# Complete Mitochondrial (mtDNA) Genome Analysis of Economically Significant Fish Cirrhinus cirrhosus in Bangladesh

## TL;DR

This paper analyzes the complete mitochondrial DNA of the economically important fish Cirrhinus cirrhosus in Bangladesh.

## Contribution

The study provides a complete mitochondrial genome annotation and phylogenetic analysis of Cirrhinus cirrhosus.

## Key findings

- The mitochondrial genome of Cirrhinus cirrhosus is 16,593 bp long with typical mitochondrial gene content.
- The genome shows an AT bias and significant skew in the ND6 gene.
- Phylogenetic analysis suggests a close evolutionary relationship between Cirrhinus cirrhosus and Cirrhinus mrigala.

## Abstract

Complete mitochondrial DNA genome annotation of an ecologically and commercially important fish species Cirrhinus cirrhosus was executed with next-generation sequencing (NGS) for nucleotide and phylogenetic analyses. The findings of this study showed that the Cirrhinus cirrhosus mitochondrial genome contained 16,593 bp, including 13 protein-coding genes, 2 ribosomal RNA genes, 22 tRNA genes, and a D-loop region. The overall base composition was 32% adenine, 25% thiamine, 16% guanine, and 27% cytosine. This mitochondrial DNA exhibits an AT biasness, with 56% AT content in its genome. Significant fluctuations were identified in the AT and GC skew values of the ND6 gene, indicating that the selection and mutation forces acting on this gene might be different from those acting on other genes. The Ka/Ks ratios of most protein-coding genes were less than 1, indicating very strong natural selection pressure. Phylogenetic analysis of Cirrhinus cirrhosus with Cirrhinus mrigala and Bangana tungting suggested a closer evolutionary relationship among these species, which might have shared a more recent common ancestor. It has been also found that the genera Labeo and Cirrhinus are not monophyletic.