title: Complete DNA sequence of the mitochondrial genome of the ascidian Halocynthia roretzi (Chordata, Urochordata).
abstract: The complete nucleotide sequence of the 14,771-bp-long mitochondrial (mt) DNA of a urochordate (Chordata)-the ascidian Halocynthia roretzi-was determined. All the Halocynthia mt-genes were found to be located on a single strand, which is rich in T and G rather than in A and C. Like nematode and Mytilus edulis mtDNAs, that of Halocynthia encodes no ATP synthetase subunit 8 gene. However, it does encode an additional tRNA gene for glycine (anticodon TCT) that enables Halocynthia mitochondria to use AGA and AGG codons for glycine. The mtDNA carries an unusual tRNA(Met) gene with a TAT anticodon instead of the usual tRNA(Met)(CAT) gene. As in other metazoan mtDNAs, there is not any long noncoding region. The gene order of Halocynthia mtDNA is completely different from that of vertebrate mtDNAs except for tRNA(His)-tRNA(Ser)(GCU), suggesting that evolutionary change in the mt-gene structure is much accelerated in the urochordate line compared with that in vertebrates. The amino acid sequences of Halocynthia mt-proteins deduced from their gene sequences are quite different from those in other metazoans, indicating that the substitution rate in Halocynthia mt-protein genes is also accelerated.
authors.affiliation: Department of Molecular Biology, School of Life Science, Tokyo University of Pharmacy and Life Science, Horinouchi, Hachioji, Tokyo 192-0392, Japan. yokobori@ls.toyaku.ac.jp
authors.forename: S i
authors.initials: Si
authors.lastname: Yokobori
authors.forename: T
authors.initials: T
authors.lastname: Ueda
authors.forename: G
authors.initials: G
authors.lastname: Feldmaier-Fuchs
authors.forename: S
authors.initials: S
authors.lastname: Pääbo
authors.forename: R
authors.initials: R
authors.lastname: Ueshima
authors.forename: A
authors.initials: A
authors.lastname: Kondow
authors.forename: K
authors.initials: K
authors.lastname: Nishikawa
authors.forename: K
authors.initials: K
authors.lastname: Watanabe
mesh_terms: D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D003062:Codon; D004272:DNA, Mitochondrial / Q000235:genetics*; D016678:Genome; D006801:Humans; D009690:Nucleic Acid Conformation; D010802:Phylogeny; D012335:RNA, Ribosomal / Q000235:genetics; D012353:RNA, Transfer, Gly / Q000737:chemistry / Q000235:genetics; D014561:Urochordata / Q000235:genetics*
chemical_list: D003062:Codon; D004272:DNA, Mitochondrial; D012335:RNA, Ribosomal; D012353:RNA, Transfer, Gly