bluuebunny/crossref_metadata_2025_split huggingface dataset:
Further studies on the mechanism of oxidation of N‐acetyldopamine by the cuticular enzymes from Sarcophaga bullata and other insects
Authors: Sugumaran Manickam , Kundzicz Heather , Bedell‐Hogan Debra , Schinkmann Karin 
Published: February 2005

AbstractIn accordance with our earlier results, quinone methide formation was confirmed to be the major pathway for the oxidation of N‐acetyldopamine (NADA) by cuticle‐bound enzymes from Sarcophaga bullata larvae. In addition, with the use of a newly developed HPLC separation condition and cuticle prepared by gentle procedures, it could be demonstrated that 1, 2‐dehydro‐NADA and its dimeric oxidation products are also generated in the reaction mixture containing a high concentration of NADA albeit at a much lower amount than the NADA quinone methide water adduct, viz., N‐acetylnorepinephrine (NANE). By using different buffers, it was also possible to establish the accumulation of NADA quinone in reaction mixtures containing NADA and cuticle. That the 1,2‐dehydro‐NADA formation is due to the action of a NADA desaturase system was established by pH and temperature studies and by differential inhibition of NANE production. Of the various cuticle examined, adult cuticle of Locusta migratoria, presclerotized cuticle of Periplaneta americana, and white puparial cases of Drosophila melanogaster exhibited more NADA desaturase activity than NANE generating activity, while the reverse was observed with the larval cuticle of Tenebrio molitor and pharate pupal cuticle of Manduca sexta. These studies indicate that both NADA quinone methide and 1, 2‐dehydro NADA are formed during enzymatic activation of NADA in insect cuticle. Based on these results, a unified mechanism for β‐sclerotization involving quinone methides as the reactive species is presented.
Chemical‐ and cuticular phenoloxidase‐ mediated synthesis of cysteinyl–catechol adducts
Authors: Sugumaran Manickam , Dali Hemalata , Semensi Victor 
Published: February 2005

AbstractN‐Acetylcysteine adducts of o‐benzoquinones derived from catechol, 4‐methylcatechol, and N‐acetyldopamine were chemically synthesized and characterized by a combination of UV, IR, and NMR spectral studies. Oxidation of catechol, 4‐methylcatechol, and N‐acetyldopamine by cuticle‐bound phenoloxidase from Sarcophaga bullata in the presence of N‐acetylcysteine resulted in the formation of covalent adducts between catecholic compounds and N‐acetylcysteine. Structural identities of these adducts were established by comparison of their HPLC retention time and UV spectra with those of synthetic adducts and by cochromatography with authentic samples. Although insect cuticle is known to contain only trace amounts of cysteine, the in vitro synthesis of quinone cysteine adducts mediated by cuticular phenoloxidase strongly indicates the occurrence of similar reactions in vivo as well and is in support of Pryor's quinone tanning hypothesis.
Binding of juvenile hormone III to lipophorin from the american cockroach Periplaneta americana
Authors: De Kort Stan , Koopmanschap Bertha 
Published: February 2005

AbstractWhole hemolymph from the American cockroach, Periplaneta americana, efficiently binds juvenile hormone (JH) III and to a lesser extent JH‐I and 10, 11‐epoxyfarnesyl diazoacetate (EFDA). The dissociation constants for racemic JH‐III and EFDA are 30 ± 2 nM and 1.0 μM, respectively. Isolated lipophorin also binds [3H]JH‐III and to a lesser extent JH‐I. Other proteins from the hemolymph do not bind JH‐III. Binding of JH‐III to lipophorin is enantioselective. The dissociation constant, measured with a 92% 10R and 8% 10S mixture, is 21 ± 2 nM. Each lipophorin molecule contains one specific binding site for JH‐III. It is concluded that lipophorin is the JH‐III‐specific transport protein in the hemolymph of the American cockroach. By a combination of photoaffinity labelling and gradient electrophoresis with sodium dodecyl sulphate on polyacrylamide gel, we showed that the JH‐III‐specific binding site is probably located on apolipophorin I.
Purification and characteristics of a specific alkaline phosphatase from the integument of the mediterranean fruit fly, Ceratitis capitata
Authors: Psachoulia Christina , Bourtzis Kostas , Marmaras Vassilis J. 
Published: February 2005

