Independent and parallel lateral transfer of DNA transposons in tetrapod genomes.
In animals, the mode of transmission of transposable elements is generally vertical. However, recent studies have suggested that lateral transfer has occurred repeatedly in several distantly related tetrapod lineages, including mammals. Using transposons extracted from the genome of the lizard Anolis carolinensis as probes, we identified four novel families of hAT transposons that share extremely high similarity with elements in other genomes including several mammalian lineages (primates, chiropters, marsupials), one amphibian and one flatworm, the planarian Schmidtea mediterranea. The discontinuous phylogenetic distribution of these hAT families, coupled with very low synonymous divergence between species, strongly suggests that these elements were laterally transferred to these different species. This indicates that the horizontal transfer of DNA transposons in vertebrates might be more common than previously thought. Yet, it appears that the transfer of DNA transposons did not occur randomly as the same genomes have been invaded independently by different, unrelated transposon families whereas others seem to be immune to lateral transfer. This suggests that some organisms might be intrinsically more vulnerable to DNA transposon lateral transfer, possibly because of a weakened defense against transposons or because they have developed mechanisms to tolerate their impact.
Novick
Peter
P
Department of Biology, Queens College, the City University of New York, Flushing, NY 11367, USA.
Smith
Jeremy
J
Ray
David
D
Boissinot
Stéphane
S
D000818:Animals; D001483:Base Sequence; D004247:DNA / Q000235:genetics*; D017931:DNA Primers; D004251:DNA Transposable Elements; D022761:Gene Transfer, Horizontal; D016678:Genome
D017931:DNA Primers; D004251:DNA Transposable Elements; D004247:DNA