دانلود رایگان مقاله توالی و مشخصه یابی ژنوم DNA میتوکندری برای ماهی Brama japonica

Abstract

In this study, the complete mitochondrial genome sequence of Brama japonica is isolated and characterized by PCR and primer-walking sequencing techniques. The complete DNA is 17,009 bp in length and contained 13 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes and a long putative control region. The gene organization and nucleotide composition are identical to those of other Bramidae fishes. In contrast, the 12S rRNA gene contains a big poly C structure which is larger than those from other Bramidae species. Of 37 genes, twenty-eight are encoded by heavy strand, while nine are encoded by light strand. Among the 13 protein-coding genes, twelve employ ATG as start codon, while only one (COI) utilizes GTG as start codon. The terminal associated sequence (TAS), the central and conserved sequence block (CSB-E and CSB-D) and a variable domain (CSB-1, CSB-2 and CSB-3) are identified in the control region, while the typical central conserved CSB-F is not detected. From the phylogenetic tree, we find that B. japonica, together with other five Bramidae species form a monophyletic group among 24 species. This work provides a set of useful data for studies on population genetic diversity and molecular evolution in Bramidae fish species.

3.5. Phylogenetic relationship analysis

To uncover the phylogenetic position of B. japonica among closely related fishes, a phylogenetic tree is constructed using the 12 concatenated protein-coding genes. The molecular phylogenetic tree using maximum-likehood (ML) analysis is shown in Fig. 3. As displayed from the tree topologies, we find that the 24 species from 14 genera are mainly divided into three welldefined clades which are boxed with color line. Six species from five genera under family Bramidea including B. japonica, P. aesticola, E. illustris, T. steindachneri, T. asper and T. rubescens form a monophyletic group. This result is identical to previous phylogeny studies by using the partial mitochondrial gene (Miya et al., 2013). Moreover, B. japonica is genetically closest to four Bramidae species (E. illustris, T. steindachneri, T. asper and T. rubescens) according to the phylogenetic tree.