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1.
Acta Biol Hung ; 59(4): 385-402, 2008 Dec.
Article in English | MEDLINE | ID: mdl-19133496

ABSTRACT

The need for more environmentally sound strategies of plant protection has become a driving force in physiological entomology to combat insect pests more efficiently. Since neuropeptides regulate key biological processes, these "special agents" or their synthetic analogues, mimetics, agonists or antagonists may be useful tools. We examined brain-suboesophageal ganglia and corpora cardiaca-corpora allata complexes of the cabbage moth, Mamestra brassicae, in order to obtain clues about possible peptide candidates which may be appropriate for the biological control of this pest. With the aid of bioassays, reversed phase high performance liquid chromatography, and mass spectrometry, five neuropeptides were unequivocally identified and the presence of a further three were inferred solely by comparing mass spectra with known peptides. Only one neuropeptide with adipokinetic capability was identified in M. brassicae. Data from the established homologous bioassay indicated that the cabbage moths rely on a lipid-based metabolism which is aided by an adipokinetic hormone (viz. Manse-AKH) that had previously been isolated in many different lepidopterans. Other groups of neuropeptides identified in this study are: FLRFamides, corazonin, allatostatin and pheromonotropic peptide.


Subject(s)
Insect Proteins/metabolism , Moths/metabolism , Neuropeptides/metabolism , Amino Acid Sequence , Animals , Biological Assay , Carbohydrate Metabolism , Chromatography, High Pressure Liquid , Cockroaches , Female , Grasshoppers , Hemolymph/metabolism , Insect Hormones/genetics , Insect Hormones/isolation & purification , Insect Hormones/metabolism , Insect Proteins/genetics , Insect Proteins/isolation & purification , Lipid Metabolism , Male , Mass Spectrometry , Molecular Sequence Data , Moths/genetics , Neuropeptides/genetics , Neuropeptides/isolation & purification , Neurosecretory Systems/metabolism , Oligopeptides/genetics , Oligopeptides/isolation & purification , Oligopeptides/metabolism , Pyrrolidonecarboxylic Acid/analogs & derivatives , Pyrrolidonecarboxylic Acid/isolation & purification , Pyrrolidonecarboxylic Acid/metabolism
2.
Body Image ; 3(3): 275-87, 2006 Sep.
Article in English | MEDLINE | ID: mdl-18089230

ABSTRACT

Research on body image has primarily been conducted among Western women who highly value the thin ideal body size. There has been limited research that has examined body image attitudes among Fijian adolescent girls who are exposed to both traditional sociocultural pressures that promote a larger body size and Western pressures that promote slimness. Using in-depth semi-structured interviews, we examined the factors associated with body image attitudes and concerns among a sample of 16 indigenous Fijian and 16 European Australian adolescent girls aged between 13-18 years. An inductive analysis of girls' responses indicated that both groups of girls experienced body image concerns including body dissatisfaction, a preference for thinness and concerns associated with weight gain. These findings have implications for our understanding of the role of culture in shaping body image among girls and may prove useful in the development of future survey research that can be implemented among both Fijian and Western adolescents.

3.
Allergy ; 60(2): 200-5, 2005 Feb.
Article in English | MEDLINE | ID: mdl-15647041

ABSTRACT

BACKGROUND: Recent reports of fatal asthma cases associated with swarms of locusts affecting African countries have highlighted the importance of this insect in causing asthma morbidity and mortality. However, only limited information is available about the allergic health outcomes such as asthma and its determinants in exposed individuals. In this study, workers exposed to the African migratory locust Locusta migratoria were evaluated for allergic health outcomes as well as the nature of the offending allergens. METHODS: Ten scientists and technicians exposed to locusts in a laboratory were investigated for locust-related allergy using questionnaires and immunological tests. The presence of allergy was determined by quantification of specific IgE and IgG to L. migratoria using the UniCAP system and via skin-prick testing (SPT). The allergens were characterized by Western blot and ImmunoCAP inhibition assays. RESULTS: Six of the 10 workers experienced symptoms ranging from urticaria and rhinoconjuctivitis to asthma. Seven individuals demonstrated sensitivity on SPT and five had specific IgE antibodies to L. migratoria. Significant cross-reactivity was demonstrated for allergens in the locust faeces, body and wings but not to cockroach allergens. Novel allergens with molecular weights of approximately 70 kDa were identified in locust wings, which are distinctly different from other known allergen sources from locusts. CONCLUSION: Exposure to L. migratoria allergens is a potential sensitizer in exposed individuals. Raised levels of locust-specific IgE can be readily quantified. The wings of this insect species have been identified as a novel allergen source.


