Xenopus, the next generation: X. tropicalis genetics and genomics.

A small, fast-breeding, diploid relative of the frog Xenopus laevis, Xenopus tropi- calis, has recently been adopted for research in developmental genetics and functional genom- ics. X. tropicalis shares advantages of X. laevis as a classic embryologic system, but its simpler genome and shorter generation time make it more convenient for multigenerational genetic, genomic, and transgenic approaches. Its em- bryos closely resemble those of X. laevis, except for their smaller size, and assays and molecular probes developed in X. laevis can be readily adapted for use in X. tropicalis. Genomic manip- ulation techniques such as gynogenesis facilitate genetic screens, because they permit the identi- fication of recessive phenotypes after only one generation. Stable transgenic lines can be used both as in vivo reporters to streamline a variety of embryologic and molecular assays, or to exper- imentally manipulate gene expression through the use of binary constructs such as the GAL4/ UAS system. Several mutations have been iden- tified in wild-caught animals and during the course of generating inbred lines. A variety of strategies are discussed for conducting and man- aging genetic screens, obtaining mutations in specific sequences, achieving homologous recom- bination, and in developing and taking advan- tage of the genomic resources for Xenopus tropi- calis. © 2002 Wiley-Liss, Inc.