Induction of a mesencephalic phenotype in the 2-day-old chick prosencephalon is preceded by the early expression of the homeobox gene en.
The homeobox gene en, homologous to the gene en-grailed of Drosophila, is expressed in the metencephalic-mesencephalic segment of the vertebrate neural tube. Using quail-chick chimeras, an antibody against en proteins, and cytoarchitectonic techniques, we demonstrate that metencephalon transplanted to prosencephalon, at E2, maintains a high level of en proteins and its presumptive cerebellar fate. The ectopic metencephalon induces in the contiguous host prosencephalon the expression of en and, subsequently, a mesencephalic phenotype. These related genetic and phenotypic expressions indicate that the transcriptional regulatory en gene is involved in cerebellar and mesencephalic cyto-differentiation. The expression of en can also be induced in chick prosencephalon by a mammalian metencephalic graft, indicating that the factors regulating the transcription of en are phylogenetically well conserved.
INSERM U-106, Hôpital de la Salpêtrière, Paris, France.
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S
Martinez
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Wassef
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RM
Alvarado-Mallart
D000818:Animals; D000911:Antibodies, Monoclonal; D016380:Brain Tissue Transplantation / Q000502:physiology*; D002642:Chick Embryo; D002678:Chimera; D004330:Drosophila / Q000235:genetics; D029721:Drosophila Proteins; D004625:Embryo, Nonmammalian; D016332:Fetal Tissue Transplantation / Q000502:physiology; D015870:Gene Expression; D005801:Genes, Homeobox; D018398:Homeodomain Proteins; D007301:Insect Hormones / Q000032:analysis / Q000235:genetics*; D008636:Mesencephalon / Q000196:embryology / Q000502:physiology*; D010641:Phenotype; D011149:Pons / Q000196:embryology / Q000502:physiology*; D011784:Quail; D014157:Transcription Factors / Q000032:analysis / Q000235:genetics*
D000911:Antibodies, Monoclonal; D029721:Drosophila Proteins; C063459:En protein, Drosophila; D018398:Homeodomain Proteins; D007301:Insect Hormones; D014157:Transcription Factors