Subject(s)
Hypersensitivity/immunology , Locusta migratoria/immunology , Medical Laboratory Personnel , Occupational Diseases/immunology , Adult , Aged , Allergens/chemistry , Allergens/immunology , Animals , Asthma/immunology , Conjunctivitis/immunology , Cross Reactions , Female , Humans , Immunoglobulin E/analysis , Immunoglobulin G/analysis , Immunologic Techniques , Male , Middle Aged , Molecular Weight , Rhinitis/immunology , Skin Tests , South Africa , Urticaria/immunology , Wings, Animal/immunology
4.
Peptides ; 24(6): 845-51, 2003 Jun.
Article in English | MEDLINE | ID: mdl-12948836

ABSTRACT

A cDNA, encoding a crustacean hyperglycemic hormone (cHH) of the South African spiny lobster, Jasus lalandii has been cloned. The cDNA consists of 1773 bp with an open reading frame of 399 bp that encodes a preprohormone of 133 amino acid residues. The preprohormone consists of a 25 amino acid hydrophobic signal peptide, a 32 amino acid cHH precursor-related peptide (CPRP) and the cHH sequence of 72 amino acid residues. The cHH sequence is flanked N-terminally by a Lys-Arg cleavage site and C-terminally by Gly-Lys, where Gly serves as an amidation site. The deduced amino acid sequence of the CPRP is in complete agreement with a peptide previously elucidated from sinus glands of J. lalandii, code-named CPRP 2 and the sequence of the cHH peptide matches that of the minor cHH isoform of J. lalandii, i.e. crustacean hyperglycemic hormone-II (cHH-II), which was also previously obtained by peptide sequencing. In situ hybridization on eyestalks revealed strong cHH-II mRNA expression in a subset of neurosecretory cells of the X-organ.


Subject(s)
DNA, Complementary/genetics , Nerve Tissue Proteins/genetics , Palinuridae/genetics , Amino Acid Sequence , Animals , Arthropod Proteins , Base Sequence , Cloning, Molecular , DNA, Complementary/isolation & purification , Eye/metabolism , In Situ Hybridization , Invertebrate Hormones/chemistry , Invertebrate Hormones/genetics , Molecular Sequence Data , Nerve Tissue Proteins/chemistry , RNA, Messenger/genetics , RNA, Messenger/metabolism , Sequence Alignment , Sequence Homology, Amino Acid , South Africa
5.
Insect Biochem Mol Biol ; 32(1): 23-32, 2001 Dec.
Article in English | MEDLINE | ID: mdl-11719066

ABSTRACT

The role of calcium in the transduction of the hyperprolinaemic signal of the endogenous neuropeptide Mem-CC was investigated in the cetoniid beetle Pachnoda sinuata using in vivo and in vitro methods to measure changes in the concentration of proline and its precursor alanine. Extracellular calcium is necessary for maximal stimulation of proline synthesis at saturating doses of Mem-CC (0.3 nM) in vitro. This effect depends on the dose of Ca(2+): maximal proline synthesis of 2.1 micromol mg(-1) protein h(-1) was stimulated by Mem-CC at calcium levels of 0.5 mM, and the EC(50) was 0.16 mM. Using the ionophore A 23187 in vivo and in vitro, we demonstrated that the extracellular calcium acts, via an influx into the cell, on the stimulation of proline production and alanine consumption. The release of calcium from intracellular sources is part of the signalling process: the agent thapsigargin, which inhibits the Ca(2+)-ATPase, is able to stimulate proline synthesis in vivo and in vitro. Thimerosal, however, which triggers the release of calcium from IP3-sensitive stores in the endoplasmic reticulum, had no influence on proline production nor alanine consumption, indicating that inositolphosphates are not part of the transduction of the hyperprolinaemic signal of Mem-CC. Both substances, thapsigargin and thimerosal, stimulate calcium entry in vitro from the medium (similar to Mem-CC), which indicates that a capacitative calcium entry takes place. Neither the entry of extracellular calcium nor the release from the endoplasmic reticulum, however, are alone sufficient for a full stimulation of proline synthesis in vitro. The results of the present study suggest that calcium from extra- as well as from intracellular sources is part of the second messenger system for the transduction of the hyperprolinaemic signal of Mem-CC in the fat body of P. sinuata. Calcium acts most likely via the elevation of cAMP levels: the concentration of this cyclic nucleotide in the fat body during in vitro incubation was elevated by 487% by Mem-CC in the presence of calcium, while the increase was only 122% when calcium was absent.


