Sequence and Structure of Japanese Flounder (Paralichthys olivaceus) Mitochondrial Genome

摘要

Flatfish and related acanthopterygian fishes with many species important in fisheries await molecular genetic studies for description and conservation of their biodiversity. We cloned and sequenced the complete mitochondrial genome of Japanese flounder Paralichthys olivaceus. A circular 17,090 bp mitochondrial genome from the flounder contains 37 structural genes as in other vertebrates so far reported. The organization including gene order is quite similar to that of other teleostean fishes as wellas placental mammals. The putative control region of the Japanese flounder mitochondrial genome contains a length variable region of about a 74 bp tandem repeat cluster. To overview genetic diversity among known sequences from fishes and representative tetrapods, we tried multiple alignments of coding genes. Alignment of rRNA-coding genes was unsuccessful. Amino-acid sequences of protein-coding genes contained several gaps and regions difficult to align among fishes and tetrapods, while it was easy to align among teleostean fishes. Stem regions of tRNA genes were successfully aligned according to known secondary structure model. We adopted the maximum likelihood inference method to examine phylogenetic relationships among teleostean and related fishes.Comparisons of amino-acid sequences of protein-coding genes and nucleotide sequences of tRNA genes resolved middle to deep branches among teleostean fishes. The flounder mitochondrial genome does not show indication of evolutionary rate difference amongteleosts leading to difficulty in phylogenetic analyses, and our data is useful for future evolutionary studies dealing with higher teleostean fishes.