CONSERVATION OF BF-1 EXPRESSION IN AMPHIOXUS AND ZEBRAFISH SUGGESTS EVOLUTIONARY ANCESTRY OF ANTERIOR CELL-TYPES THAT CONTRIBUTE TO THE VERTEBRATE TELENCEPHALON

The forkhead domain containing transcription factor BF-1 has been show n to play a major role in the correct development of the cerebral hemi spheres in the mouse. BF-1 orthologs have been isolated from zebrafish and the cephalocordate amphioxus. In both species, BF-1 is expressed in the anterior neural tube. In zebrafish zBF-1 expression is restrict ed to anterior portions of the otic vesicle and to the presumptive tel encephalon. In amphioxus AmphiBF-1 is transiently seen in the frontal part of the first somite and, at 3 days of development, in a small num ber of cells in the cerebral vesicle (cv). The anterior expression of BF-I in chordates and vertebrates and of slp-1/2 in Drosophila suggest s that BF-1 is crucial for an evolutionarily conserved specification o f anterior neuronal cell types.