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At least 19 recordsLinked to original sources
PubMed1981

Moulting hormone, juvenile hormone and the ultrastructure of the fat body of adult Sarcophaga bullata (Diptera).

In the ovoviviparous fly, Sarcophaga bullata, vitellogenesis in cyclic; a process reflected in ultrastructural changes in the fat body cells and oenocytes. At eclosion the larval fat body has not yet completely disappeared. During vitellogenesis the fat body cells are specialized for intensive protein synthesis showing a very extensive RER and numerous invaginations of the plasma membrane. These features disappear when the eggs descend into the oviducts to complete embryogenesis. The predominant feature of the oenocytes is their very prominent SER. The fat body cells of the males are never as specialized for protein synthesis as those of the females. Feeding of ecdysterone to males for 3 or more days induces a rather extensive subcellular apparatus for protein synthesis, i.e., invaginations of the plasma membrane and an extensive RER. Juvenile hormone is completely ineffective in this respect. Both ecdysterone and juvenile hormone have pronounced but different effects on the oenocytes of males.

Adipose Tissue↗
PubMed1997

Development changes in juvenile hormone and juvenile hormone acid titers in the hemolymph and in-vitro juvenile hormone synthesis by corpora allata of the silkworm, Bombyx mori.

A simple method was developed to quantify hemolymph juvenile hormone (JH) and JH acid in hemolymph extracts from Bombyx mori with an established radioimmunoassay (RIA) for JH I. When various organic solvent extracts of hemolymph were assayed by RIA, levels of non-specific binding of the labeled ligand in the assay were determined to be greater than 50% of the maximum amount of the label bound by the antiserum. When hemolymph was diluted with methanol:water:8.4N ammonium hydroxide (10:9:1) and extracted with isooctane, non-specific binding was only 50% higher than control levels obtained with the assay buffer alone. The organic phase contained only JH and aqueous phase, JH acid. Consequently, this extraction method was used to prepare samples for RIA and enabled the separate measurement of JH and JH acid in hemolymph. With this method, changes in the hemolymph titers of JH and JH acid were determined from the third instar through early pupal stage of Bombyx mori. Changes in the in vitro secretory activity of corpora allata and brain-corpora cardiaca-corpora allata complexes from fifth instar larvae were also determined by using JH I RIA of the incubation medium.

Journal Article↗
PubMed1997

Effect of juvenile hormone and juvenile hormone mimics on sperm transfer from the testes of the male cat flea (Siphonaptera:Pulicidae).

Sperm transfer into the epididymis was completed without a blood meal, when newly emerged male cat fleas. Ctenocephalides felis (Bouché), were exposed to filter papers treated with juvenile hormone III or the juvenile hormone mimics fenoxycarb, methoprene, or pyriproxyfen. As the concentration of juvenile hormone or the time of flea exposure to juvenile hormone or the juvenile hormone mimics increased, the percentage of fleas that transferred sperm also increased. The percentage of pyriproxyfen-treated males that transferred sperm reached 100% after 3 d: whereas, 7 d exposure to juvenile hormone, fenoxycarb and methoprene was required for 100% of the males to transfer sperm. Although sperm were present in the epididymis of treated fleas, insemination of females did not take place off the host either on juvenile hormone-treated filter paper or on juvenile hormone-treated dog hair.

Animals↗
PubMed1996

Activity of juvenile hormone and juvenile hormone analogues on the growth of Trypanosoma cruzi.

The effects of juvenile hormone-III (JH-III) and the juvenile hormone analogues (JHA) methoprene and fenoxycarb on the growth and macromolecular biosynthesis in Trypanosoma cruzi were studied in vitro. It was observed that JH-III and JHA blocked growth and 3H-thymidine incorporation without killing the cells within certain concentrations (< or = 1 x 10(-4) M), but they caused cellular death at concentrations over 1 x 10(-3) M. The inhibitory effect on growth was partially reversible. On the other hand, the inhibitory action of JH-III, methoprene and fenoxycarb was an unspecific effect according to the results obtained with Leishmania mexicana mexicana (promastigotes) and human peripheral blood lymphocytes. The JHA have a good possibility of being used in the control of trypanosomiasis.

