The complete mitochondrial genomes sequences of Asio flammeus and Asio otus and comparative analysis

The complete mitochondrial genomes of Asio flammeus and Asio otus were se- quenced and found to span 18858 bp and 18493 bp, respectively. It is surprising to find the for- mer to be the largest among all avian mitochondrial genomes sequenced so far. The two ge- nomes have very similar gene order with that of Gallus gallus, neither contains the pseudo con- trol region, but both have a single extra base, namely Cytidine, at position 174 in ND3 gene. The control regions of Asio flammeus and Asio otus’ mitochondrial genomes span 3288 bp and 2926 bp respectively, which are the longest among vertebrates except for Myxine glutinosa and con- tribute to the large size of two genomes. The 3′end of the control region of Asio flammeus and Asio otus contains many tandemly repeated sequences, which are highly similar to a putative control element, i.e. Mt5, and may form stable stem-loop secondary structures. Such repeated sequences probably play an important role in regulating transcription and replication of mito- chondrial genome. Our results may provide important clues for uncovering the origin and evolu- tion mechanisms of mitochondrion genome.