Identification of mutants in inbred Xenopus tropicalis.

Xenopus tropicalis offers the potential for genetic analysis in an amphibian. In order to take advantage of this potential, we have been inbreeding strains of frogs for future mutagenesis. While inbreeding a population of Nigerian frogs, we identified three mutations in the genetic background of this strain. These mutations are all recessive embryonic lethals. We show that multigenerational mutant analysis is feasible and demonstrate that mutations can be identified, propagated, and readily characterized using hybrid, dihybrid, and even trihybrid crosses. In addition, we are optimizing conditions to raise frogs rapidly and present our protocols for X. tropicalis husbandry. We find that males mature faster than females (currently 4 versus 6 months to sexual maturity). Here we document our progress in developing X. tropicalis as a genetic model organism and demonstrate the utility of the frog to study the genetics of early vertebrate development.