Animals↗
PubMedDate not supplied

The molecular site of action of juvenile hormone and juvenile hormone insecticides during metamorphosis: how these compounds kill insects.

Studies in a variety of insects during the past four decades has deepened our understanding of juvenile hormone (JH) physiology, but how this hormone works at the molecular level remains elusive. Similarly, the mechanism of toxicity of JH analogue insecticides is still in question. There is much evidence from laboratory usage that JHAs act as JH agonists and generally show the highest toxicity when applied at the onset of metamorphosis. A physiological basis for the toxicity and morphogenetic effects has been suggested by recent work linking these effects with interference with the expression or action of certain genes, particularly the Broad-Complex (BR-C) transcription factor gene, that direct metamorphic change. Misexpressed BR-C then leads to improper expression of one or more downstream effector genes controlled by BR-C gene products, resulting in abnormal developmental and physiological changes that disrupt metamorphosis. Therefore, JH is a necessary molecule at certain times in insect development but becomes toxic when present during metamorphosis.

Animals↗
PubMed2000

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.

Journal Article↗
PubMed2000

Juvenile hormone titers, juvenile hormone biosynthesis, ovarian development and social environment in Bombus terrestris.

The effects of the social environment and age on juvenile hormone (JH) and reproduction were investigated by measuring ovarian development, hemolymph levels of JH III, and rates of JH biosynthesis from the same individual bumble bees (Bombus terrestris). Differences in social environment were associated with differences in rates of JH biosynthesis, JH titer and ovarian development. Young queenless workers had a higher rate of JH biosynthesis, JH titer and ovarian development than queenright (QR) workers of similar age. Dominant workers in QR colonies had a higher rate of JH biosynthesis, JH titer and ovarian development than low ranked workers of similar size. There was a positive correlation between JH titer and ovarian development, but no correlation between rate of JH biosynthesis and ovarian development or between JH biosynthesis and JH titer. Both JH titer and rate of JH biosynthesis increased with age from emergence to 3 days of age, but 6-day-old workers, egg-laying workers, and actively reproducing queens had high JH titers and highly developed ovaries but low rates of JH biosynthesis. These results show that reproduction in B. terrestris is strongly affected by the social environment and the influence of the environment on reproduction is mediated by JH. Our data also indicate that the rate of JH biosynthesis measured in vitro is not a reliable indicator of JH titer or ovarian development in B. terrestris; possible reasons are discussed.

Journal Article↗
PubMed1991

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.

Animals↗
PubMed1994

Regulation of juvenile hormone esterase gene transcription by juvenile hormone.

Juvenile hormone (JH) is a major hormone regulating insect development. We have obtained a cDNA and a genomic clone for juvenile hormone esterase (JHE), the enzyme that is involved in the degradation of juvenile hormone and which is critical for insect development. Analysis of the regulation of JHE during the final larval stadium in the cabbage looper, Trichoplusia ni, showed that the JHE mRNA levels are maximal on days 2 and 4 of the final stadium. Nuclear run-on analyses demonstrated that changes in JHE mRNA levels are primarily due to changes in the transcription rate of the gene, which may be a single copy in the genome. Treatment with a JH analog resulted in induction of JHE gene transcription, which could be detected within three hours after treatment. Salient features present in the 5' flanking region of this JH-sensitive gene are presented, including the presence of sequences closely resembling binding sites for members of the family of nuclear receptors. This report is the first direct demonstration, by nuclear run-on analysis, of JH induction of gene transcription.

Amino Acid Sequence↗
PubMed1997

Hydroxy juvenile hormones: new putative juvenile hormones biosynthesized by locust corpora allata in vitro.

The in vitro production of sesquiterpenoids was investigated by using corpora allata (CA) of the African locust Locusta migratoria migratorioides. Labeled products from unstimulated biosynthesis were extracted, purified by normal phase HPLC, and derivatized to determine the functional groups present. An extra hydroxyl group was detected in each of two juvenile hormone (JH) biosynthetic products. One compound, NP-8, was found to co-migrate with a chemically-synthesized (Z)-hydroxymethyl isomer, 12'-OH JH-III, but not with the (E)-hydroxymethyl isomer, 12-OH JH III. Mass spectral analyses further supported the identity of the synthetic material with that biosynthesized by the corpora allata. A second compound was identified as the 8'-OH JH-III based on spectroscopic analyses. 12'-OH JH-III exhibited morphogenetic activity when tested on the heterospecific Tenebrio test. These data suggest that 12'-OH JH-III and 8'-OH JH-III are additional biosynthetically-produced and biologically-active juvenile hormones, and constitute the first known members of the class of hydroxy juvenile hormones (HJHs).

