P-element transposase induces male recombination in Drosophila melanogaster.

Male recombination in P-M dysgenic crosses has been viewed as a reflection of P-element transposase interacting with P elements. However, recent studies suggest that the transposase may catalyse double-stranded breaks in chromosomal DNA. We have, therefore, introduced P(delta 2-3 ry+) (99B), a single non-mobile P-element transposase source, into the long-standing laboratory true M strains of a flanking lethal crossover selective system, thus facilitating the examination of rare male recombination events as an assay for transposase activity. We find that the rate of male recombination in the presence of this non-mobile P element is greater than twenty times the background rate of male recombination in the control examined prior to introduction of the transposase source.