Complete mitochondrial genomes and novel gene rearrangements in two dicroglossid frogs, Hoplobatrachus tigerinus and Euphlyctis hexadactylus, from Bangladesh

Abstract

We determined the complete nucleotide sequences of mitochondrial (mt) genomes from two dicroglossid frogs, Hoplobatrachus tigerinus (Indian Bullfrog) and Euphlyctis hexadactylus (Indian Green frog). The genome sizes are 20462 bp in H. tigerinus and 20280 bp in E. hexadactylus. Although both genomes encode the typical 37 mt genes, the following unique features are observed: 1) the ND5 genes are duplicated in H. tigerinus that have completely identical sequences, whereas duplicated ND5 genes in E. hexadactylus possessed dissimilar substitutions; 2) duplicated control region (CR) in H. tigerinus has almost identical sequences whereas single control region (CR) was found in E. hexadactylus; 3) the tRNA-Leu (CUN) gene is translocated from the LTPF tRNA cluster to downstream of ND5-1 in H. tigerinus, and the tRNA-Pro gene is translocated from the LTPF tRNA cluster to downstream of CR in E. hexadactylus; 4) pseudo tRNA-Leu (CUN) and tRNA-Pro genes are observed in E. hexadactylus; and 5) two tRNA-Met genes are encoded in both species, as observed in the previously reported dicroglossid mt genomes. Almost all observed gene rearrangements in H. tigerinus and E. hexadactylus can be explained by the tandem duplication and random loss model, except translocation of tRNA-Pro in E. hexadactylus. The novel mt genomic features found in this study may be useful for future phylogenetic studies in the dicroglossid taxa. However, the mt genome with interesting features found in the present study reveal a high level of variation of gene order and gene content, inspiring more research to understand the mechanisms behind gene and genome evolution in the dicroglossid and as well as in the amphibian taxa in future studies.

Mitochondrial genomes of Japanese <i>Babina</i> frogs (Ranidae, Anura): unique gene arrangements and the phylogenetic position of genus <i>Babina</i>

“…In contrast to the former, the mt gene arrangement of the Babina sensu stricto group differs from the neobatrachian-type arrangement and shows the unique position of the ps-trnH-trnS (AGY)-nad5 gene region between the CR and the LTPF trn-cluster. The translations of nad5 from its original position (upstream of the CR) to downstream of the CR were reported in several neobatrachian mt genomes (e.g., dicroglossids, rhacophorids, mantellids, and the ranid Staurois latopalmatus; see , Alam et al, 2010. However, the CR downstream position of trnS (AGY) and trnH or its pseudogene is found only in Babina and a few ranid species (S. latopalmatus and Odorrana spp.…”

Complete nucleotide sequence and gene rearrangement of the mitochondrial genome of Occidozyga martensii

“…These sequences could be folded into typical cloverleaf structures and hold the same anticodon, CAT, which is common in most metazoan mt tRNA-Met genes. Although, two tRNA-Met genes have been reported in the complete mtDNA of F. cancrivora (Ren et al 2009), F. limnocharis (Liu et al 2005), L. bannaensis ), L. fujianensis (unpublished data), H. rugulosus (Yu et al 2012), H. tigerinus, E. hexadactylus (Alam et al 2010), P. spinosa (Zhou et al 2009) and M. madagascariensis (Kurabayashi et al 2006), the position of the extra tRNA-Met gene differs between Dicroglossidae and Mantellidae. Based on these differences, Kurabayashi et al (2006) suggested that two tRNA-Met genes in each lineage are of different origin.…”

Inter- and intra-specific genetic divergence of Asian tiger frogs (genus <i>Hoplobatrachus</i>), with special reference to the population structure of <i>H. tigerinus</i> in Bangladesh

“…We prepared two datasets: (1) a dataset containing all haplotypes from five Hoplobatrachus species in South and Southeast Asia and (2) a dataset containing H. tigerinus haplotypes in Bangladesh. In dataset (1), we also included H. chinensis and Euphlyctis hexadactylus CYTB haplotypes previously reported by Alam et al (2010Alam et al ( , 2012) (accession numbers: AB636597-AB636600 and AP011544). Based on this dataset, we constructed a Hoplobatrachus species phylogenetic tree using the neighbor-joining (NJ) (Saitou and Nei, 1987) and maximum likelihood (ML) methods.…”