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Open Access Research article

Losing helena: The extinction of a drosophila line-like element

Rita Rebollo1, Emmanuelle Lerat1, Liliana Lopez Kleine12, Christian Biémont1 and Cristina Vieira1*

Author Affiliations

1 Université de Lyon; Université Lyon 1; CNRS; UMR 5558, Laboratoire de Biométrie et Biologie Evolutive, Villeurbanne F-69622, France

2 UR477 de Biochimie Bactérienne, UR341 de Mathématiques et informatiques Appliquées, INRA. 78352 Jouy en Josas, France

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BMC Genomics 2008, 9:149  doi:10.1186/1471-2164-9-149

Published: 31 March 2008

Abstract

Background

Transposable elements (TEs) are major players in evolution. We know that they play an essential role in genome size determination, but we still have an incomplete understanding of the processes involved in their amplification and elimination from genomes and populations. Taking advantage of differences in the amount and distribution of the Long Interspersed Nuclear Element (LINE), helena in Drosophila melanogaster and D. simulans, we analyzed the DNA sequences of copies of this element in samples of various natural populations of these two species.

Results

In situ hybridization experiments revealed that helena is absent from the chromosome arms of D. melanogaster, while it is present in the chromosome arms of D. simulans, which is an unusual feature for a TE in these species. Molecular analyses showed that the helena sequences detected in D. melanogaster were all deleted copies, which diverged from the canonical element. Natural populations of D. simulans have several copies, a few of them full-length, but most of them internally deleted.

Conclusion

Overall, our data suggest that a mechanism that induces internal deletions in the helena sequences is active in the D. simulans genome.