A statistical analysis of the overexpression of the msx2 RNA in Xenopus laevis.

The msx family of genes are important during development, and implicated in the development of various craniofacial structures. Here the frog, Xenopus laevis, was used to perform gain-of-function experiments to obtain further insight into the role of the msx2 gene. mRNAs of wild-type and mutated forms of the msx2 gene were injected into developing Xenopus embryos. Phenotypic changes in these embryos were noted, scored, and subjected to statistical analyses. Overexpression of the wild-type form of the msx2 gene resulted in embryos that were ventralized, i.e. with loss of anterior structures including head and eyes. A surprising finding was the statistically significant difference in phenotypic changes (p < 0.001 when compared to a buffer-injected group) of embryos microinjected with the mRNA of a mutated form of the msx2 gene (without the homeobox region). It is proposed that the msx2 overexpression system can be used as a consistent and reliable bioassay to map and study the functions of the msx2 gene during development, especially of the craniofacial region.