AbstractA specific alkaline phosphatase (ALPase) from the integument of white pupae has been purified 500‐fold. The purification procedure included solubilization with Triton X‐100, butanol extraction, fractionation with ammonium sulfate, and chromatography on concanavalin A‐Sepharose, Sephadex G‐200, and Sepharose 6B. Two peaks with enzyme activity were observed. The major peak had a molecular weight of approximately 180,000, while the minor peak, which had identical kinetic parameters and substrate specificity as those of the major one, was eluted in a high molecular weight form (about 900,000), probably cross‐linked with chitin, since the enzyme was separated from the chitin only by lysozyme treatment. The enzyme hydrolyzes only tyrosine phosphate and β‐glycerophosphate, with apparent Kms of 0.35 mM and 0.22 mM, respectively, but not serine phosphate, threonine phosphate, ATP, and AMP. The optimum pH was in the alkaline range, with a peak at pH 9.4. The divalent cations Mn2+, Mg2+, and Ba2+ had stimulatory actions, while Cu2+ exerted a very strong inhibitory action on the enzyme activity. The ALPase was inhibited by L‐tyrosine in a dose‐dependent fashion. At a concentration of 2 mM, L‐tyrosine totally inhibited the enzyme activity, while L‐phenylalanine inactivated the enzyme about 25%. The accumulated evidence that ALPase is involved in the sclerotization process of insect integument is discussed.
Distribution, properties, and functions of midgut carboxypeptidases and dipeptidases from Musca domestica larvae
Authors: Jordão Beatriz P. , Terra Walter R. 
Published: February 2005

AbstractDipeptidase and carboxypeptidase A activities were determined in cells and luminal contents of the fore‐, mid‐, and hind‐midgut of Musca domestica larvae. Dipeptidase activity was found mainly in hind‐midgut cells, whereas carboxy‐peptidase activity was recovered in major amounts in both cells and in luminal contents of hind‐midguts. The subcellular distribution of dipeptidase and part of the carboxypeptidase A activities is similar to that of a plasma membrane enzyme marker (aminopeptidase), suggesting that these activities are bound to the microvillar membranes. Soluble carboxypeptidase A seems to occur both bound to secretory vesicles and trapped in the cell glycocalyx. Based on density‐gradient ultracentrifugation and thermal inactivation, there seems to be only one molecular species of each of the following enzymes (soluble in water or solubilized in Triton X‐100): membrane‐bound dipeptidase (pH optimum 8.0; Km 3.7 mM GlyLeu, Mr 111,000), soluble carboxypeptidase (pH optimum 8.0; Km 1.22 mM N‐carbobenzoxy‐glycyl‐L‐phenylalanine (ZGlyPhe), Mr45,000) and membrane‐bound carboxypeptidase (pH optimum 7.5, Km 2.3 mM ZGlyPhe, Mr58,000). The results suggest that protein digestion is accomplished sequentially by luminal trypsin and luminal carboxypeptidase, by membrane‐bound carboxypeptidase and aminopeptidase, and finally by membrane‐bound dipeptidase.
Microplitis croceipes teratocytes cause developmental arrest of Heliothis virescens larvae
Authors: Zhang Deqing , Dahlman D. L. 
Published: February 2005

AbstractMicroplitis croceipes teratocytes placed into nonparasitized Heliothis virescens larvae survived in the absence of a parasitoid larva and caused developmental changes in the host. Expressions of these changes included delayed larval mortality, incomplete larval‐pupal ecdysis, or delayed pupation. Two day old 4th stadium H. virescens larvae were more sensitive to injected teratocytes than were 5th stadium larvae. Three day old teratocytes were more effective than were 6 day old teratocytes. The degree of response was related to the number of injected teratocytes. For example, 750 three day old teratocytes (the approximate number from a single parasitoid egg) caused delayed larval mortality in 96% of the treated larvae whereas 175 three day old teratocytes caused delayed larval mortality in only 33% of the treated larvae. Even a dose of 80 teratocytes resulted in 15% incomplete larval‐pupal ecdysis compared to 0% for controls. Treatment with hemocyte‐and teratocyte‐free hemolymph from parasitized larvae, hemocytes from nonparasitized H. virescens, unfertilized M. croceipes eggs, Cotesia congregata teratocytes, or Micrococcus lysodeikticus cells all had very little effect either on larval growth or development time.
Juvenile hormone‐like effects of a thiazolylurea on lepidopteran larvae
Authors: Loeb Marcia J. , DeMilo Albert B. , Jones Grace , Jones Davey 
Published: February 2005

