REARRANGEMENTS INVOLVING REPEATED SEQUENCES WITHIN A P-ELEMENT PREFERENTIALLY OCCUR BETWEEN UNITS CLOSE TO THE TRANSPOSON EXTREMITIES

In a previous report we described rearrangements occurring at a high r ate (30% of the progeny of dysgenic flies) within a cluster of 5S gene s internal to a P element. These events were characterized as precise amplifications and deletions of 5S units. Here we analyze recombinatio n events within P elements containing two repeated arrays of 5S genes flanking a central white gene. Deletions (50%) and duplications (3%) o f the white gene together with various amounts of flanking 5S genes we re observed. These recombinations occur preferentially between the mos t external 5S units of P transposons. Such rearrangements could be fav ored by interactions between the proteins bound to the P terminal sequ ences.