Journal of Molecular Evolution

, Volume 57, Issue 5, pp 574–587 | Cite as

Mitochondrial Genome of Ciona savignyi (Urochordata, Ascidiacea, Enterogona): Comparison of Gene Arrangement and tRNA Genes with Halocynthia roretzi Mitochondrial Genome

  • Shin-ichi Yokobori
  • Yukari Watanabe
  • Tairo Oshima


The complete nucleotide sequence of the urochordate Ciona savignyi (Ascidiacea, Enterogona) mitochondrial (mt) genome (14,737 bp) was determined. The Ciona mt genome does not encode a gene for ATP synthetase subunit 8 but encodes an additional tRNAGly gene (anticodon UCU), as is the case in another urochordate, Halocynthia roretzi (Ascidiacea, Pleurogona), mt genome. In addition, the Ciona mt genome encodes two tRNAMet genes; anticodon CAT and anticodon TAT. The tRNACys gene is thought to lack base pairs at the D-stem. Thus, the Ciona mt genome encodes 12 protein, 2 rRNA, and 24 tRNA genes. The gene arrangement of the Ciona mt genome differs greatly from those of any other metazoan mt genomes reported to date. Only three gene boundaries are shared between the Halocynthia and the Ciona mt genomes. Molecular phylogenetic analyses based on amino acid sequences of mt protein genes failed to demonstrate the monophyly of the chordates.


Mitochondrial genome Ciona savignyi Gene arrangement tRNA 



We thank Dr. K. Watanabe, University of Tokyo, and Dr. A. Yamagishi, Tokyo University of Pharmacy and Life Science, for their valuable comments on this study. This work was supported by the grants from the Ministry of Education, Culture, Sports, Science and Technology of Japan to S.Y. and T.O.


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Copyright information

© Springer-Verlag New York Inc. 2003

Authors and Affiliations

  • Shin-ichi Yokobori
    • 1
  • Yukari Watanabe
    • 1
  • Tairo Oshima
    • 1
  1. 1.Department of Molecular BiologySchool of Life Science, Tokyo University of Pharmacy and Life Science, 1432-1, Horinouchi, Hachioji, Tokyo 192-0392Japan

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