P-element transposase induces male recombination inDrosophila melanogaster

Abstract

SummaryMale 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(Δ2–3 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.

Coincidence of P-Insertion Sites and Breakpoints of Deletions Induced by Activating P Elements in Drosophila

“…Similar to local transposition, P-induced male recombination occurred mostly near the starting element (Duttaroy et al 1990;McCarron et al 1994;. The HEI sites were also frequent Pinsertion targets (Figure 3).…”

Asymmetric exchange is associated with P element induced male recombination in Drosophila melanogaster

“…In this study, excision events are shown to be independent of the crossover events, as are P(lArB) retention events. However, since transposase has been shown to induce crossovers in the absence of a Pelement (McCarron et al, 1989(McCarron et al, , 1994, we need to invoke a prior excision to explain the P-retaining crossovers. The excision process itself is not precise; indeed, precision is rare (Tsubota and Schedl 1986;O'Brochta et al, 1991;Takasu-Ishikawa et al, 1992).…”

“…The rate of exchange of transposase-initiated crossovers in D. melanogaster males increased when two transposase producers were used. Finally, the crossover distribution of transposase-induced events corresponded with the cytological map of the metaphase chromosome (McCarron et al, 1994). The introduction of a P-element target, with its highly specific transposase binding site, has been shown to produce a marked crossover increase in the P element target region Preston and Engels, 1996;Tanaka et al, 1997) as well as a significant increase in regions genetically distinct from the target (Duttaroy et al, 1990;McCarron et al, 1994).…”

“…The construction of the male parent chromosomes A and B, without the optional P(lArB) and P(∆ 2-3), and the tester female chromosome (Figure 1) was described in McCarron et al (1989). Each stock originated from a single third chromosome in the male, balanced and checked by in situ hybridization and southern blot for the presence of P elements.…”

“…Previous genetic studies have recognized that P element-induced male recombination events are legitimate exchange products (McCarron et al, 1989;Duttaroy et al, 1990). Furthermore, induction of male crossing over was found to be possible from a bona fide transposase source, even though the genome is devoid of any other target P element (McCarron region also harbors a single P-element called P(lArB).…”