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Journal of Molecular Evolution

, Volume 54, Issue 4, pp 486–500 | Cite as

The Cephalopod Loligo bleekeri Mitochondrial Genome: Multiplied Noncoding Regions and Transposition of tRNA Genes

  • Kozo  Tomita
  • Shin-ichi  Yokobori
  • Tairo  Oshima
  • Takuya  Ueda
  • Kimitsuna  Watanabe

Abstract.

We previously reported the sequence of a 9260-bp fragment of mitochondrial (mt) DNA of the cephalopod Loligo bleekeri [J. Sasuga et al. (1999) J. Mol. Evol. 48:692–702]. To clarify further the characteristics of Loligo mtDNA, we have sequenced an 8148-bp fragment to reveal the complete mt genome sequence. Loligo mtDNA is 17,211 bp long and possesses a standard set of metazoan mt genes. Its gene arrangement is not identical to any other metazoan mt gene arrangement reported so far. Three of the 19 noncoding regions longer than 10 bp are 515, 507, and 509 bp long, and their sequences are nearly identical, suggesting that multiplication of these noncoding regions occurred in an ancestral Loligo mt genome. Comparison of the gene arrangements of Loligo, Katharina tunicata, and Littorina saxatilis mt genomes revealed that 17 tRNA genes of the Loligo mt genome are adjacent to noncoding regions. A majority (15 tRNA genes) of their counterparts is found in two tRNA gene clusters of the Katharina mt genome. Therefore, the Loligo mt genome (17 tRNA genes) may have spread over the genome, and this may have been coupled with the multiplication of the noncoding regions. Maximum likelihood analysis of mt protein genes supports the clade Mollusca + Annelida + Brachiopoda but fails to infer the relationships among Katharina, Loligo, and three gastropod species.

Key words: Cephalopod Loligo bleekeri— Mitochondrial DNA — Molluscan phylogeny — Gene rearrangement — Noncoding region — tRNA 

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Copyright information

© Springer-Verlag New York Inc. 2002

Authors and Affiliations

  • Kozo  Tomita
    • 1
  • Shin-ichi  Yokobori
    • 2
  • Tairo  Oshima
    • 2
  • Takuya  Ueda
    • 3
  • Kimitsuna  Watanabe
    • 1
  1. 1.Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-8656, JapanJP
  2. 2.Department of Molecular Biology, School of Life Science, Tokyo University of Pharmacy and Life Science, 1432-1, Horinouchi, Hachioji, Tokyo 192-0392, JapanJP
  3. 3.Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-8656, JapanJP

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