Endogenous inhibitor of ecdysone synthesis in crabs

Summary Attempts to isolate the molt-inhibiting hormone (MIH) of crustaceans from crab eyestalks (ES) resulted in the characterization of xanthurenic acid as an inhibitor of ecdysone biosynthesis in the cultured Y-organ-complex (YOC) homogenate. It was also found that 3-hydroxyl-l-kynurenine present in the ES is transformed into xanthurenic acid in the YOC and body fluid. Its mode of inhibitory action in ecdysone biosynthesis is probably inactivation of cytochrome P-450.Acknowledgments. We thank Prof. M. Oka (Nagasaki University) and Dr J. Cappuzo (Oceanographic Inst.) for information on Y-organ and molting stages, Dr J. Termini and Mr J. Cesarelli (Columbia University) for organ excision of blue crabs and experiments in the early stage of this study, the Japan Sea Farming Association for aqua culture of crabs, Prof. Y. Umebachi (Kanazawa University) for a gift of 3-OH-l-Kyn, and Mr J. Rudloe (Gulf Specimen Co.) for collection and shipping of some selected crabs. This study was partially supported by NIH grant AI 10 187 (to K. N., at Columbia University).     

Endogenous inhibitor of ecdysone synthesis in crabs

Attempts to isolate the molt-inhibiting hormone (MIH) of crustaceans from crab eyestalks (ES) resulted in the characterization of xanthurenic acid as an inhibitor of ecdysone biosynthesis in the cultured Y-organ-complex (YOC) homogenate. It was also found that 3-hydroxy-L-kynurenine present in the ES is transformed into xanthurenic acid in the YOC and body fluid. Its mode of inhibitory action in ecdysone biosynthesis is probably inactivation of cytochrome P-450.     

Gas chromatographic analysis of ecdysone

Résumé Nous avons développé une méthode d'analyse micro-quantitative de l'ecdysone (hormone de la mue des insectes) par Chromatographie gazeuse. Elle permettera l'analyse chimique de l'ecdysone, qui a été dosée jusqu'à présent par des méthodes biologiques.

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Supported by a grant from the Authority for Research and Development of the Hebrew University and by the Israel Academy of Sciences.     

Prothoracic gland synthesis of 3-dehydroecdysone and its hemolymph 3 beta-reductase mediated conversion to ecdysone in representative insects

The prothoracic glands of a variety of insects were tested for their ability to synthesize ecdysteroids in vitro. More specifically, they were evaluated for their ability to produce 3-dehydroecdysone and ecdysone using both radioimmunoassay and reverse phase high performance liquid chromatography. Three categories of insect prothoracic glands were noted: a) those producing much more 3-dehydroecdysone than ecdysone; b) glands synthesizing almost equivalent amounts of each of these two ecdysteroids; c) prothoracic glands that yielded more ecdysone than 3-dehydroecdysone. In addition, the 3-oxoecdysteroid 3 beta-reductase activity of the hemolymph of these insects was evaluated for its ability to convert 3-dehydroecdysone to ecdysone. The lepidopteran species tested yielded the most potent enzyme activity, although activity was demonstrated in members of other orders. These data indicate that the dehydroecdysone-ecdysone axis is not restricted to moths and butterflies.     

External factors and ecdysone release inCalliphora erythrocephala

Summary Ecdysone level is measured in the haemolymph of normal larvae and of larvae submitted to external stimulation. External stimulation delays the release of ecdysone and the formation of puparium. The adaptative value of the mechanism which connects the ecdysone titre to external stimulation is discussed.     

Effect of ecdysone on glutamic decarboxylase in rat brain

Résumé Nous avons étudié l'effet que produisait l'ecdysone, une hormone de la mue chez les insectes, sur l'activité de l'acide glutamique decarboxylase du cerveau de rat. Nous avons observé que l'activité de cet enzyme augmentait de façon significative chez les rats traités par cette hormone.     

