Ascidian tail formation requires caudal function

You Katsuyama, Yoshiko Sato, Shuichi Wada, Hidetoshi Saiga

Research output: Contribution to journalArticlepeer-review

35 Citations (Scopus)


Although the tail is one of the major characteristics of animals of the phylum Chordata, evolutionary aspects of the molecular mechanisms involved in its formation are not clear. To obtain insights into these issues, we have isolated and investigated the caudal gene of an ascidian, one of the lower animal groups among chordates. Ascidian caudal is expressed from the midgastrula stage onward in the lateral walls of the posterior neural tube cell lineage and also in the posterior epidermal cells from the neurula stage. Thus, ascidian caudal expression is restricted to the ectoderm of a tail-forming region throughout embryogenesis. Suppression of caudal function by an antisense oligonucleotide or a dominant negative construct caused inhibition of the cell movement required for tail formation. Overexpression of wild-type caudal mRNA in an ascidian animal cap, an animal half explant prepared at the eight-cell stage, caused elongation of the cap. Furthermore, Xenopus embryos injected with dominant negative ascidian caudal exhibited defects in elongation, suggesting a conserved caudal function among chordates. These results indicate that caudal function is required for chordate tail formation and may play a key role in its evolution.

Original languageEnglish
Pages (from-to)257-268
Number of pages12
JournalDevelopmental Biology
Issue number2
Publication statusPublished - 1999 Sept 15
Externally publishedYes


  • Ascidian
  • Caudal
  • Chordate evolution
  • Tail formation

ASJC Scopus subject areas

  • Molecular Biology
  • Developmental Biology
  • Cell Biology


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