Morphological effects of juvenile hormone mimics on embryonic development in the bug,Pyrrhocoris apterus

Summary Embryos ofPyrrhocoris apterus exposed to juvenile hormone mimics (JH) were examined throughout development to determine the progressive effects of treatment. Prior to blastokinesis whole experimental embryos did not differ morphologically from control embryos fixed at the same stage. Treated embryos failed to complete blastokinesis due to abnormal breakage of the extra-embryonic membranes.In the embryo-larva transition, JH exposure interfered with dorsal closure, with the consolidation of the nerve cord, and with the extension of appendages. Yet pigmentation and muscle differentiation occurred.These effects were interpreted and discussed with reference to the role of juvenile hormone in post-embryonic development.This is a portion of a dissertation submitted to the graduate school of Harvard University, in partial fulfillment of the requirements for the degree of Doctor of Philosophy (1973). It was previously reported in abstract (Enslee and Riddiford, 1970). This research was supported by NIGMS Training Grant T01 GM 00036-09, 11, 12, 13 to E.C.E. and NSF grants GB 6730, GB 7966 to L.M.R.     

Chemical structure, juvenile hormone activity and persistence within the insect of juvenile hormone mimics for Rhodnius prolixus.

41 chemicals were tested for juvenile hormone (JH) activity for Rhodnius prolizus by two methods of application. Several different classes of chemical were represented, viz. long chain terpenoid compounds, aryl terpenoid compounds, aryl terpenoid amines and aryl terpenoid ethers.All classes of chemical contained members which showed at least moderate activity. The most active compound was N-(2,5-dichlorophenyl)-3,7-dimethyl-2,6-octadienylamine; 0.0024 μg induced the production of an insect which was halfway between a normal adult and a complete supernumerary larva. Since several compounds with widely differing chemical groupings showed high JH activity, it is considered that overall molecular size and shape are important considerations in determining JH activity, although they do not by themselves provide a complete explanation. Some chemicals tested are specific in their JH activity to relatively few insects. JH mimic specificity is discussed and it is considered that molecular shape can explain some aspects of this phenomenon.The persistence within the insect of the JH mimics varied greatly. In general, compounds with a methyl ester group at one end and an epoxide group at the other had least persistence. The absence of one or more of these features tends to induce greater persistence. Within most classes of chemical, the members with highest JH activity tended to have least persistence and it is considered that the major factor affecting persistence with the insect is the rate of enzymic degradation of the JH mimic.     

Juvenile hormone and juvenile hormone mimics inhibit proliferation in a lepidopteran imaginal disc cell line

The action of juvenile hormone (JH) and JH mimics have been examined in vitro by utilizing the imaginal disc-derived cell line, IAL-PID2. We have discovered that the cell line was responsive to JH and a variety of JH mimics. The most consistent response obtained in our studies was inhibition of cell proliferation, in the absence of 20-hydroxyecdysone (20E), which characteristically reduces cell proliferation in its own right in this cell line. JH-I, JH-III, methoprene, fenoxycarb, and farnesol significantly inhibited cell proliferation after 3 days of exposure of the cells in vitro to each of the compounds. Linoleic acid controls had no effect on proliferation in the cultures. The cell proliferation assay demonstrates the JH responsiveness of this cell line, but the concentrations of JH required were high compared to the concentrations of 20E needed for inhibition of proliferation in these cells.     

A comparison of the morphogenetic and sterilizing activities of juvenile hormone mimics on Aedes aegypti

At 25°C, adult female aedes aegypti are most sensitive to sterilization by juvenile hormone (JH) mimics when such chemicals are applied 32 to 36 hr after the blood meal (when the ovaries are at late stage III to early stage IV). Application of JH mimics during this period reduces egg fertility and female fecundity and induces the production of large numbers of visually abnormal eggs. As the most sensitive phase for sterilization with JH mimics is well before oviposition, and as many abnormal eggs are laid following JH mimic treatment, it is likely that in this species sterilization effects are induced by some action on the developing oöcyte rather than on embryonic development.The relative activities of several JH mimics in sterilizing adult female A. aegypti are very similar to their relative activities in inhibiting metamorphosis. Thus the sterilizing action of JH mimics is likely to be a true JH effect and can be used as a test for JH activity for A. aegypti.     

Diapause termination in Anopheles freeborni with juvenile hormone mimics

Diapausing Anopheles freeborni females receiving either topical applications or ingesting the juvenile hormone mimic ZR-515 terminated diapause. This was reflected by increased blood feeding, followed by the maturation of eggs. ZR-515 also significantly increased adult mortality and decreased egg hatching. Another juvenile hormone mimic R-20458 did not increase blood feeding, but did stimulate vitellogenesis in those mosquitoes ingesting a blood meal.

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Zusammenfassung Anopheles freeborni ist eine der wichtigsten Stechmücken im nördlichen Central Valley von Kalifornien; man nimmt an, daß sie ein Malaria-Vektor in diesem Gebiet gewesen ist. Begattete Weibchen überwintern, und es erfolgt, selbst wenn sie in der Herbst-Winter-Periode Blut saugen, keine Ovarienentwicklung (d.h. also gonotrophische Dissoziation). Wir sammelten diapausierende Tiere aus dem Freiland im frühen Oktober und behandelten sie mit ZR-515 (Zoecon Co.), einem Juvenilhormon-Mimetikum, entweder durch topikale Applikation (1 und 10 g) oder durch Aufnahme von Lösungen (20 ppm und 200 ppm in 10% Rohrzucker). In beiden Fällen wurde die Diapause bei den behandelten Tieren beendet. Dies zeigte sich durch verstärktes Blutsaugen mit nachfolgender Reifung der Eier im Vergleich mit Kontrolltieren, die mit Azeton behandelt worden waren oder 10%ige Zuckerlösung aufgenommen hatten (Tab. I). Dieser Versuch wurde Ende November wiederholt. Wie zuvor vergrößerte ZR-515 signifikant das Verhältnis blutsaugender Stechmücken und den Anteil von Stechmücken, die zur Eiablage kamen (Tab. II). Jetzt saugte allerdings auch eine erhebliche Zahl von unbehandelten Kontrolltieren Blut. Dies zeigt vermutlich den nahe bevorstehenden Zeitpunkt der natürlichen Diapause-Beendigung an, die um das Ende des Dezembers eintritt. ZR-515 erhöhte auch die Mortalität der Adulten und die Autogenic-Raten, und minderte das Schlüpfen der Eier.Es wurde bei diapausierenden November-Adulten auch noch ein anderes Juvenilhormon-Mimetikum, R-20458 (Stauffer Co.) in Dosen von 1 und 10 g topikal angewandt; die Ergebnisse waren einigermaßen anders. Das Blutsaugen erhöhte sich zwar bei keiner der beiden Dosen, aber die Eireifung nahm bei den behandelten Stechmücken signifikant zu. Da unsere Ergebnisse anzeigen, daß eine gonotrophische Dissoziation unabhängig von Blutsaugetrieb zu Ende kommen kann, so vermuten wir eine verschiedene hormonale Steuerung dieser beiden Funktionen.

     

The effect of the persistence of juvenile hormone mimics on their activity on Rhodnius prolixus

The apparent juvenile hormone (JH) activity of methyl 12-homo-juvenate on fed fifth instar Rhodnius prolixus is nearly twelve times greater if the compound is applied topically over a period of 7 days (serial application) rather than as a single dose 1 day after feeding. Of five other JH mimics tested, four were more active by serial application, although none showed so great an increase in activity as methyl 12-homojuvenate; only farnesyl methyl ether was more active by single application. It is considered that the generally greater activity shown in the serial application tests is because less JH mimic is wasted by degradation and/or excretion. Therefore the serial application test provides a more accurate estimate of inna e JH activity than the single application test.     

Effects of dopamine on juvenile hormone metabolism and fitness in Drosophila virilis

The effects of dopamine (DA) on juvenile hormone (JH) metabolism and fitness (estimated as fecundity and viability levels under heat stress (38 °C)) in Drosophila virilis have been studied. An increase of DA level obtained by feeding with DA reduced fitness of wild-type (wt) flies under stress, and decreased JH degradation in young wt females while increasing it in sexually mature wt females. A decrease in DA levels resulted from 3-iodo-tyrosine treatment and caused a decrease in JH degradation in sexually mature wt and heat sensitive (hs) mutant females (DA level in hs females is twice as high in wt females). A dramatic decrease in viability under stress and fecundity under normal conditions in wt, but not hs, females was observed. 3-iodo-tyrosine treatment also reduced the number of oocytes at stages 8-14, delayed oocyte transition to stage 10 and resulted in the accumulation of mature eggs in wt females. It delayed maturation of wt, but not hs, males as well, but did not affect their fertility. This advances our understanding of the regulation of JH metabolism by DA in Drosophila and suggests a crucial role for the basal DA level in fitness.     

Comparison of effects of juvenile hormone mimic and synthetic juvenile hormone I on the bug Lygaeus kalmii

ABSTRACT. The possibility that JH mimics cause artifactual responses was investigated by comparing one such mimic (JH-M) and a 'true' JH (JH I) in the effects of each upon L.kalmii larval colouring and development. Post-blastokinesis treatment with synthetic JH I affected larval colour pattern in the same way as JH-M, but higher hormone concentrations were required. JH I also caused higher larval mortality. JH-M and JH I were equally effective in producing supernumerary instars.     

The titre of juvenile hormone during the pupal and adult stages of the life cycle of Drosophila melanogaster

Using combined gas chromatography/selected-ion mass spectroscopy, the titer of juvenile hormone was determined for whole-body extracts at various morphologically defined stages of the life cycle of Drosophila melanogaster. Only juvenile hormone III (JH-III) was detected. JH-III is present in early metamorphosis but by mid-metamorphosis it is below the level of detection (0.05 pmol/g). It then increases as the pharate adult matures and rises dramatically, beginning just prior to eclosion and reaching 5-7 pmol/g shortly after eclosion. The titer then begins to fall again as the adults mature in both males and females, though the decrease is more rapid in females. Preliminary studies show that low levels of JH-III are present during all the larval instars but are absent from eggs.     

Effects of alpha amanitin and juvenile hormone analogue (ZR-515) on labelling of RNA and protein in adult Drosophila

Approximately 2% of the RNA molecules of young adult D. melanogaster females is associated with poly(A) sequences. Topical application of juvenile hormone analogue (ZR-515) increased the polyadenylated fraction of RNA to 8%. Alpha amanitin blocked the JHA-induced increase in poly-A containing sequences and suppressed protein synthesis within the first 24 hours of adult life.     

Brain-controlled synthesis of juvenile hormone in adult insects

Conclusions and future research There is now quite substantial evidence that the MNSC and the LNSC produce CA regulatory substances which are transported along axons and released in the immediate vicinity of the gland cells and that this system forms the most important means of CA control from the brain. The putative allatostatins and allatotropins are most probably neuropeptides. Isolation and identification of these substances are priorities in the coming years. The neuroendocrinological aspects, such as the precise rôle of the MNSC and the LNSC in different species; whether allatotropins and allatostatins arise from a single precursor molecule, and the dynamics of release of the substances from the nerve terminals, provide highly interesting topics. Furthermore, questions concerning control mechanisms of JH-biosynthesis at the cellular and molecular level, including the role of second messengers, the rate limiting steps in the biosynthetic pathway, and the regulation of gland growth still need to be clarified.     

Morphogenetic and physiological effects of a juvenile hormone analogue on the light brown apple moth,Epiphyas postvittana (Lepidoptera: Tortricidae)

Abstract

The juvenile hormone analogue ZR-619—ethyl 11-methoxy-3,7,11-trimethyl-(2E,4E-dodecadienethiolate) —produced morphological and physiological effects when fed via artificial diet to larvae of Epiphyas postvittana (Walker). Morphological effects included changes in larval head and antennal structures after instar V (supernumerary instars); deformation of pupal and adult structures, particularly in genitalia and wings; and development of individuals with varying mixtures of larval and pupal structures. Physiological effects included prolongation of larval life, increase in larval weight, increase in larval instars, and decrease in fecundity. Effects were directly related to dosage concentrations.     

Effects of juvenile hormone on the ecdysone response of Drosophila Kc cells

Drosophila Kc cells are ecdysone-responsive: hormone treatment leads rapidly to increased synthesis of several ecdysone-inducible polypeptides (EIPs) and to commitment to eventual proliferative arrest. Later, the treated cells undergo morphological transformation, cease to proliferate, and develop new enzymatic activities, notably, acetylcholinesterase (AChE) activity. These responses have proven useful as models for studying ecdysone action. Here we report the sensitivity of Kc cells to another important insect developmental regulator--juvenile hormone (JH). We find that JH inhibits some, but not all, aspects of the ecdysone response. When Kc cells are treated with ecdysone in the presence of either natural JHs or synthetic analogues, the morphological and proliferative responses are inhibited and AChE induction is blocked. Most striking is that JHs protect the cells from the rapid proliferative commitment induced by ecdysone alone. The JH effects exhibit reasonable dose-response curves with half-maximal responses occurring at very low JH concentrations. Nonetheless, even at high JH concentrations the inhibitory effects are incomplete. It is interesting that EIP induction appears to be refractory to JH. It seems clear that JH is not simply a generalized inhibitor of ecdysone-induced responses.     

In vitro metabolism of juvenile hormone III and juvenile hormone III bisepoxide by Drosophila melanogaster and mammalian cytosolic epoxide hydrolase

In vitro metabolism of juvenile hormone III (JH III) and juvenile hormone III bisepoxide was investigated using purified mouse liver cytosolic epoxide hydrolase (cEH) and cell fractions from Drosophila melanogaster. JH III was metabolized faster than JH III bisepoxide by epoxide hydrolase activity in D. melanogaster cell fractions and by cEH. After incubation with JH III bisepoxide, all cell fractions and cEH produced epoxy-diol, cis- and trans-tetrahydrofuran-diols, and tetraol as metabolites. An increase in the concentration of cEH resulted in an increase in the proportion of tetraol as a JH III bisepoxide metabolite but this trend was not observed in the D. melanogaster cell fractions. Differences between cell fractions in the metabolism of JH III and JH III bisepoxide suggests the presence of juvenile hormone epoxide hydrolase isozymes.     

保幼激素类似物对白蚁的作用研究进展

本文介绍了保幼激素类似物对白蚁的影响,包括诱导前兵蚁、兵蚁和一些中间品级(形态畸形)的产生、抑制白蚁的取食、减少或消除白蚁的共生原生动物群、对白蚁产生不同水平的急性和慢性毒性、抑制工蚁蜕皮以及繁殖蚁建立新群体等方面的影响,其中最主要影响是诱导前兵、兵蚁和一些中间品级的产生破坏了白蚁群体品级比例的平衡性或完整性.因此,保幼激素类似物可用于白蚁的防治,并在田问防治散白蚁和乳白蚁均取得了较好的防治效果,并探讨了应用保幼激素类似物防治白蚁的潜力与前景.