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Enhancer traps in the Drosophila bithorax complex mark parasegmental domains
K McCall1, M B O'Connor, W Bender
1Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115.
Genetics
|October 1, 1994
Summary
Enhancer traps reveal parasegmental domains in Drosophila, maintained by Polycomb-mediated repression. These domains, crucial for development, may stem from chromatin structure differences.
Area of Science:
- Developmental Biology
- Genetics
- Molecular Biology
Background:
- The Drosophila bithorax complex regulates body plan development through three homeotic genes and nine regulatory regions.
- These regions control gene expression across successive parasegments, defining distinct body segments.
Purpose of the Study:
- To investigate the role of P elements and enhancer traps in mapping regulatory regions within the bithorax complex.
- To understand how Polycomb group genes maintain parasegmental domains.
Main Methods:
- Mapping eight P elements with beta-galactosidase (lacZ) reporters to the bithorax complex.
- Analyzing lacZ expression patterns from enhancer traps inserted at gene promoters and regulatory regions.
- Examining lacZ expression in embryos mutant for Polycomb group genes.
Main Results:
- Enhancer traps at the Ultrabithorax promoter mimicked endogenous gene patterns.
- Enhancer traps in regulatory regions expressed lacZ globally within relevant parasegments.
- Polycomb group mutations caused widespread lacZ expression, indicating repression maintenance.
Conclusions:
- Enhancer traps effectively reveal parasegmental domains.
- Polycomb-mediated repression is essential for maintaining these domains.
- Parasegmental differences in chromatin structure likely underlie these domains.