A Computational Method for the Rate Estimation of Evolutionary Transpositions

A Computational Method for the Rate Estimation of Evolutionary Transpositions

Max A. Alekseyev has been interested in genome arrangement and computational reconstruction of ancient genome for a long time (For example, check his 2009 paper with Pavel A. Pevzner). He recently uploaded a new paper in arxiv that the readers may find interesting.

Genome rearrangements are evolutionary events that shuffle genomic architectures. Most frequent genome rearrangements are reversals, translocations, fusions, and fissions. While there are some more complex genome rearrangements such as transpositions, they are rarely observed and believed to constitute only a small fraction of genome rearrangements happening in the course of evolution. The analysis of transpositions is further obfuscated by intractability of the underlying computational problems.

We propose a computational method for estimating the rate of transpositions in evolutionary scenarios between genomes. We applied our method to a set of mammalian genomes and estimated the transpositions rate in mammalian evolution to be around 0.26.

For an early introduction to this topic from Pevzner’s group, check the following PNAS paper from 2003. It is quite an interesting paper challenging the long-standing random breakage model.

Human and mouse genomic sequences reveal extensive breakpoint reuse in mammalian evolution

The human and mouse genomic sequences provide evidence for a

larger number of rearrangements than previously thought and reveal extensive reuse of breakpoints from the same short fragile regions. Breakpoint clustering in regions implicated in cancer and infertility have been reported in previous studies; we report here on breakpoint clustering in chromosome evolution. This clustering reveals limitations of the widely accepted random breakage theory that has remained unchallenged since the mid-1980s. The genome rearrangement analysis of the human and mouse genomes implies the existence of a large number of very short hidden synteny blocks that were invisible in the comparative mapping data and ignored in the random breakage model. These blocks are defined by closely located breakpoints and are often hard to detect. Our results suggest a model of chromosome evolution that postulates that mammalian genomes are mosaics of fragile regions with high propensity for rearrangements and solid regions with low propensity for rearrangements.

Written by M. //