High levels of recombination induced by homologous P elements in Drosophila melanogaster

Abstract

P element transposons in Drosophila melanogaster are capable of mobilizing incomplete P elements elsewhere in the genome, and of inducing recombination. This recombination is usually only of the order of 1% or less. We show that two P elements, located at exactly homologous sites, induce levels of recombination of 20% or higher. The recombination appears to be exact, as determined by the lack of phenotypic effects in recombinant products and the lack of size changes detectable by Southern hybridization. Female recombination is increased, but to a lesser extent than male recombination. Somatic recombination levels are also elevated. Alternative explanations for the high recombination levels are given in terms of the consequences of repair of an excision site and in terms of recombination as part of the replicative transposition process.

DNA homology requirements for mitotic gap repair in Drosophila.

“…The results are consistent with the previous conclusion (18) that strand exchange does not occur in most gap-repair events. However, the data cannot rule out the possibility that there is a small amount of crossing over in order to explain the enhanced male recombination seen at P element-containing intervals (27,28). Mismatches of each whd-R allele used and corresponding reversion rates.…”

Evidence of P-Element-Induced Sister-Chromatid Exchange in a Ring-X Chromosome in Drosophila, With Implication for a High Rate of Formation of Hybrid Elements

“…Production of the ring-X chromosome containing the P element: Female recombination in the absence of transposase was used to recombine the P element from the rod-X chromosome containing a P[CaSpeR] insertion at 17C (Ca120.10; see Sved et al 1990) to the ring-X chromosome. Male progeny of female flies heterozygous for the ring-X chromosome and for the Ca120.10 chromosome were screened (Figure 1).…”

“…P elements induce male recombination at a low rate in crosses between wild and laboratory strains of Drosophila melanogaster (Hiraizumi 1971). Comparable levels of recombination can be produced by a single incomplete P element when activated by a transposase source (Sved et al 1990). Furthermore, the level of recombination rises from ,1% to 20% if P elements are present at homologous sites on the two chromosomes (Sved et al 1991).…”

“…Comparable levels of recombination can be produced by a single incomplete P element when activated by a transposase source (Sved et al 1990). Furthermore, the level of recombination rises from ,1% to 20% if P elements are present at homologous sites on the two chromosomes (Sved et al 1991).A likely mechanism for this recombination was elucidated by Gray et al (1996), who showed that recombination can be produced when an element containing only an intact left end is brought together with an element on the homologous chromosome containing only an intact right end. The only possibility for association in this case involves ends from different chromosomes, associating to form a ''hybrid element.…”

Properties of re-arranged P elements in Drosophila melanogaster

“…The results from combinations of elements (classes (3)-(11) of Figure 4) reveal that with two exceptions, the rates of recombination are in the range 13-20%, comparable to that given by homologous unaltered elements (Sved et al, 1991). The exceptions, classes (4) and (7), are in the range 5-6%.…”