Subject(s)
Calcium/metabolism , Coleoptera/metabolism , Insect Hormones/metabolism , Neuropeptides/metabolism , Proline/biosynthesis , Animals , Calcium/physiology , Cyclic AMP/pharmacology , Cyclic GMP/pharmacology , Fat Body/metabolism , Insect Hormones/pharmacology , Intracellular Fluid/metabolism , Male , Neuropeptides/pharmacology , Octopamine/pharmacology , Pyrrolidonecarboxylic Acid/analogs & derivatives
6.
Biochim Biophys Acta ; 1499(3): 199-208, 2001 Jan 15.
Article in English | MEDLINE | ID: mdl-11341967

ABSTRACT

The role of calcium in the mediation of the hypertrehalosaemic signal of the endogenous neuropeptide Mem-CC was investigated in vitro and in vivo in the cetoniid beetle Pachnoda sinuata. The presence of Mem-CC increases the influx of extracellular 45Ca(2+) into the fat body as well as the efflux of 45Ca(2+) from pre-loaded fat body into the incubation medium. Extracellular calcium is essential to exert maximal activation of the fat body glycogen phosphorylase by saturating doses of Mem-CC (0.3 nM). This effect of extracellular Ca(2+) is dose-dependent: maximal activation of glycogen phosphorylase by Mem-CC is achieved at calcium concentrations of approximately 1.2 mM and the ED(50) was calculated to be 0.6 mM. Both, thimerosal and thapsigargin caused a stimulation of carbohydrate metabolism in the fat body, suggesting that a release of calcium from the endoplasmic reticulum is involved in this process. However, neither entry of extracellular calcium nor the release from the endoplasmic reticulum are sufficient alone for a full activation of the phosphorylase. The results of the present study suggest that calcium from extracellular as well as from intracellular sources is part of the second messenger system for the transduction of the hypertrehalosaemic signal of Mem-CC in the fat body of P. sinuata.


Subject(s)
Calcium/metabolism , Coleoptera/drug effects , Coleoptera/metabolism , Insect Hormones/pharmacology , Neuropeptides/pharmacology , Oligopeptides/pharmacology , Phosphorylases/metabolism , Animals , Calcium/pharmacology , Calcium Signaling , Endoplasmic Reticulum/drug effects , Endoplasmic Reticulum/metabolism , Enzyme Activation/drug effects , Fat Body/drug effects , Fat Body/metabolism , In Vitro Techniques , Male , Models, Biological , Nucleotides, Cyclic/pharmacology , Octopamine/pharmacology , Pyrrolidonecarboxylic Acid/analogs & derivatives , Second Messenger Systems , Signal Transduction
7.
Biochem Biophys Res Commun ; 282(4): 904-9, 2001 Apr 13.
Article in English | MEDLINE | ID: mdl-11352636

ABSTRACT

By using degenerate primers based on known mammalian somatostatin receptors and the recently identified Drosophila allatostatin receptors (AlstR), we have cloned a novel receptor for the neuropeptide, allatostatin, from the cockroach Periplaneta americana. The receptor exhibits about 60% amino acid identity in the transmembrane regions when compared to the two known AlstRs from Drosophila melanogaster. In addition, two cDNA fragments were obtained from the stick insect Carausius morosus, one of which is similar to Drosophila AlstR, whereas the other is more similar to mammalian somatostatin receptors. Functional expression in Xenopus oocytes shows that the Periplaneta-AlstR exhibits high affinity to endogenous cockroach allatostatin peptides. Studies with synthetic peptides demonstrate that agonistic activity is mediated by the conserved C-terminal pentapeptide YXFGL-amide; in this sequence, amidation of the C-terminus is obligatory to maintain affinity. Thus, our studies provide a molecular basis for understanding the widespread biological activities of the allatostatin peptides.


