Complete Mitochondrial Genome of Three Species of the Genus Microtus (Arvicolinae, Rodentia)

Abstract

The 65 species of the genus Microtus have unusual sex-related genetic features and a high rate of karyotype variation. However, only nine complete mitogenomes for these species are currently available. We describe the complete mitogenome sequences of three Microtus, which vary in length from 16,295 bp to 16,331 bp, contain 13 protein-coding genes (PCGs), two ribosomal RNA genes, 22 transfer RNA genes and a control region. The length of the 13 PCGs and the coded proteins is the same in all three species, and the start and stop codons are conserved. The non-coding regions include the L-strand origin of replication, with the same sequence of 35 bp, and the control region, which varies between 896 bp and 930 bp in length. The control region includes three domains (Domains I, II and III) with extended termination-associated sequences (ETAS-1 and ETAS-2) in Domain I. Domain II and Domain III include five (CSB-B, C, D, E and F) and three (CSB-1, CSB-2, and CSB-3) conserved sequence blocks, respectively. Phylogenetic reconstructions using the mitochondrial genomes of all the available Microtus species and one representative species from another genus of the Arvicolinae subfamily reproduced the established phylogenetic relationships for all the Arvicolinae genera that were analyzed.

Keywords: Microtus; complete mitogenome; control region; mitochondrial; phylogeny.

Figure 1

Representative map of the mitochondrial genome of the three analyzed Microtus species. Genes encoded by the heavy strand are shown outside the circle, while those encoded by the light strand are shown inside.

Figure 2

Nucleotide sequence alignment of the L-strand origin of replication (O_L) of species from the subfamily Arvicolinae. Dots indicate identity and dashes denote deletions.

Figure 3

Nucleotide sequence alignment of the control region of Microtus cabrerae (M. ca), M. chrotorrhinus (M. ch) and M. thomasi (M. th). Dots indicate the identity of the nucleotides and dashes the indels. All the conserved sequences identified are included in boxes: the two conserved extended termination-associated sequences (ETAS1 and ETAS2) in Domain I, five conserved blocks (CSB-F, E, D, C, B) in the central conserved Domain II (underlined) and three conserved blocks (CSB1, CSB-2 and CSB-3) in Domain III. Dots indicate identity and dashes denote deletions.

Figure 4

Bayesian Inference tree using the complete mitogenome sequences of ten Microtus species available in GenBank and seven representative species of genera from the subfamily Arvicolinae, and the mitogenome sequence of Akodon montensis (subfamily Sigmodontinae) used as an outgroup. Bayesian posterior probabilities are indicated at each node.