| | 2 | Author
| Jean-Paul Delbecque, Karel Sláma | Requires cookie* | | | Title
| Ecdysteroid Titres during Autonomous Metamorphosis in a Dermestid Beetle  | | | | Abstract
| The larvae of Dermestes maculatus are able to undergo several moults in complete absence o f the cephalic and prothoracic neuroendocrine system, showing thus spontaneous metamorphosis. Measurements of ecdysteroid contents by radioimmunoassay methods have revealed distinctive larval, prepupal and pupal ecdysteroid peaks, as found in other species where development requires frequent stimulation by the centrally produced hormones. Mass fragmentographic analysis has indicated that more than 80% of the ecdysteroids detected by the radioimmunoassay during the peaks consists of ecdysterone. The prothoracic glands (PG) o f D. maculatus larvae are located in the head capsule and in the cervical region. They can be separated from the body by neck-ligation. Only the larval peak o f ecdysterone can be correlated with PG function. The prepupal and pupal peaks o f ecdysterone are not produced by the central neuroendocrine system. The isolated abdominal fragments o f larvae and pupae positively produce ecdysteroids in the course of their independent development, but this synthesis has been subnormal and occasionally delayed in time. In contrast, the isolated thoracic fragments produce well synchronized peaks o f ecdysterone and this does not depend on the PG. It thus appears that some thoracic tissue other than PG is able to maintain the physiological concentration o f ecdysterone by means o f a concentration-dependent feed-back mechanism. Due to spontaneous metamorphosis and extremely good survival we have succeeded to induce in this species: a) premature formation o f the prepupal cycle of ecdysterone synthesis in the penultimate larval instar by ligation; b) inhibition and delay o f the prepupal peak by means of juvenoid treatments; c) reappearance o f the prepupal peak in the inhibited "permanent larvae" by exogenous administration of ecdysterone, or; d) modification of the pupal peak by a qualitatively new pupal-pupal one after juvenoid treatments. These experimental transformations o f the ecdysterone peaks have suggested that the kind and nature o f the peaks are closely related to nature and stage o f the ontogenetic development. We therefore believe that the process o f larval-pupal reprogramming has occurred in this species long before the increase o f ecdysterone titer in the body. Both the prepupal and pupal peaks do not represent a cause but they show to be rather consequences o f the developmental programming. Further features associated with possible physiological role o f ecdysteroids in insect development have been briefly discussed. | | | |
Reference
| Z. Naturforsch. 35c, 1066—1080 (1980); received June 19 1980 | | | |
Published
| 1980 | | | |
Keywords
| Ecdysteroids, Juvenile Hormone, Metamorphosis, Dermestes maculatus | | | |
Similar Items
| Find | | | DEBUG INFO
| | | | | TEI-XML for
| default:Reihe_C/35/ZNC-1980-35c-1066.pdf | | | | Identifier
| ZNC-1980-35c-1066 | | | | Volume
| 35 | |
| 3 | Author
| Heinz Rem, K. Laus-, Peter Sieber | Requires cookie* | | | Title
| Inhibition of Oogenesis and Ovarian Ecdysteroid Synthesis by Azadirachtin in Locusta migratoria migratorioides (R. & F.) | | | | Abstract
