bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the mechanism of formation of N‐acetyldopamine quinone methide in insect cuticle
Authors: Sugumaran Manickam , Saul Steven J. , Semensi Victor 
Published: February 2005

AbstractThe mechanism of formation of quinone methide from the sclerotizing precursor N‐acetyldopamine (NADA) was studied using three different cuticular enzyme systems viz. Sarcophaga bullata larval cuticle, Manduca sexta pharate pupae, and Periplaneta americana presclerotized adult cuticle. All three cuticular samples readily oxidized NADA. During the enzyme‐catalyzed oxidation, the majority of NADA oxidized became bound covalently to the cuticle through the side chain with the retention of o‐diphenolic function, while a minor amount was recovered as N‐acetylnorepinephrine (NANE). Cuticle treated with NADA readily released 2‐hydroxy‐3′,4′‐dihydroxyacetophenone on mild acid hydrolysis confirming the operation of quinone methide sclerotization. Attempts to demonstrate the direct formation of NADA‐quinone methide by trapping experiments with N‐acetylcysteine surprisingly yielded NADA‐quinone‐N‐acetylcysteine adduct rather than the expected NADA‐quinone methide‐N‐acetylcysteine adduct. These results are indicative of NADA oxidation to NADA‐quinone and its subsequent isomerization to NADA‐quinone methide. Accordingly, all three cuticular samples exhibited the presence of an isomerase, which catalyzed the conversion of NADA‐quinone to NADA‐quinone methide as evidenced by the formation of NANE—the water adduct of quinone methide. Thus, in association with phenoloxidase, newly discovered quinone methide isomerase seems to generate quinone methides and provide them for quinone methide sclerotization.
Vitellogenesis in the cockroach Nauphoeta cinerea: Separation of two classes of ovarian binding sites and calcium effects on binding and uptake
Authors: König Rolf , Kindle Helmut , Kunkel Joseph G. , Lanzrein Beatrice 
Published: February 2005

AbstractTwo classes of vitellogenin binding sites with Kd‐values of 7.3 nM and 290 nM were observed in follicle‐membrane preparations of the cockroach Nauphoeta cinerea using a membrane‐binding assay at pH 8. Separation of follicle cells and basal laminae from oocyte membranes prior to binding studies showed that the fraction consisting of follicle cells and basal laminae (FC/BL) contained high‐affinity binding sites for vitellogenin (Kd=16.6 nM), whereas loweraffinity binding sites (Kd=200 nM) were found in the oocyte membrane fraction. The concentration of Ca2+ had a distinct effect on vitellogenin binding and uptake: maximal binding to the oocyte membrane fraction was observed at 0.3 mM Ca2+ and to the FC/BL fraction at 10 mM, whereas uptake of vitellogenin by oocytes in vitro was highest at 4 mM Ca2+. The calcium ionophore A23187 decreased vitellogenin uptake. This effect of A23187 could be counteracted by the calcium chelator Quin2. A hypothetical model for the uptake of vitellogenin into follicles of Nauphoeta cinerea is suggested.
Alteration of hemolymph polypeptides in Manduca sexta larvae parasitized by Cotesia congregata: A two‐dimensional electrophoretic analysis and comparison with major bacteria‐induced proteins
Authors: Beckage Nancy E. , Nesbit Dorothy J. , Nielsen Barbara D. , Spence Kemet D. , Barman Miel A. E. 
Published: February 2005

AbstractAnalyses using one‐dimensional sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE) previously demonstrated that parasitization by the braconid wasp Cotesia congregata significantly alters the normal hemolymph polypeptide profile of host Manduca sexta larvae. In the present study two‐dimensional gel analyses corroborated our earlier findings and provided additional evidence that multiple parasitism‐specific polypeptides were induced, which varied according to the stage of development of the wasps. Parasitization additionally elicited changes in the total protein concentration detected in the blood. Initially an elevation was observed, with newly parasitized larvae exhibiting a twofold elevation in hemolymph protein concentration by 12–24 h postoviposition. In contrast, terminal‐stage hosts with second instar parasites had significantly less protein in the hemolymph, likely due to reduced growth and inhibition of arylphorin synthesis by the fat body during the final stages of parasitism. Comparison of the array of hemolymph polypeptides produced in unparasitized larvae injected with 106cells of the gram‐negative bacterium Enterobacter cloacae with those proteins induced by parasitization indicated the two classes are different. Our findings confirm that the hostresponse to parasitism is a specific one, and not mimicked by bacterial challenge. Duringshort‐term in vitro culture of wasp larvae dissected from the host hemocoel, several proteins were detected in the medium using SDS ‐ PAGE, with their appearance in vitro suggestive of secretion by the wasps in vivo. Moreover, hemolymph from the parasites had significant amounts of putative host proteins, including an arylphorin ‐ like polypeptide and a protein with a mobility similar to that of insecticyanin. Thus, a dynamic interchange of proteins may occur, with the parasites accumulating host proteins while simultaneously secreting a variety of factors into the host hemocoel.
Binding of octopamine to membranes from the white‐eyed and wild‐type housefly heads
Authors: Hashemzadeh‐Gargari Hossein , Wierenga Joel M. 
Published: February 2005

