Contribution of DNA-Based Transposable Elements to Genome Evolution: Inferences Drawn from Behavior of an Element Found in Fish
DNA-based transposable elements (DTEs) form one major group of transposable elements (TEs). They are transposed mostly in a cut-and-paste fashion, in contrast to RNA-mediated transposable elements (RTEs), which move in a copy-and-paste manner. Until recently, DTEs had received little attention as a contributing factor to the evolution of mammalian genomes, mainly because there was no sign of transposition activity in mammals. Genome sequencing projects, however, have shown that mammalian genomes contain huge numbers of dead copies of DTEs, suggesting that DTEs served as sources of genetic variation when they were young and active in their hosts. One important feature of DTEs that should not be overlooked is that they create genetic variation in which resultant sequences contain little or no part of the original elements. With such variation, one can no longer recognize participation of DTEs in their generation. Analyses of a currently active DTE present in fish have shown that the contribution of DTEs to the evolution of mammalian genomes may have been greater than we estimated through the analysis of sequence data.
KeywordsMammalian Genome Transposase Gene Melanin Biosynthesis Pigmentation Pattern Tyrosinase Gene
DNA-based transposable element
Million years ago
RNA-mediated transposable element