Transposable elements as a potential vectors for horizontal gene transfer in host-parasite system

Abstract

Horizontal gene transfer is one of the principle ways that maintain the genetic diversity in prokaryotes. However the genetic transfer between eukaryotes is assumptive. In light of this hypothesis DNA transposable elements are the likely candidates for the eukaryotic horizontally transmitted genetic elements. The directed horizontal transfer may only occur in the case of physical contact of organisms involved in this process. This sort of interaction takes place in host–parasite systems. Nowadays the hypothesis of horizontal gene transfer is based on the sequence similarity, sporadic distribution and conjectural ways of transposons transduction. However, all highly homologous elements found are inactive due to mutations within their ORFs. The percent of identity does not represent the origin of transposable element and therefore cannot testify to its transduction. Most of the transposable elements are inactive. Nevertheless the active copies may function as active mutators giving rise to genetic diversity under the ecological stress. In spite of the absence of direct proofs of horizontal gene transfer there are indirect data indicating that this process might occur many times in the course of eukaryotic evolution.