Drosophila P transposons in the human genome?

摘要

P elements are DNA transposons that were first discovered to be the causative agent of hybrid dysgenesis in Drosophila melanogaster (Kidwell, Kidwell, and Sved 1977) but were later found to occur in many drosophilid species. The interspecific distribution of P-element sequences, as well as their sequence relationships, is not in accordance with the phylogeny of their host species. Therefore, P elements are not merely vertically inherited but can also be transmitted horizontally between sexually isolated taxa. The most striking example is the rather recent transfer from Drosbphila willistoni to D. melanogaster (Daniels et al. 1990), which must have occurred in the last century and was followed by a rapid spread of P elements through the natural populations of this new host (Anxolabehere, Kidwell, and Periquet 1988). Additional cases of horizontal transmission show that P elements have repeatedly crossed species barriers and have even invaded species of the related genera Scaptomyza and Lordiphosa (Hagemann, Hating, and Pinsker 1996a; Clark and Kidwell 1997; Haring, Hagemann, and Pinsker 2000; Silva and Kidwell 2000). However, due to the fact that their mode of transposition requires host-encoded proteins (Rio .and Rubin 1988), the distribution of active P elements seemed to be restricted to fruit flies of the drosophilid family. Thanks to the data provided by the human genome project, we are able to show that a homolog of the P element coding sequence exists as a stationary single-copy sequence in the human genome.