WNTing to Know: Genome Editing at National Xenopus Resource Spurs New Work

The south African clawed frog, Xenopus laevis. Credit: ϲappCatalyst

Seven years ago, Marko Horb and began dreaming up a project to demystify a long-standing question: How does the first body axis emerge in the developing frog embryo? Their patience, as Horb and colleagues bred mutant frogs specific to their research question -- and their persistence to keep experimenting during the 2020 pandemic shutdown --  paid off this fall, when they published in the journal Development.

“We knew it would take a long time, but a project can never be finished if it’s not started,” Horb said in an interview published as a companion to the research report.

It was fortuitous that in the same year (2015) Horb, an ϲappSenior Scientist and Director of the National Xenopus Resource (NXR) at MBL, had received a grant to use CRISPR-Cas9 genome editing to make germline mutant frogs for the research community. For the collaboration with Houston, Professor of Biology at University of Iowa, the NXR generated females that lacked the gene Wnt11b, which was thought to be involved in axis formation. Over the next few years, they made several surprising discoveries about the activity of Wnt11b that illuminated why its presence in maternal frogs permits the first body axis (dorsoventral) to form, and the embryo to differentiate into the three germ layers that generate the tissues and organs of a new frog.

Today, the National Xenopus Resource has over 200 different frog mutants at various stages of development. Horb has also secured an R24 grant (Xenopus Mutant Resource) from the NIH’s Office of Research Infrastructure Programs to house visiting researchers who come to the ϲappto work with the NXR’s resources.

Read more about this recent NXR collaboration and paper here:

Interview: “,” Development (2022), DOI: 10.1242/dev.201215

Lay summary: , Development (2022) 149 (17): e149_e1705.

Research Paper: Douglas W. Houston, Karen L. Elliott, Kelsey Coppenrath, Marcin Wlizla, Marko E. Horb (2022) Development, DOI:

Frog embryos. Figure 4 from Houston et al, Development, 2022
Dorsal, posterior views of maternal wnt11b mutant frog embryos exhibiting delayed and reduced mesendodermal gene expression. From Figure 4, Houston et al, Development, 2022.