AbstractIn attempting to develop an octopamine (OA) receptor preparation with ready access to large amounts of tissue, we examined the binding of OA to membranes from the heads of white and red houseflies (Musca domestica L.). Binding was dependent on the presence of L‐ascorbic acid in the medium. However, equilibrium was reached only over 24–36 h at 4°C and reversal of binding was also slow and incomplete. Scatchard analysis revealed at least two binding sites in the white‐eyed housefly. A high‐affinity site (Kd = 13.9 nM and Bmax = 3.9 pmol/mg protein) was present, but the majority of the binding had low affinity (Kd = 1130 nM and Bmax = 165 pmol/mg protein). Scatchard analysis revealed a low affinity in the red‐eyed housefly (Kd = 240 nM and Bmax = 12 pmol/mg protein). Catecholamines were the best competitors for OA binding followed by phenolamines such as OA and synephrine. 5‐Hydroxytryptamine was less effective. Phentolamine and mianserin, which are good antagonists of the ability of OA to stimulate adenylate cyclase in housefly head membranes, and formamidine and imidazolines, which are potent partial agonists of this adenylate cyclase, were poor competitors of OA binding. The slow kinetics, low affinity, large amount, and unconventional pharmacological profile of this binding is not congruent with it being a neuroreceptor. When the brain was dissected free from the head, less than 10% of the total specific binding of OA was found in the brain membrane fraction. This suggests that most of the binding of OA may be to cuticular sites that possibly are associated with the metabolism of catecholamines in cuticular synthesis. Thus, binding studies made with labeled catecholamines and phenolamines on insect tissues containing significant cuticular elements should be interpreted with caution.
Repetitive DNA interspersion patterns in diptera
Authors: Cockburn Andrew F. , Mitchell Sharon E. 
Published: February 2005

AbstractA wide spectrum of repetitive DNA amounts and interspersion patterns is seen in mosquitoes and other dipterans. Using a simple and rapid technique, we show that these range from a minimal amount in five species of Anopheles through moderate amounts in Culex quinquefasciatus to large amounts in Aedes aegypti and Stomoxys calcitrans. Although Culex and Aedes are closely related and both have a considerable amount of interspersed repetitive DNA, the repetitive sequences are different between the two genera. These results and previously published information show that the amount of repetitive DNA and sequences involved have changed many times during the evolution of the Diptera.
Isolation of the vitellogenin‐binding protein from locust ovaries
Authors: Roehrkasten Axel , Ferenz Hans‐Joerg , Buschmann‐Gebhardt Beate , Hafer Johannes 
Published: February 2005

AbstractA rapid, efficient procedure for the isolation and purification of the vitellogenin binding protein from locust ovarian membranes is described. After solubilization with the nonionic detergent octyl‐β‐D‐glucoside and removal of the detergent, the binding protein is subjected to affinity chromatography on vitellogenin coupled covalently to Affi‐Gel 15. The binding protein is eluted with suramin and EDTA at low pH value. Sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis reveals a polypeptide with a molecular weight of 156,000 in the eluted fraction. By ligand blotting this polypeptide could be identified as the vitellogenin binding protein. It retains its high‐affinity binding properties. The specific binding of vitellogenin increases from 4.8 μg (intact ovarian membranes) to 170.9 μg (affinity purified binding protein) per mg membrane protein, which corresponds to a purification factor of 35.
Persistence and effects of α‐methyl‐substituted amino acids on 5‐hydroxytryptamine and dopamine concentrations in cockroach (Periplaneta americana) nervous tissue
Authors: Sloley B. Duff 
Published: February 2005