Subject(s)
Drosophila Proteins , Evolution, Molecular , Genes, Insect , Insect Proteins , Periplaneta/genetics , Receptors, Cell Surface/genetics , Receptors, Cell Surface/physiology , Receptors, G-Protein-Coupled , Receptors, Neuropeptide , Amino Acid Sequence , Animals , Cloning, Molecular , Drosophila melanogaster/genetics , Molecular Sequence Data , Neuropeptides/pharmacology , Oocytes/drug effects , Oocytes/metabolism , Phylogeny , Sequence Homology, Amino Acid , Xenopus
8.
J Comput Aided Mol Des ; 15(3): 259-70, 2001 Mar.
Article in English | MEDLINE | ID: mdl-11289079

ABSTRACT

Mem-CC (pGlu-Leu-Asn-Tyr-Ser-Pro-Asp-Trp-NH2), Tem-HrTH (pGlu-Leu-Asn-Phe-Ser-Pro-Asn-Trp-NH2) and Del-CC (pGlu-Leu-Asn-Phe-Ser-Pro-Asn-Trp-Gly-Asn-NH2) are adipokinetic hormones, isolated from the corpora cardiaca of different insect species. These hormones regulate energy metabolism during flight and so are intimately involved in an insect's mobility. Secondary structural elements of these peptides and the N7 analogue, [N7]-Mem-CC (pGlu-Leu-Asn-Tyr-Ser-Pro-Asn-Trp-NH2), have been determined in dimethylsulfoxide solution using NMR restrained molecular mechanic simulations. The neuropeptides were all found to have an extended structure for the first 4 residues and a beta-turn between residues 4-8. For Tem-HrTH and Del-CC, asparagine (N7) which is postulated to be involved in receptor binding and/or activation, projects outward form the beta-turn. Mem-CC does not have an asparagine at position 7 while, for [N7]-Mem-CC, the N7 sidechain folds inside the beta-turn preventing its interaction with the receptor.


Subject(s)
Insect Hormones/chemistry , Insect Proteins , Oligopeptides/chemistry , Amino Acid Sequence , Animals , Hydrogen Bonding , In Vitro Techniques , Insect Hormones/metabolism , Magnetic Resonance Spectroscopy , Models, Molecular , Oligopeptides/metabolism , Protein Conformation , Protein Structure, Secondary , Pyrrolidonecarboxylic Acid/analogs & derivatives , Receptors, Cell Surface/metabolism , Thermodynamics
9.
Life Sci ; 68(10): 1153-60, 2001 Jan 26.
Article in English | MEDLINE | ID: mdl-11228099

ABSTRACT

The neem toxin azadirachtin A exhibits selective toxicity on insects. Despite its well-proven efficacy, the mode of action of this toxin remains obscure. The toxicity on vertebrate cells compared to insect cells is also not well characterized. We have cultivated six human glioblastoma cell lines G-28, G-112, G-60 (TP53 mutant) and G-44, G-62, G-120 (TP53 wild-type) in the presence of 28 microM of azadirachtin. This toxin concentration was chosen because it represents the 25 to 50% lethal dose in the glioma cells. Toxicity was measured in terms of cell proliferation (binucleation index), formation of micronuclei and cell survival. In the TP53 mutant cell lines, azadirachtin reduced the proportion of dividing cells and induced formation of micronuclei. Except for G-44 which showed a decrease in binucleation index, proliferation in the TP53 wild-type cell lines was unaffected by azadirachtin. In the TP53 wild-type cell lines, the decrease in micronuclei frequency is attributed to fewer cells entering mitosis to produce micronuclei. This is also apparent from the low surviving fractions. Cell survival was suppressed by 25-69% in all cell lines. The reduction of cell survival is a clear indication that azadirachtin affects reproductive integrity and cell division. The induction of micronuclei reflects DNA damage. Similar studies on damage induction in insect cell lines could elucidate the processes which precede the antifeedant and antimoulting effects of azadirachtin and other neem toxins in insects.


