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P element homing to the Drosophila bithorax complex
Development (Cambridge, England)
|August 23, 2000
Summary
P elements with a DNA fragment from the Drosophila bithorax complex show preferential insertion, revising segmental domain mapping. This DNA fragment acts as a boundary element, influencing gene expression patterns.
Area of Science:
- Developmental Biology
- Genetics
- Molecular Biology
Background:
- P elements in Drosophila melanogaster are mobile genetic elements used for gene insertion and manipulation.
- The bithorax complex (BX-C) controls segment identity in the fly's abdomen.
- Boundary elements are crucial for organizing chromatin and regulating gene expression domains.
Purpose of the Study:
- To investigate the 'homing' property of a specific DNA fragment from the Drosophila bithorax complex.
- To characterize the function of this DNA fragment as a boundary element.
- To refine the mapping of segmental domains within the bithorax complex and study Ultrabithorax (Ubx) gene function.
Main Methods:
- Construction of an enhancer-trap P element containing a 7 kb DNA fragment from the BX-C and FRT sites.
- Flp-mediated recombination to excise P element sequences, leaving only the lacZ reporter.
- Analysis of beta-galactosidase expression patterns in P element insertions within the BX-C.
- Generation of duplications and deletions using FRT sites for manipulating the Ultrabithorax transcription unit length.
Main Results:
- The 7 kb DNA fragment exhibits preferential insertion into the BX-C and adjacent regions ('homing').
- This fragment functions as a boundary element, separating segmental domains without containing a known promoter.
- Beta-galactosidase expression patterns from P element insertions revealed revised mapping of BX-C segmental domains (abx/bx, bxd/pbx, iab-3).
- Variations in the Ultrabithorax transcription unit length (37-138 kb) had minimal impact on its function.
Conclusions:
- The 7 kb DNA fragment from the BX-C acts as a boundary element, influencing gene expression and aiding in the revision of segmental domain maps.
- The developed enhancer-trap P element system with FRT sites is effective for studying gene function and regulatory elements.
- The Ultrabithorax gene exhibits robustness in function despite significant variations in its transcription unit size.