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Hox genes regulate the same character by different strategies in each segment.
Takuya Tsubota1, Kaoru Saigo, Tetsuya Kojima
1Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Mechanisms of Development
|July 1, 2008
Summary
Different Hox genes use distinct mechanisms to regulate the same traits in different body regions. In Drosophila, Sex combs reduced and Ultrabithorax control sternopleural bristle absence via separate pathways.
Area of Science:
- Developmental biology
- Genetics
- Animal development
Background:
- Hox genes establish regional identity along the anterior-posterior axis in animals.
- While individual Hox gene regulation is studied, how different Hox genes control shared traits in distinct regions remains less understood.
- Sternopleural bristles are a mesothoracic characteristic in Drosophila, with spineless (ss) gene involvement in their development.
Purpose of the Study:
- To investigate the distinct mechanisms employed by different Hox genes to regulate the same morphological characteristic in different body segments.
- To elucidate how Sex combs reduced (Scr) and Ultrabithorax (Ubx) Hox genes achieve the absence of sternopleural bristles in the prothorax and metathorax, respectively.
Main Methods:
- Analysis of regulatory relationships between Hox genes (Scr, Ubx) and the spineless (ss) gene in Drosophila.
- Examination of ss gene expression patterns in relation to Scr and Ubx activity.
- Assessing the effect of ss misexpression on sternopleural bristle formation in the prothorax.
Main Results:
- Sex combs reduced (Scr) represses spineless (ss) expression in the prothorax, inhibiting sternopleural bristle formation.
- Misexpression of ss alone can induce ectopic sternopleural bristles in the prothorax, independent of Scr.
- Ultrabithorax (Ubx) activity in the metathorax does not involve ss repression; Ubx blocks bristle formation through alternative mechanisms.
Conclusions:
- Different Hox genes can achieve the same developmental outcome (e.g., absence of bristles) through divergent molecular mechanisms in distinct body segments.
- This study reveals functional divergence in Hox gene action, highlighting how distinct regulatory pathways can lead to conserved morphological traits.
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