Regulatory gene expressions in the ascidian ventral sensory vesicle: evolutionary relationships with the vertebrate hypothalamus.
In extant chordates, the overall patterning along the anteroposterior and dorsoventral axes of the neural tube is remarkably conserved. It has thus been proposed that four domains corresponding to the vertebrate presumptive forebrain, midbrain-hindbrain transition, hindbrain, and spinal cord were already present in the common chordate ancestor. To obtain insights on the evolution of the patterning of the anterior neural tube, we performed a study aimed at characterizing the expression of regulatory genes in the sensory vesicle of Ciona intestinalis, the anteriormost part of the central nervous system (CNS) related to the vertebrate forebrain, at tailbud stages. Selected genes encoded primarily for homologues of transcription factors involved in vertebrate forebrain patterning. Seven of these genes were expressed in the ventral sensory vesicle. A prominent feature of these ascidian genes is their restricted and complementary domains of expression at tailbud stages. These patterning markers thus refine the map of the developing sensory vesicle. Furthermore, they allow us to propose that a large part of the ventral and lateral sensory vesicle consists in a patterning domain corresponding to the vertebrate presumptive hypothalamus.
Moret
Frédéric
F
Development, Evolution and Plasticity of the Nervous System, Institut de Neurobiologie Alfred Fessard, Centre National de la Recherche Scientifique, UPR2197, 1 ave de la terrasse, F-91198 Gif-sur-Yvette, France.
Christiaen
Lionel
L
Deyts
Carole
C
Blin
Maryline
M
Vernier
Philippe
P
Joly
Jean-Stéphane
JS
D000818:Animals; D016375:Antisense Elements (Genetics) / Q000235:genetics; D005075:Biological Evolution; D019521:Body Patterning; D002490:Central Nervous System / Q000196:embryology* / Q000378:metabolism; D002938:Ciona intestinalis / Q000196:embryology* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D005809:Genes, Regulator / Q000235:genetics*; D007031:Hypothalamus; D017403:In Situ Hybridization; D020133:Reverse Transcriptase Polymerase Chain Reaction
D016375:Antisense Elements (Genetics)