AbstractHeliothis virescens maintained on a diet containing 50 ppm of thiazolylurea (5‐[[[2‐thiazolylamino]amino]carbonyl]‐1,3‐benzenedicarboxylic acid dimethyl ester) showed symptoms of juvenile hormone overdose in the last larval instar. Increases in development time and weight, as well as larval color changes, were similar in animals fed thiazolylurea or topically treated with the juvenile hormone mimic methoprene. The juvenile hormone esterase titer profile in hemolymph of animals fed thiazolylurea was much broader than in controls, and peaked 2 days later than in controls; the premolt ecdysteroid peak in hemolymph of animals fed thiazolylurea appeared 2 days earlier than in controls. These events are characteristic of high hemolymph JH titers throughout the last larval instar.
Relationship between the fatty acids of fat body triacylglycerol and lipophorin diacylglycerol of non‐diapause and diapause larvae of the southwestern corn borer, Diatraea grandiosella
Authors: Kuthiala Arun , Chippendale G. Michael 
Published: February 2005

AbstractThe fatty acids of the triacylglycerol reserves in the fat body and of the diacylglycerol of lipophorin in the hemolymph of non‐diapause and diapause larvae of D. grandiosella were compared. For both non‐diapause and diapause larvae palmitate, palmitoleate, oleate, and linoleate were the predominant fatty acids present in fatty body triacylglycerol, and palmitate, oleate, and linoleate were the predominant fatty acids present in lipophorin diacylglycerol. However, differences were detected in the relative amounts of oleate and linoleate present in lipophorin diacylglycerol of non‐diapause and diapause larvae. The relative amount of linoleate in lipophorin diacylglycerol declined during diapause, whereas that of oleate remained relatively high during diapause. The fatty acid profile of lipophorin diacylglycerol from non‐diapause larvae treated with a juvenile hormone analog to induce a diapause‐like state more closely matched that of diapause larvae than that of non‐diapause larvae. The differences detected in the fatty acid composition of lipophorin diacylglycerol in non‐diapause and diapause larvae appear to be due mainly to the different physiological states rather than to the different rearing temperatures employed. The results are discussed in relation to the essential role fatty acids, especially oleate, play in the survival of diapause larvae.
Catecholamines in the cuticles of four strains of the german cockroach Blattella germanica (L.) during sclerotization and melanization
Authors: Czapla Thomas H. , Hopkins Theodore L. , Kramer Karl J. 
Published: February 2005

AbstractCatecholamines were extracted from the cuticles of four strains of the cockroach Blattella germanica at different times 48 h after adult ecdysis and analyzed by reverse phase HPLC with electrochemical detection. The wild (VPl), black (Bl), orange (or), and yellow (y) phenotypes differ in cuticular pigmentation, particularly in the extent of melanization. N‐β‐Alanyldopamine (NBAD) and N‐β‐alanylnorepinephrine (NBANE) were major o‐diphenolic compounds in extracts from cuticle of all strains during the main period of sclerotization. N‐Acetyldopamine (NADA) and N‐acetylnorepinephrine (NANE) were minor the first day after ecdysis, but accumulated to higher levels thereafter. Dopamine (DA) concentrations were higher in the darker pigmented cuticles of strains Bl and or than in the lighter‐colored cuticles of strains VPl and y. Extractable DA rapidly increased in VPl, Bl, and or cuticles shortly after ecdysis, reached peak levels 6–24 h later, and then decreased after melanization. Only small amounts of DA were detected in strain y cuticle, whereas NBANE concentrations were very high. Therefore, high DA levels in cuticle are correlated with melanization that occurs during the first few hours after adult ecdysis, whereas sclerotization is correlated with high levels of the N‐β‐alanylcatecholamines. Sclerotization appears to be delayed in strain Bl, since only low concentrations of the N‐acylated catecholamines accumulate until after melanization is completed.
Characterization of quinone tautomerase activity in the hemolymph of Sarcophaga bullata larvae
Authors: Saul Steven J. , Sugumaran Manickam 
Published: February 2005

