Retrotransposons are a major component of eukaryotic moderately repetitive DNA. In Drosophila, many spontaneous mutations are caused by movement of these elements. Mutant phenotypes result from insertions into both coding and noncoding regions. Drosophila retrotransposons are developmentally programmed transcription units, and insertions into noncoding regions introduce transcriptional control signals that can affect the expression of genes at the sites of insertion. Some phenotypes resulting from retrotransposon insertions into noncoding gene regions can be reversed by extragenic suppressor mutations. The long term objective of this study is to understand how these elements disrupt the expression of nearby genes and to elucidate the role of suppressors in modulating the mutagenic activity of retrotransposons.
