TRANSPOSITION OF THE LINE-LIKE RETROTRANSPOSON TART TO DROSOPHILA CHROMOSOME TERMINI

TART, a telomere-associated DNA element from Drosophila, is shown in t his paper to have structural homology to LINE (long interspersed eleme nt)-like retrotransposons and to transpose to broken chromosome ends. TART DNA was detected by in situ hybridization in 7 of 10 independent additions of DNA to a chromosome end. We found evidence that a TART el ement had transposed to the chromosome end in each of two additions th at were examined in detail. From the DNA sequence of a TART element th at recently transposed, we infer that TART encodes two proteins having significant sequence similarity to the putative proteins of many LINE s. These results support the hypothesis that TART elements preferentia lly retrotranspose to the termini of chromosomes as part of the essent ial process by which Drosophila telomeres are maintained.