AbstractThe hemolymph of Sarcophaga bullata larvae was activated with either zymosan or proteolytic enzymes such as chymotrypsin or subtilisin and assayed for phenoloxidase activity by two different assays. While oxygen uptake studies readily attested to the wide specificty of activated phenoloxidase, visible spectral studies failed to confirm the accumulation of quinone products in the case of 4‐alkyl substituted catechols such as N‐acetyldopamine and N‐β‐alanyldopamine. Sepharose 6B column chromatography of the activated hemolymph resolved phenoloxidase activity into two fractions, designated as A and B. Peak A possessed typical o‐diphenoloxidase (o‐diphenol, oxygen oxidoreductase EC 1.10.3.1) activity, while peak B oxidized physiologically important catecholamine derivatives such as N‐acetyldopamine, N‐acetylnorepinephrine, and N‐β‐alanyldopamine into N‐acetylnorepinephrine, N‐acetylarterenone, and N‐β‐alanylnorepinephrine, respectively, and converted 3,4‐dihydroxyphenylacetic acid, 3,4‐dihydroxymandelic acid, and 3,4‐dihydroxyphenylglycol into 3,4‐dihydroxymandelic acid, 3,4‐dihydroxybenzaldehyde, and 2‐hydroxy‐3′,4′‐dihydroxyacetophenone, respectively. These transformations are consistent with the conversion of phenoloxidase‐generated quinones to quinone methides and subsequent non‐enzymatic transformations of quinone methides. Accordingly, Peak B contained both o‐diphenoloxidase activity and quinone tautomerase activity. Sepharose 6B column chromatography of unactivated hemolymph resulted in the separation of quinone tautomerase from prophenoloxidase. The tautomerase rapidly converted both chemically made and mushroom tyrosinase‐generated quinones to quinone methides. Thus the failure to observe the accumulation of quinones with N‐acyl derivatives of dopamine and related compounds in the whole hemolymph is due to the rapid conversion of these long lived toxic quinones to short lived quinone methides. The latter, being unstable, undergo rapid non‐enzymatic transformations to form side‐chain‐oxygenated products that are non‐toxic. The possible roles of quinone isomerase and its reaction products—quinone methides—as essential components of sclerotization of cuticle and defense reaction of Sarcophaga bullata are discussed.
Ecdysone oxidase and 3‐oxoecdysteroid reductases in Manduca sexta midgut: Kinetic parameters
Authors: Weirich Gunter F. , Thompson Malcolm J. , Svoboda James A. 
Published: February 2005

AbstractEcdysone and 20‐hydroxyecdysone are converted to their 3‐epimers by enzymes in the midgut cytosol of Manduca sexta larvae. A partially purified cytosol preparation has been used to analyze the nature of and the interaction between these enzymes. The cytosol was shown to contain ecdysone oxidase, one or more 3‐oxoecdysteroid 3α‐reductase(s), and one or more 3‐oxoecdysteroid 3β‐reductase(s). The reductases reacted at different velocities with NADH and NADPH. With NADH, 3α‐reduction was the major reaction; with NADPH, 3β‐reduction was the major reaction. The apparent kinetic parameters for the enzymes support the assumed two‐step mechanism for the 3‐epimerization with a 3‐oxoecdysteroid as intermediate.
Two hypolipidemic agents, cholestyramine and niacin, affect the development and lipid content of Heliothis zea
Authors: Ritter Karla S. , Smith V. Blair 
Published: February 2005

AbstractTwo vertebrate hypolipidemic agents, cholestyramine and niacin, affected the growth and development of Heliothis zea as well as the quantity of acylglyceride or sterol present in the larva. As the concentration of cholestyramine in the diet increased to 6.0%: the number of larval molts increased from 5 or 6 to as many as 7 or 8, the time required for the onset of pupation increased from 11 or 12 to 20 days, and the number of adults that emerged decreased from at least 70 to 0%. The growth and development of the insect may have slowed, at least in part, because this agent reduced the quantity of sterol and glyceride in the tissues of the larva. Niacin also affected the growth and development of the insect. As the concentration of niacin in the diet increased to 5.0%: the number of larval molts increased by 1, the time required for the onset of pupation increased to 21 days, pupal weight decreased significantly, but adult emergence was normal. The growth and development of the insect may have slowed, at least in part, because this agent caused sterol to accumulate in the hemolymph of the larva. A water‐soluble component in the hemolymph also increased in the presence of niacin, but there was little or no change in the glyceride content. Further studies are warranted to determine the mode of action of these hypolipidemic agents in H. zea.
Contributing factors to reduced ecdysteroid titers in Heliothis virescens parasitized by Microplitis croceipes
Authors: Dahlman Douglas L. , Coar Danise L. , Noah Koller C. , Neary Todd J. 
Published: February 2005

