Distribution of P Elements in Muscomorpha

Abstract

Partial P elements (some almost full-length) were recovered from genomic libraries of the three species. The sequences of these newly recovered P element homologues have shed light on the distribution and evolution of P elements. First of all, these P element homologues are ancient and now defective. Second, P elements are not confined to Drosophilidae but are in fact widespread in the infraorder Muscomorpha of Diptera. Third, phylogenetic analyses showed that P elements have evolved into distinct Lucilia and Drosophila subfamilies. Fourth, the conservation of the leucine zipper domains and GTP-binding domain of the P element transposase in these flies indicates that they were important for the activity of these P elements. Finally, given the long evolutionary history of these flies, horizontal transfers of these P elements must have occurred at recent points in time for the P elements in the three flies to be reasonably well conserved.