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Cell and Tissue Research

, Volume 295, Issue 1, pp 13–19 | Cite as

Peripheral synapses at identifiable mechanosensory neurons in the spider Cupiennius salei : synapsin-like immunoreactivity

  • Ruth Fabian-Fine
  • Walter Volknandt
  • E.-A. Seyfarth
REGULAR ARTICLE

Abstract

Indirect immunocytochemical tests were used at the light- and electron-microscopic levels to investigate peripheral chemical synapses in identified sensory neurons of two types of cuticular mechanosensors in the spider Cupiennius salei Keys.: (1) in the lyriform slit-sense organ VS-3 (comprising 7–8 cuticular slits, each innervated by 2 bipolar sensory neurons) and (2) in tactile hair sensilla (each supplied with 3 bipolar sensory cells). All these neurons are mechanosensitive. Application of a monoclonal antibody against Drosophila synapsin revealed clear punctate immunofluorescence in whole-mount preparations of both mechanoreceptor types. The size and overall distribution of immunoreactive puncta suggested that these were labeled presynaptic sites. Immunofluorescent puncta were 0.5–6.8 μm long and located 0.5–6.6 μm apart from each other. They were concentrated at the initial axon segments of the sensory neurons, while the somata and the dendritic regions showed fewer puncta. Western blot analysis with the same synapsin antibody against samples of spider sensory hypodermis and against samples from the central nervous system revealed a characteristic doublet band at 72 kDa and 75 kDa, corresponding to the apparent molecular mass of synapsin in Drosophila and in mammals. Conventional transmissionelectron-microscopic staining demonstrated that numerous chemical synapses (with at least 2 vesicle types) were present at these mechanosensory neurons and their surrounding glial sheath. The distribution of these synapses corresponded to our immunofluorescence results.Ultrastructural examination of anti-synapsin-stained neurons confirmed that reaction product was associated with synaptic vesicles. We assume that the peripheral synaptic contacts originate from efferents that could exert a complex modulatory influence on mechanosensory activity.

Key words Mechanoreceptors Synaptic proteins Histochemistry Ultrastructure Slit sensilla Hair sensilla Cupiennius salei (Chelicerata) 

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Copyright information

© Springer-Verlag Berlin Heidelberg 1999

Authors and Affiliations

  • Ruth Fabian-Fine
    • 1
  • Walter Volknandt
    • 2
  • E.-A. Seyfarth
    • 1
  1. 1.Zoologisches Institut, J.W. Goethe-Universität, Siesmayerstrasse 70, D-60054 Frankfurt am Main, Germany Tel.: +49 69 798 24704; Fax: +49 69 798 24820; e-mail: seyfarth@zoology.uni-frankfurt.deDE
  2. 2.Zoologisches Institut, Biozentrum der J.W. Goethe-Universität, Marie-Curie-Strasse 9, D-60439 Frankfurt am Main, GermanyDE

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