XL-FLI, THE XENOPUS HOMOLOG OF THE FLI-1 GENE, IS EXPRESSED DURING EMBRYOGENESIS IN A RESTRICTED PATTERN EVOCATIVE OF NEURAL CREST CELL DISTRIBUTION

The Xenopus laevis fli cDNA, belonging to the ets family of transcript ion factors, was isolated from a library prepared from unfertilized eg gs. It encodes a polypeptide with extensive homology to murine and hum an Fli proteins. The long 3'-untranslated region contains five nuclear polyadenylation signals and three cytoplasmic polyadenylation element s, as well as many A/T rich elements. Two polyadenylated transcripts a ppear at the early neurula and accumulate up to the tadpole stage. In situ hybridization reveals an expression in territories invaded by neu ral crest cells. In the head region, fli is expressed in the peri-ocul ar zone, in the branchial buds and at the level of the brain floor. In the trunk, a metamerized expression is detected in the dorsum. At a l ower level, the tailbud and the peri-cardiac region also appear positi ve.