Mobile Elements in Animal and Plant Genomes

Abstract

This chapter discusses the different classes of mobile elements seen in some of the best-characterized animal genome and plant genome. It talks about the some of the general concepts behind the colonization of genomes by mobile elements. There are basically three classes of autonomous mobile elements, all three of which can be found to various extents in different genomes of all animals and plants. These are the DNA transposons, the long terminal repeat (LTR) retrotransposons, and the non-LTR retrotransposons. DNA transposons are very common in the Caenorhabditis elegans genome, as well as several relatively high-copy-number families of their nonautonomous relatives, miniature inverted-repeat transposable elements (MITEs). Other site-specific mobile elements are the HetA and TART elements that make up the telomeres in Drosophila. Only sporadic data are available on mobile elements in reptiles, amphibians, and fish. Almost all the classes of mobile elements are present to some degree in almost all animal and plant genomes. The density of mobile elements has also been shown to extend into the centromeric region in Arabidopsis. Not only is the impact of mobile elements on their genome a direct result of insertional mutagenesis, but there are also a series of secondary impacts on the genome including recombination and many more subtle changes that may alter the stability or evolution of an organism’s genome. Retrotransposition has also given rise to gene duplications or other useful gene modifications that allowed evolution to new function.