Subject(s)
Glioblastoma/pathology , Insecticides/toxicity , Limonins , Triterpenes/toxicity , Cell Survival/drug effects , DNA Damage , Humans , Micronuclei, Chromosome-Defective/drug effects , Tumor Cells, Cultured
10.
J Insect Physiol ; 47(4-5): 311-24, 2001 Apr.
Article in English | MEDLINE | ID: mdl-11166295

ABSTRACT

In this brief overview we give the historical background on the discovery of myostimulatory neuropeptides in cockroaches. Related peptides were later found in other insect groups as well. We summarize the current knowledge on primary structures, localization, physiological and pharmacological effects of the different cockroach neuropeptides, including kinins, sulfakinins, pyrokinins, tachykinin-related peptides, periviscerokinins, corazonin, and proctolin. In addition, we briefly comment on the development of mimetic pseudopeptide analogs in the context of their possible use in insect pest management.

11.
Peptides ; 21(9): 1313-21, 2000 Sep.
Article in English | MEDLINE | ID: mdl-11072117

ABSTRACT

We have isolated a peptide from extracts of sinus glands from a South African spiny lobster species, Jasus lalandii, by high-performance liquid chromatography (HPLC) and identified it as a putative molt-inhibiting hormone (MIH) by (i) an in vitro assay with J. lalandii Y-organs to measure the inhibition of ecdysteroid synthesis and (ii) an immunoassay using antiserum raised against MIH of the edible crab. The MIH of J. lalandii has 74 amino acid residues, a molecular mass of 9006 Da, a free N-terminus and an amidated C-terminus. The full primary sequence has been obtained from sequencing various digest fragments (tryptic, endoproteinase Asp-N, cyanogen bromide) of the unreduced (native) peptide: RFTFDCPGMMGQRYLYEQVEQVCDDCYNLYREEKIAVNCRENCFLNSWFTVCLQATMREHETPRFDIWR SIILKA-NH(2). Structural comparisons with other peptides show that the J. lalandii MIH belongs to the peptide family which includes the crustacean hyperglycemic hormone, molt-inhibiting hormone and vitellogenesis-inhibiting hormone (cHH/MIH/VIH). This novel peptide has 36-43% sequence identity to putative MIHs from other decapod crustaceans and 32-34% identity to the two cHH peptides previously identified in this spiny lobster species. This is the first report of a peptide with MIH activity in the Palinuridae infraorder.


Subject(s)
Crustacea/physiology , Invertebrate Hormones/isolation & purification , Molting/physiology , Neuropeptides/isolation & purification , Amino Acid Sequence , Animals , Biological Assay , Cyanogen Bromide , Hyperglycemia/chemically induced , Invertebrate Hormones/pharmacology , Molecular Sequence Data , Neuropeptides/pharmacology , Peptide Fragments/isolation & purification , South Africa , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
12.
Radiology ; 217(2): 321-30, 2000 Nov.
Article in English | MEDLINE | ID: mdl-11058625

ABSTRACT

The communication between radiologists and their surgical colleagues is particularly important in the setting of back pain. This common disorder often does not have a definable cause, even when the imaging findings are abnormal. A shared understanding of the various causes of back pain, the appropriate terminology, and the needs of the surgeon is vital to proper patient treatment. Unfortunately, little standardization in the terminology for and management of back pain syndromes exists. This article elucidates the approaches to problems of back pain used in one clinical setting.


Subject(s)
Low Back Pain/diagnostic imaging , Low Back Pain/etiology , Magnetic Resonance Imaging , Tomography, X-Ray Computed , Humans , Intervertebral Disc Displacement/diagnostic imaging , Male , Sciatica/diagnostic imaging , Spinal Cord/diagnostic imaging , Spinal Cord/pathology , Spinal Stenosis/diagnostic imaging , Spine/diagnostic imaging , Spine/pathology , Terminology as Topic
13.
Acta Biol Hung ; 51(2-4): 369-77, 2000.
Article in English | MEDLINE | ID: mdl-11034162

