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  • Nervous system  (2)
  • Bud formation  (1)
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 183 (1977), S. 207-214 
    ISSN: 1432-041X
    Schlagwort(e): Hydra mutant ; Morphogenetic substances ; Bud formation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Non-budding mutants ofChlorohydra viridissima regenerate heads 6 h faster thanHydra attenuata and the number of tentacles per head is higher. The polarity in pieces from the gastric region is the more labile, the smaller the pieces are. In regenerates heads and tentacles form much more frequently than feet, giving rise to bipolar or multiheaded structures. Buds very seldom form under normal conditions, but they occasionally occur in regenerating animals with two cut surfaces. The higher head-forming potential in the mutant is paralleled by a higher head-activator concentration (20-fold in head, 4-fold in body), than inHydra attenuata, which is not accompanied by an equivalent increase in head-inhibitor concentration (1.4-fold in head, 2-fold in body). The foot-activator concentration is slightly reduced (1.3-fold), the foot-inhibitor concentration is higher (1.6-fold) than inH. attenuata. The mutant is extremely insensitive to head activator, relatively insensitive to head inhibitor and foot inhibitor, but sensitive to foot activator.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 246 (1986), S. 463-479 
    ISSN: 1432-0878
    Schlagwort(e): RFamide ; Neuropeptide ; Nervous system ; Siphonophores ; Coelenterates
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary An antiserum to the sequence Arg-Phe-amide (RFamide) was used to stain the nervous systems of various physonectid siphonophores. In the stem of Nanomia bijuga, this antiserum stained an ectodermal nerve net, which was interrupted, at regular intervals, by transverse collars of neurons. Injection of Lucifer yellow into the “giant axon” of the stem showed that this axon was dye-coupled to an ectodermal nerve net that resembled the RFamide-positive network. Ectodermal nets of neurons were also found in the pneumatophore, gastrozooids, tentacles and tentilla. At the junctions of the pneumatophore, the gastrozooids, the dactylozooids and the gonozooids with the stem, and at the junctions of tentacles and tentilla, collars or rings of neurons occurred. The stem was connected to the phyllozooids and nectophores by muscular lamellae, which were bordered by chains of neurons. At the margin of the nectophores, an immunoreactive nerve ring was found. Connected to this ring and located in the“seitliche Zapfen” (“sidely-located patche”), were two agglomerations of nerve cells. On the upper side of the bell margin, positioned at 90° relative to the “seitliche Zapfen”, a delta-shaped neuronal structure was found. This structure was connected to the nerve ring and was associated with a muscle, which ran a short distance along the exumbrellar surface. The nervous systems of Agalma elegans, Forskalia edwardsi, Forskalia leuckarti and Halistemma rubrum resembled that of Nanomia bijuga in all major respects.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 241 (1985), S. 171-182 
    ISSN: 1432-0878
    Schlagwort(e): RFamide ; Neuropeptides ; Nervous system ; Reproduction ; Hydrozoa
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Antisera to the sequence Arg-Phe-amide (RF-amide) have a high affinity to the nervous system of fixed hydroid polyps. Whole-mount incubations of several Hydra species with RFamide antisera visualize the three-dimensional structure of an ectodermal nervous system in the hypostome, tentacles, gastric region and peduncle. In the hypostome of Hydra attenuata a ganglion-like structure occurs, consisting of numerous sensory cells located in a region around the mouth opening and a dense plexus of processes which project mostly radially towards the bases of the tentacles. In Hydra oligactis an ectodermal nerve ring was observed lying at the border of hypostome and tentacle bases. This nerve ring consists of a few large ganglion cells with thick processes forming a circle around the hypostome. This is the first direct demonstration of a nerve ring in a hydroid polyp. Incubation of Hydractinia echinata gastrozooids with RFamide antisera visualizes an extremly dense plexus of neuronal processes in body and head regions. A ring of sensory cells around the mouth opening is the first group of neurons to show RFamide immunoreactivity during the development of a primary polyp. In gonozooids the oocytes and spermatophores are covered with strongly immunoreactive neurons. All examples of whole-mount incubations with RF-amide antisera clearly show that hydroid polyps have by no means a “diffuse nerve net”, as is often believed, and that neuronal centralization and plexus formation are common in these animals. The examples also show that treatment of intact fixed animals with RFamide antisera is a useful technique to study the anatomy or development of a principal portion of the hydroid nervous system.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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