AbstractHeliothis virescens parasitized by Microplitis croceipes stop development at a predictable point prior to parasite emergence. The objectives of this study were to examine several factors which might contribute to the syndrome by comparing parasitized and nonparasitized larvae at specific and correspondingly similar physiological points in their development. Fifth stadium nonparasitized larvae experience a small pupal commitment burst of ecdysone followed by a large burst. In contrast, ecdysteroid titers in parasitized larvae remained at the pupal commitment level during the entire 5th stadium. Data shows that ecdysone 20‐monooxygenase and sterol precursors are not limiting factors, with the possible exception of limited hemolymph sterol at the end of parasitoid development. In addition, isolated prothoracic glands from parasitized larvae produce amounts of ecdysteroid comparable to controls when stimulated with a crude Manduca sexta prothoracicotropic hormone preparation. Juvenile hormone esterase titers in parasitized larvae are low throughout the 5th stadium. They do not show the major rapid increase in activity normally associated with the latter part of the active feeding period in the nonparasitized 5th instar. Possible explanations for the low ecdysteroid titers in parasitized larvae include failure to synthesize and release prothoracic gland stimulatory factor by the poorly developed fat body, insufficient sterol precursors at the critical time of ecdysteroid synthesis, inhibition of the release of PTTH, failure of the prothoracic gland to respond to PTTH, and the consequences of abnormally high juvenile hormone titers.
Developmental responses of Trichoplusia ni (Lepidoptera: Noctuidae) to parasitism by the ectoparasite Euplectrus plathypenae (Hymenoptera: Eulophidae)
Authors: Coudron Thomas A. , Kelly Thomas J. , Puttler Benjamin 
Published: February 2005

AbstractParasitism by Euplectrus plathypenae inhibits larval–larval ecdysis in Trichoplusia ni by injecting nonparalytic factor(s) into the host during the stinging process via the parasitoid's ovipositor. The parasitized host moves freely, feeds, and gains weight prior to the time of the normal ecdysis but does not molt. Parasitoid development is not required for the expression of molt arrest in the host. Parasitism during the first three fourths of the larval stadium results in molt arrest. Arrestment of molting is independent of 20‐hydroxyecdysone and juvenile hormone. The arrestment factor(s) affect the epidermal tissue of the thorax and abdomen in ligated hosts without apparent interaction from other areas of the body. Cuticle and epidermal tissue of parasitized insects do not show signs of apolysis or ecdysis.
Arylphorin of Trichoplusia ni: Characterization and parasite‐induced precocious increase in titer
Authors: Kunkel Joseph G. , Grossniklaus‐Buergin Christa , Karpells Sharon T. , Lanzrein Beatrice 
Published: February 2005

AbstractArlyphorin (Ap) is the principal protein of the last larval instar hemolymph of Trichoplusia ni. It was shown to be homologous with the Aps of Manduca sexta and Lymantria dispar by Western blot and quantitative immunoelectrophoresis. Another hemolymph storage protein in T. ni of lesser titer was shown to be homologous with larval hemolymph protein (LSP) of M. sexta. Ap titer increased dramatically in the last larval instar of T. ni, as in other holometabolous insects studied. Parasitization by Chelonus sp. caused the Ap titer to rise prematurely in the penultimate larval instar of T. ni. This rise in Ap in the fourth instar is one of the earliest diagnostic signs of parasitization. Among the suite of behaviors of the Chelonus larva on exiting the host is depletion of the host cadaver of most remaining protein. The T. ni Ap titer in the alimentary tract of Chelonus peaks at that time and declines to zero in the first 24 h after parasitoid emergence, prior to its pupation. Aps are a source of phenolic storage compounds. Hence, premature induction of T. ni is advantageous for the parasitoid's own pupation and adult development.
Metabolism of parasitized Manduca sexta examined by nuclear magnetic resonance
Authors: Thompson Stewart N. , Lee Robert W.‐K. , Beckage Nancy E. 
Published: February 2005

AbstractMetabolism of fifth instar Manduca sexta larvae was significantly altered during parasitization by Cotesia congregata. The in vivo 13C natural abndance spectrum and histological examination of the fat body demonstrated significantly reduced fat levels and increased deposition of glycogen in parasitized insects. 1H NMR analysis demonstrated that the free amino acid level was reduced in the hemolymph of parasitized larvae, but control and parasitized insects had similar levels of trehalose. [13C]2‐pyruvate injected into the dorsal vessel was incorporated into numerous metabolites including amino acids, Krebs cycle intermediates, trehalose, and fat. In control larvae pyruvate was incorporated primarily into fat following oxidation to CoASAc. Pyruvate was metabolized slower in parasitized larvae and following decarboxylation to oxaloacetate was metabolized by Krebs cycle and incorporated into amino acids. Only small amounts of trehalose were synthesized from pyruvate in control and parasitized larvae and glycogen synthesis was not observed. Analysis of hemolymph indicated no net synthesis of glucose by gluconeogenesis. Control and parasitized larvae incorporated [13C]1‐glucose primarily into trehalose. Control larvae also synthesized fat from gulcose. In contrast, fat synthesis was not observed in parasitized insects which incorporated glucose into glycogen. Differences in glucose metabolism, therefore, appeared to explain the difference in storage metabolite levels between control and parasitized larvae.