A brief history of the status of transposable elements: from junk DNA to major players in evolution

Abstract

The idea that some genetic factors are able to move around chromosomes emerged more than 60 years ago when Barbara McClintock first suggested that such elements existed and had a major role in controlling gene expression and that they also have had a major influence in reshaping genomes in evolution. It was many years, however, before the accumulation of data and theories showed that this latter revolutionary idea was correct although, understandably, it fell far short of our present view of the significant influence of what are now known as "transposable elements" in evolution. In this article, I summarize the main events that influenced my thinking about transposable elements as a young scientist and the influence and role of these specific genomic elements in evolution over subsequent years. Today, we recognize that the findings about genomic changes affected by transposable elements have considerably altered our view of the ways in which genomes evolve and work.

Figure 1.—

Estimated proportion of TEs in genomes of various eukaryote organisms. The data consist only of the TEs clearly identified as such. Parts of the genome that had simply been derived from TEs—such as TE-derived non-TE sequences (i.e., sequences derived from TEs, but no longer recognizable as TEs and that appear as “unique” DNA sequences), non-TE sequences duplicated as a result of TE activity, TE-derived sequences included within genes, satellite DNA, and minisatellites and microsatellites derived from TEs (Pavlícek et al. 2002; Jurka and Gentles 2006; Ma and Jackson 2006)—have not been taken into account. Courtesy of C. Lœvenbruck.