Meeting Abstract

P2-75   -   Exploring resegmentation in the African clawed frog, Xenopus laevis, with in-situ hybridization of the Tbx18 and Uncx genes Hassan, S*; Korneisel, DE; Carleton University, Ottawa, ON; Carleton University, Ottawa, ON dana.korneisel@carleton.ca

Segmentation in the vertebrate embryo is a crucial process in the early stages of development. It is identified first through the formation of somites along the anteroposterior axis of an embryo and later by the development of vertebrae and muscle segments. The sclerotome cells in each somite that will form vertebrae are widely considered to shift relative to myotome, the precursors of muscle, to enable spine movement. To account for the shift that occurs, the resegmentation model proposes that somitic sclerotome cells first polarize rostro-caudally, then recombine when the caudal half of one sclerotome combines with the rostral half of the next sclerotome. Under this model, each vertebra is derived from two somites. Previous studies have demonstrated that resegmentation occurs in some vertebrate model organisms through grafting surgeries. While resegmentation is well-supported in model organisms such as axolotl and chick, studies have yet to explore resegmentation within Anura. As the somites of anuran embryos are very small, and sclerotome cells make up a much smaller portion of a somite in amphibians than they do in amniotes, we aim to use genetic landmarks rather than surgeries to assess whether resegmentation occurs in the African clawed frog, Xenopus laevis. The genes Uncx and Tbx18, both homeobox genes, have been shown to contribute to somite polarization in mice. In this study, we employ in situ hybridization of Uncx and Tbx18 in X. laevis embryos to examine whether this model amphibian in developmental biology exhibits evidence of sclerotome polarization within the somite, and thus whether the resegmentation model is a good candidate to explain vertebral segmentation in these unique vertebrates.