Transposon-mediated transgenesis in the frog: New tools for biomedical and developmental studies

The amphibian, Xenopus laevis has been an excellent developmental model for over half a century. The large egg size, external fertilization and simple husbandry make this frog an ideal tool to study early vertebrate development. The tetraploid genome and long generation time, however, has hindered the use of X. laevis in largescale genetic efforts. A close West African relative, Xenopus tropicalis (also commonly known as Silurana tropicalis), overcomes the limitations of X. laevis in genetic studies as X. tropicalis has a diploid genome and breeding adults can be obtained in six to nine months. We have focused our efforts on developing transposon systems for efficient transgenesis and insertional mutagenesis in the frog. Transposon systems have been used for transgenesis in a wide variety of model organisms. In this review, we will discuss the advantages and limitations of different transposon systems for generating transgenic Xenopus. In addition, we will describe strategies for the identification of novel genes through an insertional mutagenesis approach using transposable elements.