033: Superfrog

Created by Elsie Place, Alex Eve, Melissa Estima, Rita Monteiro (Smith lab)

‘SuperFrog’ was inspired by past and current research undertaken by the Smith lab. Because most members of our lab work on mesoderm or its derivatives, we chose to present SuperFrog as an energetic action hero. In fact, the pose we have chosen is genuinely characteristic of these animals. However, rather than springing around their tanks as we have depicted, adult Xenopus spend much of their time dangling, motionless, at the surface of their tanks with their arms and legs splayed. The boxed ‘T’ symbol on SuperFrog’s chest represents Brachyury and other members of the T-box transcription factor family. SuperFrog was made from felt, the background was painted in acrylics, and the construction is mostly held together by SuperGlue.

Jim Smith’s ‘frog connection’ dates back to the 1980s, when he worked with Jonathan Slack on the process of mesoderm induction in the clawed frog, Xenopus laevis. The embryonic mesoderm gives rise to many clinically-relevant cell types, including muscle, bone, and cardiovascular tissues. Thus discoveries such as Jim’s identification of activin A as the mesoderm-inducing factor have found new relevance in the field of stem cell research.

Another highlight came at NIMR in the early 1990s, when Dave Wilkinson presented an in situ hybridization analysis of the mouse gene T (also known as Brachyury), showing expression in the posterior mesoderm and notochord. More exciting still, it had been known for years that heterozygous mutants developed with shortened tails, and homozygous mutant embryos lacked posterior mesoderm and their notochord development was impaired. Jim promptly cloned the Brachyury homologue in his favourite species, christened it Xbra – for Xenopus – and showed that it was expressed in the presumptive mesoderm of the frog embryo. He found that Brachyury expression was an immediate early response to mesoderm induction, and that Xbra transcription factor activity is essential for mesoderm formation in the embryo.

With the high-throughput techniques available to us now, the complete range of Xbra genomic targets has been identified in Xenopus tropicalis. Frog mesoderm development, and in particular the role of Brachyury and other so-called T-box transcription factors, remains a key interest of the Smith lab, but we also work on other aspects of development – notably, cardiovascular tissues – and various members of our team utilise zebrafish, mouse, and cell culture models.