AbstractThe α‐methylated derivatives of tryptophan, tyrosine, and dihydroxyphenylalanine were injected into cockroaches (Periplaneta americana). The levels of these compounds and those of dopamine, 5‐hydroxytryptamine, tyrosine, and tryptophan in the nervous tissue, hemolymph, and fat body were measured at various times after drug administration. Levels of 5‐hydroxytryptamine and tryptophan in the nervous tissue are significantly reduced by α‐methyltryptophan administration. Concentrations of dopamine in nervous tissue are reduced by α‐methyltyrosine administration. This effect also persists for several weeks, and α‐methyltyrosine is observed in the nervous tissue 3 weeks after injection. Levels of dopamine and 5‐hydroxytryptamine in the nervous tissue are unaffected by α‐methyldihydroxyphenylalanine, and this compound is less persistent in nervous tissue than α‐methyltyrosine or α‐methyltryptophan demonstrates that these compounds can be absorbed and affect amine levels in the nervous tissue when included in the diet. Inhibition of tryptophan hydroxylation by crude enzyme preparations of cockroach nervous tissue was demonstrated with both α‐methyltryptophan and α‐methyltyrosine, with α‐methyltryptophan being the more effective inhibitor. Aromatic amino acid decarboxylase activity toward dihydroxyphenylalanine in crude enzyme preparations of cockroach nervous tissue was strongly inhibited by α‐methyldihydroxyphenylalanine and monofluoromethyldihydroxyphenylalanine, slightly inhibited by α‐methyltyrosine and unaffected by α‐methyltryptophan at concentrations up to 10−3 M. The results indicate that α‐methyltyrosine and α‐methyltryptophan, but not α‐methyldihydroxyphenylalanine, can selectively alter amine concentrations in insect nervous tissue and that insects are only poorly able to metabolize or excrete these compounds. The selective and long‐lasting depletion of dopamine or 5‐hydroxytryptamine by some of these compounds suggest that they may be useful in behavioral studies designed to elucidate the roles of these amines in insects.
Synthesis and nuclear magnetic resonance study of 3‐dehydroecdysteroids
Authors: Girault Jean‐Pierre , Blais Catherine , Beydon Philippe , Rolando Christian , Lafont René 
Published: February 2005

AbstractSeveral 3‐dehydro‐ (or 3‐oxo‐) ecdysteroids have been prepared by enzymatic and/or chemical means. Methods for their purification using various high‐performance liquid chromatography systems are described. Proton and carbon nuclear magnetic resonance analyses show that 3‐dehydroecdysteroids when dissolved in water or methanol (but not in chloroform) present a temperature‐dependent equilibrium between two forms. The possible structure of these two forms is discussed.
Apolar conjugates of ecdysteroids are not used as a storage form of molting hormone in the argasid tick Ornithodoros moubata
Authors: Connat Jean‐Louis , Dotson Ellen Marie , Diehl Peter Allan 
Published: February 2005

AbstractFifth (last) instar nymphs of th e tick Ornithodoros moubata convert ingested 20‐hydroxyecdysone (20E) to apolar conjugates AP2, which are then converted to th e more polar conjugates API. Only small quantities of free hormone were transferred to th e hemolymph and the carcass within t h e first 2 days after the blood meal. The proportion of radiolabel in these two compartments was highest at the time of the endogenous ecdysteroid peak; however, no traces of free [3H]20E were detected. The conversion probably occurs principally in the intestinal cells. Eleven days after ingestion, 84% of the radiolabel is located in the digestive tract, mainly in the form of API conjugates.API obtained in second instar nymphs fed with [3H]ecdysone ([3H]E) remain stable throughout the following nymphal instars. The ecdysteroid moiety of APT remained unchanged. The hydrolysis, although not complete, always yielded a peak comigrating with the reference E but never 20E or any other clearly distinct peaks that may have corresponded to metabolites of 20E. Less label per individual was present in adults, but its nature remained the same, viz., API mainly located in the digestive tract. In females, 2.5% of the label was transferred to the progeny during the first ovipositional cycle.Apolar products (mainly AP2) that accumulated in eggs of females injected with [3H]E or [3H]20E during vitellogenesis remained unchanged during the whole embryonic development. During the molting cycle of larvae, there was only a slight conversion of AP2 to API, but esterase hydrolysis of these products released the same percentages of E and 20E as in the freshly laid eggs.We conclude that in this tick species apolar conjugates of ecdysteroids are inactivation metabolites that are not reutilized during the development of the animal. These metabolites are mainly retained in the tick, probably because of its peculiar blocked midgut. Several studies have shown that in other arthropod species (ticks, spiders, and insects), these apolar metabolites are excreted in the feces.
Changes in the titer of the female‐predominant storage protein (81K) during larval and pupal development of the waxmoth, galleria mellonella
Authors: Bean Daniel W. , Silhacek Donald L. 
Published: February 2005

