DNA-seq of Drosophila mdg4 induced X-linked female sterile alleles

The retrotransposon mdg4 preferentially inserts near binding sites of the female germline transcription factor OVO in Drosophila melanogaster, most notably at the ovo locus itself. We leveraged this relationship to screen for X-linked recessive female-sterile mutations generated by mdg4 mobilization in flamenco mutant females. From 1,192 chromosomes, we recovered 17 female-sterile alleles across 11 complementation groups. mdg4 insertions were significantly enriched in OVO-bound regions but accounted for only a subset of sterility phenotypes, revealing substantial background mutagenesis by other transposable elements. These results refine the OVO-mdg4 relationship and highlight both the promise and limitations of transposon-based genetic screens.