摘要:

AbstractIn 12‐h‐starved larvae of the tobacco hornworm,Manduca sexta, fat body glycogen phosphorylase was quickly inactivated when insects were refed with normal diet and agar which contained 3% sucrose. Only the first 2 min of refeeding were necessary to induce enzyme inactivation. During this short period, larvae did not ingest enough sucrose to increase the hemolymph glucose concentration. This may indicate that the gut released a hormone(s) which directly or indirectly led to the inactivation of fat body glycogen phosphorylase.Inactivation of the enzyme could also be induced by injection of glucose (30 mg) into the hemolymph of starvingM. sextalarvae suggesting that there may be separate control from a neuroendocrine site such as the brain or the corpora cardiaca. Trehalose was less effective.Bovine insulin (2 and 4 μg/starved larva) did not induce phosphorylase inactivation over 20 min or decrease hemolymph carbohydrate or lipid concentrations within 60 min. It is, therefore, necessary to screen insect tissues for substances which could bring about inactivation of fat body glycogen phosphorylase. © 1992 Wiley‐Li

ISSN:0739-4462    

DOI:10.1002/arch.940190402

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

年代:1992

数据来源: WILEY

摘要:

AbstractWhen precocene II was fed to last instar larvae ofHeliothis zea, it caused significant reductions in the calculated rate of growth, rate of nutrient assimilation, and conversion of ingested and digested food to body mass. No change in the rate of food consumption occurred but respiration was significantly higher. Transport of the nutrient [1‐14C] linoleic acid across midgut tissue was hindered when larvae were fed precocence II. There was also a precocene‐induced change in the apical (luminal) morphology of midgut cells, including absence of the glycocalyx and loss of the microvillar absorptive surface. The influence of precocene II on the midgut physiology and metabolic processes in last instar larvae ofH. zeamay account for the observed reduced growth and delayed development. © 1992 wiley‐Lis

ISSN:0739-4462    

DOI:10.1002/arch.940190403

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

年代:1992

数据来源: WILEY

摘要:

AbstractThis study describes the preparation and characterization of a highly specific antiserum toHelicoverpa zeapheromone biosynthesis activating neuropeptide (Hez‐PBAN), and the use of thsi antiserum, in an enzyme linked immunosorbent assay (ELISA), to determine: (a) the content of endogenous PBAN in head extracts of male and femaleHeliothis peltigera; (b) the level of PBAN at different developmental stages; and (c) the content of PBAN in four different moth species. Cross‐reactivity studies revealed that the antiserum is directed mainly toward the N‐terminal region of the neuropeptide, and that it exhibits similar binding affinities toward the oxidized and reduced forms of PBAN. Analysis of PBAN content in head extracts of male and femaleH. peltigera, at scotophase, revealed the presence of 4.97 and 4.58 pmol, respectively, in 3‐day‐old moths, and 5.33 and 4.78 pmol, respectively, in 7‐day‐old moths. The similarity in the content of PBAN at both ages and sexes was in accordance with the amount of pheromonotropic activity in these extracts which stimulated pheromone biosynthesis to a similar level. Analysis of PBAN‐like immunoreactivity (IR) in head extracts ofH. peltigeralarvae and pupae demonstrated the existence of the neuropeptide in the 4th larval instar and continued to increase as a function of development. No IR could be detected in the first three larval instars. The larval and pupal extracts also exerted pheromonotropic activity which followed a similar pattern. The activity in these extracts, however, was considerably lower than that found in adult male and female heads. IR was also detected in head extracts of three other Noctuidae moths:Helicoverpa armigera, Cornutiplusia circumflexaandSpodoptera littoralis, indicating a high degree of chemcial and structural similarity of PBAN in these moths. © 1992

ISSN:0739-4462    

DOI:10.1002/arch.940190404

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

年代:1992

数据来源: WILEY

摘要:

AbstractThe present study documents that the secondary plant metabolites, especially α‐terthienyl, exert phototoxic action through inhibition of certain enzymes and generation of singlet oxygen. Some of the reports have emerged exhibiting involvement of free radical generation in vitro by α‐terthienyl. We provide evidence for the generation of a free radical viz., superoxide anion radical, by α‐terthienyl employing spin‐trapping techniques, probably due to the extension of the latter reaction. On the basis of this observation the phototoxic action of α‐terthienyl onAedes aegyptilarvae is explained. © 1992 W

ISSN:0739-4462    

DOI:10.1002/arch.940190405

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

年代:1992

数据来源: WILEY

摘要:

AbstractThe properties of cuticular enzymes involved in sclerotization ofDrosophila melanogasterpuparium were examined. The cuticle‐bound phenoloxidase from the white puparium exhibited a pH optimum of 6.5 in phosphate buffer and oxidized a variety of catecholic substrates such as 4‐methylcatechol, N‐β‐alanyldopamine, dopa, dopamine, N‐acetyldopamine, catechol, norepinephrine, 3,4‐dihydroxyphenylglycol, 3,4‐dihydroxylbenzoic acid, and 3,4‐dihydroxyphenylacetic acid. Phenoloxidase inhibitors such as potassium cyanide and sodium fluoride inhibited the enzyme activity drastically, but phenylthiourea showed marginal inhibition only. This result, coupled with the fact that syringaldazine served as the substrate for the insoluble enzyme, confirmed that cuticular phenoloxidase is of the “laccase” type. In addition, we also examined the mode of synthesis of the sclerotizing precursor, 1,2‐dehydro N‐acetyldopamine. Our results indicate that this catecholamine derivative is biosynthesized from N‐acetyldopamine through the intermediate formation of N‐acetyldopamine quinone and N‐acetyldopamine quinone methide as established forSarcophage bullata[Saul, S. and Sugumaran, M., F.E.B.S. Letters 251, 69–73 (1989)]. Accordingly, successful solubilization and fractionation of cuticular enzymes involved in the introdution of a double bond in the side chain of N‐acetyldopamine indicated that they included o‐diophenoloxidase, 4‐alkyl‐o‐quinone:p‐quinone methide isomerase, and N‐acetyldopamine quinone methide: dehydro N‐acetyldopamine isomerase and not a

ISSN:0739-4462    

DOI:10.1002/arch.940190406

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

年代:1992

数据来源: WILEY

摘要:

AbstractWe have partially characterized the proteolytic activity within luminal contents of the digestive tracts of larvae of the western corn rootworm,Diabrotic virgiferaLeConte. At least 15 proteinases were detected based on chromatographic behavior on ion exchange high‐performance liquid chromatography and their mobility on sodium dodecyl sulfate gels containing gelatin. Inhibitors of proteolytic activity indicated that these enzymes are primarily sulfhydryl proteinases. Native polycrylamide gel electrophoresis revealed that a single proteinaceous inhibitor, egg white cystatin, was capable of abolishing a substantial part of the proteolytic acitivity. Our data suggest, accordingly, that gene transfer experiments utilizing the cystatin gene may generate lines of maize which have increased resistance to western corn rootworm larvae. © 1992 Wiley‐Liss,

ISSN:0739-4462    

DOI:10.1002/arch.940190407

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

年代:1992

数据来源: WILEY

ISSN:0739-4462    

DOI:10.1002/arch.940190408

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

年代:1992

数据来源: WILEY

ISSN:0739-4462    

DOI:10.1002/arch.940190401

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

年代:1992

数据来源: WILEY