Recently, considerable progress in the genetic and molecular analyses of development has been obtained. There are powerful new molecular techniques that can be applied to analyze those genes important in the regulation of development; however, those techniques must be used with genetically defined research animals. Isogenic lines are available in the mouse and drosophila, but are not available in the amphibian. The research presented in this proposal focuses on the development of clonal isogenic stocks of the amphibians, Xenopus laevis and Ambystoma mexicanum. The availability of such stocks would provide research materials of tremendous value to the biomedical research community.Division of Research Resources (NCRR)