Xenopus tropicalis: an ideal experimental animal in amphibia

Studies using amphibians have contributed to the progress of life science including developmental biology and cell biology for more than one hundred years. Since the 1950s Xenopus laevis in particular has been used by scientists in many fields for experiments, resulting in the development of various techniques such as microsurgery on early embryos, biosynthesis of gene-encoded protein in oocytes by mRNA injection, misexpression experiments by mRNA injection into embryos, gene knockdown studies by injection of morpholino anti-sense oligonucleotide into fertilized eggs, transgenesis by the I-SceI meganuclease method, and so on. In this paper we will introduce Xenopus tropicalis as an alternative experimental animal. It has a shorter generation time and smaller diploid genome, together with whole-genome sequence data. The procedures available for Xenopus laevis can work well with Xenopus tropicalis, and embryos of both species develop at similar rates according to the developmental staging system of Nieuwkoop and Faber. Experimental systems of Xenopus tropicalis will pave the way for a new era of vertebrate genomics and genetics.