Generation of a Xenopus laevis F1 albino J strain by genome editing and oocyte host-transfer

• Generation of F1 null mutants in X. laevis.
• Oocyte host-transfer method effective method to induce mutations in both homeologs.
• Unique mutations identified in each organ of F0 adult.
• Highly-penetrant germline mutations in X. laevis using oocyte host-transfer.

Completion of the Xenopus laevis genome sequence from inbred J strain animals has facilitated the generation of germline mutant X. laevis using targeted genome editing. In the last few years, numerous reports have demonstrated that TALENs are able to induce mutations in F0 Xenopus embryos, but none has demonstrated germline transmission of such mutations in X. laevis. In this report we used the oocyte host-transfer method to generate mutations in both tyrosinase homeologs and found highly-penetrant germline mutations; in contrast, embryonic injections yielded few germline mutations. We also compared the distribution of mutations in several F0 somatic tissues and germ cells and found that the majority of mutations in each tissue were different. These results establish that X. laevis J strain animals are very useful for generating germline mutations and that the oocyte host-transfer method is an efficient technique for generating mutations in both homeologs.