BILBO, A NON-LTR RETROTRANSPOSON OF DROSOPHILA-SUBOBSCURA - A CLUE TOTHE EVOLUTION OF LINE-LIKE ELEMENTS IN DROSOPHILA

We used the repetitive character of transposable elements to isolate a non-LTR retrotransposon in Drosophila subobscura, bilbo, as we have c alled it, has homology to TRIM and LOA elements. Sequence analysis sho wed a 5' untranslated region (UTR), an open reading frame (ORF) with n o RNA-binding domains, a downstream ORF that had structural homology t o that of the I factor, and, finally, a 3' UTR which ended in several 5-nt repeats. The results of our phylogenetic and structural analyses shed light on the evolution of Drosophila non-LTR retrotransposons and support the hypothesis that an ancestor of these elements was structu rally complex.