AbstractThe levels of an 81K storage protein in the waxmoth, Galleria mellonella, were monitored during the course of development using rocket immunoelectrophoresis. During the fifth and sixth larval stadia, 81K protein levels increased during feeding and growth but sharply declined at each larval molt. During the fifth and sixth stadia hemolymph levels of the 81K protein increased to about 1 and 2.5 mg/ml, respectively, with no discernible differences between levels in males and females. Neither the fat body nor the remainder of the carcass contained the 81K protein, indicating that the accumulation of this protein during the intermolt period was exclusively in the hemolymph and redistribution of the 81K protein into other tissues does not occur at the final two larval molts. During the seventh (final) larval stadium the absolute quantities of the 81K protein increased from 23 μg per insect to over 1,600 μg in females and to 300 μg in males. The hemolymph concentration of the 81K protein reached 28 mg/ml in females and 6 mg/ml in males with only low levels found in the remaining tissues. Shortly after pupal apolysis, marked by eyespot retraction, the fat body in both sexes rapidly and quantitatively sequestered the 81K protein from the hemolymph. The 81K protein in the hemolymph of both males and females rapidly dropped to nearly zero concentration by pupation. The 81K storage protein remained localized in the fat body cells after uptake occurred, even though the fat body cells disaggregate and reaggregate during metamorphosis. During pharate adult development the 81K storage protein disappeared from the fat body without entering the hemolymph. At adult eclosion 81K was virtually absent from the tissues of both males and females.
Ecdysteroids from developing eggs of Pieris brassicae
Authors: Beydon Philippe , Permana Agus‐dana , Colardeau Jacqueline , Morinière Madeleine , Lafont René 
Published: February 2005

AbstractEcdysone metabolism in Pieris brassicae eggs was revealed after injection of [3H]ecdysone into eggs. Labeled ecdysteroids were analyzed by HPLC. The metabolic fate of [3H]ecdysone is similar to that observed during postembryonic development, i.e., the larval instars and pupal instar. The ecdysone molecule is affected by hydroxylations at C‐20 and at C‐26; 26‐hydroxyecdysteroids can be further oxidized into ecdysteroid acids. In an effort to identify egg ecdysteroids, we examined the metabolism of [3H]cholesterol injected into female pharate adults to achieve long‐term labeling. In eggs, [3H]cholesterol was converted to 20‐hydroxyecdysonoic acid, ecdysonoic acid, 20‐hydroxyecdysone, and ecdysone. The rates of [3H]cholesterol incorporation into ecdysteroids increase according to the age of the eggs (from 0.06% at laying to 0.12% at hatching), while the cholesterol level remains constant throughout embryogenesis, suggesting that the embryos of Pieris brassicae can produce ecdysteroids either from cholesterol or from apolar ecdysteroids not identified by the analytical method. Pieris eggs contain amounts of ecdysteroids which increase from 1.5 nmol/g at laying to 3.8 nmol/g at hatching.
Metabolism of dietary Δ8‐sterols and 9β, 19‐cyclopropyl sterols by Locusta migratoria
Authors: Corio‐Costet Marie F. , Charlet Maurice , Benveniste Pierre , Hoffman Jules 
Published: February 2005

