Transposable Elements as Catalysts for Chromosome Rearrangements

Abstract

Barbara McClintock first showed that transposable elements in maize can induce major chromosomal rearrangements, including duplications, deletions, inversions, and translocations. More recently, researchers have made significant progress in elucidating the mechanisms by which transposons can induce genome rearrangements. For the Ac/Ds transposable element system, rearrangements are generated when the termini of different elements are used as substrates for transposition. The resulting alternative transposition reaction directly generates a variety of rearrangements. The size and type of rearrangements produced depend on the location and orientation of transposon insertion. A single locus containing a pair of alternative transposition-competent elements can produce a virtually unlimited number of genome rearrangements. With a basic understanding of the mechanisms involved, researchers are beginning to utilize both naturally occurring and in vitro-generated configurations of transposable elements in order to manipulate chromosome structure.

The multi-speed genome ofFusarium oxysporumreveals association of histone modifications with sequence divergence and footprints of past horizontal chromosome transfer events

“…Moreover, it provides a means to escape “Muller’s ratchet” in mainly asexual species by exchanging at least parts of core chromosomes. The transposons that reside on pathogenicity chromosomes can play a role in fast adaptation to host-resistance, [19,74] probably mostly by mediating rearrangements [5,8,75], thus potentially disrupting modular genomic organizations and creating novel chromosome segments. Moreover, transposons may disperse into core chromosomes [76] where the chance of harmful effects of transposon insertion is larger than on dispensable chromosomes.…”

“…There is accumulating evidence that this is more likely to occur when an avirulence gene is located near transposon sequences. The occurrence of multiple almost identical sequences in a genome increases the likelihood of homologous recombination that can result in genome rearrangements or deletions [5], which can contribute to pathogen adaptation [1-3,6-15]. In addition, transposon insertion into an avirulence gene can result in regain of virulence [16-19].…”

Transposons, Genome Size, and Evolutionary Insights in Animals

“…Moreover, the increase in DNA content also depends on an amount of non-coding sequences whose repetition is no longer detectable [Kidwell, 2002;Metcalfe and Casane, 2013]. A possible reason for this occurrence could depend on the different insertion sites of the transposons into the host genome [Zhang et al, 2011]. Transposons inserting within or near genes have a mutagenic effect or may affect gene expression, being detrimental to the host genome, and therefore are subject to purifying selection and more frequent deletions [Metcalfe and Casane, 2013;Shen et al, 2013;Lee and Kim, 2014].…”

EpiTEome: Simultaneous detection of transposable element insertion sites and their DNA methylation levels

“…TE sequences have diversified and are classified by families with common sequences, domains, structures, and mobilization strategies [3, 4]. Some TE families have been evolutionarily successful, going through bursts of activity [5], which result in the expansion and rearrangement of genomes [6, 7]. Due to their ability to create rearrangements and mutations, TEs are targeted for epigenetic silencing.…”