A Database of Drosophila Genes & Genomes

FB2013_03, released May 7th, 2013
 

Reference Report

Reference
Citation Blumenstiel, J.P., Hartl, D.L., Lozovsky, E.R. (2002). Patterns of Insertion and Deletion in Contrasting Chromatin Domains.  Mol. Biol. Evol. 19(12): 2211--2225. (Export to RIS)
FlyBase ID FBrf0152209
Publication Type Research paper
PubMed ID 12446812
PubMed Abstract Transposable elements (TEs) play a fundamental role in the evolution of genomes. In Drosophila they are disproportionately represented in regions of low recombination, such as in heterochromatin. This pattern has been attributed to selection against repeated elements in regions of normal recombination, owing to either (1) the slightly deleterious position effects of TE insertions near or into genes, or (2) strong selection against chromosomal abnormalities arising from ectopic exchange between TE repeats. We have used defective non-long-terminal repeat (LTR) TEs that are "dead-on-arrival" (DOA) and unable to transpose in order to estimate spontaneous deletion rates in different constituents of chromatin. These elements have previously provided evidence for an extremely high rate of spontaneous deletion in Drosophila as compared with mammals, potentially explaining at least part of the differences in the genome sizes in these organisms. However, rates of deletion could be overestimated due to positive selection for a smaller likelihood of ectopic exchange. In this article, we show that rates of spontaneous deletion in DOA repeats are as high in heterochromatin and regions of euchromatin with low recombination as they are in regions of euchromatin with normal recombination. We have also examined the age distribution of five non-LTR families throughout the genome. We show that there is substantial variation in the historical pattern of transposition of these TEs. The overrepresentation of TEs in the heterochromatin is primarily due to their longer retention time in heterochromatin, as evidenced by the average time since insertion. Fragments inserted recently are much more evenly distributed in the genome. This contrast demonstrates that the accumulation of TEs in heterochromatin and in euchromatic regions of low recombination is not due to biased transposition but by greater probabilities of fixation in these regions relative to regions of normal recombination.
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Language of Publication English
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Publication Type Journal
Abbreviation Mol. Biol. Evol.
Title Molecular Biology and Evolution
Publication Year 1983-
ISBN/ISSN 0737-4038 1537-1719
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