ECTOPIC NEURAL EXPRESSION OF A FLOOR PLATE MARKER IN FROG EMBRYOS INJECTED WITH THE MIDLINE TRANSCRIPTION FACTOR PINTALLAVIS

The floor plate, a cell group that develops at the midline of the neur al plate in response to inductive signals from the notochord, has been implicated in the control of dorsoventral neural pattern. The frog Pi ntallavis gene, encoding a member of the HNF-3/fork head transcription factor family, is expressed in the notochord and in midline neural pl ate cells that give rise to the floor plate. To examine whether Pintal lavis might be involved in regulating the differentiation of the floor plate, we ectopically expressed Pintallavis by injecdon of synthetic mRNA into two-cell frog embryos. Injection of Pintallavis mRNA resulte d in the ectopic expression of F-spondin, a gene encoding a floor plat e-specific adhesion molecule, at the dorsal midline of the neural tube . The expression of Pintallavis in midline cells may therefore contrib ute to the establishment of the floor plate fate.