DISTRIBUTION OF THE MITOCHONDRIAL DEVIANT GENETIC CODE AUA FOR METHIONINE IN HETEROKONT ALGAE |
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Authors: | Megumi Ehara Kazuo I Watanabe Hiroshi Kawai Yuji Inagaki Yasuko Hayashi-Ishimaru Takeshi Ohama |
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Institution: | Department of Biology, Faculty of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan; Research Center for Inland Seas, Kobe University, Rokkodai, Kobe 657–8501, Japan; JT Biohistory Research Hall, 1-1 Murasaki-cho, Takatsuki, Osaka 569-1125, Japan |
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Abstract: | The DNA sequence of the cytochrome oxidase subunit I ( COX I) gene (1059 bp), was determined in a number of heterokont algae, including five species of the Phaeophyceae Chorda filum (Linnaeus) Stackhouse, Colpomenia bullosa (Saunders) Yamada, Ectocarpus sp., Pseudochorda nagaii (Tokida) Inagaki, Undaria pinnatifida (Harvey) Suringar], and a member of the Raphidophyceae Chattonella antiqua (Hada) Ono]. The distribution of a deviant mitochondrial code, the AUA codon for methionine (AUA/Met), which was previously reported in the Xanthophyceae, was inferred from these COX I sequences. Comparative analyses of these sequences revealed that all the algae described above bear the universal genetic code, including the assignment for the AUA codon. A phylogenetic tree was constructed using the obtained sequences along with already-published COX I sequences of various heterokont algae. The clusters of the Xanthophyceae and the Phaeophyceae were resolved as sister groups with high bootstrap support, excluding a bacillariophycean species, a raphidophycean species, and three species of the Eustigmatophyceae. Taking the distribution of the deviant code and the COX I phylogenetic tree together, the genetic code change most probably occurred in an ancestor of the Xanthophyceae after it had branched off from the Phaeophyceae. |
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Keywords: | cytochrome oxidase subunit I deviant genetic code heterokont algae Phaeophyceae Xanthophyceae |
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