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1984 (1)
1980 (1)
1Author    Jean-Paul Delbecque, Karel SlámaRequires 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 
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 TEI-XML for    default:Reihe_C/35/ZNC-1980-35c-1066.pdf 
 Identifier    ZNC-1980-35c-1066 
 Volume    35 
2Author    U. Bührlen, H. Emmerich, H. RemboldRequires cookie*
 Title    Titer of Juvenile Hormone III in Drosophila hydei during Metamorphosis Determined by GC-MS-MIS  
 Abstract    The titer of juvenile hormone III (JH-III) has been determined by the use of combined gas chromatography-mass spectroscopy (GC-MS) in whole body extracts of the larvae, prepupae, pupae and adults of Drosophila hydei. A characteristic JH-III titer curve was established by use of the hormone derivatives. No other juvenile hormone homologs were detected. JH-III shows a broad peak maximum of about 30 pmol/g fresh weight during the last larval instar, whereas only traces of the hormone are detectable at pupariation. Prepupae and pupae exhibit about the same JH-III level. In older pupae and in the pharate adults there was no JH-III detectable but it reappeared soon after emergence. Low values of JH-III are found in young male and female flies. The JH contents rise to distinct peaks in older and reproductive adults, both in male and female animals. 
  Reference    Z. Naturforsch. 39c, 1150—1154 (1984); received June 29 1984 
  Published    1984 
  Keywords    Juvenile Hormone, Drosophila hydei, Metamorphosis, Reproduction, Gas Chromatography-Mass Spectroscopy 
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 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-1150.pdf 
 Identifier    ZNC-1984-39c-1150 
 Volume    39