H: Mitochondrial genome of the Komodo dragon, efficient sequencing method with reptile-oriented primers and novel gene rearrangements

Abstract

The mitochondrial genome of the Komodo dragon (Varanus komodoensis) was nearly completely se-quenced, except for two highly repetitive noncoding regions. An efficient sequencing method for squamate mitochondrial genomes was established by combining the long polymerase chain reaction (PCR) technol-ogy and a set of reptile-oriented primers designed for nested PCR amplifications. It was found that the mitochondrial genome had novel gene arrangements in which genes from NADH dehydrogenase subunit 6 to proline tRNA were extensively shuffled with duplicate control regions. These control regions had 99% sequence similarity over 700 bp. Although snake mitochondrial genomes are also known to possess dupli-cate control regions with nearly identical sequences, the location of the second control region suggested independent occurrence of the duplication on lineages leading to snakes and the Komodo dragon. An-other feature of the mitochondrial genome of the Komodo dragon was the considerable number of tandem repeats, including sequences with a strong secondary structure, as a possible site for the slipped-strand mispairing in replication. These observations are consistent with hypotheses that tandem duplications via the slipped-strand mispairing may induce mitochondrial gene rearrangements and may serve to maintain similar copies of the control region. Key words: lizard; reptile; mitochondrial DNA; polymerase chain reaction; tandem repeat 1