Hideaway, a repeated element from Ascobolus immersus, is rDNA-associated and may resemble a retrotransposon

Abstract.

A λ library of Ascobolus immersus stock 50 was screened for repeated DNA sequences by employing differential hybridization to identify transposable elements. Several λ clones carrying repeated DNA sequences were obtained. One clone contains a repeated DNA sequence with unusual characteristics. This DNA element appears to be associated with rDNA sequences. Its methylation pattern is also reminiscent of rDNA. Sequence analysis indicates that all or at least many copies of the element have integrated in the external spacer sequence separating the rDNA repeats, possibly to avoid complete inactivation by methylation. The element has been named "Hideaway". It possesses structural characteristics of class I retrotransposons, most notably the presence of long direct repeats. The data presented here are discussed with respect to the ability of repeated DNA sequences to escape host defense mechanisms.