Analysis of codon usage pattern of mitochondrial protein-coding genes in different hookworms.

The phenomenon of unequal usage of synonymous codons encoding an amino acid in which some codons are more preferred to others is the codon usage bias (CUB) and it is species specific. Analysis of CUB helps in understanding evolution at molecular level and acquires significance in mRNA translation, design of transgenes and new gene discovery. In our current study, we analyzed synonymous codon usage pattern and the factors influencing it on mitochondrial protein coding genes of 6 different hookworms i.e. Ancylostoma ceylanicum, Ancylostoma duodenale, Necator americanus, Ancylostoma tubaeforme, Ancylostoma caninum and Uncinaria sanguinis as no work was reported yet. The effective number of codons for mitochondrial genes suggested that codon usage bias was high in most species. The GC content was lower than AT content i.e. genes were AT rich as indicated by nucleotide composition analysis. The overall nucleotide composition along with its composition at 3rd codon position and correspondence analysis suggested that both natural selection and mutation pressure might have affected the codon usage bias in mitochondrial genes. However, neutrality plot revealed that mutation pressure might have played a major role in A. ceylanicum while natural selection might have played the dominant role in Ancylostoma duodenale, Necator americanus, Ancylostoma tubaeforme, Ancylostoma caninum and Uncinaria sanguinis.