title: Patterning of brain precursors in ascidian embryos.
abstract: In terms of their embryonic origins, the anterior and posterior parts of the ascidian central nervous system (CNS) are associated with distinct germ layers. The anterior part of the sensory vesicle, or brain, originates from ectoderm lineages following a neuro-epidermal binary fate decision. In contrast, a large part of the remaining posterior CNS is generated following neuro-mesodermal binary fate decisions. Here, we address the mechanisms that pattern the anterior brain precursors along the medial-lateral axis (future ventral-dorsal) at neural plate stages. Our functional studies show that Nodal signals are required for induction of lateral genes, including Delta-like, Snail, Msxb and Trp Delta-like/Notch signalling induces intermediate (Gsx) over medial (Meis) gene expression in intermediate cells, whereas the combinatorial action of Snail and Msxb prevents the expression of Gsx in lateral cells. We conclude that despite the distinct embryonic lineage origins within the larval CNS, the mechanisms that pattern neural precursors are remarkably similar.
authors.affiliation: Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Napoli 80121, Italy.
authors.forename: Rosaria
authors.initials: R
authors.lastname: Esposito
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-mer, Observatoire Océanologique, Villefranche-sur-mer 06230, France.
authors.forename: Hitoyoshi
authors.identifier: 0000-0002-0817-3796
authors.initials: H
authors.lastname: Yasuo
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-mer, Observatoire Océanologique, Villefranche-sur-mer 06230, France.
authors.forename: Cathy
authors.initials: C
authors.lastname: Sirour
authors.affiliation: Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Napoli 80121, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Palladino
authors.affiliation: Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Napoli 80121, Italy clare.hudson@obs-vlfr.fr nietta.spagnuolo@szn.it.
authors.forename: Antonietta
authors.initials: A
authors.lastname: Spagnuolo
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-mer, Observatoire Océanologique, Villefranche-sur-mer 06230, France clare.hudson@obs-vlfr.fr nietta.spagnuolo@szn.it.
authors.forename: Clare
authors.identifier: 0000-0003-1585-8328
authors.initials: C
authors.lastname: Hudson
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D019521:Body Patterning / Q000502:physiology*; D001921:Brain / Q000196:embryology*; D002938:Ciona intestinalis / Q000196:embryology*; D004625:Embryo, Nonmammalian; D004627:Embryonic Induction / Q000502:physiology; D054258:Neural Plate / Q000196:embryology; D058953:Neural Stem Cells / Q000502:physiology*; D014561:Urochordata / Q000196:embryology*
keywords: Ascidian; Brain; Ciona; Neural patterning; Sensory vesicle