Transposon-Induced Hotspots for Genomic Instability
- Department of Ecology and Evolutionary Biology, The University of Arizona, Tucson, Arizona 85721, USA
This extract was created in the absence of an abstract.
Although the potential of transposable elements (TEs) to produce genomic rearrangements, such as inversions and translocations, has been appreciated for some time from the results of laboratory experiments, estimates of the frequency and evolutionary importance of such events in natural populations have been difficult to come by. Now, with the ability to obtain nucleotide sequence data on a large scale, we are starting to learn about the nature and frequency of TE-induced changes in the structure of their host genomes. Not only is direct evidence being provided to support predictions that TEs can initiate chromosomal rearrangements by ectopic recombination and other mechanisms, but surprising examples of massive local genomic instability are being reported that were not predicted by earlier models of TE behavior. In this issue, a remarkable example of an unprecedented degree of genome restructuring is reported in a study of the breakpoints of a TE-induced inversion in Drosophila buzzatii (Caceres et al. 2001).
Genomic Rearrangements are Abundant in Drosophila
The unusually rich inversion polymorphism seen in many species of the Drosophila genus provides fertile ground for study of the mechanisms involved in generating genomic rearrangements. The rate of chromosomal reshuffling in Drosophila appears to be higher than that of any other animal or plant taxon that has been studied similarly (Ranz et al. 2001). D. buzzatii is a cactophylic species associated with host plants of the Opuntia genus. The species originated in Argentina and is distributed widely in South America. Recently this species colonized the Mediterranean region of the Old World and Australia. Chromosome 2 of D. buzzatii is polymorphic for two major structural configurations that are found throughout the species range. The standard ancestral configuration,2st, has a gene order …
