Search results for "ecdysone"
showing 10 items of 30 documents
Biosynthesis of ecdysones in isolated prothoracic glands and oenocytes of Tenebrio molitor in vitro.
1974
Abstract Isolated prothoracic glands from Tenebrio larvae synthesize in vitro α-ecdysone, but not β-ecdysone from 4-14C-cholesterol. Isolated abdominal oenocytes from the larvae synthesize mainly β-ecdysone, but only little α-ecdysone. When prothoracic glands and oenocytes are cultured together, the α-ecdysone derived from the prothoracic glands is oxidized by the oenocytes to β-ecdysone. The newly synthesized hormones are not stored in the cells, but are secreted into the medium if sufficient amounts of non-labelled hormones are present. If no unlabelled hormones are added to the culture medium, the newly formed hormones are converted to a large extent into polar conjugates.
Furostanol saponins and ecdysones with cytotoxic activity from Helleborus bocconei ssp. intermedius
2009
Two furostanol saponins helleboroside A (1) and helleboroside B (2) were isolated from the methanol extract of Helleborus bocconei Ten. subsp. intermedius (Guss.) Greuter and Burdet, along with the furospirostanol saponin 4 and two ecdysones: ecdysterone (5) and polypodyne B (6). Compound 2 was enzymatically hydrolysed to give product 3. The biological activity of all compounds was tested against rat C6 glioma cells showing a significant cytotoxicity for compounds 3, 4 and 6. Copyright © 2009 John Wiley & Sons, Ltd.
Woc (without children) gene control of ecdysone biosynthesis in Drosophila melanogaster.
2001
Abstract The first step in ecdysteroidogenesis, i.e. the 7,8-dehydrogenation of dietary cholesterol (C) to 7-dehydrocholesterol (7dC), is blocked in Drosophila melanogaster homozygous woc (without children) third instar larval ring glands (source of ecdysone). Unlike ring glands from wild-type D. melanogaster larvae, glands from woc mutants cannot convert radiolabelled C or 25-hydroxycholesterol (25C) to 7dC or 7-dehydro-25-hydroxycholesterol (7d25C) in vitro, nor to ecdysone (E). Yet, when these same glands are incubated with synthetic tracer 7d25C, the rate of metabolism of this polar Δ5,7-sterol into E is identical to that observed with glands from comparably staged wild-type larvae. The…
Evolution of ecdysteroids and of their apolar conjugates during the post-embryonic development of the tickOrnithodoros moubata
1997
The ecdysteroid (ES) content of the soft tick Ornithodoros moubata was investigated during the five successive nymphal molting cycles by means of an enzyme immunoassay (EIA). Samples were submitted to esterase hydrolysis in order to release free ecdysteroids from the acyl-ester conjugates (AP = apolar products). Crude and hydrolysed extracts were then analyzed by EIA using two different antibodies, a monoclonal raised against 20-hydroxyecdysone (20E) and a polychlonal raised against ecdysone (E). With the crude extracts, each molting cycle was associated with an ES peak, occurring in the middle of the instar. 20E was preponderant during the first 2 nymph cycles, but the proportion of E and …
INHIBITION OF FATTY ACID DESATURASES INDrosophila melanogasterLARVAE BLOCKS FEEDING AND DEVELOPMENTAL PROGRESSION
2016
International audience; Fatty acid desaturases are metabolic setscrews. To study their systemic impact on growth in Drosophila melanogaster, we inhibited fatty acid desaturases using the inhibitor CAY10566. As expected, the amount of desaturated lipids is reduced in larvae fed with CAY10566. These animals cease feeding soon after hatching, and their growth is strongly attenuated. A starvation program is not launched, but the expression of distinct metabolic genes is activated, possibly to mobilize storage material. Without attaining the normal size, inhibitor-fed larvae molt to the next stage indicating that the steroid hormone ecdysone triggers molting correctly. Nevertheless, after moltin…
Development and characterization of a 293 cell line with regulatable expression of the hepatitis B virus large envelope protein
2004
During the life cycle of hepatitis B virus (HBV) the large L envelope protein plays a pivotal role that is related to its peculiar dual transmembrane topology. To study the complex structure and diverse functions of L under regulated conditions of production, a human 293 cell line stably expressing L under the control of the ecdysone-inducible promoter was generated. Cells demonstrated stringent dose- and time-dependent kinetics of induction with undetectable background expression in the absence of the inducer. Temporal control of L expression allowed to trace (i) its posttranslational reorientation resulting in the mixed topology; (ii) its spatial redistribution from the endoplasmic reticu…
The precocious commitment of wing Anlagen in Tenebrio molitor revealed by the addition of 20-hydroxyecdysone.
1992
Abstract An injection of 20-hydroxyecdysone (10 μg per animal) 6–13 days after the moult of the last larval instar of Tenebrio molitor induces the development of prothetelic larvae and larval-pupal intermediates. The state of larval-pupal switchover, or commitment, is only disclosed at the time of injection of the moulting hormone. Prothetelic A and B larvae, with small and medium sized wing Anlagen, undergo another larval or pupal instar. Prothetelic C larvae with bigger Anlagen are unable to moult, but the adult programme is expressed. Ecdysed larval-pupal intermediates give more or less perfect adults, while unecdysed mealworms, imprisoned in their larval cuticle, also expressed the adul…
A functional analysis of ACP-20, an adult-specific cuticular protein gene from the beetle Tenebrio. Role of an intronic sequence in transcriptional a…
2004
0962-1075 (Print) Comparative Study Journal Article Research Support, Non-U.S. Gov't; A gene encoding the adult cuticular protein ACP-20 was isolated in Tenebrio. It consists of three exons interspersed by two introns, intron 1 interrupting the signal peptide. To understand the regulatory mechanisms of ACP-20 expression, ACP-20 promoter-luciferase reporter gene constructs were transfected into cultured pharate adult wing epidermis. Transfection assays needed the presence of 20-hydroxyecdysone, confirming that ACP-20 is up-regulated by ecdysteroids. Analysis of 5' deletion constructs revealed that three regions are necessary for high levels of transcription. Interaction experiments between i…
Morphogenesis of mechanoreceptor and epidermal cells of crickets during the last instar, and its relation to molting-hormone level.
1980
(1) The fine structure of the cercal campaniform sensilla and epidermal cells of Gryllus bimaculatus Deg. (Saltatoria, Gryllidae) was examined, and the ecdysteroid level was monitored throughout the last larval instar. (2) The epidermal cells show changes in shape, cytoplasmic inclusions and differentiation of the apical cell membrane, coupled to the phases of buildup and breakdown of the (cercus) cuticle. (3) The imaginal epicuticle of the epidermal cells begins to form later (by about approximately 6h) than that of the campaniform sensilla. (4) The campaniform sensilla were studied with respect to (a) the morphogenesis of the cuticular apparatus, (b) the inclusion of phenol oxidases in th…
Tenectin is a novel alphaPS2betaPS integrin ligand required for wing morphogenesis and male genital looping in Drosophila.
2010
International audience; Morphogenesis of the adult structures of holometabolous insects is regulated by ecdysteroids and juvenile hormones and involves cell-cell interactions mediated in part by the cell surface integrin receptors and their extracellular matrix (ECM) ligands. These adhesion molecules and their regulation by hormones are not well characterized. We describe the gene structure of a newly described ECM molecule, tenectin, and demonstrate that it is a hormonally regulated ECM protein required for proper morphogenesis of the adult wing and male genitalia. Tenectin's function as a new ligand of the PS2 integrins is demonstrated by both genetic interactions in the fly and by cell s…