Search results for "ECD"
showing 10 items of 195 documents
The ecdysone-induced DHR4 orphan nuclear receptor coordinates growth and maturation in Drosophila
2005
0092-8674 (Print) Journal Article Research Support, Non-U.S. Gov't; A critical determinant of insect body size is the time at which the larva stops feeding and initiates wandering in preparation for metamorphosis. No genes have been identified that regulate growth by contributing to this key developmental decision to terminate feeding. We show here that mutations in the DHR4 orphan nuclear receptor result in larvae that precociously leave the food to form premature prepupae, resulting in abbreviated larval development that translates directly into smaller and lighter animals. In addition, we show that DHR4 plays a central role in the genetic cascades triggered by the steroid hormone ecdyson…
Diflubenzuron-Induced alterations during in vitro development ofTenebrio molitor pupal integument
1987
The effects of diflubenzuron (DFB) in Tenebrio molitor pupae were first investigated on cuticle secretion induced by 20-hydroxyecdysone in vitro. The sternal integuments were treated by DFB either 3 days before culture or during culture. DFB, when applied before culture, did not prevent the molting hormone from inducing a new cuticle deposition by integument explants in vitro. However, this cuticle showed several architectural alterations and a thickness reduction. When applied during the culture in the presence of 20-hydroxyecdysone, DFB at high dose (≥ 20 μg/ml) was able to inhibit cuticle secretion, but lower doses (⩽ 10 μg/ml) resulted in epicuticle deposition. These observations confir…
Alternative sites for ecdysteroid production in insects
1990
Summary Several evidences have been obtained in various insect species demonstrating that, besides prothoracic glands and ovaries, other tissues could be alternative sites of moulting hormone production. After a detailed review on the various methods of investigation and criteria required to validate such observations, the nature of these sites, namely oenocytes, epidermis and testes, is discussed. Their possible involvement in moulting and/or reproduction is analyzed, giving the opportunity to put forward several new hypotheses. In particular, autocrine and paracrine secretions of ecdysteroids could play a role in localized developmental events, more difficult to control from endocrine gla…
Inhibition of ovarian steroidogenesis by cyclic-GMP in a fly
2003
1479-6805 0022-0795; Previous investigations in the female blowfly Phormia regina have shown that 3-isobutyl-1-methylxanthine (IBMX), a broad spectrum inhibitor of phosphodiesterases (PDEs), fails to mimic the steroidogenic effects of cAMP on ovaries, although it efficiently increases the concentrations of this second messenger. In this study, experiments carried out to clear up this contradiction demonstrated that IBMX, besides its effect on cAMP, also increased cGMP concentrations in blowfly ovary and that these two cyclic nucleotides controlled ovarian steroidogenesis antagonistically. In particular, a selective inhibitor of cGMP-specific PDEs, unlike IBMX, had a very strong negative eff…
Developmental changes and acetylcholinesterase activity in the metamorphosing brain ofTenebrio molitor: Correlation to ecdysteroid titers
1994
The brain of Tenebrio molitor exhibited marked fluctuations in acetylcholinesterase (AChE) activity throughout metamorphosis. This was true AChE activity, since it was inhibited by high substrate concentrations and by 10 μM of the specific AChE inhibitor BW284C51 [(1,5-bis'4-allyldimethylammoniumphenyl)-pentan-3-one dibromide] but not by iso-OMPA (tetraisopropylpyrophosphoramide), a cholinesterase (but not AChE) inhibitor. The histochemical AChE activity was localized in the neuropile and the nuclear envelope of neurons and glial cells. The enzyme extracted from brains with 1% Triton X-100 and 1 M NaCl sedimented as a single peak in a sucrose density gradient, with a sedimentation coefficie…
Calcium inhibits ovarian steroidogenesis in the blowfly Phormia regina.
2002
1479-6805 0022-0795; Calcium is frequently involved in the stimulation of steroidogenesis in gonads and endocrine glands, generally in association with cAMP. However, our present observations show that it has the opposite effect in the ovary of the blowfly Phormia regina. Our in vitro experiments first showed that extracellular calcium does not play a role during the stimulation of steroidogenesis in fly ovaries; indeed steroidogenesis was activated in vitro as efficiently in a medium with or without calcium, either by pharmacological compounds mimicking cAMP signaling or by active brain extracts. When calcium was experimentally introduced into biosynthetic cells by ionophores or liberated …
Ovicidal Activity of Maternally Applied Ecdysteroids in the Large Milkweed Bug (Heteroptera: Lygaeidae)
1982
Exogenous ecdysteroids (ecdysone, 20-hydroxyecdysone and makisterone A) administered to reproducing females of Oncopelus fasciatus (Dallas) reduced egg hatch drastically. The ovicidal activity apparently stemmed from ecdysteroids—unchanged hormone or metabolites—transferred from mother into oocyte. Different stages of embryogenesis were affected. Makisterone A, the predominant ecdysteroid in normal embryos, is by far the most effective ecdysteroid.
The non-appearance of female-specific proteins in male Spilostethus pandurus)
1990
1. 1. Female-specific peptides can be detected by SDS-PAGE in the haemolymph when the female insects are 48 hr old. 2. 2. The age of the male insect at the moment of treatment with juvenile hormone I (JH I), JH III or ecdysone has no influence on the induction of the female-specific bands in male S. pandurus. 3. 3. Male insects exposed to the hormones for periods of time longer than 24 hr were also unable to show female-specific bands in their haemolymph. Consecutive treatments with JH were unable to induce these peptides in the males.
Characterization of the synthetic cannabinoid MDMB-CHMCZCA
2016
The synthetic cannabinoid MDMB-CHMCZCA was characterized by various spectroscopic techniques including NMR spectroscopy and tandem mass spectrometry. The synthetic sample was found to be of S-configuration by VCD spectroscopy and comparison of the data with DFT calculations, while ECD spectroscopy was found to be inconclusive in this case. The enantiomeric purity of samples from test purchases and police seizures was assessed by a self-developed chiral HPLC method.
Recensione a: Polipticum quod appellatur Perpendiculum
2021
Recensione alla prima vera e propria edizione critica del Polipticum quod appellatur Perpendiculum di Attone di Vercelli, curata da Giacomo Vignodelli e con un saggio di Luigi G.G. Ricci, apparsa a Firenze, presso la SISMEL – Edizioni del Galluzzo, nel 2019, all'interno dell'Edizione Nazionale dei Testi Mediolatini d’Italia. Review of the first real critical edition of the Polipticum quod appellatur Perpendiculum by Attone di Vercelli