Protoplasma

, Volume 229, Issue 2, pp 193–203

Morphometric investigations of sensory vestibular structures in tadpoles (Xenopus laevis) after a spaceflight: implications for microgravity-induced alterations of the vestibuloocular reflex

Authors

  • E. Horn
    • Gravitationsphysiologie, Abteilung NeurobiologieUniversität Ulm
  • S. Böser
    • Gravitationsphysiologie, Abteilung NeurobiologieUniversität Ulm
  • H. Membre
    • Aspects Cellulaires et Moléculaires de la Reproduction et du Développement, Equipe d’Accueill 3442Université Henri Poincare
  • C. Dournon
    • Aspects Cellulaires et Moléculaires de la Reproduction et du Développement, Equipe d’Accueill 3442Université Henri Poincare
  • D. Husson
    • Centre de Biologie du DéveloppementUniversité Paul Sabatier
  • L. Gualandris-Parisot
    • Centre de Biologie du DéveloppementUniversité Paul Sabatier
Article

DOI: 10.1007/s00709-006-0213-z

Cite this article as:
Horn, E., Böser, S., Membre, H. et al. Protoplasma (2006) 229: 193. doi:10.1007/s00709-006-0213-z

Summary.

In lower vertebrates, gravity deprivation by orbital flights modifies the vestibuloocular reflex. Using the amphibian Xenopus laevis, the experiments should clarify to which extent macular structures of the labyrinth are responsible for these modifications. In particular, the shape of otoconia and number and size of sensory macular cells expressing CalBindin were considered. CalBindin is common in mature sensory cells including vestibular hair cells and is probably involved in otoconia formation. Two developmental stages were used for this study: stage 26/27 embryos, which were unable to perform the roll-induced vestibuloocular reflex (rVOR) at onset of microgravity, and stage 45 tadpoles, which had already developed the reflex. The main observations were that the developmental progress of the animals was not affected by microgravity; that in the young tadpole group with normal body shape the rVOR was not modified by microgravity, while in the older group with microgravity experience, the rVOR was augmented; and that significant effects on the shape of otoconia and on the number and size of CalBindin-expressing cells of the labyrinthine maculae cells were absent. In addition, behavioural data were never significantly correlated with morphological features of macular structures such as size and number of CalBindin-expressing cells. It is postulated that mechanisms of vestibular adaptation to microgravity during early development are probably based on mechanisms located in central structures of the vestibular system.

Keywords: Adaptation; Behavior; CalBindin protein; Immunohistochemistry; Microgravity; Sensory cell; Xenopus laevis.

Copyright information

© Springer-Verlag 2006