摘要:

AbstractA structure‐activity relationship study of Hez‐PBAN was performed with respect to its pheromonotropic activity, usingHeliothis peltigeraas the test animal. The activity of N‐ and C‐terminally derived sequences was examined in a time‐ and dose‐dependent mode. Using a variety of Hez‐PBAN‐derived fragments at two doses (1 and 10 pmol) and at different times post‐injection (5–120 min), we were able to demonstrate that peptides lacking 12 and 16 amino acids from their N‐terminus are as potent as the full length PBAN, and that the C‐terminally derived hexapeptide was capable of stimulating sex pheromone production to a similar extent as PBAN 1–33NH2, when its activity was analyzed at shorter post‐injection times. Within the C‐terminal sequence, the amide was found to play a crucial role. In addition, it was observed that the region between amino acids 9 and 13 is important for the biological activity of the full length PBAN. The fact that the pheromonotropic activity of the hexapeptide was similar to that of the full length PBAN, under specific conditions, suggests that this sequence constitutes the biologically active site of the neuropeptide. The discovery that PBAN‐derived peptides reacted in a time‐ and dose‐dependent mode, strengthens the assumption that proteolytic enzymes interfere with the pheromonotropic activity of the PBAN‐derived fragments. The ability of a variety of peptides to stimulate sex pheromone biosynthesis suggests two possible mechanisms: (1) Existence of multiple pheromonotropic mechanisms which may be mediated by multiple PBAN receptors that are activated at different kinetics; (2) Existence of only one mechanism mediated by short C‐terminally derived peptides. In the first case, the C‐terminally derived sequences fulfill the conformational requirement of only one class of receptors, and other regions in the PBAN molecule (e.g., 9–13) fulfill the conformational requirements of a second (or other) class of receptors. In the second case, the C‐terminally derived sequence is the only conformationally important sequence, and other sequences, which were found to be essential for the biological activity, serve other non‐conformational purposes (e.g., protection against p

ISSN:0739-4462    

DOI:10.1002/arch.940300402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractAnalysis by TLC and HPLC revealed that the triacylglycerols comprise the most abundant lipid class in the sex pheromone glands ofManduca sextafemales. Also, conjugated olefinic acyl analogs of the major pheromone aldehydes occur principally in the triacylglycerols. The amount of triacylglycerols with conjugated diene acyl moieties significantly decreased when the period of pheromone production was extended by 7 h beyond the normal period of pheromone production by 3 injections of pheromone biosynthesis activating neuropeptide (PBAN) at 3 h intervals. This decrease indicates that the triacylglycerols stored in the gland may serve as major sources of pheromone precursors in the biosynthesis of the sex pheromone aldehydes. Furthermore, analysis of pheromone aldehydes and triacylglycerols in the gland from moths treated with PBAN showed that the proportions of the triacylglycerols with conjugated diene moieties were closely correlated with the proportions of aldehydes found in the same gland. This correlation suggests that the proportions of fatty acids bound to certain triacylglycerols regulates the proportions of aldehydes in biosynthesis of the pheromone blend inM. sexta. © 1995 Wiley‐Liss, Inc.This article is a USGovernment work and, as such, is in the public domain in the United States of Ameri

ISSN:0739-4462    

DOI:10.1002/arch.940300403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

Abstract32P‐Labelled midguts (32P‐midguts) ofRhodnius prolixusfemales were incubated in the presence of nonradioactive purified lipophorin and the release of radioactivity to the medium was analysed. The radioactivity found in the medium was associated with lipophorin phospholipids. When the32P‐midguts were incubated in the absence of lipophorin, no32P‐phospholipids were found in the medium. Comparative analysis by thin‐layer chromatography of32P‐phospholipids derived from metabolically labelled32P‐midgut or lipophorin particles after incubation with32P‐midgut showed some differences, revealing a possible selectivity in the process of phospholipids transfer. The transfer of phospholipids to lipophorin was linear with time up to 45 min, was saturable with respect to the concentration of lipophorin, and was half‐maximal at about 5 mg/ml. The binding of32P‐lipophorin to the midgut at O°C reached the equilibrium at about 1 h of incubation. The binding of32P‐lipophorin was inhibited by an excess of nonradioactive lipophorin, which suggests a specific receptor for lipophorin. The capacity of midguts and fat bodies to transfer phospholipids to lipophorin varied during the days following the meal. When lipophorin enzymatically depleted of phospholipids by treatment with phospholipase A2was incubated with32P‐midguts, the same amount of phospholipids was transferred, indicating a net gain of phospholipids by the particle

