Zebrafish wnt4b expression in the floor plate is altered in sonic hedgehogand gli-2 mutants

The floor plate of the neural tube serves an important function as a source of signals that pattern cell fates in the nervous system as well as direct ing proper axon pathfinding. We have cloned a novel zebrafish wnt family me mber, wnt4b, which is expressed exclusively in the floor plate. To place wn t4b in the context of known regulators of midline development, its expressi on was analyzed in the zebrafish mutants cyclops (cyc), floating head (flh) , you-too (yot), and sonic you (syu) wnt4b expression in the medial and lat eral floor plate are shown to be regulated independently: medial floor plat e expression occurs in the absence of a notochord, while lateral floor plat e expression requires a functional notochord. sonic hedgehog and gli-2. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.