ABSTRACT

The biological potencies of a number of naturally-occurring octa- and decapeptides of the large AKH/RPCH family of peptides were determined in Locusta migratoria using the lipid-mobilising assay in vivo and the acetate uptake assay in vitro. The most potent of the newly-tested peptides in the in vitro assay, Phl-CC, differs from the endogenous major locust peptide, Lom-AKH-I, only by an exchange of serine versus threonine at position 10. However, the most active peptide in the in vitro assay remains Lom-AKH-III. At the other extreme is the peptide Mem-CC which contains a tyrosine residue at position 4 rather than the more typical phenylalanine. This peptide is over 20,000 times less potent than Lom-AKH-III in the in vitro assay, and also results in an unusual dose-response curve in the in vivo assay. Only a few peptides are approximately equipotent in both assays, but mostly the bioanalogues have a higher potency in vitro. The majority of them are 2- to 10-fold more potent in vitro, but Ani-AKH and Lom-AKH-III are 19- and 48-fold more potent. The results are discussed in relation to either the actions of proteases or of possible preferential binding of different receptors involved in the different assays.


Subject(s)
Grasshoppers/drug effects , Insect Hormones/pharmacology , Oligopeptides/pharmacology , Acetic Acid/metabolism , Amino Acid Sequence , Animals , Biological Transport, Active/drug effects , Female , Grasshoppers/metabolism , In Vitro Techniques , Insect Hormones/chemistry , Lipid Metabolism , Oligopeptides/chemistry , Pyrrolidonecarboxylic Acid/analogs & derivatives
14.
Insect Biochem Mol Biol ; 30(11): 1061-7, 2000 Nov.
Article in English | MEDLINE | ID: mdl-10989293

ABSTRACT

The corpora cardiaca of the African pyrgomorphid grasshoppers Phymateus morbillosus and Dictyophorus spumans contain three adipokinetic hormones (AKHs): besides two already known AKHs, Phm-AKH-I and Scg-AKH-II (Gäde et al., 1996 [Gäde, G., Kellner, R., Rinehart, K.L., 1996. Pyrgomorphid grasshoppers of the genus Phymateus contain species-specific decapeptides of the AKH/RPCH family regulating lipid-mobilisation during flight. Physiol. Entomol. 21, 193-202]), a new AKH-III, denoted Phm-AKH-III, pGlu-Ile-Asn-Phe-Thr-Pro-Trp-Trp-NH(2), has been characterised. This is only the second AKH-III identified so far, thus, only three insect species - all of them grasshoppers - contain three active AKHs. Phm-AKH-III differs from Lom-AKH-III from the migratory locust, Locusta migratoria, only in position 2: isoleucine is present instead of leucine. The structure of the Phm-AKH-III was confirmed by synthesis, subsequent mass determination and reversed-phase high-performance liquid chromatography. The synthetic peptide also induced hyperlipaemia in D. spumans and L. migratoria.


Subject(s)
Grasshoppers/enzymology , Insect Hormones/metabolism , Lipid Metabolism , Locomotion/physiology , Oligopeptides/metabolism , Animals , Chromatography, High Pressure Liquid , Insect Hormones/chemical synthesis , Insect Hormones/isolation & purification , Oligopeptides/chemical synthesis , Oligopeptides/isolation & purification , Pyrrolidonecarboxylic Acid/analogs & derivatives
15.
J Insect Physiol ; 46(12): 1575-1584, 2000 Dec 01.
Article in English | MEDLINE | ID: mdl-10980303

ABSTRACT

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.

16.
Insect Biochem Mol Biol ; 30(8-9): 711-8, 2000.
Article in English | MEDLINE | ID: mdl-10876114

ABSTRACT

Eighteen peptides were isolated from brain extracts of the stick insect Carausius morosus. The peptides were purified in four steps by high-performance liquid chromatography, monitored by their ability to inhibit juvenile hormone biosynthesis by corpora allata of the cricket Gryllus bimaculatus in vitro, and chemically characterised by Edman degradation and mass spectrometry. We obtained complete primary-structure information for nine peptides, four of which belong to the peptide family characterised by a common C-terminal pentapeptide sequence -YXFGLamide. The remaining five belong to the W(2)W(9)amide peptide family, nonapeptides characterised by having the amino acid tryptophan in positions 2 and 9. The amino-acid sequence of two other peptides could not be completely resolved by means of Edman degradation; however, these peptides could be allocated to the -YXFGLamide and the W(2)W(9)amide family, respectively, by comparison of retention times, co-elution and mass spectrometry. Both classes of neuropeptides strongly inhibit juvenile hormone biosynthesis in crickets but show no inhibiting effect on the corpora allata of the stick insect.