AbstractAdult female locusts were reared on wheat seedlings (experimental wheat) containing more than 97% of 9,10‐cyclopropyl sterols and Δ8‐sterols and less than 2% of Δ5‐sterols. These insects showed a dramatic decrease in their cholesterol, cholestanol and Δ7‐cholestanol content compared with control insects. These changes were more dramatic for steryl esters than for free sterols. Similar results were observed in eggs laid by the insects fed on experimental wheat. The decrease in Δ5‐, Δ0‐ and Δ7‐sterols in insects reared on experimental wheat was compensated by a marked accumulation of Δ8‐sterols and 9β, 19‐cyclopropyl sterols in the free sterol fraction and especially in the steryl ester fractions. The ecdysteroid content of eggs laid by experimental female insects was reduced by up to 80% compared with controls. These and other results suggest that the dietary 9β, 19‐cyclopropyl sterols and Δ8‐sterols cannot be used by Locusta in place of Δ5‐sterols for ecdysteroid biosynthesis. To give support to this hypothesis, the experimental wheat was supplemented with various sterols before being presented to the insects immediately after the first egg laying. When cholesterol, sitosterol, or cholestanol were used as supplements, there was a complete recovery of the ecdysteroid titer in the eggs, a disappearance of 9β, 19‐cyclopropyl sterols, and a restoration of the cholesterol content in both the animals and the eggs. Stigmasterol, stigmastanol, and ergosterol were much less efficient in reversing the effects of the experimental wheat. As expected, 9β, 19‐cyclopropyl sterols were totally ineffective. These results are discussed in the light of our information on the role played by sterols in insect development and on the structural features required by the sterols to fulfill their role.
Ecdysone metabolism in the host‐parasitoid‐system Trichoplusia ni/Chelonus sp
Authors: Grossniklaus‐Buergin Christa , Connat Jean‐Louis , Lanzrein Beatrice 
Published: February 2005

AbstractIn unparasitized 4th and 5th‐instar larvae of Trichoplusia ni and in 4th‐instar larvae parasitized by Chelonus sp. 20‐hydroxyecdysone, 20,26‐dihydroxyec‐dysone, and 20‐hydroxyecdysonoic acid were the predominant metabolites formed 2 h after injection of [3H]ecdysone. Other unidentified metabolites were seen, but none seemed to be specific for either parasitized or unparasitized larvae. The major difference between parasitized and unparasitized larvae was seen with respect to the quantity of apolar (unidentified) and polar metabolites (20‐hydroxyecdysonoic acid and unidentified ones), which were produced to a greater extent in parasitized larvae. Ecdysone was rapidly converted into 20‐hydroxyecdysone and the other polar metabolites in all stages investigated, and the parasitoid seemed not to affect the conversion of ecdysone into 20‐hydroxyecdysone. When analyzing the fate of [3H]ecdysone in host and parasite separately, at a stage when the parasite drinks hemolymph of its host, we observed that 10–20% of the radioactivity was recovered from the parasitoid. Analysis of the parasitoid's ecdysteroids revealed that ecdysone and 20‐hydroxyecdysone represented only a small proportion of the recovered labeled ecdysteroids, the majority being apolar and polar metabolites. Our data suggest that the parasitoid takes up ecdysteroids from its host, converts them, and to some extent releases apolar metabolites into the host.
Juvenile hormone esterase activity from Manduca sexta corpora allata in vitro
Authors: Sparks Thomas C. , Allen L. Gregory , Schneider Frank , Granger Noelle A. 
Published: February 2005

AbstractJuvenile hormone esterase (JHE) activity released by the corpora allata (CA) into incubation media (CA‐JHE) was titered daily during the course of the last (fifth [V]) larval stadium of Manduca sexta. This CA‐JHE activity was relatively low during the early last stadium up to the time of commitment (V4), then rose rapidly to a peak on V6. Activity declined sharply almost to precommitment levels by V8, before rising to a second peak on the first day of the pupal phase (P0). This pattern of activity is distinct from that of hemolymph JHE activity, which peaks just prior to wandering on V4 and again just prior to pupation (V9). Although the CA‐JHE and hemolymph‐JHE possess different temporal patterns of activity, isoelectric focusing, gel electrophoresis, and initial studies with selected inhibitors suggest that the enzymes responsible for the CA‐JHE and hemolymph‐JHE activities are similar, but not identical, in nature.Exposure of the V6 CA in vitro to JH II (0.1 μM) or fluoromevalonolactone (FMev; 0.1 mM) produced an approximate fivefold increase and 60% decrease in JH acid synthesis, respectively. Conversely, the same treatments resulted in an inhibition (JH II) and stimulation (FMev) of CA‐JHE activity. These observations suggest that JH may be involved in the direct positive feedback regulation of postwandering larval CA and that the CA‐JHE may also be integrally related to this positive feedback mechanism.