ISSN:0739-4462    

DOI:10.1002/arch.940300404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractBiochemical and metabolic alterations inAcyrthosiphon pisum(Harris) (Homoptera: Aphididae) parasitized by the endophagousAphidius erviHaliday (Hymenoptera: Braconidae) are reported. Total ecdysteroid titer was determined by radioimmunoassay. The hemolymph levels of acylglycerols and proteins were assessed with an enzymatic method and Bradford's method, respectively. Alterations of the electrophoretic pattern of host hemolymph proteins were assessed by SDS‐PAGE. Analyses were carried out on hosts parasitized as 1st instars, as well as on hosts which were parasitized later, as 3rd or 4th instars. Parasitism did not significantly alter the ecdysteroid titer of pre‐adult stages when parasitized as 3rd instars. In contrast, the ecdysteroid titer in developmentally arrested 4th instars ofA. pisum, previously parasitized as 1st instars, was significantly lower than in the case of synchronous nonparasitized controls. Ecdysteroids were detected also in adult aphids, which, when previously parasitized as 3rd instars, showed a precocious end of reproductive activity associated with a hormonal titer that was significantly lower than in actively reproducing nonparasitized controls of the same age. Acylglycerol and protein titers were significantly higher in the hemolymph of both early and late parasitized hosts, 5–6 days after parasitoid oviposition. SDS‐PAGE analysis of hemolymph collected 5 days after parasitization revealed the presence of both upregulated proteins and of parasitoid‐specific proteins. The observed biochemical changes in parasitized hosts were synchronized with the major part of parasitoid larval growth and, apparently, strictly related to parasitic castration of the host. The role and importance of host regulation factors controlling these biochemical and developmental alterations in parasitized pea aphids are discussed. © 1995 Wiley

ISSN:0739-4462    

DOI:10.1002/arch.940300405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractA highly sensitive enzyme linked immunosorbent assay (ELISA) for the determination of the pheromone biosynthesis activating neuropeptide (PBAN) has been developed. Six antisera have been obtained that recognize the carboxyl terminal side of this peptide. Two immunogens have been rationally designed and synthesized in order to direct antibody specificity, using as haptens PBAN or PBAN(20‐33) with a Cys residue attached to their amino‐terminal side. The Cys thiol group has been used to covalently bind the peptide to keyhole limpet hemocyanin (KLH) by using N‐succinimidyl‐4‐(maleidimidomethyl) cyclohexane carboxylate (SMCC) as a convenient heterobifunctional cross‐linker. Several usable competitive immunoassays have been obtained by synthesizing eight different coating antigens and screening the sera against all of them. The best assay was obtained with antibody 4 using Cys‐Hez‐PBAN(20‐33) coupled to bovine serum albumin (BSA) through the Lys groups by using the homobifunctional cross‐linker dimethylpimelidate dihydrochloride (DMP) as the coating antigen. The optimized assay allows to detect PBAN at concentrations as low as 1 fmol/well (l50= 2.5 fmol/well). An extraction procedure for the hemolymph has been developed that allows to perform PBAN measurements in this tissue even after a tenfold dilution. In these conditions matrix effect is negligible. Preliminary results on the presence of PBAN like immunoreactivity (PBAN‐IR) in the hemolymph ofSpodoptera littoralisfemales are reported.

ISSN:0739-4462    

DOI:10.1002/arch.940300406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractThe participation of juvenile hormone (JH) in the regulation of growth and protein synthesis in the accessory reproductive gland of maleLocusta migratoriahas been investigated. After elimination of endogenous JH with ethoxyprecocene, the accessory gland failed to grow, but growth was restored by a single application of the JH analog, pyriproxyfen. Pyriproxyfen appeared to stimulate total protein synthesis by 3 h, with a significant effect by 12 h, in contrast to 24 h observed in fat body. The dose curve for stimulation of protein synthesis 12 h after applying pyriproxyfen gave an ED50of 0.1 μg; the dose curve for gland growth at 72 h was biphasic, with steps at about 0.01 μg and 10 μg, suggesting two phases in JH action. SDS‐PAGE analysis showed several components that were stimulated by pyriproxyfen, the effect being strongest in an 11 kDa band. A 5 kDa component was enhanced in the soluble and reduced in the particulate fraction after precocene treatment. The accessory gland contained JH esterase activity at levels about 100 times those in fat body or hemolymph, and was higher in precocene treated locusts. Binding activity for [3H]10R‐JH III was high in cytosolic and nuclear fractions, and was identified immunologically as due to the previously described hemolymph JH binding protein. The results indicate that the mode of action of JH in the accessory gland may differ from that in the fat body. The presence of intracellular JH binding protein suggests a direct action of JH within the gland, that may be modulated by JH esterase. © 1995 Wiley‐

ISSN:0739-4462    

DOI:10.1002/arch.940300407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

ISSN:0739-4462    

DOI:10.1002/arch.940300408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

ISSN:0739-4462    

DOI:10.1002/arch.940300401

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY