Juvenile Hormone Activity Research Articles

Hormonal Control of Vitellogenin Uptake in Rhodnius prolixus Stål

SYNOPSIS. In Rhodnius , vitellogenesis is characterized by the appearance of large spaces between the cells of the follicular epithelium, a condition which is called patency. Patency is a response to juvenile hormone (JH) secreted by the corpus allatum. JH brings about an increase in patency by causing the follicle cells to shrink, an effect which may be mediated by (Na+-K+) ATPase. Follicle cells which have differentiated in the absence of JH fail to respond to JH with an increase in patency. The follicle cells are also affected by an andgonadotropin from neurosecretory cells in the abdomen. This anti-JH antagonizes the patency-inducing action of JH.

Perturbation of phospholipid membranes by juvenile hormone

The effects of juvenile hormone and its analogs Altozar 4E and ZR-777 5E on the phase properties of liposomes prepared from dipalmitoyl phosphatidyl-choline (DPPC) have been examined by differential scanning calorimetry. Each of these compounds reduced the co-operativity of the gel to liquid-crystalline phase transition, which is manifest as a distinct broadening of the main transition endotherm, and split the transition into two distinguishable components centered at 34 and 37°C. However, there was no significant change in enthalpy of the main phase transition, suggesting that juvenile hormone and its analogs perturb the bilayer primarily in the vicinity of the phospholipid headgroups. Moreover, this perturbation does not appear to influence bilayer permeability since the osmotic swelling rates of liposomes prepared from either phosphatidylcholine or dipalmitoyl phosphatidylcholine that contained up to 33 mol% juvenile hormone were not significantly different from the swelling rates of corresponding liposomes containing no juvenile hormone. Splitting of the transition endotherm into two peaks appeared to be peculiar to compounds possessing juvenile hormone activity. A mixture of fatty acid methyl esters broadened the main transition of DPPC, but did not split the endotherm or shift the transition midpoint, and the insect hormone ecdysone had no discernible effect on the DPPC transition apart from eliminating the pretransition. The data indicate that juvenile hormone and its analogs can modulate the physical properties of phospholipid bilayers, and raise the prospect that some of the physiological effects of this hormone may be achieved through its influence on the molecular organization of membrane lipid.

Synthesis of compounds with juvenile hormone activity. Synthesis and biological activity of some dibromoalkadienyl ether analogs of juvenile hormone.

Synthesis of compounds with juvenile hormone activity. Synthesis and biological activity of some dibromoalkadienyl ether analogs of juvenile hormone.

Studies on the utilization of methoprene, a synthetic compound with juvenile hormone activity, for the silkworm rearing

Studies on the utilization of methoprene, a synthetic compound with juvenile hormone activity, for the silkworm rearing

The syntheses of biologically active 2-(4-hydroxybenzyl)-1-cyclohexanone derivatives

The syntheses of various 2-(4-hydroxybenzyl)-1-cyclohexanone derivatives are described in connection with the development of the research of substances with juvenile hormone activity.

A new method of preparation of α,β-γ,δ-unsaturated secondary alcohols

A method of preparation of β-hydroxy-γ,δ-unsaturated nitriles used as intermediates for the synthesis of α,β-γ,δ-unsaturated ketones and alcohols, and having the activity of insect juvenile hormone is described.

Regulation of the Juvenile Hormone Titer

Juvenile hormone (JH) is produced by the corpora allata (CA) of insects. It regulates development and reproduction and also plays a crucial role in polymorphism. These functions have been amply reviewed (13, 21, 23, 29, 30, 112, 141). However, little information is available on the mechanisms of these effects, mainly because of the difficulty in interpreting the results of in vivo experiments. For example, the experimental insect is often treated with JH or a JH analogue, but the exogenously supplied JH may interact with other insect hormones such as ecdysone and neurosecretory hormones (68), may be metabolized rapidly, and may interfere with endocrine feed­ back loops. An unequivocal explanation of the role of JH in insect development and reproduction will be obtained only with an approach in vitro, in which these disadvantages play no role. As suitable organ and tissue culture systems for insects have become available during the last few years, the mechanism of JH action may soon be resolved. The effect of any hormone is actually determined by three factors (29): (a) The concentration of the circulating hormone, i.e. the hormone titer, (b) The interaction between hormone and cellular receptors, and (c) Regu­ lation by the hormone or hormone-receptor complex of transcriptional,

Isolation of ommochromes and 3-hydroxykynurenine from the tobacco hornworm, Manduca sexta

A complex of the two red pigments was prepared from epidermis of the fifth instar larvae of the black mutant of the tobacco hornworm according to the method generally available for ommochromes. The primary component, a brick-red pigment (II), was shown to be identical with synthetic l-dihydroxanthommatin by various physico-chemical tests. The other red pigment (I) was similar to pigment (II), except in the i.r. spectra in 1000–1150 cm −1 region and is thought to be also an ommatin. A red pigment identical with pigment (I) was obtained during the chemical oxidation of 3-hydroxy- l-kynurenine. These same two pigments were found in the red epidermis underlying the black cuticle of larvae either allatectomized or neck-ligatured before the critical period for juvenile hormone action during the last larval molt. Also, they were found in the dorsal epidermis of wandering stage larvae. 3-Hydroxykynurenine, the immediate precursor of the ommochrome pigments, was found to accumulate in the epidermis before the synthesis of the ommochromes began.

Juvenile hormone-controlled vitellogenin synthesis in the fat body of the locust ( Locusta migratoria): Isolation and characterization of vitellogenin polysomes and their induction in vivo

With the aid of EGTA to control the endogenous RNase activity, a predominant population of heavy polysomes was isolated from the fat body of reproductively active female locusts. The identity of these as vitellogenin (Vg)-synthesizing polysomes was established by precipitation of the associated nascent polypeptides with anti-vitellin serum and by translation of the polysomal RNA in Xenopus laevis oöcytes. By EM observation these polysomes were found to contain 40–50 ribosome monomers. In normal development, accumulation of ribosomes in the fat body of female locusts began at about day 6 after adult ecdysis (terminal oöcyte = 2 mm or smaller), and was followed by the appearance of Vg-polysomes beginning at 3 mm terminal oöcyte length (about day 8–10 after adult ecdysis). The content of Vg-polysomes reached a maximum at 5–6 mm oöcyte length (about day 14), and then fell to an undetectable level as the oöcytes reached their maximum size (7 mm). In allatectomized females, Vg-polysomes were induced by treatment with an active juvenile hormone analogue, ZR-515. A single application with ZR-515 produced a massive accumulation of ribosomes and light polysomes in the first 48 hr which was followed by the rapid formation of Vg-polysomes to give a maximum at 72 hr. After the decay of this effect a second dose of ZR-515 resulted in the rapid appearance of Vg-polysomes without the initial generation of ribosomes.

Insect endocrinology: action of hormones at the cellular level.

The endocrine regulation of the life of the insect is based on the ecdysteroids (ecdysone, 20-hydroxyecdysone), juvenile hormone (JH), and a myriad of neurosecretory peptide hormones, most of which have yet to be purified and sequenced. Ecdysteroids and JH control both growth and development and later reproductive maturation. The neurohormones regulate the release of these two hormones and also a variety of homeostatic activities and behav­ ior. The preceding review in this volume (47) discusses the regulation of the endocrine glands and the chemistry and metabolism of the hormones. This review is concerned with the hormonal regulation of physiological pro­ cesses. Since there have been many recent reviews of various aspects of insect endocrinology and insect hormone action (13, 26, 36,48, 50-52, 60, 99, 111, 112, 120) I concentrate here on a few systems that promise to better our understanding of the action of ecdysteroids and juvenile hormone at the cellular level, in both morphogenesis and reproduction. I then discuss the actions of two identified peptide hormones.

Juvocimenes: Potent Juvenile Hormone Mimics from Sweet Basil

Two compounds with highly potent juvenile hormone activity were isolated and identified from the oil of sweet basil, Ocimum basilicum L., Labiatae.

Juvenile hormone mimics the photoperiodic apterization of the alate gynopara of aphid, Aphis fabae

Extensive investigations of the environmental factors influencing the alate–apterous dimorphism of the summer, parthenogenetic, virginoparous generations of aphids have shown that crowding has a major influence on the development of the alate morph, although temperature and nutrition are also important1,2. These factors may act prenatally, postnatally or both, depending on the species. However, the physiological control of this dimorphism within the individual has not been elucidated. As the apterous adult and the larvae share certain morphological features3 it has been suggested that the hormone controlling larval–adult metamorphosis, juvenile hormone (JH), also influences development of apteriform characteristics4,5. Indirect evidence from measurements of corpus allatum (CA) volumes and CA nuclei were believed to support this theory6 and early experiments with topically applied JH extracts and analogues seemed to divert alate development towards the apterous condition2,5. Attempts to obtain more direct evidence have been negative or inconclusive6. Recently, Lees7 has questioned this hypothesis, citing the following evidence: (1) examination of more extreme forms produced by topical application of JH mimics to middle instar alatae shows them to be developing towards a fifth instar, supernumerary larva (that is juvenilization) rather than towards an apterous morph (that is apterization); (2) in an autumn, short-day-induced alate morph of Aphis fabae, namely the gynopara (see below), authentic apterization can be effected by postnatal exposure to long photoperiods, the first larval instar being most sensitive to this treatment. By contrast, it was the late second and the third instars that were most sensitive to juvenilization following topical application of JH analogues. It is shown here that larger doses of a more active hormone (JH1) will closely mimic the photoperiodic apterization of these gynoparae but that apterization is not due to the neotenic action of JH. Evidence is also presented suggesting that the alateapterous dimorphism in summer, long-day generations is not controlled by JH.

Diapause development in the tobacco hornworm: A role for ecdysone or juvenile hormone?

Injection of a moderate dose of 20-hydroxy-ecdysone (20-HE) or a large dose of juvenile hormone analog leads to prompt termination of diapause in pupae of the tobacco hornworm, Manduca sexta (Johannson). Both agents appear to exert their major stimulatory effect directly on the neuroendocrine system. There is little or no change in the 20-HE ED 50 during diapause development, and injection of a subthreshold dose of 20-HE does not alter the duration of diapause. Hemolymph juvenile hormone activity is indetectable in diapausing pupae, and allatectomy of young pupae does not affect diapause duration. Results are discussed in light of a possible role for ecdysone or juvenile hormone in diapause development.

Independently regulated juvenile hormone activity and vitellogenesis in mosquitoes

Temporally distinct, head-mediated processes regulate vitellogenic development as well as juvenile hormone (JH)-mediated development of ovarian follicles of Aedes aegypti. In blood-fed adult mosquitoes, vitellogenic development is stimulated during the first day after blood is imbibed and JH secretion is stimulated 2 days later. JH secretion in recently ecdysed adult mosquitoes is stimulated during or shortly before ecdysis. These observations suggest that vitellogenesis follows blood-ingestion, whereas JH activity may secondarily be promoted by vitellogenesis. It may be that vitellogenesis and JH activity are mediated by different brain hormones

Juvenile hormone and moulting hormone titres in diapause- and non-diapause destined flesh flies

Failure of the brain to stimulate the prothoracic gland to release ecdysone has been widely regarded as the basis for diapause in insect pupae. In diapause-destined flesh flies, the absence of a peak of moulting hormone around the time of pupal head eversion supports this contention, but in addition, major pulses of juvenile hormone (JH) activity with a rhythmicity of 24 hr are unique to flesh flies destined for pupal diapause. JH activity persists during diapause, and a pulse of JH precedes the rise of moulting hormone that initiates adult development.

The action of insect juvenile hormone on the hatching of eggs of the nematode, Haemonchus contortus, and its role in the development of infective and non-infective stages

1. 1. With a gas phase of CO 2-free air the inhibitory action of the analogues of juvenile hormone, “dichlorofarnesoate” and farnesol (JH) on the hatching of eggs of Haemonchus contortus was markedly affected by [H +]. The pK of the inhibitory effect was 6.8; above pH 7 inhibition was weak, below 6.5 it was strong. 2. 2. The inhibition of hatching of eggs in 0.1 M NaCl containing JH, 3 × 10 −4 M, and under a gas phase of air, increased as the temperature was raised from 20 to 37°C. 3. 3. In buffer at pH 6 and under air, increases in temperature to 37°C did not inhibit hatching in the absence of added JH. However, when CO 2 was removed from the gas phase hatching was inhibited at the higher temperatures. 4. 4. Acetazolamide, 10 −3M, and ethoxyzolamide, 2 × 10 −5 M, inhibited the exsheatment (ecdysis) of third stage juveniles of H. contortus. 5. 5. The significance of these results in providing a hypothesis for features in the life cycle of nematodes, and in providing a hypothesis describing the action of JH on the target cell, is discussed.

Juvenile Hormone Activity of 4-Oxa-Farnesane Derivatives

Juvenile hormore activity of 63 derivatives of 4-oxa-farnesane with various substituents at C-1 and C-11 on Dysdercus koenigii (Hemiptera : Pyrrhocoridae) is reported and structure/activity relationship is discussed. Highest activity was found in aromatic amides with carboalkoxy group in the p-position. Substitution of methoxy group at C-11 enhanced activity.

Products active on arthropod. II. Insect juvenile hormone mimics. 2. Insect juvenile hormone mimics based on bakuchiol.

Several derivatives of bakuchiol, a meroterpenoid from Psoralea corylifolia Linn., have been prepared and evaluated for insect juvenile hormone activity against Dysdercus koenigii nymphs. Almost all of these were found to be more active than the standard farnesyl methyl ether, while some of these proved to be many times more potent.

Influence of ecdysterone, precocene and compounds with juvenile hormone activity on induction, termination and maintenance of diapause in the parasitoid wasp, Nasonia vitripennis

ABSTRACT. Using the Galleria bioassay, no difference could be found between the JH titre of diapausing and developing Nasonia larvae. Compared to the values found in some Lepidoptera, the JH titres in Nasonia larvae are low, c. 14 Galleria units/g live weight. Induction of diapause could not be brought about by topical application of JH I, JH analogues, precocene, or ecdysterone to the maternal generation, nor by treating eggs or larvae with compounds with JH activity. Diapause was easily terminated by topical application of ecdysterone, however. If ecdysterone treatment was preceded by JH‐treatment, the percentage of larvae terminating diapause was reduced: JH II seems to be more potent than JH I or JH III in this effect if the interval between JH and ecdysterone treatment is 72 h.

In vitro induced pinocytotic activity by a juvenile hormone analogue in oocytes of Drosophila melanogaster.

Pinocytotic activity has been analyzed in Drosophila oocytes following either in vivo or in vitro exposure to horseradish peroxidase. The enzyme tracer gains access to the yolk spheres only when supplied to the oocyte in vivo. In oocytes cultured in vitro, peroxidase remains restricted to the residual coated vesicles and to the tubular profiles formed in excess in the cortical ooplasm. In an attempt to induce peroxidase uptake by oocytes cultured in vitro, various incubations were tested. Among these, hemolymph from both sexes is capable of promoting peroxidase uptake up to a level comparable to that detectable in vivo. On the other hand, fat body extracts fail to promote such cellular activity. Finally, the juvenile hormone analogue ZR-515 is shown to be the only factor required to promote pinocytotic activity under the experimental conditions tested. The observations are interpreted to indicate that vitellogenin has no inductive role on pinocytosis but simply acts by adhering to the forming coated vesicles which in turn are produced by the oolemma in response to the action of juvenile hormone.