Subject(s)
Cockroaches/metabolism , Gryllidae/metabolism , Hormone Antagonists/metabolism , Neuropeptides/metabolism , Peptides/metabolism , Animals , Biological Assay , Corpora Allata/metabolism , Hormone Antagonists/chemistry , Neuropeptides/chemistry , Peptides/chemistry , Sequence Analysis/methods , Sesquiterpenes/metabolism
17.
Insect Biochem Mol Biol ; 30(10): 899-907, 2000 Oct.
Article in English | MEDLINE | ID: mdl-10899456

ABSTRACT

The potencies of natural adipokinetic hormones and synthetic variants have been determined in Locusta migratoria using the lipid mobilisation assay in vivo, and/or the acetate uptake assay in vitro. These data are combinations of previously published and unpublished data (a total of sixty-nine analogues), and form data sets for the construction of mathematical models of the hormone potencies. The sequence variations of amino acids in both natural and artificial adipokinetic hormone analogues were described using continuous descriptor scales z(1)', z(2)', and z(3)', each previously published scale being derived from various properties of the amino acids. By means of these z'-scales and partial least squares regression we attempted to model the potencies in Locusta migratoria of adipokinetic hormones in the two assays. Correlations (r(2) values) between predicted and actual potencies of the different peptides were up to 0.73. We discuss the potential of the partial least squares method for formulating quantitative relationships between different hormone structures and their potencies, and describe how the procedure might be used in structure-activity prediction with the construction of an optimised peptide data set.


Subject(s)
Grasshoppers/chemistry , Insect Hormones/chemistry , Neuropeptides/chemistry , Oligopeptides/chemistry , Amino Acid Sequence , Animals , Models, Biological , Molecular Sequence Data , Pyrrolidonecarboxylic Acid/analogs & derivatives , Structure-Activity Relationship
18.
Peptides ; 21(1): 19-27, 2000 Jan.
Article in English | MEDLINE | ID: mdl-10704715

ABSTRACT

We have isolated a 72-amino acid peptide from extracts of sinus glands of the South African rock lobster, Jasus lalandii, and identified it, functionally and immunologically, as a hyperglycemic hormone. This is the second peptide with hyperglycemic activity found in this palinurid species and, because it occurs in smaller quantities (approximately 3 pmol/sinus gland) than the previously identified hyperglycemic hormone [14], this minor isoform is designated Jala cHH-II. The complete elucidation of the primary structure of cHH-II, as determined by automated Edman degradation of the N-terminus enzymatic digests of the non-reduced peptide, chemical cleavage and mass spectrometry, is presented here. Jala cHH-II (molecular mass of 8357 Da) is more hydrophobic than Jala cHH-I (8380 Da). The two cHHs have a free N-terminus a blocked C-terminus; and share 90% sequence homology. We also present structural data of a further two peptides isolated from sinus gland extracts that were immunopositive to cHH antisera. These peptides, with masses of 7665 and 7612 Da, structurally represent C-terminally truncated forms of the major and the minor Jala cHH peptides, respectively, but do not have any hyperglycemic activity in vivo. We demonstrate that the prevalence of these truncated forms can be reduced by the addition of proteases to the homogenization buffer during preparation of the tissues.


Subject(s)
Invertebrate Hormones/chemistry , Nephropidae/chemistry , Nerve Tissue Proteins/chemistry , Amino Acid Sequence , Animals , Arthropod Proteins , Chromatography, High Pressure Liquid , Enzyme-Linked Immunosorbent Assay , Invertebrate Hormones/genetics , Invertebrate Hormones/physiology , Molecular Sequence Data , Nephropidae/genetics , Nephropidae/physiology , Nerve Tissue Proteins/genetics , Nerve Tissue Proteins/physiology , Peptide Fragments/chemistry , Peptide Fragments/genetics , Sequence Homology, Amino Acid , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
19.
Biochim Biophys Acta ; 1495(1): 78-89, 2000 Jan 10.
Article in English | MEDLINE | ID: mdl-10634934

