The complete mitochondrial genome of the raccoon dog

In the present paper, the complete mitochondrial genome of the raccoon dog was sequenced for the first time on ABI 3730xl using a primer-walking strategy and the long and accurate PCR, with 5 pairs of long-PCR primers and 11 pairs of sub-PCR primers. A liver sample was obtained from a female raccoon dog captured from the Dalai Lake Nature Reserve in Inner Mongolia, China. The mitochondrial genome is a circular doublestranded DNA sequence that is 16,713 bp long including 13 protein-coding genes, two rRNA genes, 22 tRNA genes and one control region (Table I). The accurate annotated mitochondrial genome sequence was submitted to GenBank with accession number NC_013700. The arrangement of the multiple genes is in line with other canine animals (Nowak 1991; Kim et al. 1998; Inoue et al. 2007; Meng et al. 2009) and most mammals (Lopez et al. 1996; Ursing and Arnason 1998; Gissi et al. 1998; Gu et al. 2007; Peng et al. 2007; Wei et al. 2009). The total length of the protein-coding gene sequences is 11,396 bp. Most protein-coding genes initiate with ATG except for ND2, ND3 and ND5, which begin with ATA. Eight protein-coding genes terminate with TAAwhereas theND2 gene terminates with TAG and the Cytb gene terminates with AGA. The incomplete stop codons (TA_ and T_) are used in ND3, COXIII andND4. A strong bias against G at the third codon position is observed in the protein-coding genes. The frequencies of CTA (Leu), ATA (Ile) and TTC (Phe) are higher than those of other codons. The length of tRNA genes vary from 60 to 74 bp. Twenty-one of them could be folded into the typical cloverleaf secondary structure except the tRNA-Ser (AGY), whose complete dihydrouridine arm is lacking. Most raccoon dog mitochondrial genes are encoded on the H strand, except for the ND6 gene and eight tRNA genes, which are encoded on the L strand. Some reading frame intervals and overlaps are found. One of the most typical is between ATP8 and ATP6. The L-strand replication origin (OL) is located within the WANCY region containing five tRNA genes (tRNA-Trp, tRNA-Ala, tRNA-Asn, tRNA-Cys, tRNA-Pro). This region is 33 bp long and has the potential to fold into a stable stem-loop secondary structure. The total base composition of raccoon dog mitochondrial genome is A (32.1%) . T (27.0%) . C (26.7%) . G (14.2%). The base compositions present clearly the A–T skew, which is most obviously in the 16S rRNA gene and tRNA genes. The control region of the raccoon dog mitochondrial genome is located between the tRNA-Pro and tRNA-Phe genes, and contains only promoters and regulatory sequences for replication and transcription, but no structural genes. Three domains are defined in the raccoon dog mitochondrial genome control region (Sbisà et al. 1997): the extended terminationassociated sequence (ETAS) domain, the central conserved domain and the conserved sequence block (CSB) domain. Three CBSs are found in the CSB domain and they are located in positions 16,093– 16,119, 16,445–16,463 and 16,509–16,520, respectively. Only ETAS1 is found, which is located in the position 15,532–15,585. Also only one repetitive sequence region (RS3) is found, which is located