The Novel Gene Rearrangement Of The Mitochondrial Genome Of The Occidozyga Martensii And The Phylogenetic Relationships Within Neobatrachia

We determined the complete nucleotide sequence (18, 321bp) of the mitochondrial DNA of Occidozyga martensii using the polymerase chain reaction (PCR) and LA-PCR in this paper. Although the base composition and codon usage of Occidozyga martensii conforms to the typical vertebrate patterns, this genome contains 23 tRNAs (a tandem duplication of tRNA⁽Met( gene). The LTPF tRNA (gene) cluster (tRNA^Leu(CUN)-tRNA^Thr- tRNA^Pro-tRNA^Phe) and the position of the ND5 gene downstream of the control region were also confirmed. Moreover, we found that in the WANCY tRNA gene cluster, the tRNA^Asn gene was located between the tRNA^Tyr and CO I genes instead of between the tRNA^Ala gene and tRNA^Cys gene. This represents a novel mtDNA gene rearrangement in vertebrates. According to the gene arrangement mechanism, at least one duplication-deletion events through an intermediate arrangement would be needed to generate the Occidozyga martensii gene order in the WANCY tRNA gene cluster (tRNA^Trp-tRNA^Ala- tRNA^Asn-tRNA^Cys- tRNA^Tyr) from that of typical vertebrates.Based on the concatenated sequences of 13 protein co-ding and two rRNAs, we constructed MP, ML and BI trees in order to further confirm the phylogenetic relationships within neobatrachia. In our MP tree the family Ranidae formed a monophyletic group. By contrast, our ML and BI trees supported the paraphyly of Ranidae with Mantellidae and Rhacophoridae. In our phylogenetic study, the subfamily of Chinese ranids is uncertain, but our result suggested two subfamily (Raninae and Dicroglossinae) for Chinese ranid species according to the relationships between gene rearrangement and phylogeny. Finally, Anura animal mitochondrial gene rearrangements and phylogenetic relationships are discussed.