| The sterilizing effect of azadirachtin, an insect growth regulator from the neem tree, Azadirachta indica A. Juss, was tested with mature females o f Locusta migratoria. After a single injection of 10 |ig into females between 2 and 13 days after emergence, about 60% died during the following four days and all lost weight in the range of about 50%. If the compound was injected into animals of an age between 2 and 10 days, no maturation o f the terminal oocytes could be observed. Injection at an age between 10 and 13 days after adult emergence resulted in ovaries which contained almost mature oocytes. Most o f the treated locusts had no oviposition and only traces of ecdysteroids were present in their ovaries, as quantified by radioimmunoassay. The inhibition of oogenesis and o f ovarian ecdysteroid synthesis by azadirachtin is discussed on the basis of its interference with the neuroendocrine control of hormone synthesis. | | | |
Reference
| Z. Naturforsch. 36c, 466 (1981); received November 10 1980/February 23 1981 | | | |
Published
| 1981 | | | |
Keywords
| Locusta migratoria, Azadirachta indica, Ecdysteroids, Azadirachtin, Ovary | | | |
Similar Items
| Find | | | DEBUG INFO
| | | | | TEI-XML for
| default:Reihe_C/36/ZNC-1981-36c-0466.pdf | | | | Identifier
| ZNC-1981-36c-0466 | | | | Volume
| 36 | |
| 4 | Author
| Lutz Reum, G. Erd Käuser, U. Lrike Enderle, Jan Koolman | Requires cookie* | | | Title
| A Steroid-Binding Protein from Insect Haemolymph Isolated by PhotoafTinity Labelling and Immunoadsorption | | | | Abstract
| Endogenous ecdysteroids as well as radiolabelled exogenous ecdysone were crosslinked to a protein when haemolymph from blowfly larvae was irradiated with UV-light under optimized conditions. This indicates that larval haemolymph of blowflies contains an ecdysteroid-binding protein. The crosslinked ecdysteroid-protein complex was shown to form a ternary complex when mixed with ecdysteroid-specific antibodies. Formation of the ternary complex was due to a specific interaction of the binding sites of the antibodies with the steroid. This specific interaction was used to isolate the ecdysteroid-protein complex from irradiated crude larval haemolymph by immunoadsorption. The method described here represents a rapid approach for the isolation o f steroid-binding proteins by a combination o f photoaffinity labelling and immunoadsorption. | | | |
Reference
| Z. Naturforsch. 37c, 967—9 (1982); received March 11/June 8 1982 | | | |
Published
| 1982 | | | |
Keywords
| Immunoadsorption, Ecdysteroids, Calliphorin, Steroid-Binding Protein, Photoaffinity-Labelling | | | |
Similar Items
| Find | | | DEBUG INFO
| | | | | TEI-XML for
| default:Reihe_C/37/ZNC-1982-37c-0967.pdf | | | | Identifier
| ZNC-1982-37c-0967 | | | | Volume
| 37 | |
| 5 | Author
| Franz Römer, Ilona Eisenbeis | Requires cookie* | | | Title
| DNA Content and Synthesis in Several Tissues and Variation of Moulting Hormone-Level in Gryllus bimaculatus DEG (Ensifera, Insecta) | | | | Abstract
| The mode of growth o f several tissues in Gryllus bimaculatus was investigated during postembryonic development by cytophotometric methods. In contrast to the situation in holo-metabolous insects, the tissues growing by endomitosis reach only moderate levels of polyploidy. In this case the growth o f tissues is achieved by mitotic divisions o f small cells with subsequent polyploidization. The time courses of D NA synthesis were measured within the 3rd and, for comparison, the 8th larval instar by incorporation o f labelled thymidine followed by autoradiography. Hemocytes, cells of the regeneration crypts of the midgut, gonads and nervous tissue showed a continuous incorporation rate; by contrast, DNA synthesis in other tissues was confined to a given time within the moulting cycle. The changes in moulting hormone titre o f the 3rd larval instar were investigated. The quantities of ecdysone and 20-C)H-ecdysone were estimated by radioimmunoassay, and the hormones were identified by high pressure liquid chromatography (HPLC). The titre changes in time with at least 2 distinct maxima. The DNA synthesis periods are correlated with the hormone peaks, that o f epidermis and tracheae with the first peak, and that of pylorus, ileum, rectum, Malpighian tubules and fat body with the second. DNA synthesis in prothoracic glands and oenocytes exhibits a time course that is the inverse of the hormone-secretion time course. The question whether moulting hormones have an influence on D NA synthesis is discussed. | | | |
