Two-Round Ca 2+ transient in papillae by mechanical stimulation induces metamorphosis in the ascidian Ciona intestinalis type A

Maiki K. Wakai, Mitsuru J. Nakamura, Satoshi Sawai, Kohji Hotta, Kotaro Oka

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


Marine invertebrate larvae are known to begin metamorphosis in response to environmentally derived cues. However, little is known about the relationships between the perception of such cues and internal signalling for metamorphosis. To elucidate the mechanism underlying the initiation of metamorphosis in the ascidian, Ciona intestinalis type A (Ciona robusta), we artificially induced ascidian metamorphosis and investigated Ca 2+ dynamics from pre- to post-metamorphosis. Ca 2+ transients were observed and consisted of two temporally distinct phases with different durations before tail regression which is the early event of metamorphosis. In the first phase, Phase I, the Ca 2+ transient in the papillae (adhesive organ of the anterior trunk) was coupled with the Ca 2+ transient in dorsally localized cells and endoderm cells just after mechanical stimulation. The Ca 2+ transients in Phase I were also observed when applying only short stimulation. In the second phase, Phase II, the Ca 2+ transient in papillae was observed again and lasted for approximately 5-11 min just after the Ca 2+ transient in Phase I continued for a few minutes. The impaired papillae by Foxg-knockdown failed to induce the second Ca 2+ transient in Phase II and tail regression. In Phase II, a wave-like Ca 2+ propagation was also observed across the entire epidermis. Our results indicate that the papillae sense a mechanical cue and two-round Ca 2+ transients in papillae transmits the internal metamorphic signals to different tissues, which subsequently induces tail regression. Our study will help elucidate the internal mechanism of metamorphosis in marine invertebrate larvae in response to environmental cues.

Original languageEnglish
Article number20203207
JournalProceedings of the Royal Society B: Biological Sciences
Issue number1945
Publication statusPublished - 2021 Feb 24


  • Ca 2+ signalling
  • Ca 2+ transient
  • epithelial conduction
  • mechanosensory
  • settlement
  • tunicate

ASJC Scopus subject areas

  • General Immunology and Microbiology
  • General Biochemistry,Genetics and Molecular Biology
  • General Environmental Science
  • General Agricultural and Biological Sciences


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