RT Journal
A1 Villasante, Alfredo
A1 Abad, José P.
A1 Planelló, Rosario
A1 Méndez-Lago, María
A1 Celniker, Susan E.
A1 de Pablos, Beatriz
T1 Drosophila telomeric retrotransposons derived from an ancestral element that was recruited to replace telomerase
JF Genome Research 
JO Genome Research 
YR 2007 
FD December 01 
VO 17 
IS 12 
SP 1909 
OP 1918 
DO 10.1101/gr.6365107 
UL http://genome.cshlp.org/content/17/12/1909.abstract 
AB Drosophila telomeres do not have arrays of simple telomerase-generated G-rich repeats. Instead, Drosophila maintains its telomeres by occasional transposition of specific non-long terminal repeat (non-LTR) retrotransposons to chromosome ends. The genus Drosophila provides a superb model system for comparative telomere analysis. Here we present an evolutionary study of Drosophila telomeric elements to ascertain the significance of telomeric retrotransposons (TRs) in the maintenance of Drosophila telomeres. PCR and in silico surveys in the sibling species of Drosophila melanogaster and in more distantly related species show that multiple TRs maintain telomeres in Drosophila. In addition to TRs with two open reading frames (ORFs) capable of autonomous transposition, there are deleted telomeric retrotransposons that have lost their ORF2, which we refer to as half telomeric-retrotransposons (HTRs). The phylogenetic relationship among these telomeric elements is congruent with the phylogeny of the species, suggesting that they have been vertically inherited from a common ancestor. Our results suggest that an existing non-LTR retrotransposon was recruited to perform the cellular function of telomere maintenance.