Generation and Characterization of Developmental Mutations in Xenopus tropicalis

Amphibians have been favored organisms by experimental embryologists for more than a century. Their large, resilient embryos are ideal for manipulations, such as tissue transplantation, explantation and recombination, methods that have been used to demonstrate the existence and location of inducing centers in developing embryos and to define important embryological principles. Molecular biological approaches developed primarily in Xenopus, including a highly efficient method for transgenesis, have provided another dimension to our understanding of a multitude of cellular and developmental problems. Although there have been many developmental mutants reported in amphibians, mainly in axolotl and Xenopus laevis, amphibians have not been as widely used for genetic approaches as other vertebrates, like the mouse and zebrafish. This has been in part because of the long generation time of these species and their large genome size, especially in the case of axolotl. The duplicated genome of X. laevis also presents potential limitations. But another factor mitigating use of these systems for genetics in past times has been the lack of complementary techniques for studying mutants in detail at the molecular level. A more recently introduced model, Xenopus tropicalis, offers an array of new opportunities for genetic studies. Its short generation time and smaller, diploid genome, together with accumulating genomic resources, make X. tropicalis a very attractive model organism for addressing complex issues in modern cell and developmental biology. Here we will introduce the main features of the X. tropicalis system and briefly discuss possible methodologies for isolating developmental mutants for genetic studies.