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Segment boundary formation in Drosophila embryos.
Camilla W Larsen1, Elizabeth Hirst, Cyrille Alexandre
1National Institute for Medical Research, The Ridgeway Mill Hill, London NW7 1AA, UK.
Development (Cambridge, England)
|October 3, 2003
Summary
Drosophila segment boundary formation involves cell shape changes and requires distinct genetic signals. Engrailed expression and Hedgehog signaling are crucial for groove formation, while Wingless signaling prevents it anteriorly.
Area of Science:
- Developmental Biology
- Cell Biology
- Genetics
Background:
- Segment boundaries in Drosophila embryos are critical for proper development.
- These boundaries form at the posterior edge of engrailed expression stripes.
- Understanding the cellular and genetic mechanisms is key to developmental biology.
Purpose of the Study:
- To elucidate the cellular dynamics during segment boundary formation in Drosophila.
- To identify the genetic requirements for boundary formation.
- To investigate the roles of Hedgehog and Wingless signaling pathways.
Main Methods:
- Transmission electron microscopy (TEM) using an HRP-CD2 transgene.
- Observation of cell shape changes and cell-cell contact alterations.
- Genetic analysis of signaling pathway involvement.
Main Results:
- Apical constriction and inward movement of engrailed-expressing cells form grooves.
- Groove formation and regression correlate with germ band movements.
- Hedgehog signaling activation is necessary for groove formation.
- Engrailed expression is required anterior to the boundary.
- Wingless signaling represses groove formation anteriorly.
Conclusions:
- Segment boundary formation involves coordinated cell shape changes and signaling.
- Distinct genetic inputs from engrailed, Hedgehog, and Wingless pathways are required.
- Asymmetric signaling dictates boundary formation at the posterior of engrailed stripes.