ABSTRACT
Transposable elements (TEs) are repeated DNA sequences that can constitute a substantial part of genomes. Studying TEs' activity, interactions, and accumulation dynamics is thus of major interest to understand genome evolution. Here, we describe the transposition dynamics of cut-and-paste mariner elements during experimental (short- and longer-term) evolution in Drosophila melanogaster Flies with autonomous and nonautonomous mariner copies were introduced in populations containing no active mariner, and TE accumulation was tracked by quantitative PCR for up to 100 generations. Our results demonstrate that (i) active mariner elements are highly invasive and characterized by an elevated transposition rate, confirming their capacity to spread in populations, as predicted by the "selfish-DNA" mechanism; (ii) nonautonomous copies act as parasites of autonomous mariner elements by hijacking the transposition machinery produced by active mariner, which can be considered as a case of hyperparasitism; (iii) this behavior resulted in a failure of active copies to amplify which systematically drove the whole family to extinction in less than 100 generations. This study nicely illustrates how the presence of transposition-competitive variants can deeply impair TE dynamics and gives clues to the extraordinary diversity of TE evolutionary histories observed in genomes.
Subject(s)
DNA Transposable Elements , Directed Molecular Evolution , Drosophila melanogaster/genetics , Genome, Insect , Animals , DNA-Binding Proteins/genetics , Female , Linear Models , Male , Phenotype , Phylogeny , Polymerase Chain Reaction , Species Specificity , Transposases/geneticsABSTRACT
Rotaviruses attach to intestinal cells in a process that requires glycan recognition. Some bacteria from the gut microflora have been shown to modify cell-surface glycans. In this study, human intestinal cultured cells were incubated with bacteria-derived soluble factors and infected with rotavirus. Results show that only bacterial soluble factors that increase cell-surface galactose namely, those of Bacteroides thetaiotaomicron and Lactobacillus casei were able to efficiently block rotavirus infections. Increasing cell-surface galactose using galactosyltransferase resulted in a similar blockage of rotavirus infections. These results indicate that manipulation of cell-surface intestinal glycans by bacterial soluble factors can prevent rotavirus infection in a species-specific manner, and should now be considered a potential therapeutic approach against rotavirus infection.