Juvenilizing effect of ecdysone mimic RH 5849 inGalleria mellonella larvae

The response of the final instar larvae ofG. mellonella to topical application of the non-steroidal ecdysone mimic, RH 5849, was age-related as well as dose-dependent. In young final instar larvae, moderate doses of RH 5849 induced perfect supernumerary larval moults, but doses equal to and higher than 8.5 μg per larva caused premature formation of larval cuticle and were lethal. Application of RH 5849 significantly increased allatotropic activity of the brain, and also activated synthesis of juvenile hormone (JH) by the corpora cardiaca/corpora allata complex. Simultaneous application of RH 5849 and FMev, a potent inhibitor of JH synthesis, to young final instar larvae lowered the incidence of perfect supernumerary larval moults. We conclude that the effect of RH 5849 on the developmental programme inG. mellonella is mediated by the corpora allata.     

Presence of ecdysone and ecdysterone in the tickAmblyomma hebraeum Koch

Summary Ecdysone and ecdysterone, the moulting hormones of insects and crustaceans, are also present in nymphs of the tickAmblyomma hebraeum. They were demonstrated by means of radioimmunoassay and of gas-liquid chromatography combined with mass fragmentography or mass spectrometry of their trimethylsilyl-drivatives.Acknowledgments. We thank Proff. A. Aeschlimann and C. Noirot and Dr J. Delachambre for their help and encouragement. We are grateful to Proff. Maume and Padieu (Département de Biochimie, Université de Dijon) for the use of the LKB 9000 GLC-MS, and to Drs M. L. De Reggi, M. H. Hirn and Prof. M. A. Delaage for the gift of some RIA-antigens and antibodies. We thank Ciba-Geigy Ltd for the supply with ticks. The work was in part supported by grant Nr. 3. 734. 76 of the Swiss National Science Foundation and by a grant of the Emil Barrel Stiftung.     

Effect of administration of synthetic ecdysone on the moulting ofPalamnaeus bengalensis

Summary Synthetic analogue of ecdysone, 3, 14-dihydroxy-5-cholest-7-en-6-one did not bring the scorpionPalamnaeus bengalensis to moult. It also failed completely in stimulating the scorption to produce any change related to moulting.Acknowledgment. Author is grateful to Dr Suresh C. Shrivastava for providing research facilities, Dr S.P. Tewarson for encouragement and S.C.S.T. (U.P.) for funds. Present address: Department of Zoology, Lucknow Christian College, Lucknow-226001.     

Sterol metabolism in insects and biosynthesis of ecdysone in the silkworm

Cellular and Molecular Life Sciences -     

Critical period and ecdysone titers in the pupae ofPieris brassicae

Summary The ecdysone titer in the haemolymph of pupae of Pieris brassicae shows a sharp peak (1.90 g/ml) on days 5 and 6 of the pupal stage. Isolated abdomens were able to form adult abdomens at 72 h, this being 2 or 3 days before maximum ecdysone levels and at a time when the concentration of hormone in the abdominal haemolymph was only 0.23 g/ml.     

Occurrence of ecdysone in the blood of the chelicerate arthropod,Limulus polyphemus

Summary A molt promoting substance, assumed to be ecdysone, was discovered inLimulus haemolymph. Preliminary bioassay suggests a titre of 9 ng ecdysone per ml of haemolymph.Supported by the University of Minnesota Graduate School, NSF Grant No. GB 16607 and USPHS Grant No. HO 07336.     

The synthesis of jaceidin

Zusammenfassung Durch Kondensation nachAllan-Robinson wurde aus 2,4,6-Trihydroxy-3, -dimethoxy-acetophenon das 4-Benzyloxy-5,7-dihydroxy-3,6,3-trimethoxyflavon dargestellt. Entbenzylierung in C-4-Stellung führte zum 5,7,4-Trihydroxy-3,6,3-trimethoxyflavon. Die Eigenschaften dieser Verbindung und ihre Derivate sind identisch mit dem ausCentaurea jacea L. isolierten Jaceidin bzw. seinen Derivaten.     

The synthesis of isohalfordin

Zusammenfassung Die Synthese von Isohalfordin (3,4, 8-Trimethoxyfuro[3,2:6, 7]cumarin) aus 6,7-Dihydroxy-2, 3-dihydrobenzo[b]furan wird beschrieben.     

The synthesis of toxicarol isoflavone

Zusammenfassung Die Synthese von Toxicarol Isoflavon (2, 2-Dimethylpyrano(6, 5: 7,8)-5-hydroxy-2,4 5-trimethoxyisoflavon) aus 2,2-dimethyl-5-hydroxy-7-methoxychroman wird beschrieben.