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Expression of the homeobox Chick-en gene in chick/quail chimeras with inverted mes-metencephalic grafts
S Martinez1, R M Alvarado-Mallart
1Unité 106 INSERM Hôpital de la Salpêtrière, Paris.
Insights
The homeobox gene Chick-en
Area of Science:
- Developmental biology
- Neuroscience
- Genetics
Background:
- The homeobox gene Chick-en shows homology to Drosophila's engrailed gene.
- Chick-en is expressed in the chick embryo's mes-metencephalic neuroepithelia during early development.
Purpose of the Study:
- To investigate the regulation of Chick-en gene expression in response to positional cues.
- To determine the role of the engrailed protein in mes-metencephalic neuroepithelium positional specification.
Main Methods:
- Utilized chick/quail chimeric embryos for transplantation experiments.
- Transplanted mes-metencephalic neuroepithelium into an inverted position within the host neural tube.
- Employed a monoclonal antibody (Mab 4D9) to detect engrailed proteins.
Main Results:
- Chick-en gene expression in the transplanted neuroepithelium adapted to its new position within 20 hours.
- The expression pattern was regulated based on the host neural tube environment.
- Previous findings indicated phenotypic expression also depends on the new position.
Conclusions:
- Engrailed protein is likely crucial for positional specification of the mes-metencephalic neuroepithelium.
- Positional cues within the neural tube regulate homeobox gene expression.
- This suggests a conserved mechanism for developmental patterning.
Abstract:
The homeobox gene Chick-en, sharing homologies to the engrailed gene of Drosophila, is expressed, during early steps of development, in a restricted area of the chick embryo including mes-metencephalic neuroepithelia. The expression of the Chick-en gene has been analyzed in chick/quail chimeric embryos in which a portion of the 2-day-old mes-metencephalic neuroepithelium has been transplanted in an inverted position. By means of a monoclonal antibody, "Mab 4D9," recognizing engrailed proteins, it is shown that the expression of the Chick-en gene is regulated in the inverted neuroepithelium according to its new position in the host neural tube. The regulation takes place within 20 hr after transplantation. These results, together with previous data demonstrating that the phenotypic expression of the inverted neuroepithelium depends, also, on its new position in the host neural tube, strongly suggest that the engrailed protein could play an important role in the positional specification of the mes-metencephalic neuroepithelium.