摘要：Horizontal transfer (HT) of transposable elements has been recognized to be a major force driving genomic variation and biological innovation of eukaryotic organisms. However, the mechanisms of HT in eukaryotes remain poorly appreciated. The non-autonomous Helitron family, Lep 1, has been found to be widespread in lepidopteran species, and showed little interspecific sequence similarity of acquired sequences at 3′ end, which makes Lep 1 a good candidate for the study of HT. In this study, we describe the Lep 1-like elements in multiple non-lepidopteran species, including two aphids, Acyrthosiphon pisum and Aphis gossypii , two parasitoid wasps, Cotesia vestalis , and Copidosoma floridanum , one beetle, Anoplophora glabripennis , as well as two bracoviruses in parasitoid wasps, and one intracellular microsporidia parasite, Nosema bombycis . The patchy distribution and high sequence similarity of Lep 1-like elements among distantly related lineages as well as incongruence of Lep 1-like elements and host phylogeny suggest the occurrence of HT. Remarkably, the acquired sequences of both NbLep 1 from N. bombycis and CfLep 1 from C. floridanum showed over 90% identity with their lepidopteran host Lep 1. Thus, our study provides evidence of HT facilitated by host-parasite interactions. Furthermore, in the context of these data, we discuss the putative directions and vectors of HT of Lep 1 Helitrons .
