Chromosome rearrangement by ectopic recombination in Drosophila melanogaster: genome structure and evolution.

Abstract

Ectopic recombination between interspersed repeat sequences generates chromosomal rearrangements that have a major impact on genome structure. A survey of ectopic recombination in the region flanking the white locus of Drosophila melanogaster identified 25 transposon-mediated rearrangements from four parallel experiments. Eighteen of the 25 were generated from females carrying X chromosomes heterozygous for interspersed repeat sequences. The cytogenetic and molecular analyses of the rearrangements and the parental chromosomes show: (1) interchromosomal and intrachromosomal recombinants are generated in about equal numbers; (2) ectopic recombination appears to be a meiotic process that is stimulated by the interchromosomal effect to about the same degree as regular crossing over; (3) copies of the retrotransposon roo were involved in all of the interchromosomal exchanges; some copies were involved much more frequently than others in the target region; (4) homozygosis for interspersed repeat sequences and other sequence variations significantly reduced ectopic recombination.

Coevolution between transposable elements and recombination

“…One of the ways in which selection can act against TEs is to remove deleterious chromosomal rearrangements caused by non-allelic homologous recombination, also known as ectopic recombination [62,63]. This occurs due to the high sequence similarity between insertions of the same family located across the genome and can lead to large deletions or inversions when the insertions are on the same chromosome.…”

Transposable elements in natural populations ofDrosophila melanogaster

“…In Drosophila, diverse experiments from Sturtevant's (1925Sturtevant's ( , 1929 classic Bar duplication studies to the characterization of putative duplications arising in early intralocus recombination studies at white (Green 1959;Judd 1959;Goldberg et al 1983;Davis et al 1987) fostered this hypothesis. Indeed, a systematic study of ectopic exchange indicated that it could be the most common mutation process in female Drosophila (Montgomery et al 1991).…”

Transposon-induced inversions activate gene expression in the maize pericarp

“…If two DSBs occur on the same chromosome, re-ligation of the DNA molecule via NHEJ can form inversions ( Hefferin and Tomkinson 2005 ), deletions, or inversions flanked by inverted duplications, if the DSBs are staggered cuts ( Ranz et al 2007 ). Additionally, inversions can result from ectopic recombination (Non-Allelic Homologous Recombination, NAHR) between dispersed repeated sequences including transposons ( Delprat et al 2009 ), retrotransposons ( Kupiec and Petes 1988 ), interspersed repeat sequences ( Montgomery et al 1991 ), or interspersed duplications ( Cáceres et al 2007 ). For example, NAHR between pairs of homologous TEs present in opposite orientations at different positions on a chromosome can lead to inversions of the DNA segment between the two TEs ( Delprat et al 2009 ).…”