摘要:

AbstractOctopamine and 5‐hydroxytryptamine (5‐HT) were previously shown to affect phagocytosis in cockroach hemocytes through unidentified receptor‐mediated events. In the present study, we examined the ability of 5‐HT and octopamine to enhance inositol trisphosphate (IP3) production using hemocyte membranes of the American cockroach,Periplaneta americana. Octopamine enhanced IP3production with a maximal peak at 100 nM. Similarly, 5‐HT enhanced IP3production with a maximal effect at 10 nM. The effects of 5‐HT and octopamine are not additive, suggesting that both are working through the same receptor. Phentolamine, a general octopamine antagonist, blocked the effects of octopamine and 5‐HT, while a mammalian 5‐HT2antagonist that blocks 5‐HT‐sensitive receptors in insect peripheral tissue, ketanserin, did not. A pharmacological profile indicates that the receptor is similar to an octopamine1‐type.Octopamine at 1 μM increased phagocytosis in cockroach hemocytes exposed toStaphylococcus aureusin vitro, and this effect was mimicked by IP3(10 μM). The octopamine‐treated hemocytes were shown to increase IP3production in the latter stage of phagocytosis.Adult cockroaches exposed to an LD50dose ofS. aureusin conjunction with either 0.1 mM octopamine or the octopamine1agonist, clonidine, had higher survival rates compared to saline‐treated cockroaches. Correspondingly, the octopamine1antagonist, chlorpromazine, partially blocked the octopamine‐mediated increase in cockroach sur

ISSN:0739-4462    

DOI:10.1002/arch.940260402

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

年代:1994

数据来源: WILEY

摘要:

AbstractTestis sheaths and fat body from developing male pupae ofHeliothis virescenssynthesize soluble growth factor‐like products when exposed to 20‐hydroxyecdysone (20HE). These factors promote growth and development of the genital tract. Saline extracts of modified Grace's medium and 20HE‐treated testis sheaths and fat body were subjected to heat, freeze‐thaw, organic solvents, and low pressure size exclusion chromatography. Although extracts were stable to repeated freeze‐thawing, activity was lost after exposure to organic solvents; activities of fractions heavier than 6.5 KDa were inhibited by heating to 100°C. Size exclusion chromatography yielded 10 active testis extract fractions and 9 active fat body fractions. Although the approximate molecular weights of most of the extract fractions were similar, enzyme studies using protease, lipase, and α‐amylase indicated differences in the chemistry of active fractions derived from the two tissues. Active factors were inhibited by protease or lipase or both enzymes. © 1994 W

ISSN:0739-4462    

DOI:10.1002/arch.940260403

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe effect of 10,11‐methylenetetradec‐10‐enoic acid on the sex pheromone biosynthetic pathway ofSpodoptera littoralisis reported. This new cyclopropene fatty acid inhibited the biosynthesis of the main pheromone component from labeled myristicacid. The study of each Z desaturation step revealed that the Z9‐desaturase of E11–14:Acid was inhibited, whereas the Z11‐desaturase of 16:Acid was not affected. The results presented in this article agree with our hypothesis that the methylenehexadecenoic acids are beta‐oxidized in the pheromone gland to the corresponding methylenetetradecenoic acids. © 1994 W

ISSN:0739-4462    

DOI:10.1002/arch.940260404

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe 32 kD juvenile hormone binding protein (JHBP) and two 80 kD proteins in larvalManduca sextahemolymph were labeled with [3H]FDK, a photoaffinity analog of methyl farnesoate (MF). The labeling could be completely displaced by a 30‐fold excess of either MF or JH II, demonstrating that [3H]FDK binds specifically to the JH binding sites of the 32 kD JHBP and the 80 kD proteins. In addition, a high molecular‐mass protein was labeled with [3H]FDK; labeling could be displaced by excess MF but not by JH II, demonstrating the selectivity in binding MF. The 32 kD JHBP also appeared to weakly bind the potent juvenoid, methoprene, at the JH binding site.Covalent modification by [3H]FDK induced a change in the apparent size and the isoelectric point of the JHBP. These changes were not induced by substrate alone, nor by UV irradiation alone. The same effect was also observed during labeling with [3H]MDK, an analog of methoprene. These data provide an important caveat for anticipating artifactual changes of protein properties during chemical or photochemical affinity labeling experiments. The molecular dimensions of [3H]FDK more closely resemble those of JH II than those of [3H]EHDA, a photoactivatable analog of JH II. We suggest that covalent modification by a diazoketone photolabel involves a hydrophilic amino acid important in the recognition of the ester group of JH. © 1994 Wiley‐Lis

ISSN:0739-4462    

DOI:10.1002/arch.940260405

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

年代:1994

数据来源: WILEY

摘要:

AbstractIn the midgut ofSpodoptera frugiperdalarvae, subcellular fractionation data suggest that aminopeptidase and part of amylase, carboxypeptidase A, dipeptidase, and trypsin are bound to the microvillar membranes; that major amounts of soluble dipeptidase, cellobiase, and maltase are trapped in the cell glycocalyx; and finally that soluble carboxypeptidase, amylase, and trypsin occur in intracellular vesicles. Most luminal acetylglucosaminidase is soluble and restricted to the ectoperitrophic contents. Aminopeptidase occurs in minor amounts bound to membranes both in the ectoperitrophic contents and incorporated in the peritrophic membrane. Amylase, carboxypeptidase A, and trypsin are found in minor amounts in the ectoperitrophic contents (both soluble and membrane‐bound) and in major amounts in the peritrophic membrane with contents. Part of the activities recovered in the last mentioned contents corresponds to enzyme molecules incorporated in the peritrophic membrane. The results suggest that initial digestion is carried out in major amounts by enzymes in the endoperitrophic space and, in minor amounts, by enzymes immobilized in the peritrophic membrane. Intermediate and final digestion occur at the ectoperitrophic space or at the surface of midgut cells. The results also lend support to the hypothesis that amylase and trypsin are derived from membrane‐bound forms, are released in soluble form by a microapocrine mechanism, and are partly incorporated into the peritrophic membrane. © 1994 Wiley‐Lis

ISSN:0739-4462    

DOI:10.1002/arch.940260406

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe potato tuber moth is susceptible to at least three insecticidal crystal proteins (ICPs) fromBacillus thuringiensis: CrylA(b), CrylB, and CrylC. To design useful combinations of toxin genes either in transgenic plants or in new genetically modifiedB. thuringiensisstrains, it is necessary to determine the binding characteristics of the different ICPs so as not to combine a pair sharing the same binding site. This has been accomplished using two different techniques:125I‐labeling of the ICPs with further measurement of the radioactivity bound to brush border membrane vesicles, and microscopic visualization of the bound ICPs by enzyme‐linked reagents such as antibodies or streptavidin using biotinylated ICPs. Our results show that CrylA(b), CrylB, and CrylC bind to different sites in the brush border membrane of midgut epithelial cells. Also, the affinity of the binding sites for the ICPs and their concentration in brush border membrane vesicles has been determined in a laboratory strain and a storage collected population. No significant differences were found between these two strains. © 1994 Wiley‐Lis

ISSN:0739-4462    

DOI:10.1002/arch.940260407

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

年代:1994

数据来源: WILEY

ISSN:0739-4462    

DOI:10.1002/arch.940260401

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

年代:1994

数据来源: WILEY