Reference
| Z. Naturforsch. 38c, 112 (1983); received June 28/September 16 1982 | | | |
Published
| 1983 | | | |
Keywords
| Polyploidy Levels, DNA Synthesis Development, Ecdysteroids, Gryllus bimaculatus | | | |
Similar Items
| Find | | | DEBUG INFO
| | | | | TEI-XML for
| default:Reihe_C/38/ZNC-1983-38c-0112.pdf | | | | Identifier
| ZNC-1983-38c-0112 | | | | Volume
| 38 | |
| 7 | Author
| Karl-Heinz Tomaschko | Requires cookie* | | | Title
| Defensive Secretion of Ecdysteroids in Pycnogonum litorale (Arthropoda, Pantopoda) | | | | Abstract
| In response to disturbance, the pycnogonid Pycnogonum litorale discharges a mixture o f eight ecdysteroids (ES). Repeated intensive m olestation causes 99% secretion o f the endogenous ES present. The concentration o f the total ES in the defensive effluent is 1.0 x 10" 3 m o lT '1. 20-Hydroxyecdysone 22-acetate, the predominant ES, reaches 0.8 x 10" 3 m ol T_1. This is sufficient to deter significantly feeding by the com m on shore crab Carcinus maenas, a generalist predator in the habitat o f the pycnogonid. There is evidence that the secreted ES o f P. litorale contribute to its unpalatability. The present paper describes for the first time defensive secretion in marine arthropods. | | | |
Reference
| Z. Naturforsch. 49c, 367—371 (1994); received February 10 1994 | | | |
Published
| 1994 | | | |
Keywords
| Pycnogonids, Pycnogonum litorale, Ecdysteroids, Defensive Secretion, Chemical Defense | | | |
Similar Items
| Find | | | DEBUG INFO
| | | | | TEI-XML for
| default:Reihe_C/49/ZNC-1994-49c-0367.pdf | | | | Identifier
| ZNC-1994-49c-0367 | | | | Volume
| 49 | |
| 8 | Author
| FranzR. Öm Er, Hans-Ulrich Bressel | Requires cookie* | | | Title
| Secretion and Metabolism of Ecdysteroids by Oenocyte-Fat Body Complexes (OEFC) in Adult Males of Gryllus bimaculatus D EG (Insecta) | | | | Abstract
| Extracts of w hole adult males o f Gryllus bimaculatus show distinct maxima o f free ecdy steroids on the 8th, 12th and 14th day after imaginal moult at a breeding temperature of 25 °C. Isolated O EFC of 11 days old males secrete in vitro free as well as conjugated ecdy steroids, although the latter predominate. The bulk of free ecdysteroids seem s to consist of E and 20 E according to their retention times in two HPLC systems. Apart from the polar ones, apolar m etabolites appear during incubation. By esterase the apolar m etabolites are m ostly split into polar ones, partly into 20 E and E. Further treatment of the polar m etabolites with helicase leads again to E and 2 0 E. OEFC transform [3H]E preferably into apolar and polar conjugates, with dominance of the apolar ones at the beginning and o f polar ones in the further course o f incubation. Only a small quantity o f free 2 0 E is found during this experim ent, but it can be produced in significant quantities by splitting the polar conjugates. N o conversion o f [3H]cholesterol into [3H]ecdysteroids could be detected. | | | |
Reference
| Z. Naturforsch. 49c, 871 (1994); received February 14/August 26 1994 | | | |
Published
| 1994 | | | |
Keywords
| Ecdysteroids, Secretion, Metabolism, Oenocyte-Fat Body Complexes, G ryllus bimaculatus | | | |
Similar Items
| Find | | | DEBUG INFO
| | | | | TEI-XML for
| default:Reihe_C/49/ZNC-1994-49c-0871.pdf | | | | Identifier
| ZNC-1994-49c-0871 | | | | Volume
| 49 | |
|
