Evolutionary insights into Mariner-like elements in Apis species
AbstractBackgroundMariner and mariner-like elements (MLEs) are distributed in various species and their sequences are highly diverse. In previous reports, a few transposable element in the genomes of Apis species mainly consist of mariner and MLE. For further insight of Apis MLEs, detailed classifications of Apis MLE and sequences analysis of long MLEs, which may potentially encode the transposase, are needed.ResultsMuch more MLEs were detected in A. mellifera genome compared to other Apis species genomes. They were classified into 31 Drosophila MLE classes. In this classification, almost all of MLEs were classified into the three classes belonging to mellifera subfamilies, suggesting that Apis MLEs which exist thorough Apis species derived from single MLE belonging to mellifera subfamily. Phylogenetic analysis using MLEs in the three classes showed that there two types of clusters, of which one consist of multiple Apis species MLEs, and others of only A. mellifera MLEs. Long MLEs analysis showed that only one long MLE encoding complete transposase was found in all Apis genome except for A. mellifera genome, and the MLE and multiple MLEs similar to it were found in A. mellifera genome. The analysis also showed that other several long MLEs encoding complete transposase were found only in A. mellifera genome.ConclusionsAlmost all of Apis MLEs are mellifera subfamilies. Of these MLEs, one types of them settled in Apis species and burst in A. mellifera genome. The other one of MLEs invaded into A. mellifera genome by horizontal transfer and exploded in A. mellifera genome. This is the first example of the finer aspects of MLE evolution among closely related species.