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Journal of Molecular Evolution

, Volume 34, Issue 4, pp 331–335 | Cite as

Planarian mitochondria II. The unique genetic code as deduced from cytochrome c oxidase subunit I gene sequences

  • Yoshitaka Bessho
  • Takeshi Ohama
  • Syozo Osawa
Article

Summary

The cytochrome c oxidase subunit I (COI) gene sequences from planarian (Dugesia japonica) DNA, most probably of mitochondrial origin, are heterogeneous. Taking advantage of the heterogeneity that occurs primarily in silent sites of the COI DNA sequences, amino acid assignments of several codons have been deduced as nonuniversal: UGA = Trp, AAA = Asp, and AGR (R: A or G) = Ser. In addition, UAA, a stop codon in the universal genetic code, is tentatively assumed to be a tyrosine codon, because three of the sequences examined have UAA at the well-conserved tyrosine site of UAY (Y: U or C) in other planarian sequences as well as in the mitochondria of human, Xenopus, sea urchin, Drosophila, Trypanosoma, and Saccharomyces cerevisiae. AUA would most probably be an isoleucine codon in these mitochondria, whereas it is a methionine codon in the majority of nonplant mitochondria.

Key words

Genetic code Mitochondria Planarian Dugesia japonica Cytochrome c oxidase subunit I gene UAA tyrosine codon 

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References

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Copyright information

© Springer-Verlag New York Inc 1992

Authors and Affiliations

  • Yoshitaka Bessho
    • 1
  • Takeshi Ohama
    • 1
  • Syozo Osawa
    • 1
  1. 1.Laboratory of Molecular Genetics, Department of Biology, School of ScienceNagoya UniversityChikusa-ku, NagoyaJapan

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