dual control also exists in other species, in particular in hemimetabolous ones, we applied similar methods as were used to discover AF in Bombyx to the locusts Locusta migratoria and Schistocerca gregaria. Our results unequivocally show that locust PGs also secrete an as yet unidentified autocrine factor. Possible roles of AF are discussed.

Animals↗
PubMed1996

Steroid control of muscle remodeling during metamorphosis in Manduca sexta.

During metamorphosis in the tobacco hornworm, Manduca sexta, the abdominal body-wall muscle DEO1 is remodeled to form the adult muscle DE5. The degeneration of muscle DEO1 involves the dismantling of its contractile apparatus followed by the degeneration of muscle nuclei. As some nuclei are degenerating, others begin to incorporate 5-bromodeoxyuridine (BrdU), indicating the onset of nuclear proliferation. This proliferation is initially most evident at the site where the motoneuron contacts the muscle remnant. The developmental events involved in muscle remodeling are under the control of the steroid hormones, the ecdysteroids. The loss of the contractile elements of the larval muscle requires the rise and fall of the prepupal peak of ecdysteroids, whereas the subsequent loss of muscle nuclei is influenced by the slight rise in ecdysteroids seen after pupal ecdysis. Incorporation of BrdU by muscle nuclei depends on both the adult peak of the ecdysteroids and contact with the motoneuron. Unilateral axotomy blocks proliferation within the rudiment, but it does not block its subsequent differentiation into a very thin muscle in the adult.

Animals↗
PubMed2002

Molecular characterization of a cDNA from the silk moth Bombyx mori encoding Manduca sexta allatotropin peptide.

Allatotropin is a 13-residue amidated neuropeptide isolated from pharate adult heads of the tobacco hornworm, Manduca sexta and strongly stimulates biosynthesis of juvenile hormones in adults, but not larval, lepidopteran corpora allata. From a Bombyx mori midgut cDNA library, a cDNA that encodes a 130-amino-acid polypeptide containing M. sexta allatotropin sequence was isolated. The B. mori allatotropin cDNA consists of 1196 nucleotides. The encoded allatotropin peptide is identical to that isolated from M. sexta and that predicted from Pseudaletia unipuncta, with 84% and 81% identity in the amino acid sequence of the allatotropin peptide precursor, respectively. M. sexta allatotropin is flanked by two different endoproteolytic cleavage sites within the precursor of the B. mori allatotropin peptide. Evidence from northern blotting of B. mori tissues showed that the allatotropin gene is expressed in the cells of midgut, head and integument with different transcription amount, but not in the fat body and silk gland. Midgut has also a number of allatotropin-immunoreactive cells and nerve fibers. These results will provide valuable information in understanding the AT gene of insects.

Amino Acid Sequence↗
PubMedDate not supplied

Adipokinetic hormone controls lipid metabolism in adults and carbohydrate metabolism in larvae of Manduca sexta.

The peptide hormone which controls activation of fat body glycogen phosphorylase in starving larvae of Manduca sexta was isolated from larval corpora cardiaca and sequenced by FAB tandem mass spectrometry. It was found to be identical with Manduca AKH. This, together with earlier observations, demonstrates that in M. sexta AKH controls glycogen phosphorylase activation in starving larvae while in adults it controls lipid mobilization during flight. Larval corpora cardiaca contain about 10 times less AKH than the corpora cardiaca of adults. The corpora cardiaca of M. sexta appear to contain only one AKH.

Animals↗
PubMed1989

A member of the steroid hormone receptor gene family is expressed in the 20-OH-ecdysone inducible puff 75B in Drosophila melanogaster.

