Development Genes and Evolution

, Volume 209, Issue 1, pp 31–39

Distinct structural domains in the planarian brain defined by the expression of evolutionarily conserved homeobox genes

Authors

  • Y. Umesono
    • Graduate School of Science and Technology, Kobe University, Nada, Kobe 657-8501, Japan
  • Kenji Watanabe
    • Laboratory of Regeneration Biology, Department of Life Science, Faculty of Science, Himeji Institute of Technology, Hyogo 678-1279, Japan
  • K. Agata
    • Laboratory of Regeneration Biology, Department of Life Science, Faculty of Science, Himeji Institute of Technology, Hyogo 678-1279, Japan
ORIGINAL ARTICLE

DOI: 10.1007/s004270050224

Cite this article as:
Umesono, Y., Watanabe, K. & Agata, K. Dev Gene Evol (1999) 209: 31. doi:10.1007/s004270050224

Abstract

 Homeobox genes such as orthodenticle in Drosophila and its mouse homologues, Otx1 and Otx2, are known to be essential for rostral brain development. To investigate the molecular basis of brain evolution, we searched for otd/Otx-related homeobox genes in the planarian Dugesia japonica, and identified two genes, DjotxA and B, whose expression appears to be restricted to the cephalic ganglion (brain). DjotxA was expressed more medially, in the region containing the termini of the visual axons, and in the visual cells, suggesting involvement in establishment of the visual system. DjotxB was expressed in a discrete region just lateral to the DjotxA-positive domain, but not in the more lateral branch structures, which in turn are characterized by the expression of Djotp, a planarian homeobox gene related to mouse Orthopedia (Otp). In transverse sections of planarians, DjotxA and B expression were observed only at the anterior ends of the stumps, corresponding to the regional pattern of the regenerating brain. Our findings suggest that the planarian brain is composed of structurally distinct and functionally diverse domains which are defined by the discrete expression of the three evolutionarily conserved homeobox genes.

Key words Homeobox geneBrainotd/OtxotpPlanarian

Copyright information

© Springer-Verlag Berlin Heidelberg 1999