Sequencing and characterisation of complete mitogenome DNA for Rasbora sarawakensis (Cypriniformes: Cyprinidae: Rasbora) with phylogenetic consideration

The Blueline Rasbora (Rasbora sarawakensis) is a small ray-finned fish categorized under the genus Rasbora in the Cyprinidae family. In this study, the complete mitogenome sequence of R. sarawakensis was sequenced using four primers targeting overlapping regions. The mitogenome is 16,709 bp in size, accommodating 22 transfer RNA genes, 13 protein-coding genes, two ribosomal RNA genes and a putative control region. Identical gene organisation was detected between this species and other genus counterparts. The heavy strand houses 28 genes while the light strand stores the other nine genes. Most protein-coding genes employ ATG as start codon, excluding COI gene, which utilizes GTG instead. The central conserved sequence blocks (CSB-F, CSB-E and CSB-D), variable sequence blocks (CSB-3, CSB-2 and CSB-1) as well as the terminal associated sequence (TAS) are conserved in the control region. The maximum likelihood phylogenetic tree revealed the divergence of R. sarawakensis from the basal region of the Rasbora clade, where its evolutionary relationships with R. maculatus and R. pauciperforata are poorly resolved as indicated by the low bootstrap values. This work acts as steppingstone towards further molecular evolution and population genetics studies of Rasbora genus in future

Complete Mitochondrial DNA Sequence of Rasbora : Mitogenome Characterization and Phylogenetic Implications

Rasbora are freshwater fishes that belongs to Cyprinidae family whereby most of its member share similar morphology which makes them difficult to be differentiated between species. In this study, both the morphometry analysis and mitochondrial DNA approach were used to resolve the phylogenetic relationship between these species. The complete sequence of mt-genome for R. argyrotaenia, R. myersi, R. sarawakensis and Rasbora sp. were 16,574 bp, 16,581 bp, 16,709 bp and 16,518 bp respectively. The structure of all study species mtDNA was characterized using bioinformatics analysis. Rasbora mt-genome comprises of a standard set of 22 tRNAs, two rRNAs, 13 PCGs and two typical non-coding regions. The AT-skew and GC-skew values in the whole genome of Rasbora were 0.141 and -0.268 respectively, revealing that the H-strand had the amount of C and A were more prevalent. All the tRNA genes could be folded into cloverleaf secondary structures, while the secondary structure of Ser (AGY) lacked a D arm (DHU stem). By comparing Rasbora genome sequence with the recognition sites in teleost species, five conserved sequence blocks were identified in the control region. The common conserved motif sequence of origin of L-strand replication were also identified. The phylogenetic analyses were based on the concatenated of nucleotide sequence and amino acid sequence from 13 PCGs. The phylogenetic position of R. argyrotaenia, R. myersi, R. sarawakensis and Rasbora sp. were evaluated from the Maximum likelihood trees. Overall, this study enriches the knowledge of Rasbora mt-genomes while partially resolving the ambiguity of the phylogenetic relationships of Rasbora taxonomy