ABSTRACT

The role of cyclic nucleotides in the transduction of the hyperprolinaemic and hypertrehalosaemic signal of the endogenous neuropeptide Mem-CC was investigated in the cetoniid beetle Pachnoda sinuata. Flight and injection of Mem-CC into the haemocoel of the beetle induce an increase of cAMP levels in the fat body of the beetle. This increase is tissue-specific and does not occur in brain and flight muscles. An elevation of cAMP levels was also found when in vitro preparations of fat body tissue were subjected to Mem-CC. Elevation of the cAMP concentration after injection of Mem-CC is time- and dose-dependent: the maximum response is measured after 1 min, and a dose of 25 pmol Mem-CC is needed. Injection of cpt-cAMP, a cAMP analogue which penetrates the cell membrane, causes a stimulation of proline synthesis but no mobilisation of carbohydrate reserves. The same is measured when IBMX, an inhibitor of phosphodiesterase, is injected. cGMP seems not to be involved in synthesis of proline nor carbohydrate release, because injection of cpt-cGMP has no influence on the levels of proline, alanine and carbohydrates in the haemolymph. Although glycogen phosphorylase of the fat body is activated by Mem-CC in a time- and dose-dependent manner, it cannot be stimulated by cpt-cAMP. The combined data suggest that cAMP is involved in regulation of proline levels by Mem-CC but not in regulation of carbohydrates. Octopamine has no effect on metabolites in the haemolymph and is not capable of activating glycogen phosphorylase, indicating that it is not involved in the regulation of substrates in this beetle. Furthermore, the requirements of the receptor of Mem-CC are different for eliciting a hypertrehalosaemic and a hyperprolinaemic effect, respectively, suggesting that differentiation in signal transduction begins at the receptor level.


Subject(s)
Coleoptera/metabolism , Cyclic AMP/metabolism , Insect Hormones/metabolism , Neuropeptides , Oligopeptides/metabolism , Animals , Enzyme Activation/drug effects , Glycogen/metabolism , Hemolymph/metabolism , Insect Hormones/pharmacology , Octopamine/pharmacology , Oligopeptides/pharmacology , Phosphorylases/metabolism , Proline/biosynthesis , Pyrrolidonecarboxylic Acid/analogs & derivatives
20.
J Insect Physiol ; 46(3): 343-351, 2000 Mar.
Article in English | MEDLINE | ID: mdl-12770239

ABSTRACT

Specimens of the fruit beetle Pachnoda sinuata were starved for up to 30 days. The weight of the beetles declined consistently throughout the starvation period. Concentrations of carbohydrates and alanine in flight muscles, fat body and haemolymph decreased rapidly after onset of starvation, while the concentration of proline remained high. Whereas the lipid concentrations in the haemolymph did not change significantly upon starvation, the lipid content in flight muscles and fat body decreased significantly.Beetles that had been starved for 14 days responded to injection of Mem-CC, the endogenous neuropeptide from its corpora cardiaca, with hyperprolinaemia and a decrease in the alanine level, but no such effect was monitored after prolonged starvation of 28 days. Regardless of the period of starvation, Mem-CC injection could not cause hypertrehalosaemia or hyperlipaemia, although carbohydrates were increased in fed beetles after injection.Flight ability of beetles that had been starved for 15 or 30 days was apparently not impaired. During such periods, beetles used proline exclusively as fuel for flight as evidenced by the increase in the level of alanine in the haemolymph and decrease of the level of proline; the concentrations of carbohydrates and lipids remained unchanged.Activities of malic enzyme and alanine aminotransferase (enzymes involved in transamination in proline metabolism), glyceraldehyde-3-phosphate dehydrogenase (enzyme of glycolysis), 3-hydroxyacyl-CoA dehydrogenase (enzyme of beta-oxidation of fatty acids) and of malate dehydrogenase (enzyme of Krebs cycle) were measured in fat body and flight muscles. In flight muscle tissue the maximum activity of NAD(+)-dependent malic enzyme increased, while that of glyceraldehyde-3-phosphate dehydrogenase decreased during starvation, and malate dehydrogenase, 3-hydroxyacyl-CoA dehydrogenase and alanine aminotransferase were unchanged. In fat body tissue, activities of NADP(+)-dependent malic enzyme and 3-hydroxyacyl-CoA dehydrogenase increased during food deprivation and activities of glyceraldehyde-3-phosphate dehydrogenase, malate dehydrogenase and alanine aminotransferase remained unchanged.

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