Plasticity of transposed rhombomeres: Hox gene induction is correlated with phenotypic modifications
| Autor: | Marie-Ange Bonnin, L.A. McNaughton, N M Le Douarin, Robb Krumlauf, Anne Grapin-Botton |
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| Předmět: |
Rhombomere
Gene Expression Chick Embryo Xenopus Proteins Biology Research Support Quail Fate mapping Embryonic Induction/ genetics Notochord medicine Animals Homeobox Non-U.S. Gov't Hox gene Molecular Biology In Situ Hybridization Transcription Factors/biosynthesis Rhombencephalon/ embryology Embryonic Induction Homeodomain Proteins Homeodomain Proteins/biosynthesis Trans-Activators/biosynthesis Genes Homeobox Neural tube Anatomy Rhombomere boundary formation Rhombencephalon Transplantation Somite surgical procedures operative medicine.anatomical_structure Genes Trans-Activators Transcription Factors Developmental Biology |
| Zdroj: | Europe PubMed Central Scopus-Elsevier |
| Popis: | In this study we have analysed the expression of Hoxb-4, Hoxb-1, Hoxa-3, Hoxb-3, Hoxa-4 and Hoxd-4 in the neural tube of chick and quail embryos after rhombomere (r) heterotopic transplantations within the rhombencephalic area. Grafting experiments were carried out at the 5-somite stage, i.e before rhombomere boundaries are visible. They were preceeded by the establishment of the precise fate map of the rhombencephalon in order to determine the presumptive territory corresponding to each rhombomere. When a rhombomere is transplanted from a caudal to a more rostral position it expresses the same set of Hox genes as in situ. By contrast in many cases, if rhombomeres are transplanted from rostral to caudal their Hox gene expression pattern is modified. They express genes normally activated at the new location of the explant, as evidenced by unilateral grafting. This induction occurs whether transplantation is carried out before or after rhombomere boundary formation. Moreover, the fate of the cells of caudally transplanted rhombomeres is modified: the rhombencephalic nuclei in the graft develop according to the new location as shown for an r5/6 to r8 transplantation. Transplantation of 5 consecutive rhombomeres (i.e. r2 to r6), to the r8 level leads to the induction of Hoxb-4 in the two posteriormost rhombomeres but not in r2,3,4. Transplantations to more caudal regions (posterior to somite 3) result in some cases in the induction of Hoxb-4 in the whole transplant. Neither the mesoderm lateral to the graft nor the notochord is responsible for the induction. Thus, the inductive signal emanates from the neural tube itself, suggesting that planar signalling and predominance of posterior properties are involved in the patterning of the neural primordium. |
| Databáze: | OpenAIRE |
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