Drosophila melanogaster DNA has been cloned which encompasses a major part of the 20-OH-ecdysone inducible puff 75B. One 20-OH-ecdysone responsive transcription unit was detected which is expressed into two transcripts which accumulate upon the incubation of salivary glands of 3rd instar larvae with 20-OH-ecdysone. This accumulation is correlated with the 20-OH-ecdysone induced activity of puff 75B. 75B cDNA analysis indicates that the activity of puff 75B leads to the synthesis of a protein which belongs to the steroid and thyroid hormone receptor superfamily. The highest similarity of the derived 75B protein sequence was found to the DNA and ligand binding domains of human retinoic acid receptor. A study of the tissue distribution in larvae revealed that 75B mRNA is present in most, if not all 20-OH-ecdysone target tissues. It is proposed that 75B protein is a DNA-binding protein playing a key role in mediating the regulation of the larval molt by 20-OH-ecdysone.

Amino Acid Sequence↗
PubMed1984

Single step purification of locust adipokinetic hormones I and II by reversed-phase high-performance liquid chromatography, and amino-acid composition of the hormone II.

Locust adipokinetic hormones I (AKH I) and II (AKH II) are separated by reversed-phase high-performance liquid chromatography using a mu-Bondapak phenyl column with a trifluoroacetic acid/acetonitrile gradient. The eluant was monitored at 210 nm and the hyperlipaemic activity was detected using a bioassay. The amino-acid composition of AKH II was determined after acid hydrolysis with HCl or methane-sulfonic acid. It contained the following amino-acid residues in almost equimolar amounts: Asp, Ser, Glu, Gly, Ala, Leu, Phe and Trp.

Amino Acids↗
PubMed1995

Regulation and consequences of cellular changes in the prothoracic glands of Manduca sexta during the last larval instar: a review.

The prothoracic glands of the tobacco hornworm, Manduca sexta, respond to prothoracicotropic hormone (PTTH) by a regulatory pathway involving cAMP, protein phosphorylation, protein synthesis, and enhanced secretion of ecdysteroids including ecdysone and 3-dehydroecdysone. Recent investigations have revealed that PTTH acts by this general mechanism throughout the fifth larval instar, i.e., during the transition from larva to pupa. However, the glands undergo developmental changes in size, steroidogenic capacity, and in elements of the signalling pathway associated with synthesis, degradation, and intracellular action of cAMP. The present review describes such changes, and their possible regulation and consequences, in the general context of endocrine events underlying larval-pupal metamorphosis during the fifth larval stage.

Animals↗
PubMed1997

Synthesis, radiolabeling and biological activity of peptide oostatic hormone and its analogues.

A series of Pro peptides containing the sequence of the oostatic hormone 3d and its shorter analogues 3a-3c differing in a number of the C-terminal Pro residues was prepared for a study of its effect on oogenesis in Sarcophaga bullata Parker (Diptera). Peptides 3a-3d were synthesized in solution by the fragment condensation of Boc-Tyr-Asp(OtBu)-Pro-Ala-Pro-OH (2f) with Pro oligopeptides H-(Pro)2-5-OtBu. The amino-terminal protected pentapeptide acid 2f was prepared by a stepwise procedure from TFA.H-Ala-Pro-OMe using Boc-Pro-OH, Z-Asp(OtBu)-OSu and Boc-Tyr-OSu. The H(Z)-(Pro)2-5-OtBu oligopeptides 1a-1h were synthesized from Z-Pro-OH and H-Pro-OtBu by a combination of stepwise procedure and fragment condensation. The 125I-labeled molecules of the octapeptide 3b and decapeptide 3d were used for radiotracer distribution studies. Evidence of content of the labeled peptide material in various parts of the insect body (ovaries, head, intestine) is presented. The time distribution of the labeled material in the insect organs was correlated with results of histological analysis of ovaries treated by nonlabeled peptides. The peptides assayed affected processes of egg development in 20-60% of ovarioles. The decapeptide 3d caused changes consisting in some resorbed egg chambers and normal appearance of vitellogenic eggs, whereas the octapeptide 3b caused abnormal yolk deposition and formation of big eggs with irregular yolk granules, proliferation of follicular epithelium in some egg chambers and about the same amount of resorbed egg chambers as decapeptide. These structural differences are complementary to the different values of organ radioactivities.

Animals↗