Analyzing Inverse Symmetry with Original and Terminal Sites of Prokaryotic Genome

The segmental duplication has long been known to be a major mechanism for genome growth and evolution. Beyond that, the large-scale genomic duplication is important in the evolution of species. Recent studies have spotted occurrence of whole-genome duplication provided great insight into many aspects of biology. In this work we investigate possible association of inverse symmetry with whole-genome inverse duplications on genomes. Our findings, through analyses of word-frequency nucleotides and distributions of homologous conserved regions on publicly available complete genomes of 18 archaea and 139 bacteria, are positive. These findings suggest that, first, statistically significant inverse symmetry is found within some prokaryotic genomes. Second, there is inverse symmetry around the replication original and terminal sites on the prokaryotic genomes. The mechanism of generation of inverse symmetry involves whole-genome inverse duplications. Whole-genome inverse duplications have occurred in most prokaryotic chromosomes near original sites and terminal sites. Our research integrates the abundance of knowledge with evolution of genomes and creates a new approach for predicting loci of original sites and terminal sites in prokaryotic chromosomes. Whole-genome inverse duplication events probably are ancient, may have occurred not frequently but probably in more than one incident. Our findings suggest that whole-genome duplication is a great feature of prokaryotic genome evolution.