In Ciona intestinalis, leprecan was identified as a target of the notochord-specific transcription factor Ciona Brachyury (Ci-Bra) (Takahashi, H., Hotta, K., Erives, A., Di Gregorio, A., Zeller, R.W., Levine, M., Satoh, N., 1999. Brachyury downstream notochord differentiation in the ascidian embryo. Genes Dev. 13, 1519-1523). By screening approximately 14 kb of the Ci-leprecan locus for cis-reg...

A series of microsurgical operations was performed in chick embryos to study the factors that control the polarity, position and differentiation of the sympathetic and dorsal root ganglion cells developing from the neural crest. The neural tube, with or without the notochord, was rotated by 180 degrees dorsoventrally to cause the neural crest cells to emerge ventrally. In some embryos, the noto...

The intervertebral discs, located between adjacent vertebrae, are required for stability of the spine and distributing mechanical load throughout the vertebral column. All cell types located in the middle regions of the discs, called nuclei pulposi, are derived from the embryonic notochord. Recently, it was shown that the hedgehog signaling pathway plays an essential role during formation of nu...

The Ciona Brachyury gene (Ci-Bra) is regulated, in part, by a 434-bp enhancer that mediates restricted expression in the notochord. Here we present evidence that a Ciona Suppressor of Hairless ¿Ci-Su(H)¿ protein functions as an activator of this enhancer. Point mutations that reduce the binding of a GST/Ci-Su(H) fusion protein in vitro diminish the expression of mutagenized Ci-Bra/lacZ transgen...

The notochord is required for the differentiation of nearby tissues, including the neural tube and the floor plate. Because the dorsal aorta and axial vein are midline structures, their development might also be influenced by the notochord. To investigate this possibility, we cloned zebrafish VEGR-2, homologous to the earliest known marker of endothelial cells in mammals. In flh and ntl mutant ...

Elimination of the floor plate, a row of distinctive cells at the ventral midline of the spinal cord, dramatically increased the frequency of errors made by specific growth cones in the zebrafish embryo. This demonstrated that the floor plate participated in guiding specific growth cones at the ventral midline of the spinal cord. However, since a significant proportion of these growth cones fol...

Near the floor plate of the embryonic neural tube there is a group of neuroepithelial precursor cells that are specialized for production of the oligodendrocyte lineage. We performed experiments to test whether specification of these neuroepithelial oligodendrocyte precursors, like other ventral neural cell types, depends on signals from the notochord and/or floor plate. We analyzed heterozygou...