Animals↗
PubMed1997

Ultraspiracle: an invertebrate nuclear receptor for juvenile hormones.

Juvenile hormones (JH), a sesquiterpenoid group of ligands that regulate developmental transitions in insects, bind to the nuclear receptor ultraspiracle (USP). In fluorescence-based binding assays, USP protein binds JH III and JH III acid with specificity, adopting for each ligand a different final conformational state. JH III treatment of Saccharomyces cerevisiae expressing a LexA-USP fusion protein stabilizes an oligomeric association containing this protein, as detected by formation of a protein-DNA complex, and induces USP-dependent transcription in a reporter assay. We propose that regulation of morphogenetic transitions in invertebrates involves binding of JH or JH-like structures to USP.

Animals↗
PubMed1992

In vivo and in vitro biosynthesis and metabolism of methyl farnesoate, juvenile hormone III, and juvenile hormone III acid in the mosquito Aedes aegypti.

Biosynthesis and metabolism of juvenile hormone (JH) III in vivo and in vitro were studied in female Aedes aegypti (L.). [12-3H]Methyl farnesoate was used to follow the synthesis and [12-3H]-(10R)-JH III to study metabolism. The rate of biosynthesis of [12-3H]JH III in vivo after adult eclosion increased from 9 fmol/h per female at 1 h to 22 fmol/h per female at day 6. The rate of biosynthesis by exposed corpora allata (CA) in vitro was 23 fmol/h per CA during the 1st d after adult eclosion, then dropped to 4.8 fmol/h per CA on day 3, then increased again to a constant level of synthesis (12 fmol/h per CA) at days 4-6. Immediately after blood feeding, the rate of synthesis of [12-3H]JH III in vivo and in vitro increased to 27 fmol/h per female and to 23 fmol/h per CA, respectively. The rate of synthesis then decreased in vivo to 12 fmol/h per female at 4 h and in vitro to 6 fmol/h per CA 10 h after the blood meal. After this decrease, the rate of synthesis of [12-3H]JH III increased again reaching a peak of 25 fmol/h per female at 48-96 h in vivo and 12 fmol/h per CA at 72 h in vitro. These results indicated that the CA of sugar-fed and blood-fed female A. aegypti synthesized JH III in vivo and in vitro from [12-3H]methyl farnesoate. When [12-3H]-(10R)-JH III metabolism was followed in vivo in female A. aegypti, the ratio between JH III diol acid:JH III acid:JH III diol was 17:4:1, indicating that JH III was first hydrolyzed by JH III esterase to the acid form, then hydrated to the diol acid by JH III epoxide hydrase. Females treated with [12-3H]JH III acid converted 46% of the JH III acid in 60 min to the diol acid. These results indicated that the enzyme epoxide hydrase acted on JH III acid 17 times faster than JH III.

Aedes↗
PubMed1991

Reversible juvenile hormone inhibition of ecdysteroid and juvenile hormone synthesis by the ring gland of Drosophila melanogaster.

Juvenile hormone bisepoxide (JHB3) and juvenile hormone III (JH III) both inhibited the in vitro production of ecdysteroids by ring glands and brain-ring gland complexes from third instar post-feeding larvae of Drosophila melanogaster in a reversible manner, although JHB3 had greater efficacy. The JH III and JHB3 precursor, methyl farnesoate, did not affect ecdysteroid production. The in vitro synthesis of total detectable JH (JHB3 + JH III + methyl farnesoate) by the corpus allatum portion of the isolated ring gland was also inhibited reversibly in the presence of exogenous JHB3 and JH III, but not by methyl farnesoate. These data indicating negative feedback are in agreement with the accepted dogma of endocrine gland regulation.

Animals↗