Enhancer Traps in the Drosophila Bithorax Complex Mark Parasegmental Domains

AUTOR(ES)

McCall, K.

RESUMO

Eight P elements carrying a β-galactosidase (lacZ) reporter have been mapped to sites within the Drosophila bithorax complex. The bithorax complex contains three homeotic genes, and at least nine regulatory regions which control their expression in successive parasegments of the fly. The enhancer traps inserted at the promoter of one of the genes, Ultrabithorax, express lacZ in patterns which mimic the Ultrabithorax protein pattern. Enhancer traps in the regulatory regions do not mimic the endogenous genes, but express lacZ globally in the relevant parasegments. Some P elements carry large DNA fragments upstream of the lacZ promoter but internal to the P element. In cases where these internal sequences specify a lacZ pattern, that pattern is generally suppressed when the element is inserted in the bithorax complex. In embryos mutant for genes of the Polycomb group, the lacZ expression from the enhancer traps spreads to all segments. Thus, the enhancer traps reveal parasegmental domains that are maintained by Polycomb-mediated repression. Such domains may be realized by parasegmental differences in chromatin structure.

Documentos Relacionados

• Transcription defines the embryonic domains of cis-regulatory activity at the Drosophila bithorax complex
• A new homeotic mutation in the Drosophila bithorax complex removes a boundary separating two domains of regulation.
• Complete sequence of the bithorax complex of Drosophila.
• The trithorax gene, a trans-acting regulator of the bithorax complex in Drosophila, encodes a protein with zinc-binding domains.
• Mcp and Fab-7: molecular analysis of putative boundaries of cis-regulatory domains in the bithorax complex of Drosophila melanogaster.